Simrit 10 - Vibration Control (Technical Manual 2007)

8/12/2019 Simrit 10 - Vibration Control (Technical Manual 2007)

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Freudenberg Simrit GmbH & Co. KG | Technical Manual 2007 813

Technical Principles | Vibration Control

Technical Principles

Vibration Control 814

Engineering Basics 816

Modelling 817

Vibration Control i s a Trade-of f between Confl icting Objectives 818

Procedure for Component Selection 820

Static Compressive Def lection 821

Mount Reaction/ Force 822

Notes 823

Assembly 827

Basic and Operational Characteristics of Elastomer Materials 829

Overview 830

Products

Products 831

Design Types 832

Vibration Control


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Freudenberg Simrit GmbH & Co. KG | Technical Manual 2007814


Vibration Control

Modern vibration control reliably protects increasinglycomplex machinery and units against vibration, thusextending their service life on a sustained basis. Thesimultaneous reduction of noise provides for greatersystem operating comfort, at the same time enablingadherence to legal regulations regarding noise emis-sions. Within the scope of vibration control, Simrit offershydraulic cushioning components such as Hydro Mountand Hydro Bush as well as a broad spectrum of elas-tomer dampers (Ultra Bush, Spherical Mount, Conical

Mount, Machine Mount, Tapered Mount, InstrumentMount, Centering Mount and much more).

Requirements

General vibration reduction for protecting systemsand their adjacent componentsAccommodation for axial, radial and torsional move-ments and cardanic deflectionDamping of vertical vibrationsAccommodation of horizontal forces, e.g. brakingeffectMechanical vibration sound insulation for reducing

noise emissionsEqualising of components to extend the range of theoperating conditionsLimitation of movements.


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Features

Frequency and amplitude based or dependentdamping

Integrated limitation of the spring displacement andpossibilities for load levellingSolutions for extremely rough operating conditionsRoHS-compliantA high degree of adaptability to individual applica-tion situationsVery robust designExcellent insulation behaviour at various frequencyranges.

Application areas

Vibration control-related solutions from Simrit are usedaround the world in agricultural and constructionmachinery, in general mechanical engineering, in shipbuilding, in wind power plants, drive engineering andthe railway industry.

Engine mounts in construction and agriculturalmachinery, shipsRoller bearing mounts in construction machineryMesh bearing mounts in combine harvestersGenerator bearing mounts (e.g. in wind power plants)

Cabin and superstructure mountsMounting of electronic assembliesMounting of pumps, mixers, centrifugesMounting of assemblies in rolling millsetc.


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An example involving a driver's cabin is used here toclarify the factors that cause vibrations in a system ofmounts with resilient and damping elements.

A vehicle cabin is affixed to a base frame with anelastic and damping mount configuration. The for themost part rigid base frame moves with large vibrationamplitudes, owing to the travelling motion of the vehi-cle. The result of the movements of the base frame arevibrations of the cabin, which is equally as rigid.

The vibration amplitudes result from these influencingfactors:

Mass of the cabinSpring characteristics of the mount configurationDamping characteristics of the mountsPreloading of the mounts(e.g. compressive deflection at the working point)Kinetic energy of the cabinExcitation frequencyExcitation amplitude.

If the base frame or the cabin are considered to beelastic, then a differentiated approach must identifyand include additional influencing factors (that arenot a part of the consideration). The objective of usingvibration-control components is to reduce any vibrationamplitudes that occur, whether in the form of noise orvibration.

"Yaw"

cab"Pitch"

"Sway"

lengthwise

crosswise

stroke

x Y

Z

Fig. 1 Possible movements of a rigid body

Possible movements:

Linear movement in x: "Longitudinal motion" Linear movement in y: "Transverse motion" Linear movement in z: "Vertical motion" Rotation about x: "Sway" Rotation about y: "Pitch" Rotation about z: "Yaw"

Engineering Basics


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Modelling

1 000

100

10

1

0,10,1 1,0 10,0

Natura

lfr

equency

[HZ

]

Static deflection [mm]

Diagram 1 Calculation of the spring deflection at the natural frequency [3]

One of the fundamental assessment aids in vibrationcontrol is the model of the single-mass oscillator witha degree of freedom, consisting of spring and mass( Figure 2). It has the typical characteristic of anatural frequency. It is used to examine and describeperiodic processes (vibrations). The model presentedhere has been expanded by one damper. The dampingmechanism provides for a reduction of vibrations.

Model of a single-mass oscillator (1 degree of freedom)

c

x(t)m

by(t)

Fig. 2 Single-mass oscillator

Differential equation as the basis for the mathematicalsolution

[1] m x + b(xy) + c(xy)= 0

Amplification function as the result of mathematicalconsiderations with various degrees of damping.

[2]

It is not intended to go into the application of math-ematical equations here.In the equation [1], the single-mass oscillator (Fig. 2)is described with its behaviour as dependent on the pe-riod and the other dimensions. Equation [2] describesthe relationship of oscillation response to oscillatory ex-citations, dependent on the damping and the frequency

ratio. With the assumption of a linear spring charac-teristic curve and a damping-free mounts, the naturalfrequency, see equations [3], can be read directly fromthe following Diagram 1.

[3] ne=950______

s [ 1___min]If superimposed vibrations occur translationally, rota-tionally or a combination thereof, see ( Fig. 1),then the single-mass oscillator model, as depicted in

Figure 2, can no longer be applied. The mathematicalmodels describing the oscillatory behaviour must beextended. Modern software tools can be of assistancehere.

x_y

=________________1+(2D)2______________(1 2)2+ (2D)2


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Vibration Control is aTrade-off betweenConflictingObjectives

In very many instances, it is desirable to achieve signifi-cant reductions in the vibrations occurring at stipulatedpoints.

The essential characteristic of oscillatory systems isthe resonance. It occurs when there is synchronicity ofthe excitation frequency and the natural frequency,frequency ratio 1, ( Diagram 2).

Theoretically, the amplitudes of the resonance can be

infinitely large, see equation [2]. In reality, however,damping always occurs, limiting the oscillation ampli-tude.

Fig. 4 Movement possibilities of the cabin

Fig. 5 Vertical vibrations of the cabin before optimisation

Fig. 6 Vertical vibrations of the cabin after optimisation

After optimisation:amplitude is +/ 0,2 mm

Before optimisation:amplitude is +/ 1 mm

Isolation80%

Fig. 3 Optimisation of the cabin suspension


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Usage of damping in a targeted manner can signifi-cantly reduce the vibration amplitudes. In mounts with

elastomeric components, a frequency ratio of greaterthan 2,5 to 3 and beyond can be recommended.

D >0 corresponds to steel and comparablematerials

D ~0,1 corresponds to NRD ~0,25 corresponds to AEM with high Shore

hardnessD ~0,1... 0,3... hydr. damping components.

Due to an increase in the damping, the reduction ofthe amplitudes, starting from a frequency ratio above

2, is lessened (

Fig. 2). A significantly reducedamplitude at a frequency ratio greater than 2 requiresreduced damping. This results in a central conflict ofobjectives in the design of the vibration control-relatedsuspension and the selection of the suitable suspensioncomponents.

The assessment of the reduction of the amplitude of thevibrations is made based on the degree of insulation i.A degree of insulation of 80% means that only 20% ofthe original amplitude introduced to a suspension com-

ponent is then further transmitted by it.

6

5

4

3

2

1

00 1 2 3 4 5 6

1,00,50,30,2

0,10,0

2

Mountforce

/excitation

force

amp

litude

[1]

Frequency ratio [1]

Diagram 2 Amount of the transfer function (quotient resulting from the force reaction and exciter force amplitude)


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Terms of r eference

The objective is to select a suitable mount configurationon the basis of the target degree of insulation i.

Notes

The procedure described below is iterative, in otherwords it has to be repeated as often as necessary until

the criterion is satisfied in accordance with the originalpostulations.

