# How do I understand this gear diagram?

• Navier-Stokes
In summary, the conversation is about a diagram depicting gears and their possible connections. The speakers are trying to figure out the correct arrangement of the gears and whether there is enough information to determine it. They mention the possibility of a common shaft and the importance of the gear sizes being compatible for proper meshing. Ultimately, they conclude that gears 1 and 4 are on a common axis and gears 2 and 3 need to be connected by a shaft for correct meshing. The dotted line in the diagram is not a physical shaft, but rather a center line.
Navier-Stokes
I'm finding it a bit too confusing to imagine how it actually would look like. But once I understand that, I'd easily be able to solve the problem!

The attempt at a solution:
I'm thinking that the dotted line might be the place where the gears mesh, however that assumption isn't helping me to make any advances.

I'm fairly confused too.
I would say that in 1 and 4 only the top halfof the gear is shown, whereas for 2 and 3 the whole gear is shown. 1 and 2 mesh at the parallel horizontal lines, likewise 3 and 4.
From the diagram, I would have said 1 and 4 were connected by being on a common shaft, but that does not make sense given the other information. So I have to guess that 2 and 3 are supposed to be on a common shaft.
There does not seem to be enough information to answer either a or b in isolation, but I see only one combination of answers that works.

Gears 1 and 4 are on a common axis but can rotate independently .

There is to be a shaft between gears 2 and 3 . Correct meshing of all gears is only possible if the number of teeth on gear four is chosen so that the centre distances of gear pairs 1 to 2 and 3 to 4 are the same .

Last edited:
It certainly looks like a shaft was omitted between gear 2 and gear 3. If this is included, then the result is an epicyclic train. Correct meshing is assured because we are given that all gears have a common module. The dotted line is nothing more than a center line, not a physical shaft.

## 1. How do I read a gear diagram?

A gear diagram is typically read by starting at the center and moving outward. The center circle represents the input gear, while the outer circles represent the output gears. The lines connecting the gears show the direction of rotation, and the number of teeth on each gear determines the gear ratio.

## 2. What is the purpose of a gear diagram?

A gear diagram helps to visually represent the relationship between different gears in a system. It can also be used to calculate gear ratios and determine the speed and torque of the output gears based on the input gear.

## 3. How do I calculate gear ratio from a gear diagram?

To calculate gear ratio from a gear diagram, divide the number of teeth on the output gear by the number of teeth on the input gear. For example, if the input gear has 20 teeth and the output gear has 40 teeth, the gear ratio would be 40/20 or 2:1.

## 4. What is the difference between a gear diagram and a gear train diagram?

A gear diagram shows the relationship between individual gears, while a gear train diagram shows the entire system of interconnected gears. A gear train diagram also includes additional components such as shafts, bearings, and other supporting parts.

## 5. Can I use a gear diagram to design a gear system?

While a gear diagram can provide useful information about gear ratios and relationships, it is not typically used as a design tool. Engineers and designers typically use more sophisticated software and calculations to design gear systems for specific applications.

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