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Exam Preparation Notes 2016

MOW 217

Presenter 1: Wanga Mbasa

Table of Contents1. Vesconite Bearing..................................................................................................................................2

1.1. Vesconite Bearing Drawing............................................................................................................2

1.2. Vesconite Calculations...................................................................................................................2

2. Rolling Element Bearing........................................................................................................................3

2.1. Drawing..........................................................................................................................................3

2.2. Calculations....................................................................................................................................4

3. Chain Drive.............................................................................................................................................4

4. Belt Drive...............................................................................................................................................4

5. Drawing..................................................................................................................................................4

5.1. Important and necessary ....................................................................................................................5

5.2. Drawing parts/components.................................................................................................................5

5.2.1. Shaft..............................................................................................................................................5

5.2.2. Bearing.........................................................................................................................................6

5.2.3. Bikon Coupling..............................................................................................................................7

5.2.4. Taper lock.....................................................................................................................................8

5.2.5. Pulleys..........................................................................................................................................9

5.2.6. Sprocket........................................................................................................................................9

5.3. Drawing Fasteners.............................................................................................................................10

5.3.1. Shoulders....................................................................................................................................10

5.3.2. Bolts............................................................................................................................................10

5.3.3. Circlip..........................................................................................................................................11

5.3.4. Key..............................................................................................................................................11

5.3.5. Undercuts...................................................................................................................................12

5.4. Mounting...............................................................................................Error! Bookmark not defined.

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1. Vesconite Bearing

Journal bearing

This is a “simple”, low cost type of bearing and is made up of a bearing surface such that the journal (the part of the shaft that is in contact with the bearing) slides over the surface of the bearing. A vesconite bearing is a simple/plain type of bearing made from a synthetic material called vesconite.

1.1. Vesconite Bearing Drawing

1.2. Vesconite Calculations

Refer to Vesconite pdf document

Example 1:Determine the length of the journal bearing given the following: Vesconite hilube with initial lubricationDiameter of the shaft = 60 mmTemperature = 60 degrees Celsius N = 200 rpmF = 2500N

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Example 2: Calculate the necessary length of the journal bearings if they’re manufactured from Vesconite Hilube with regular lubrication and are expected to carry a radial load of 250 N each. The shaft has a diameter of 50 mm and rotates at 1800 rpm with a operating temperature of 55◦C. Round your answer up to the nearest integer then calculate the required tolerances on the inside diameter, outside diameter, and length of the bearing. It is not required to include a sketch.

Example 3: Determine the force carried by a 120mm long journal bearing made from phenolics. The shaft has a diameter of 75mm and rotates at a speed of 450rpm with operating temperature of 60 degrees.

2. Rolling Element Bearing

This is a bearing that comprises of rolling elements between two bearing rings. In this bearing the inner ring rotates with the shaft but the outer ring remains stationary. The main types of roller bearings include; ball bearing, roller bearing, spherical roller bearing, tapered roller bearing.

2.1. Drawing

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2.2. Calculations

Example 1:Select a suitable bearing to meet the following conditions:Fa = 1.5 kN, Fr = 10.2kN, N = 1200rpm, L10h = 200 hours, di = 30mm, a2 = a3 = 1, Reliability = 90%

Example 2 A deep-groove ball bearing with the code 6407 is initially chosen for the machine. If a radial load of10 kN and an axial load of 3.5 kN is expected, determine the static safety factor and the adjusted bearing life in hours if the operating temperature is 80 ◦C

3. Chain Drive

Catalogue example

Example 1: A vibrating screen operates at 900 rpm and is driven by means of a chain drive which is attached to an 11 kW direct-on-line AC motor which rotates at 1000 rpm and runs for 8 hrs/day. Select a chain drive for the system.

4. Belt Drive

Catalogue example

5. Drawing

Marking Schedule

General: Can it work Can it be manufactured Can it be assembled Can it be maintained Do moving parts touch stationary parts

Shaft and Bearings:

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Can shaft slide out of bearings Can shaft and bearings slide out Lubrication of Bearings Dust protection Undercut on shaft Thermal expansion

Pulleys, Gears, V-Belts etc. Secured rotationally Secured axially

5.1. Important and necessary

Centre lines;

Centre lines must be drawn whenever there is a round object or feature e.g. shaft, bolts, holes in shafts …..etc.

Hatching:

This is a means of differentiating between different parts that make up an assembly. NOTE: BEARINGS ARE CROSS HATCHED

5.2. Drawing parts/components

5.2.1. Shaft

Picture

5.2.2. Bearing

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Definition:

This is an element that is used to reduce friction between moving parts.

Bearing Housing

Must protect/cover the bearing Must make provision for lubrication Must not obstruct thermal expansion Must not hinder the rotation of the shaft

1. Plummer block

This is a type of bearing housing.

o Picture

o How to draw

5.2.3. Bikon Coupling

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Definition:

This is a component that is used when the housing/ covering element (of the shaft) is required to rotate with the shaft.

Picture

How to draw

5.2.4. Taper lock

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Picture

How to draw

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5.2.5. Pulleys

Definition :It is a wheel with a grooved rim around which a cord passes.

Picture

How to draw

5.2.6. Sprocket

Picture

How to draw

5.3. Drawing Fasteners

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5.3.1. Shoulders

Picture

5.3.2. Bolts

Picture

How to draw

5.3.3. Circlip

Picture

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5.3.4. Key

Picture

5.3.5. Undercuts

Picture

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5.3.6. EccentricsAn eccentric drive consists of a round disk mounted on a shaft with the geometric centre point of the disk not coinciding with axis of rotation of the shaft.

Picture

How to draw

5.3.7. Y - bearingsY bearings consist of a sealed radial bearing assembled within a bearing housing. The outer ring of the bearing and the internal ring of the housing are both spherical which allows the bearing unit to be self-aligning.

• The units are either maintenance-free or relubricating. The maintenance-free units are greased before they are sealed and do not require regreasing. Relubricating units come with a grease fitting and may be regreased.

• The bearing units are generally mounted onto the shaft by using two set screws which are located perpendicular to one another. Sometimes adaptor sleeves similar to those found in plummer blocks are used.

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Picture

Y-BEARINGS WERE ASKED IN THE CENTRIFUGAL FAN PRACTICAL.

5.3.7. Shaft Couplings

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