Calculation 1 ( static deflection)

In the first step, the desired degree of insulation (step 1)is selected in diagram 3. If the excitation frequency isknown (step 2), then the necessary compressive deflec-tion which is required for the desired insulation can bedetermined (step 3). For this, a horizontal straight line is

drawn mentally through the scale of the excitation fre-quency and at the chosen value through the selected in-sulation line running diagonally (step 2). Subsequently,through the intersection which this creates a perpendicu-lar line is also drawn mentally that forms an intersectionwith the scale of the compressive deflection (step 3).This marks the necessary deflection required for thedesired insulation at the viewed excitation frequency.The diagram can also be used in a different manner.For example, it allows for examining whether a chosenmount configuration consequentially has the necessary

insulation at the excitation frequency that occurs.

Calculation 2 (mount reaction/ force)It is recommended to still determine the mount reaction(force F) based on the load distribution of the weight tobe mounted. With this, the static compressive deflectionsin~smax/Fmax*F is determined according to the factorssmaxand Fmax of the product selected from the catalogprogramme. The static compressive deflection should be

a maximum of 80% of smaxwith compressive deflectionunder load.

The static compressive deflection should be a maximumof 50% of smaxwith compressive deflection under loadand high dynamic loading. As a rule, numerous prod-ucts can be identified for selection. An equal compres-sive deflection and the choice of identical mount com-ponents for a mass carried by the mounting componentsshould be sought.

Calculation 3 ( Notes)

It is recommended to examine the compressive deflec-tion to be selected, with consideration being given tothe safety factor. This takes into account the increase inamplitude (Diagram 2) of the suspended mass withthe assistance of the amplification function of a simplesuspension gradient. The amplification functions can bederived from relevant vibration control publications. Re-garding handling of the safety factor, numerous detailsare given in the notes.

Criteria

The compressive deflection corresponding to the mountreaction should be harmonised with the compressivedeflection for the desired insulation, while adhering tothe safety factor.

A certain degree of flexibility is called for in the choiceof i, the degree of insulation, because

Geometric dimensions

Design orientationFitting and installationRequisite clearancesNecessary oscillation limitationsResonance transientVibration insulation in other spatial directionstemperature rangeMediaOther requirements

are all points that cannot be ignored.

Procedure for Component Selection


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Based on Diagram 3, the requisite compressive deflec-tion can be determined with the help of steps 1 to 3,leading to the desired degree of insulation i.

Step 1 Select the desired degree of insulationStep 2 Select the excitation frequencyStep 3 Take a reading of the compressive deflection

Static Compressive Deflection

99

95

90

85807060500

1 2 3 4 5 6 7 8 9 10100

200

300

400

500

600700800900

1000

2000

3000

4000

50006000

700080009000

10000

2800

1400

2

3

1

Static deflection [mm]

Exc

ita

tion

frequency

[1/

min

]

Degreeo

finsu

lation

[%]

Diagram 3 Determining the static compressive deflection depending on the excitation frequency and the desired degree ofinsulation


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Mount Reaction/Force

In order to position the weight properly (design require-ments play an important role here) it is necessary toknow the mount reaction.

This will be demonstrated here using the example ofa four-point mounting system with an offset centre ofgravity.

a

b

c d

1F 2F

3F4F

GF

Fig. 7 Mount pattern (example)

Relationship of mount reactions to the weight force ofthe mass

[4] F1= FG b_____

a + b d_____

c + d

[5] F2= FGb_____

a + b c_____

c + d

[6] F3= FG a_____a + b c_____c + d[7] F4= FG

a_____a + b

d_____c + d

Worked example

Weight [m] 400 kg

Gravitational acceleration [g] approx.10m/s

Gravitational force [FG] 4000 N

Tbl. 1 Weight and gravitational force

Spacing of m ount positions relative to the

centre of gravity

Spacing

a 100 mm

b 110 mm

c 100 mm

d 110 mm

Mount reaction

F1 1098 N

F2 998 N

F3 907 N

F4 998 N

Tbl. 2 Mount spacing and mount reactions (forces)


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Safety factor for selection of products on the

basis of compressive defl ection

The following design implementations constantly referto the contents of Figure 8. The following relationshipto additional usage (disregarding the settling) can berecommended for the design of the mount configura-tion and the selection of the product (see Procedure forComponent Selection).

[8] 0 smax sin S A

The recommendation applies to the working point. If acomponent is integrated, then it compresses due to theweight of the load.

The point up to which it compresses is called the work-ing point. Retention of the inequality leads to a situationwhere the mounting component is stressed by the forcepath characteristic curve over a virtually linear range.The safety factor will be explained in more detail in thefollowing text. As a rule, for the factor S a value of ~2or larger is recommended. This way, with slight damp-ing (D = 0,1 and smaller) of the resonance, it is entirelypossible that superelevations of the oscillation ampli-tudes of 5 and higher occur ( Diagram 2). The safety

factor should be selected accordingly.

s

F

S

S

A

PressureTension

Progressive

range

Working point

Static load

Progressive

range

max

one

Fig. 8 Working point and oscillation amplitude

Notes

Diagrammatic presentation


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Settling of elastomeric components

s

F

Progression path

PressureTension

Progressiverange

Working pointStatic load

Operating area

Settling

Quasi-linear range/free path

Fig. 9 Settling of elastomeric components

Other considerations regarding settling of

mounts

The settling of elastomeric components is a phenom-enon which, under static load, leads to time-dependent,

non-reversible, additional compressive deflection and isalways component-specific and application-related.Simply stated, for many applications a settling amountof 20% of the compressive deflection can be assumedafter 3 years. At increased temperatures and especiallywith dynamic loading of the component, this settlingamount can be quickly reached. If necessary, thefollowing points must also be considered: elastomercompound, load, the resultant load on the elastomerinvolved, geometry of the elastomer component, ori-entation of the component to the static primary load,

and more.

Example of aspects of more complex terms of

reference

Due to installation space limitations, there is a concreterequirement for the settling amount if maximum usage

and good insulation is to be achieved with mountingcomponents.

Step 1

Definition of a permissible threshold value for settling.

[9] smax. settling= 0,2 sin

Maximum settling should be 20% of compressive de-flection under static load, after which the mounts willhave to be replaced.

Step 2

Definition of a maximum permissible compressive de-flection value under a static load.

[10] sinmax 0,5 smax

Empirical data shows that this definition is frequentlyacceptance for components subject to highly dynamicloading.


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Step 3

Establishment of the static compressive deflection valuefor further consideration.

[11] sin= 0,5 smax

This value should be arrived at as an optimum compro-mise between high insulation and allowance for thesettling amount traded off against high utilisation of thecomponent's virtually linear spring displacement.

Step 4

Definition of an inequality for design and selection ofthe mounting components.

[12]0 smax sin S A ssetting max0 smax sin S A 0,2 s in0 smax sin 0,2 sin S A0 smax sin (10,2) S A

0 1 sin_____smax (10,2) S A_____smax

0 1 0,5 (10,2) S A_____smax

0 1 0,4 S A_____smax

0 0,6 S A_____smax

The inequality [12] presented here for assessmentapplies under the following set of postulations:

Steady-state operation at resonanceThe oscillatory system can be considered as a single-mass oscillatorA present, yet minor dampingLinear spring characteristic curve.

Once the maximumcompressive deflection has been determined, a suitablecomponent can be selected in the product part.

Example:

The safety factor is selected in accordance with themaximum value of the amplitude increase at the pointof resonance and, if excitation amplitudes occur, thenit can lead to the following maximum deflection valuescorresponding to the inequality [12].

By selecting a correspondingly high damping rate themaximum required compressive deflection sinks, result-ing in a greater availability of mount components forthe product part. The compressive deflection or upward

deflection can effectively be limited by stops.

Typically, mount components are selected so that thelowest excitation frequency is insulated. That does notgenerate the requirement for the assessment shownhere. Reference is made again here to the design imple-mentations with respect to the conflicting objectives ofvibration control.

Explanatory notes on the safety factor

In case of weakly dampened vibration control systems,large vibration amplitudes can arise close to or atthe natural frequency itself. In order to analyse thesesystems with forced vibrations (permanent excitations),a maximum increase of the response amplitudes witha specific frequency relationship (point of resonance)is just as important as the relationship between theresponse amplitudes and the excitation amplitude at thestationary operating frequency of the exciting system(insulation; see previous reference). The amplification

functions are used for this assessment. Refer to the pub-lications on these. At resonance, the following relation-ship can be posited.

