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Information Guide 

·Gear Manufacturing

·Technical Information ·Gear Materials 

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Worm Gears / Worm Wheels

Types   Manfacturing Process   Characteristics 

Worm Gear Efficiency Improving Efficiency Lubrication 

Worm Gears: 

Product Code: AWWW001

Product Specifications: 

Materials used in

making our worm

gears: 

Ferrous and

Non Ferrous

ManufacturingCapacity: 

200 mm to 6,00mm Outside

Diamete

Type: 

We offer Single,

Double or

Multiple Starts

» Send Enquiry 

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A Few Bare Facts About

Worm Gears 

Archimedes is considered

as the person who invented

worm gear, he used an

ubiquitous screw forrotating a toothed wheel.

A very interesting fact

about the Worm gear isthat the worm easily moves

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Worm gears  are the perfect choice when the need is for

producing large motor speed Gear reductions in a single

step. A single reduction range of 5:1 - 100:1 is considered

quite a normal thing for Worm Gears. It can climb up to

127:1 or even more, under special circumstances. Worm

Wheel Gears are quite in operation. Using a single-leadworm along with a 100 tooth wheel, can do wonders in a

single simple step.

Actually by taking a low motor out put of 100 rpm, worm

gears can give you 1 rpm with 100 times of the torque

(approx). This means that if two of these worm wheel gears

sets is put in series, a whopping 10,000:1 speed reduction, is

not a remote possibility any more. This can drive, for

example a huge telescope with even a tiny motor. For safety

linked systems, a worm should not be applied as a braking

device, for example as in hoists.

Types of Worm Gears For the purposes of industrial application there are three

different kinds of Worm And Wheel Gears.

  Non Throated Worm Gears In non-throated worm gears, both the worm and the driven gear is not throated. The

image of a non-throated worm Gear is depicted below.

  Single Throated Worm Gears In the Single-throated worm gears one element that is generally the driven gear is

throated. Tooth contact takes place in a single moving point on a worm drive.

the gear, but not the other

way round. This is because

of the shallow angle on the

worm. As soon as the gear

tries to spin it, the resulting

friction between the wormand gear keeps the worm

in place.

In latest Worm Gears a

single reduction range can

reach up to 300:1

Efficiency ranges from

around 98% - lowest ratios

and 20% for highest ratios.

Pitch line velocity up to 30

m/s is considered as ideal.

Worm gear can facilitate a

50:1 speed reduction but

not a speed increase of 

1:50.

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  Double Throated Worm Gears In case of double-throated worm gears, it is the driven gear as well as the worm that

gets throated. Higher loads are permissible without undergoing excessive wear.

Manufacturing Process of Worm Gears Worm Gears can be formed by the process of milling the teeth on a

special type of machine. They are then consequently carburized,

thread ground and hobbed to size. Manufacturing materials include

cast iron or Bronze.

Characteristics of Worm Gears The Worm Gears shows the following distinct characteristics:

  Worm gears are cut Helically for maximum mating

  Perfect for accurate movement of load

  Occurrence of pure sliding motion

  Single step conversion of high speed inputs to low speeds and high Torque outputs

  Large speed reductions

Factors affecting the Worm Gears efficiency 

The following factors affect Worm Gears efficiency:» Lead angle of the worm

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» Installation conditions

» Sliding Speed

» Quality of the Surface

» Choice of Lubricant

Improving the Worm Gears Efficiency These days by using a latest technology called the Double enveloping, the efficiency of the

Worm gears have been greatly enhanced. Double-enveloping technology for worm gearing

has given numerous distinct advantages over the normal cylindrical worm gearing. This

includes great features like an increased torque throughput, more life, better accuracy. Let's

analyse each of the features of double enveloping and find out what makes them special.

  Design of Double Enveloping Worm Gear The design made for the double-enveloping worm gearing is very unique in many

aspects. It is completely based on the novel tooth form concept. Actually the double

enveloping Worm gear Technology has straight-sided forms on both of the gear teeth.

This is a better option than involute or other types of curved tooth forms.

  Backlash It has been seen that Double-enveloping worm gearing offers a very low backlash as

compared with the traditional cylindrical worm gearing. Now this low backlash

invariably translates into more accuracy than those obtained from cylindrical worm

gearing.

  Better Lubrication In the double enveloping technology, there is an increase in the number of gear teeth

that comes in touch with worm threads. This property has the capacity to lessen the

load at any given point on each of the gear tooth, thereby significantly improvinglubrication.

  Better Contact Patterns The diagram here depicts the contact pattern for a Gear

tooth using superior Cone Drive double enveloping

worm gearing. It can be seen that the portion between

the third and the fifth Gear teeth lies in mesh with the

worm at any given point of time. In the ongoing mesh

cycle, the improved geometry of the double-enveloping

worm gear forms two lines of contact on every single

gear tooth. In normal cases of cylindrical Worm Gears itis just one. The gear tooth is then rotated through its

own arc of contact with the worm. This leads to one line

of contact being maintained at the center of the tooth.

While the other contact line then sweeps from the left

hand side of the tooth towards the center. As the tooth's

movement ends through the contact arc (see positions 4

and 5), the two distinct lines of contact now converges into a single line at the center

of the tooth. This line of contact is more or less perpendicular to the worm thread

sliding action.

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Advantage of Double Enveloping It is reported that the benefits derived from the double-enveloping design are truly dramatic.

One advantage is that the total load here, gets divided among individual gear teeth. As a

result of this, there is considerable enhancement in the load carrying capacity. Secondly, there

is improvement in the torque throughput. This allows for a smaller size reducer to even

produce the same amount of torque. This leads to size and weight savings.

Ratio 

Cylindrical

Worm For 4''

center distance 

Double

enveloping

Worm gear For

4'' center

distance

10:1

10.71 HP @

1750 RPM

3304lb.In.Output

Torque

18.40 HP @

1750 RPM

6190lb.In.Output

Torque

25:1:00

5.08 HP@ 1750

RPM

3743

lb.In.Output

Torque

8.13 HP@ 1750

RPM

6370

lb.In.Output

Torque

Lubrication for Worm Gears 

Lubrication for Gear oil is a challenge in itself. In worm gears there is continuous sidewaysliding motion. This makes it hard in maintaining a hydrodynamic oil wedge. The result is

gears operating under conditions of boundary lubrication. Also, high operating temperatures

that sometimes borders on 190°F (88°C) and even higher generally requires oil with a

specification of ISO VG of 460 (AGMA Class 7) or even higher. These oils also need good

oxidative and thermal stability.

The types of lubricants that are commonly applied for worm gears are the following:

  Compounded mineral oils - Finds extensive use in worm gears

- The temperature limitation is around 180°F (82°C)- Normal use of AGMA Class 7 or Class 8 compounded oils (ISO VG 460 and 680)

  Extreme Pressure (EP) mineral gear oils - Also extensive use in high temperature and pressure

- Normal use of AGMA 7 and 8 viscosity grades

- The temperature limitation just like Compounded mineral oils is around 180°F

(82°C)

  Synthetic worm gear oils - Major types are polyalphaolefins and polyalkelene glycols

- Extensive application

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- No major drawbacks except costs

- Polyalkylene glycols suffers from incompatibility with other fluids