Simple Gear Train: Pitch Circle Diameter and Typo in Homework

In summary: You can have a single stage with a bigger ratio but I think there are frequently better options, eg a multi stage might be smaller or have less wear. I am not a mechanical engineer but I think single stage spur gears for power transmission are normally limited to somewhere under 10. Some sites say under 7. The issue is with the small gear, where I think the practical minimum number of teeth is around 20 teeth.Technically a rack and pinion has an infinite ratio.
  • #1
EastWindBreaks
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Homework Statement


upload_2017-12-18_6-8-28.png


Homework Equations

The Attempt at a Solution


if you do 38*25/pi , you would get 302.394 for the exact pitch circle diameter, similarly, exact d2 should be 907.183 mm, is it a typo? or did I miss something?
 

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  • #2
The used a slightly different value for pi. Probably 3.142
 
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  • #3
CWatters said:
The used a slightly different value for pi. Probably 3.142
the new exact d1 should be T1*Pc/pi, correct? but it has only Pc/T1
 
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  • #7
You can have a single stage with a bigger ratio but I think there are frequently better options, eg a multi stage might be smaller or have less wear. I am not a mechanical engineer but I think single stage spur gears for power transmission are normally limited to somewhere under 10. Some sites say under 7. The issue is with the small gear, where I think the practical minimum number of teeth is around 20 teeth.

Technically a rack and pinion has an infinite ratio.

Some tower cranes have a small pinion turning a very large ring gear under the cab and I think the ratio there might be more than 20. That's in addition to a sealed gearbox between the electric motor and pinion.
 

1. What is a simple gear train?

A simple gear train is a mechanical system made up of two or more gears that transfer power and motion from one shaft to another. It is used to increase or decrease the speed or torque of an input shaft.

2. How does a simple gear train work?

A simple gear train works by meshing two or more gears together, with the teeth of the gears interlocking. When the input gear rotates, it transfers its motion and power to the output gear, causing it to rotate in the opposite direction. The gear ratio, or the number of teeth on each gear, determines the speed and torque of the output gear.

3. What are the advantages of using a simple gear train?

Simple gear trains are often used in machines and vehicles because they provide a smooth and efficient transfer of power and motion. They are also relatively easy to design and maintain, and can be used to achieve a wide range of gear ratios.

4. What are some common applications of simple gear trains?

Simple gear trains are used in a variety of machines and devices, including cars, bicycles, watches, and industrial machinery. They are also commonly used in power transmission systems, such as in wind turbines and hydraulic systems.

5. What is a typo in the context of a simple gear train?

In the context of a simple gear train, a typo refers to an error or mistake made in the design or implementation of the gear train. This could include incorrect gear ratios, misaligned gears, or incorrect placement of the gears. Typos can affect the performance and efficiency of the gear train, and may need to be corrected for optimal functioning.

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