[13] S Vmax

The excitation amplitude can, for example, be detectedby measurement or detailed scrutiny of the exciting sys-tem already during the design. If a stationary state is nolonger valid, then the point of resonance will be gonethrough with increasingly rapidity and the amplitudes

are no longer formed in the same resounding manner.Less energy is "pumped" into the oscillatory system.An increase of the damping also reduces the vibrationamplitudes at the point of resonance. Among otherthings, this offers the potential to utilise mounts that havea smaller smax. This means that smaller mounts can beselected. According to diagram 2, a certain disadvan-tage can arise regarding the insulation at the operatingfrequency. A compromise depends o the criteria forselecting the degree of insulation.


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Regarding loads

A conflict of objectives that is inherent with manysuspension systems is the desire for good insulation

at operating frequency and effective limitation of theamplitudes resulting from jolting excitations. Neithercomfort and acoustic expectations should be reducednor are component movements beyond a specific valuedesirable in order to avoid damage, for instance.

With oscillatory suspension systems, jolting loads leadto vibration excitations at the natural frequency. As aresult of the singular input of energy, the excited vibra-tion cannot increase unrestricted over a time period atthe resonance frequency. However, larger shock-load

impulses lead to remarkable counter-amplitudes, whichcan have a negative influence on the comfort andacoustics and cause component damage as well.

Mount configurations that have a low stiffness at theworking point (compressive deflection through staticload) and have stops for limiting the amplitudes areoptimum for these demands. This recommendation is di-rected towards components that are evaluated againsthigh insulation demands. However, the shock loadsshould seldom occur and the maximum operable forces

stated in the product part should not be exceeded.

Stops are already provided for or can be made availa-ble for many components. Hydro Bush, Conical Mount,Tapered Mount and V Mount ought to be cited here asproduct examples that are included in the catalogue.

For the non-anchored installation of

machines, uni ts, devices, cabinets, etc.

A machine is supposed to be installed non-anchored onthe workshop floor. After two years, the final locationis supposed to be specified. Due to the presence ofmachines in the immediate vicinity, oil moistening on thefloor can not prevented.

What factors wi ll have to be taken into

account in positioning the machine?

When selecting the mounts (M Mount, Buffer, etc.), at-tention should be given to oil-resistant elastomers such

as NBR. The compressive deflection (also refer to mountreaction) of the mount should be identical or virtuallyidentical. Here as well, the previously introduced in-equality [8] for determining the compressive deflectioncan be used.Oscillatory excitations in the horizontal direction shouldbe avoided or, in any case, regarded within the contextof the design.

Any fur ther instructions?

The stability of the installation is improved by a low

centre of gravity and a large, most evenly spaced hori-zontal spacing of the mounts to the centre of gravity.If necessary, a subframe would be suitable here. Themoistening of the installation location due to lubricatingoil or grease reduces the stability of the installation po-sition. This plays an even greater role with correspond-ingly greater horizontal oscillatory excitations, possiblyin interaction with substantial vertical oscillatory excita-tions and a smooth workshop floor as well. The likeli-hood of a moistening of the mounts can be reduced byoil pans for the machines in the vicinity.

Height adjusters (M Mount) or comparable solutionscan be used to level the machines. If the final machinelocation is certain and the mount configuration hasproven reliable, then it can be retained. The designshould be examined if necessary, also the choice of thecompressive deflection with consideration being givento the desired degree of insulation, as well as the com-pressive deflection resulting from the static load. If thevaried requirements can only be met through compro-mise, then the catalog programme can offer another,

more technically optimised offering (V Mount, MachineMount, etc.).The objective of these suggestions is a stable machineinstallation.


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Fitting is an essential step before using the vibrationcontrol-related components.Proper execution ensures the functionality and hasa major influence on the service life of the mountingcomponent.

For a p roper fitting, care must be given to

the proper arrangement of components.

Please ensure that:

The radially loaded cylindrical mounts are arrangedcentred and perpendicular to the equidistant axis ofsymmetryCylindrical mounts whose interior are not positionedin a centred manner and are also loaded radially,are positioned so that the greatest distance from theaxle inner sleeve to the axle outer sleeve is reducedthroughout the plane by both axlesCylindrical mounts, if possible, absorb the load /vibrations over the entire cylindrical geometryAxially loaded cylindrical mounts are positioned

both centric and coaxially to the axis of the mainloadNon-cylindrical mounts with a distinctive axis of sym-metry under axial load are positioned centric andcoaxial to the to the axis of the main loadNon-cylindrical mounts with a distinctive axis of sym-metry under radial load are positioned centred andperpendicular to the axial symmetry.

When preparing for fitting, it is impor tant to

observe that:

The mounting surfaces for threaded connections onthe mounting component, such as on housings, con-soles and the mass to be carried, are flat and free ofdamage and contaminationThreaded holes and threaded studs for fastening areready, with standard commercial threaded fastenersand nuts

Surfaces for a lengthwise pressure seat are not dam-aged and are free of contaminationThreads are not damaged and are free of contami-nationThe connection geometries and their connective sur-faces are flat and free of fluids and clinging particles,such as bursIn the movement space of the mounts, particularly onthe exposed elastomer surfaces, no sharp edges, tipsor other components non-essential to the function arejutting inside

Mounting components should not be installed closedto sources of heat. The mounting components shouldnot be exposed to any higher-level heat radiation.Similarly, with highly dynamically loaded mounts theself-generated heat can accumulate, possibly pre-venting necessary coolingWhile preparing for fitting, the mounting componentshould not be subjected to any loadsNo rough damage occurs during preparation forfitting of the corrosion protection of the mountingcomponent.

Assembly


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While carrying out the fitting and applying the

forces, it should be ensured that:

The fitting force is equally distributed across the con-tact surfaces of the force-transmitting components.

As regards cylindrical mounts with thin-walledmetal parts, forces used to press in and on, as wellas press out, are distributed equally over the facesurfaces of the precision sleeves.The loads are distributed across the entire flangesurface intended for the fitting.The forces are applied over large, flat surfaces forthreaded connections; by using plain washers, forexample.The axial main loads are applied equally acrossthe entire connection geometries on the connective

surfaces.The radial main loads are applied equally acrossthe entire connection geometries on the connectivesurfaces.Boreholes for the pressing-in of mounting compo-nents are provided with a chamfer at the insertionopening, chamfer angle < = 15, chamfer lengthapprox. 3 mm(depending on the tolerances of the bore and theoutside diameter of the mounting component).Studs for the pressing-in of mounts are provided with

a chamfer at the insertion opening, chamfer angle< = 15, chamfer length approx. 3 mm (dependingon the tolerances of the stud and the inside diameterof the mounting component).The ends of the threaded fasteners are screwed intothe threaded hole at least the 1,25 times.The elastomer component is not heated or cooledany more than what is permissible(see the product description) while fitting.The mounting component is not subjected to anyunintended loads.

No rough damage occurs while fitting the corrosionprotection of the mounting component.Friction-reducing fluids are used when joining thelengthwise pressure seat. Plain machine oil is usu-ally sufficient. Attention: after fitting, approx. 1 dayshould pass before applying load.Washers should be used when fastening flanges.

Standards

Ensure that the boreholes for accommodating thethreaded studs are compliant with DIN EN 20273.It is advisable to use DIN-compliant threaded fasten-

ers and corresponding components for fitting.

Fitting results

Compensation of minor, fitting-related offset or angu-lar offset is possible, depending on the component.Ensure that the connection geometriesare tightened properly in relation to each other afterthe static load has been applied.

Usage, application of force

The force of impact of the mounting componentshould be introduced in the direction of the mainload.

Product environment, housing

Care should be taken to ensure that fasteners, brack-ets, frames, etc. do not restrict the area of movementof the mounts.Please prevent sharp edges, tips or other compo-nents non-essential to the function from jutting into themovement space of the mounts, particularly wherethere are exposed elastomer surfaces.

