Need help getting started with gears

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In summary, the conversation is about designing a system with two arms connected by gears. The goal is to determine the optimal number of teeth for the gears in order to support the intended load and minimize costs. The materials under consideration are brass, aluminum, and stainless steel. The recommended approach is to search for technical resources on gear fundamentals, such as QTC Gears technical manual.
  • #1
emarthinsen
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I'm trying to design a system of two arms connected by a couple of gears. The attached picture shows the setup better than I can describe it. Note, the arms are of equal length and the gears are of equal size.

What I'm trying to understand is how to calculate the optimal number of teeth per gear. I want them strong enough to support the intended load (say, 150 lbs puling in the direction of the blue arrow - and I do realize that the arm length matters) and to minimize machining costs, but small enough to ensure smooth operation. I'm not sure what material I'll use, but brass, aluminium, and stainless steel are all on the table.

Can anyone point me in the right direction? I'm not looking so much for the absolute answer, but where go to start learning about how to do this sort of analysis and design.

Thanks in advance.
 

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  • #2
Since few teeth are in contact, each must be capable of carrying the entire load.
For involute profile gears the minimum number of teeth will be about 20.
That will give strongest teeth.
The strength will be a trade-off between gear diameter to gear thickness.

Google search including the quotes for
"This section presents a technical coverage of gear fundamentals"
and you should find QTC Gears technical manual.
 
  • #3
That's a great resource. Thanks.
 

1. What are gears and their purpose?

Gears are rotating mechanical components with teeth that mesh with one another to transmit power and motion from one part of a machine to another. They are used to change the speed, direction, and torque of rotational motion.

2. How do I determine the size and type of gear I need?

The size and type of gear you need depends on the application and the desired output. Factors to consider include the speed, torque, and power requirements of the system, as well as the number of teeth, pitch, and pressure angle of the gears. Consulting a gear manufacturer or using gear design software can help in selecting the appropriate gear.

3. What materials are gears commonly made of?

Gears can be made of various materials such as steel, cast iron, brass, bronze, and plastic. The choice of material depends on the application and the desired properties of the gear, such as strength, durability, and resistance to wear and corrosion.

4. How do I calculate gear ratios?

Gear ratio is the ratio of the number of teeth on the driven gear to the number of teeth on the driving gear. To calculate gear ratio, divide the number of teeth on the driven gear by the number of teeth on the driving gear. For example, a gear with 20 teeth driving a gear with 40 teeth would have a gear ratio of 1:2.

5. What are some common gear types and their uses?

Some common gear types include spur gears, bevel gears, helical gears, worm gears, and rack and pinion gears. Spur gears are used for parallel shafts and can transmit high power. Bevel gears are used for intersecting shafts and can change the direction of rotation. Helical gears are similar to spur gears but have angled teeth for smoother operation. Worm gears are used for large speed reductions and are self-locking. Rack and pinion gears are used to convert linear motion to rotary motion.

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