Corrosion protection

When applying corrosion protection to the elastomercomponent, it must be ensured that it is not heatedany more than what is permissible (see productdescription).Ensure that, when applying corrosion protection, theelastomer component does not come into contactwith any solvents or fluids containing solvents, or any

acidic or base substances.


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Basic and operational characteristics of elastomer materials

The basic characteristics of an elastomer are essentiallydetermined by the base polymer used. The technicaloperational characteristics can, of course, be influencedwithin specific limits by a corresponding mixture designand adapted to the respective requirements.

Given the multiplicity of basic elastomers available andthe variety of compound orders developed by Freuden-berg, it is possible to select the ideal elastomeric mate-rial for virtually any application.

ACM

Vulcanisations made of polyacrylate rubbers (ACM)exhibit excellent ozone, UV and weather resistance aswell as excellent resistance to high temperatures. Essen-tially, ACM vulcanisations have a significantly higherdamping than vulcanisations made of NR and NBRalong with a comparatively restricted low-temperatureapplicability.

AEM

By contrast, vulcanisations made of the ethylene-acr-ylate rubber VAMAC (AEM) contain ethylene groupsin their polymer even series, which result in an improvedsuitability for low temperatures combined with improvedwater and glycol resistance. On the other hand, theyoffer no resistance to acids and alkalis and only limitedresistance to mineral oil. AEM vulcanisations are alsostrongly cushioning materials.

CR

Chloroprene rubber (CR) is distinguished from natural

rubber by a better temperature resistance and goodweather and ozone resistance.CR vulcanisations distinguish themselves by a moderateresistance to grease and oil as well as good nonflam-mability. On the other hand, CR inferior to NR withregard to damping and regarding suitability for lowtemperatures.

EPDM

Ethylene-propylene rubber (EPDM) is the material ofchoice if resistance to valent media (e.g. water, water

vapour, watery media and glycol) must be ensured. Fur-thermore, EPDM offers outstanding resistance to ozoneand UV and weathering combined with excellent high

and low temperature resistance (-50 C to 130 C,or transient 140 to 150 C). Compared to NR, EPDMattains only a low level of firmness. EPDM is also notresistant to mineral oil or grease.

HN BR, FKM,

In addition we offer many customer-specific materialsolutions. Thus, for example, we also process HNBR(hydated nitrile rubber) or FKM (fluoro rubber).

NBRAcrylonitrile butadiene rubber is a polymerisation madeof butadiene and acrylonitrile. The acrylonitrile (ACN)portion of the material can be between 18% to 50%.NBR is used as a standard material especially for min-eral oil applications and also suitable for covalent me-dia. With a low ACN content, the material has excellentlow-temperature flexibility (approx. -38 C), however,with reduced oil and fuel resistance. A higher ACNcontent provides for optimum oil and fuel resistance, butat the same time, however, with a lower temperature

flexibility (approx. -3 C).

NR

Natural rubber (NR) is still the widely used rubbertoday for vibration control owing to its unsurpassedmechanical characteristics over a wide applicationtemperature range (-45 C to 100 C). Vulcanisa-tions of NR are distinguished by an exceptionally highstrength class combined with low crack propagationspeed (greater tearing propagation resistance), whichderives from a self-reinforcing effect through crystallisa-

tion upon elongation. In contrast to synthetic rubber,this also applies to very soft and even unfilled vulcanisa-tions. Its high elasticity is accompanied by a low lossfactor, which only leads to a low self-warming withdynamic loading. Its cold temperature characteristicsare excellent, the resistance to heat is, however, limited.It can be raised through the optimisation of materials ina targeted manner, however, up to a peak temperatureof 100 C. NR vulcanisations are not resistant to min-eral oil or grease.


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Base

elastomer Natural rubber

Acrylonitrile

butadiene

rubber

Acry-

late

rubber

Ethylene

acrylate

rubber

Chloroprene

rubber

Ethylene

propylene

rubber

Compound

order,

code (ISO)

NR NBR ACM AEM CR EPDM

Compoundorder

NR 11 NR 39 NR 97NBR38

NBR68

ACM 18 AEM 33 CR 56 CR 57EPDM

22EPDM

32

Hardness range(Shore A)

35 80

40 75

40 75

45 85

45 85

50 75 55 8540 80

40 80

50 80

45 80

Tensile strengthVeryhigh

High High High HighLow tomedium

Mediumto high

High HighMediumto high

Mediumto high

Reboundelasticity

Veryhigh

High HighMe-dium

Me-dium

Low Low Medium Medium Medium Medium

DampingVerylow

Low LowMe-dium

Me-dium

High High Medium Medium Medium Medium

Flexibility whencold

(to C)45 40 45 40 25 5 20 30 30 40 40

Maximum long-

term safe tem-perature (C)

+60 +90 +90 +80 +90 +120 +120 +100 +100 +130 +120

Transienttemperature

(C)+80 +100 +100 +100 +110 +150 +150 +130 +130 +150 +130

Shrinkage be-haviour

Mediumverygood

verygood

Good Good Medium Medium Medium Mediumverygood

Good

Agingand weather

resistance

Mediumto good

Mediumto good

Mediumto good

Good Goodverygood

very good Good Goodverygood

Good

Mineral oil

resistance Low Low Low

very

good

very

good

very

good Medium Medium Medium Low Low

Resistance todiluted acidsand alkalis(low temp.)

Good Good Good Good Good Low Lowmoder-

atemoder-

ateverygood

Good

Water 80 C Medium Medium Medium Good Good Low Low Medium Mediumverygood

Good

Tbl. 3

Overview


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Freudenberg Simrit GmbH & Co. KG | Technical Maual 2007 831

Products | Vibration Control

Products

Pre- Selection Vibration Control 832

Hydraulic Damping Components

Hydro Bush 834

Hydro Mount DL 836

Hydro Mount VL 839

Hydro Mount KL 842

Elastomer Dampers

Ultra Bush 845

O-Bush 848

Spherical Mount 850

Conical Mount 852

V Mount 854

MO Mount 856

Machine Mount 858

Flat Mount 860

Rails 862Tapered Mount 864

Double U-Shear Mount 866

Circular Mount 868

Buffer 871

M Mount 873

Instrument Mount 875

O-Shaped Mount 877

Top Mount 879

Spherical Roller Bearing 881

Layered Springs 883Height Adjusters 885

Rubberised Stop Washer 886

Washers and Centering Washers 888

Pipe Mounting Block 889

Rubberised Drive Wheels

Rubberised Sprockets 892

Belt Pulley with Elastomer Track 893

Decoupled Chain Gear 894

Decoupled Gears 895

Decoupling Elements

896


20/84


Pre-Selection | Vibration Control

Pre-Selection Vibration Control

The table is based on years of supplier activity

and is adapted to current knowledge.Hy

dro

Bush

Hy

dro

Mount

DL

Hy

dro

Mount

VL

Hy

dro

Mount

KL

Ultra

Bush

Sp

herica

lMoun

t

Con

ica

lMoun

t

VMoun

t

MOMoun

t

Mach

ine

Mou

nt

FlatMoun

t

Ra

ils

Exhaust-air ducts, exhaust pipes, ... B

Electrical/electronic components

and subassemblies B B

Instruments, devices,

displays, ... B

Levers, steering gear,coupling links, ... B B

Cabs, superstructures, ... B B B B B B B

Radiators B B

Bearings general B B B B B B B B B B B B

Measuring devices B B B B B

Reaction-support links B B B B B B B B

Pumps B B B B B B B B B

Mixers, separators,

centrifuges, agitators, ... B B B B B B B B B

Stirrers B B B B B B B B B

Screen mounts B

Panels B

Rolling mills B B B B

Maintenance-free articulation B B B

Machine tools B B B B B B B B B B B

Engines, units,

compressors, ... B B B B B B B B B B B

Subassemblies,

attached devices, ... B B B B B B B B B B B

Stationary machines

and gearboxes, ... B B B B B B B B B B

Levelling

Limitation of movements

Hydraulic and pneumatic hoses


21/84


Pre-Selection | Vibration Control

Tapere

dMoun

t

Dou

bleU-S

he

ar

Moun

t

Circu

lar

Moun

t

Bu

ffer

M

Moun

t

Ins

trumen

tM

oun

t

O-S

hape

dMoun

t

Top

Moun

t

Sperica

lRo

lle

r

Bearing

Layere

dSprin

gs

Additiona

l

componen

ts

O-Bus

h

Pipe

Mountin

g

Block

Ru

bberise

d

Sprocke

ts

Be

ltPu

lleyw

ith

Elastomer

Track

Decoup

led

Cha

inGear

Decoup

ledG

ears

Decoup

ling

Elemen

ts

B B B B B

B B B B B B B

B B B B B B

B B

B B

B B B

B B B B B B B B B B B

B B B B B B B

B B B B B

B B B B

B B B B B

B B

B

B B B B

B B B

B B

B B B B B B B B B

B B B B B B B B B B

B B B B B B B B B B B

B B B B B B B B

B

B

B


22/84



Hydro Bush

Hydro Bush

Product description

Hydro bushes are elastomer springs with integratedhydraulic damping.

Product advantages

Frequency & amplitude selective dampingIntegrated limitation of the spring displacementAllowing twist in all directionsEasily installedRoHS-compliant.

Application

Suitable for mountings of combustion engines, cabs,pumps and compressors, mainly in agriculturalmachines and construction machinery.

Material

Standard material Hardness

Natural rubber NR 11 35, 45, 55, 62, 68 Shore A

Operating conditions

Compressive forces in Z direction 1100 N 4200 N Maximum permissible force

Max. temperature +60 C, transient +80 C

Min. temperature 45 C

They are specifically suited when low frequenciesoccur as excitation frequency in the mount system.

They achieve a high damping in the natural frequencyrange of the system as well as gut isolation propertiesabove this range. Vibrations in the mount system whichhave a sound-conducting or radiating characteristic,generated primarily through excitation amplitudesor dynamic forces in the audible frequency rangeare significantly reduced. The integrated hydraulicmechanism in the bush with the frequency and ampli-tude dependent damping is designed for effect in theZ direction. By matching the damping maximum ofthe hydro bush to the critical frequency (resonance

frequency) of the spring-supported mass, the resonancemagnification can be noticeably reduced. For higher

Z

Y

X

Primary load directions


23/84



frequencies, the insulating capability of elastomer bondcomponents can be utilised. The hydro bushes aredesigned so that the translatory stiffness increase in theorder X,Z,Y. The bushes are designed for the primary

load in the radial (Z direction) as well as the axial di-rection (X direction) but can also absorb slight cardanicand torsional deformations. Depending on the design,limiters for deflection (labelled as HD) with or withoutreinforcement can be integrated in the Z direction.

Design notes

The mount configuration comprises an elastomer-metalcomposite with load-bearing element in Vee-shape,

stops, fluid chambers and overflow ducts. The compo-site is mounted in an outer sleeve and fluid-filled.

Fitting & installation

Hydro bushes have an outside fit and accommodatea threaded fastener on the inside for installation

Hydro bushes can be secured with Loctite or other,similar adhesive if a press fit is not desiredIndividual components permit slight adjustmentto allow for in-situ offsetAlways install hydro bushes centred and at rightangles to the axis of primary radial load and ifpossible, utilise the entire cylindrical surface areaof the outer sleeve as the bearing surfaceIf possible, utilise the entire cylindrical length of theinner sleeve bore as the bearing surfacePosition the bush relative to the weight load in such

a way as to reduce the largest distance between theaxis of the inner sleeve to the axis of the outer sleevein the place through both axes.

1/2 FZ

1/2 FZ

FZ

1/2 1/2

R5

Rz16100H9

FZ

FZ

FZ

Installation instructions

Loading case I

Installation direction

Installation directionLoading case II

(Frame) (Frame)

(Frame)

Fitting

Radiused edge indicates direction for fitting the hydro bush

Fitting & installation instructions: Hydro Bushes


24/84



Hydro Mount DL

Hydro Mount DL

Product description

The hydro mount, as a hydraulically damping rubbermount, solved the designer's conflict of how to mount amass that is excited by wide frequency spectrum. Par-ticularly if low frequencies between 5 Hz and 15 Hz can occur as the excitation frequency, on the onehand high damping in the natural frequency range ofthe system, and on the other, a good isolation propertyabove this natural frequency (supercritical mounting)is necessary.

Product advantages

Frequency & amplitude selective dampingCross-stiffnessIntegrated capability for levelling the loadHD version for "extra-hard" useRoHS-compliant.

Application

Hydro Mounts DL are suitable for use as mounts forpumps, compressors and engines in utility vehicles andin boats and for vehicle superstructures, particularlydriver's cabs.

Material


Natural rubber NR 11 40, 45, 50, 55, 60,65 Shore A






25/84



Z

XY


Hydro Mounts DL are predominantly used in vehiclesof all types. In these applications the related assembly

must be mounted as softly as possible to achieve agood structure-borne sound isolation. At low frequen-cies near the natural frequency of the spring-masssystem engine/engine mounts, such soft mountingresults in inadmissibly high amplitudes at the motor.Hydro Mounts DL have a soft spring characteristic andthus a large static deflection.

m

c

c

d

m

d

1

2

c1

c2

d

m

= load bearing spring= bulge spring= hydraulic

damper= dimensions

c1

c2

Mode of operation

The hydraulic mechanism with frequency and amplitudedependent damping integrated in the mount is designedfor effect in the Z direction. By matching the dampingmaximum of the mount to the critical frequency (reso-nance frequency) of the spring-supported mass, theresonance magnification can be noticeably reduced.For higher frequencies, the insulating capability of elas-tomer bond components can be utilised. These hydromounts have a greater flexibility in the Z direction thanin the X,Y direction. Hydro mounts are designed forprimary loading in the axial as well as radial directionbut they can also withstand cardanic deformation. Thelongitudinal axis should be selected for the introductionof the static primary load.

01 23 45 67

3618700 HD3618 029

3618701 HD3618 028

3618702 HD3618 026

0

500

1 000

2 000

1 500

Spring displacement in mm

ForceinN

Static spring characteristic curve in Z direction

05 10 15 200

5

10

30

35

20

25

15

3618700 HD3618 029

3618701 HD3618 028

3618702 HD3618 026

Frequency f in Hz

Lossang

ledindegrees

Transient of the loss angle as a function of frequency


26/84



05 0 100 150 2000

400

200

600

1 000

800

3618700 HD3618 029

3618701 HD3618 028

3618702 HD3618 026

Frequency f in Hz

DynamicspringrateC

dyn

inN

/mm

Dynamic spring rate as a function of frequency

Machineor cabto be insulated

Base plate

Fitting & installation instructions: Hydro Mount DL

Design notes

The mount configuration comprises a conical mountwith integrally moulded/integral expansion bellows

with threaded stud. The expansion bellows is filled witha special fluid. A control plate is located between theexpansion bellows and the securing plate for setting ofthe specific hydraulic damping characteristics.

Fitting & installa tion

Hydro mounts are designed to be secured bymeans of the threaded fastener with securing plateassembly and the flange of the conical mount

Individual components permit slight adjustment to al-low for in-situ offset or angular offsetIt is important to ensure that the mating faces of theframe and the mass carried by the mount are flatand smoothIn particular, the area underneath the flange mountmust be free of sharp edges, burrs and filings, so thatthe rubber element can expand on it without risk ofdamagePosition the mount relative to the static load in sucha way that securing plate and flange are preloaded

relative to each otherUse HD-rated hydro mounts by preference for ap-plications with extra-harsh conditions characterisedby many hard shock loads: fork-lift trucks running onsolid-rubber tyres is a typical example.


27/84



Hydro Mount VL

Hydro Mount VL

Product description

The mount design, the chosen fluid and the hydraulicmechanism provide the characteristic wide-banddamping. In cases with remote excitation frequencies inthe lower frequency range, the use of this hydro mountpermits an optimal mounting. By precise reduction ofthe fluid chamber stiffness of one of the chambers, a sig-nificantly improved compromise of effective vibration re-duction and structure-borne sound isolation is achievedas opposed to the hydro mounts without this design.

Product advantages

Broad-band damping at high amplitudesSignificantly reduced damping at low amplitudesOptimised elastomer springCompactRoHS-compliant.

Application

The Hydro Mount VL offers a wide range of possibleapplications such as cab and engine mounts, foragricultural and construction machinery, industrialvehicles, forest machinery, communal vehicles, shipsand for mounting superstructures, pumps and compres-sors. It is equally suited for mounting machinery andsystems/units with severe resonance transients.

Material

Standard material Hardness Special design

Natural rubber NR 11 40, 45, 50, 55, 60, 65 Shore A on enquiry


Axial forces in Z direction 3000 N 8500 N Maximum permissible force




28/84



The hydraulic mechanism with frequency and amplitudedependent damping integrated in the mount is designedfor effect in the Z direction. The effective dampingover the wide-band frequency is also present forchanges to the spring-supported mass. At low excitationamplitudes, the Hydro Mount VL has a significantlyreduced damping. Hydro Mounts VL have a greater

flexibility in the Z direction as in the X,Y direction. Themount configuration is designed for primary loadingin the axial as well as radial direction but it can alsowithstand cardanic deformation. The longitudinal axisshould be selected for the introduction of the staticprimary load.

12000

10000

8000

6000

4000

2000

0

0 2 4 6 8 10 12 14

65 ShA

55 ShA

45 ShA

Force in Z direction (N)

Spring displacement (mm)

Force-deflection characteristics, 036 18 704

0 10 20 30 40 50

2000

1500

1000

500

0

2500

55 ShA

s = 5 0,1 mm

s = 5 0,5 mm

s = 5 2,0 mms = 5 4,0 mm

Frequency (Hz)

A*Specific.

dampingwork

(Nmm

/mm

)

Specific damping work, 036 18 704; 55 ShA

1000

800

600

400

200

0

1200

0 5 10 15 20 25 30 35 40 45 50

55 ShAs = 5 0,1 mm

s = 5 0,5 mm

s = 5 2,0 mm

s = 5 4,0 mm

Frequency (Hz)

Dynamice

lasticspringrate(N/mm

)

Dynamic spring rate, 036 18 704; 55 ShA

Fz

Fxy



29/84



Design notes

The mount configuration comprises a conical mount withouter metal component with rectangular flange and

bore holes. It also contains an inner metal componentwith central thread hole to which a washer is attachedwhich extends into a fluid-filled chamber. This is formedby the tapered mount and the cup mounted on thetapered mount. The base of the cup is closed off witha diaphragm.


Hydro Mounts VL are designed to be secured by

means of threaded fastenersIndividual components permit slight adjustment toallow for in-situ offsetThe flat part of the flange must make full-surfacecontact with the supporting structureIt is important to ensure that the mating face is flatand smooth, and the same applies to the mating faceof the mass carried by the mount. It is also importantto ensure full-surface contact with the inner metal partof the mountPosition the mount relative to the static load in such

a way that the inner metal part of the conical mountand the flange are preloaded relative to each other.


30/84



Hydro Mount KL

Hydro Mount KL

Product description

The new Hydro Mount KL is ideally suited for mountingsystems with the highest comfort and acoustic demands.The mount configuration can be individually adjusted tosuit the specific customer application.

Product advantages

Characteristics can be customised to suit the specificapplicationFrequency and amplitude-selective dampingGood insulation at low excitation amplitudesOptimised elastomer springTwo selectable cross-stiffness stagesCan be used in combination with sturdy tensile stopsRoHS-compliant.

Application

Through the use of the Hydro Mount KL, an efficient,narrow-band damping effect in a wide frequencyrange is achieved. This resilient connecting elementthus has wide application for the mounting of cabs,superstructures, engines, pumps and compressors.

Material


Natural rubber NR 11 40, 45, 50, 55, 60, 65 Shore A






31/84



Fz

Fxy


The mount component can be specifically mounted withdifferent components for realising different definablecharacteristics which are primarily based on the addi-tional hydraulic damping characteristics to the conicalmount characteristics. The integrated hydraulic mecha-nism in the mount with the frequency and amplitudedependent damping is designed for effect in the Zdirection. By matching the damping maximum of themount to the critical frequency (resonance frequency)of the spring-supported mass, the resonance magnifi-

cation can be noticeably reduced. With small excitationamplitudes (structure-borne noise), these mounts havea very slight damping. The Hydro Mounts KL havea greater flexibility in the Z direction than in the X, Ydirection; The stiffness relationship has two adjustmentlevels. They are designed for the primary loadingin axial and radial direction but can also withstandcardanic deformation. The longitudinal axis should beselected for the introduction of the static primary load.

0

1000

2000

3000

4000

5000

6000

7000

8000

9000

0 2 4 6 8 10

40

4550

55

60

65

057 18 794


ForceinZdirectioninN

Static spring characteristic curves in Z direction

0

1000

2000

3000

4000

5000

6000

7000

8000

9000

0 2 4 6 8 10

40

45

50

55

60

65

057 18 795


ForceinZdirectioninN

Static spring characteristic curves in Z direction


32/84



s = 5 +/0,1 mm

s = 5 +/4,0 mm

s = 5 +/2,0 mm

s = 5 +/1,0 mm

s = 5 +/0,5 mm

Frequency [Hz]

Dynamicst

iffness[N/mm]

Dynamic stiffness

s = 5 +/0,1 mm

s = 5 +/4,0 mm

s = 5 +/2,0 mm

s = 5 +/1,0 mm

s = 5 +/0,5 mm

Frequency [Hz]

Lossangle[](damping)

Transient of the loss angle as a function of frequency(example, qualitative)

s = 5 +/0,1 mm

s = 5 +/4,0 mm

s = 5 +/2,0 mm

s = 5 +/1,0 mm

s = 5 +/0,5 mm

Frequency [Hz]

A*Specific.

dampingwork[Nmm/mm]

Specific damping work as a function of frequency(example, qualitative)

Design notes

The component consists of conical mount and hydraulicelement filled with a special damping fluid and formed

by a cylindrical sheet-steel housing containing a fluid-tight, roll-shaped diaphragm.

Fitting & installa tion

Hydro Mounts KL are designed to be secured bymeans of the threaded fastener through the coreand in the flange of the mountIndividual components permit slight adjustment toallow for axial, radial or angular in-situ offset

The flat part of the flange must make full-surfacecontact with the supporting structureSize the diameter of the bore only a few tenths ofa millimetre larger than the diameter of the housing(108 mm) or as a slight interference fitEnsure that the mating face is flat and smooth, andthe same applies to the mating face of the masscarried by the mount. It is also important to ensurefull-surface contact with the inner metal part of themountPosition the mount relative to the static load in such

a way that the inner metal part of the conical mountand the flange are preloaded relative to each other.


33/84



Ultra Bush

Ultra Bush

Product description

The ultra bush is a cylindrical bush capable ofabsorbing axial, radial and torsional movementsand cardanic deflections.

Product advantages

Maintenance-freePrevents sound transmissionAdjustment of manufacturing tolerancesUsable as a coupling element in drives/powertrainsReduced settling under radial loadIncreases load-bearing capability in the radial direc-tionRoHS-compliant.

Application

Ultra bushes have a wide range of possible applica-tions as resilient connecting element. Typical applica-tions are elastic articulations on vibrating machinesor bearing blocks for shafts, axles as well as steeringgears and couplings.

Material


Ethylene-acrylate rubber AEM 23, AEM 33 60 Shore A

Natural rubber NR 11, NR 91, NR 39, NR 97 40, 45, 60, 70 Shore A

Acrylonitrile-butadiene rubber NBR 68 60 Shore A


Radial forces 350 N 460000 N Maximum permissible force

Axial forces 120 N 60000 N Maximum permissible force

Max. temperature 60 C, transient +80 C



34/84



F r

Radial load

Fa

Axial load

Torsional load

Cardanic deflection

Ultra bushes are available in different versions by thespecified article (see article list) which range for appli-cations up to load ranges of 460 kN. Ultra bushes cantolerate radial axial, torsional and also slight cardanic

deformation. The recommended primary loadingdirection is perpendicular to the longitudinal axis andcentred to the longitudinal elongation (radial load).

When calculating dynamic loading, use values ofsaand sr

reduced by approx. 50%.

Design notes

They are manufactured from an inside and outside

precision metal sleeve which are joined together bya vulcanised elastomer insert. Ultra bushes have apressure "preloaded elastomer" that is produced bypermanently reducing the outside diameter of the outersleeve and increasing the inside diameter of the innersleeve through plastic deformation of the metal parts.This increases the service life considerably.


Ultra bushes are designed for inner and outerpress fittingIndividual components permit slight adjustmentto allow for in-situ planar or angular offsetIf possible, ensure that the entirecylindrical surface area of the sleeves is utilisedas load-bearing contact surfaceAlways apply installation and removal press-fit forc-es uniformly to the end faces of the precision sleeves.


35/84



Body DIN 912 cap screw

Ultra bush

Body

Ultra bush

Shaft

BodyDIN 472 circlip

Ultra bush

Lever

Fitting & installation instructions: Ultra Bushes


36/84



O-Bush

O-Bush

Product description

O-bushes receive forces in the radial direction. Theyisolate and compensate for tolerances of the stud.Radial deflection of the mass carried by the mountis also limited.

Product advantages

Low weightLow space requirementsIndependent centringTolerance compensationRoHS-compliant.

Application

The O-bushes are particularly suitable as a resilientconnecting element for mounting auxiliary units,electronic components, small units, pumps andcompressors in mobile and stationary applications.

Material


Natural rubber

NR 11, NR 1350, 60, 70 Shore A

Acrylonitrile-butadiene

rubber NBR 6850, 60, 70 Shore A

Chloroprene rubber CR 57 50, 60, 70 Shore A


O-bushes have different stiffness in axial and radialdirection. In the radial direction the stiffness is manytimes that of the axial direction. The primary loaddirection is recommended to be perpendicular tothe longitudinal axis and central to the longitudinalextension.

Design notes

The O-bush with central through-bore consists of a pipesection with an elastomer pad vulcanised to its innersheath. It can be designed in an axial and a radialdirection. During assembly the elastomer pad is com-pressed radially. This makes the O-bush self-holding,forms the friction connection between the elastomer padand the stud and increases the service life. The radialstiffness depends on the size of the cover. Only slight

forces should be applied in the axial direction.


37/84




O-bushes are prepared externally for installationin a locating bore with press fitting

The internal dimensions are designed for press-inof a stud with coverA slight axial offset required by the installation ispossible depending on the componentAlways apply installation and removal press-fit forcesuniformly to the end faces of the pipe section.

l

D

d

Dimensional drawing of O-Bush


38/84



Spherical Mount

Spherical Mount

Product description

Spherical mounts, as the name suggests, are sphericalbushes capable of absorbing axial, radial and torsionalmovements and cardanic deflections.

Product advantages

Maintenance-free articulationReduced settling under radial loadIncreased cardanic loadingAllowing twist in all directionsRoHS-compliant.

Application

Spherical mounts are ideal vibration-control compo-nents for articulations that are subjected to twisting in alldirections. The mounts are primarily used in bearings,brake levers and steering gears in buses and trucks aswell as in reaction-support links in industrial applica-tions.

Material


Natural rubber NR 11, NR 13 50, 60, 65, 70 Shore A


Radial forces 1200 N 46000 N Maximum permissible force


Max. temperature up to + 60 C, transient up to +80 C



39/84



Fr

Fa


Spherical mounts are generally stiffer in the radialdirection than in the axial direction and permit angulardeflections of 49 for all three spatial axes.

Design notes

This component consists of an inner ball and an outerspherical shell; the joining element is a vulcanisedelastomer insert between ball and shell.Spherical mounts have a preloaded rubber element,so, as is the case with Ultra Bushes, the mount can be

calibrated (see the description of Ultra Bushes) forextended durability.


As a rule, spherical mounts are designed for pressfitting of the outer

metal part and have a threaded fastener on the innermetal partAlternatively, the inner metal ball can be designed topush onto a stud for preloading against a collar orfor press-fitting on a studIndividual components permit slight adjustment to al-low for in-situ planar or angular offsetIf possible, utilise the entire cylindrical surface ofthe outer sleeve as the bearing surface for sphericalmountsIf the inner stud has threaded ends, ensure full-sur-

face contact of the flats in the threaded fastenerIf the inner sleeve is thin, if possible, utilise the entirecylindrical inner face of the inner-sleeve bore as thebearing surface of the spherical mountAlways apply installation and removal press-fit forcesuniformly to the end faces of the precision sleeves.


40/84



Conical Mount

Conical Mount

Product description

Conical mounts damp vertical vibrations, isolate againststructure-borne noise and can simultaneously acceptlarge horizontal forces (e.g. deceleration forces under

braking). Conical mounts are delivered without wash-ers as standard. The suitable washers and stops canbe found in the section on Washers and CenteringWashers as well as in Rubberised Stop Washers.

Product advantages

Long service lifeOptimum settling

Auto-centring under axial loadRoHS-compliant.

Application

Conical mounts are ideal, resilient connecting elementsfor mounting engines, driven machinery and super-structures for both stationary operation and in vehiclesand ships.

Material


Natural rubber NR 11, NR 39 35, 40, 45, 50, 55, 60, 65, 70, 76, 80 Shore A

Acrylonitrile-butadiene rubber NBR 68 55, 65, 70 Shore A

Ethylene-acrylate rubber AEM 33 55, 60 Shore A



Max. temperature up to 60 C,

transient up to +80 C

Min. temperature up to 45 C


41/84



Z

Y

X


Properly positioned conical mounts for mounting en-gines lightly cushions the torque which reduces the vi-

brations introduced into the anchorages and thus contri-butes to a better running smoothness. The weight shouldprimarily be absorbed in the longitudinal axis (+Z).The range of conical mounts offers a large number ofdifferent designs for the optimal solution of all conceiv-able application/installation cases. Tear-off or separa-tion protection is also thus possible.

Design notes

The mount configuration is manufactured from an innerand outer metal part. The outer metal part has a multi-

hole flange and the inner metal part has a through-holewith or without a thread or a tapped blind hole. Bothtapered metal parts are connected in tapered parallelorientation by an elastomer insert.


The conical mounts are designed to be securedby means of threaded fastenersIndividual components permit slight adjustment to al-

low for in-situ offsetIt is important to ensure that the mating faces of theframe and the mass carried by the mount are flatand smoothEnsure that the underside of the flange is in full-surface contact with the mating face of the frameanchoragePosition the mount relative to the static load in sucha way that the inner metal part and the flange arepreloaded relative to each otherAvoid tensile loads or use the stop and centering

washers to limit these loads (see the section on stopwashers).

Machine or cabto be insulated

Frame or flange

Secured by threaded fasteners in base

Frame or flange

Machine or cabto be insulated

Secured by threaded fasteners in flange


42/84



V Mount

V Mount

Product description

V mounts are ideal for a multiplicity of applications invibration control and structure-borne sound insulation.

Product advantages

Chrome-free galvanisation for optimum corrosionprotectionEasy fittingMaintenance-freeGood insulation even at low interference frequenciesRoHS-compliant.

Application

The range of possible applications for V mounts in-cludes internal combustion engines, electric motors,pumps, compressors and tool machines. V mounts arealso used for maritime engineering. There are versionswith type approval from Lloyds Register of Shippingavailable.

Material





Max. temperature up to 60 C, transient up to +80 C

Min. temperature up to 45 C


43/84



ZY

X


V mounts feature a robust compressive-deflection stopin the vertical direction (Z direction). The same highstiffness in both horizontal directions (X,Y) preventsa "floating", i.e. a lateral deflection of the vibration-insulated driven machinery, the machine or the engine.

Versions with built-in tensile stops are also offered whichlimit the limit rebound in (Z) direction. All V mountsare limited in their radial spring displacement at thesame time. The bell-shaped designed top section of themount protects against too strong a compressive deflec-tion and dripping media (e.g. oil). When subjected toextreme overload a positive lock forms between the topand bottom section of the mount. The progressive springcharacteristic and a thin rubber layer on the stop collarof the bottom section prevents a hard metal impact.The primary load direction (+Z) is perpendicular to the

planes of attachment centred to the cap.

Design notes

V mounts comprise a flat, cylindrical metal cap withthreaded insert and a base plate with rectangular

flange and through-holes. Both metal parts are alignedparallel on top of each other and joined with a vulcan-ised elastomer insert.


V mounts are designed to be secured by means ofthreaded fastenersIndividual components permit slight adjustment toallow for in-situ offset

It is important to ensure that the mating faces of theframe and the mass carried by the mount are flatand smoothPosition the mount relative to the static load in sucha way that the cap and the flange are preloadedrelative to each other.


44/84


45/84




Radial forces1000 N

2800 N

Maximum

permissible force

Axial forces1800 N

2400 N

Maximum

permissible force

Max.

temperature

+100 C,

transient +130 C

Min.

temperature30 C

MO mounts feature equal stiffness in the horizontaldirections (X,Y). These mounts have a greater flexibilityin the Z direction which leads to a correspondinglyhigher isolation. The limitation of the spring displace-

ments in the radial direction generally appear morethan in the axial direction. The longitudinal axis isrecommended as the primary load direction.

Design notes

The MO mount with central borehole comprises anelastomer body and a vulcanised elastomer metal part.These parts attached to each other create an annularclamping groove. This mount configuration is expand-

able through layers or spatially corresponding limitercomponents for the axial spring displacement whichleads to a progressive spring characteristic curve andserves as tear-off protection at the same time.


MO mounts are designed to accommodate athreaded fastener inserted through the central

boreholeIndividual components permit slight adjustmentto allow for in-situ offsetCombine the mount with a tubular spacer iftightening torques are highDepending on the quality of the material selected,threaded-fasteners of at least one strength classhigher can be usedSelect a tubular spacer with an outside diameterallowing slight play for the inside diameter d1ofthe MO mount

Select the through-hole of the tubular spacer toaccommodate the securing screw according toDIN EN 20273The surfaces for force transfer to the threadedfastener by the elastomer part should be largeand flatPosition MO mounts such that the rubber-metal partbolts directly to the component to be insulatedInstall the elastomer-only part with a washer(see the section on washers and centering washersfor details of the washer)

Make sure that the edges of bore SDare chamfered,or preferably radiused, at both endsMO mounts with steel reinforcement (Type 3) requirethis radiusing only at the rubber-only end.

Fitting & installation instructions: MO Mount with load directions

Z

XY

T

H

S

R

D

M

Radial

Axial Machine orcab to beisolated

Washer

Z

XY

T

SD

R

H

Axial

Machine orcab to beisolated

Washer

Radial


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Machine Mount

Machine Mount

Product description

The special shape of the machine mount protects thebuilt-in flat mount against mechanical damage and oilattack.

Product advantages

Elastomer spring elements are replaceable andthe metal connecting components are reusableSpring elements are protected against randomdamage and direct oil splashesReduced settling in the Z directionRoHS-compliant.

Application

Machine mounts are particularly suitable for mount-ing heavy machines, compressors, engines, etc. Theyenable machine- and unit-generated vibrations intro-duced into the foundation or the enclosing building tobe reduced by a significant margin.

Material








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The combined compression and shear loading of theflat mounts fitted provides a long service life and goodvibration insulation, even at lower interference frequen-

cies (i.e. lower rotational speed). The mount is easilyattached to the foundation and the machine using thestandard boreholes and threads. Anchoring to thefoundation and the machine permits the application ofcompressive loads (Z direction) to the mount as wellas shear loads (X & Y direction). The primary loaddirection is perpendicular to the planes of attachment,centred to the cap.

Z

YX


Design notes

The machine mount comprises a rectangular cap andtwo metal parts with equally angled side faces and

flange. Flat mounts are screwed in between the twostacked metal parts.Both metal parts are provided withthrough-holes or threaded holes.


Machine mounts are designed to be anchoredby threaded fastenersIndividual components permit slight adjustmentto allow for in-situ offset

It is important to ensure that the mating facesof the frame and the mass carried by the mountare flat and smoothPosition the mount relative to the static load insuch a way that the cap and the flange arepreloaded relative to each other.


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Flat Mount

Flat Mount

Product description

Flat mounts are mount configurations for customapplications.

Product advantages

Easily integrated into assembliesEasily installedSpring characteristics can be widely adaptedto the constructionRoHS-compliant.

Application

Used as mounts for machines, engines or subassembliesin mechanical-engineering and automotive applications.

Material


Natural rubber NR 1145, 50, 55, 60, 65,

70 Shore A


Shear forces X,Y direction 440 N 7500 N Maximum permissible force




Depending on the installation conditions or requireddegree of vibration insulation, compressive loads(Z direction), shear loads (X, Y direction) or combinedcompressive/shear loads (mount tilted by a specific an-gle) can be applied to flat mounts. The mounts achievean optimal utilisation and thus also the highest dynamicload with a compressive/shear loading.The loading is dependent on the surface area of therubber, shape, thickness of the pad and hardness ofthe rubber. The static loading and the dynamic forcesand deflection must be taken into account for con-

tinuous use. Flat mounts have different stiffness in theshear direction (X,Y) and compressive direction (Z) in

Z

X,Y



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dependence on the width, length and thickness andtheir total number in the mount component. The effectivestiffness of the mounts can be varied by turning of themount to the static load. The primary load direction can

be absorbed perpendicular to or at an angle to the at-tachment levels.

Design notes

Flat mounts consist of parallel metal plates paralleledone on top of the other and separated by vulcanisedelastomer pads.


Flat mounts are designed to be secured by meansof threaded fastenersIndividual components permit slight adjustment toallow for in-situ offsetIt is important to ensure that the mating faces of theframe and the mass carried by the mount are flatand smoothIt is also important to ensure full-surface contactbetween the outer metal plates and the frame and

the mass carried by the mountsPosition the mount relative to the static load in sucha way that the cap and the flange are preloadedrelative to each other.


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Rails

Rails

Product description

Rails are often used when space is at a premium orif loads are too high to permit the use of buffers.

Product advantages

Mount can be customisedRails have the flexibility to be adapted to the loadUniversalRoHS-compliant.

Application

Rails from Simrit are suitable for mounting the mostheavy machines, plants, units and foundations. Theyare suitable for a wide range of possible applicationfor mounting ships engines, large stationary engines,heavy-duty lathes, hoists for lifts as well as vibratorymachines of all kinds.

Material


Natural rubber 57 Shore A


Length of rail in mm 25 2000

L

D

H

A

s

s

A

A-A


The rails are available in 2000 mm lengths. You mustensure that the length is not shorter that the sectionwidth. Approximately 10% of the rubber height "h"can be pressed together under static load.

Design notes

The component consists of two metal parts separated

by a vulcanised elastomer pad.


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Rails can be drilled and chased on site to accommo-date threaded fasteners

Rails can also be installed without threaded fastenersif compressive-load deflection is significantly greaterthan maximum amplitude.

Fitting & installation: rails with load directions

F

F

Base plate

Isolated mass

Rail

Pressure

Shear

Fitting: Individually screwed

F

F

Base plate

Isolated mass

Rail

Pressure

Shear

Fitting: With mould closing or bonded


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Tapered Mount

Tapered Mount

Product description

Tapered mounts are used primarily to carry light,medium and heavy engines for mobile and stationaryapplications.

Product advantages

RobustSlight settling on compressive deflectionin the Z directionEffective limitation of compressive and rebounddeflectionLimitation of horizontal spring displacementNarrow, ideal for mounting on steel sectionsRoHS-compliant.

Application

Tapered mounts can be utilised for agricultural andconstruction machinery. They are also suited formounting generators of ships' engines.

Material


Natural

Simrit 10 - Vibration Control (Technical Manual 2007)

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Transcript of Simrit 10 - Vibration Control (Technical Manual 2007)