# Tag Info

### How do bike wheels keep turning when the rider stops pedalling?

The soft clicking sound you hear when coasting is the pawl going over the ratchet as in the picture below.
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### Is it possible for a bicycle chainwheel to have a fractional number of teeth?

Gear ratio This is a Roller Chain drive system, and as such it's a timed system. The ratio between the two connected pieces depends entirely on the number of teeth on either end. Even if you ...
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### How do bike wheels keep turning when the rider stops pedalling?

it is called a freewheel. Inside the sprocket gear, there is a mechanism that lets the chain engage the rear wheel only when it is moving faster than the wheel is turning; else the wheel will turn ...
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### Why does a gear have extra holes?

Different gears have different drivers for having holes. One way you can categorize gears is by whether they are used primarily for transferring: motion: transferring angular position and angular ...
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### Effective ways to drive a single shaft with multiple motors?

A differential is a mechanical device designed to do exactly what you propose. It will allow the two motors to spin at slightly different rates while still combining the power. The most common use ...
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### Effective ways to drive a single shaft with multiple motors?

While a mechanical differential does what you ask, you don't really need it. You can connect two identical electric motors together on the same shaft. There is no "slipping out of sync" because ...
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### Is it possible for a bicycle chainwheel to have a fractional number of teeth?

I suspect that the answer to this is that, ultimately the gear ratio comes from the ratio of diameters of the gears rather than the number of teeth, although in most circumstances practicality ...
• 15k
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### What is the mechanical element that holds a worm gear shaft in place called?

Anything that holds a shaft and allows it to rotate is called a "bearing". It could be a simple metal bushing or a complete assembly with inner and outer races holding balls or rollers. A bearing ...
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### Involute gear curve when root diameter falls below base diameter

In general, each tooth of an involute gear is made up of two curves: the involute curve and the root fillet. The involute curve is essential for gears to operate properly, and allows power to be ...
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### Why do tower cranes have gear shifts?

You need very slow speeds to make precise movements of the load. At high speed, the cables will stretch as the load accelerates and decelerates and then oscillate longitudinally, "bouncing" the load ...
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### Is there a mechanism that can turn circular motion into alternating circular motion?

What about a crank-rocker mechanism? (source: udec.cl) When I am looking for inspiration for mechanisms, I have a look in the book Mechanisms and mechanical devices, by Neil Sclater.
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### How to fix this gear

Oddly enough, this problem can be fixed using a set of car keys and your wallet. Here are the steps to follow: 1) put the keys in the ignition of your car, start it, and drive to the motorcycle ...
• 11.7k
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### How does a (pulley based) continuous variable transmission (CVT) work?

Review of geared transmissions In general, the idea of a geared transmission is depended on the gear ratio. The gear ratio $i$ affects many aspects of a gear transmission, and the following equations ...
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### Mechanism of gear rotation

There are many examples of low input speed to high output speed gearing: kitchen "salad spinner" old-fashioned hand-cranked siren electrical generator attached to a tractor PTO (power takeoff) —...
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### How do bike wheels keep turning when the rider stops pedalling?

Basically several ratchets, below animation shows when you are not pedalling. In the other direction the ratchet will engage and provide force. If you lift a bike and get the wheel spinning or just ...
Accepted

### What does "tol" mean in a gear box?

Oh, I get it. The typo is a missing space. It's supposed to mean "23 to 1".
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### What is the use of gears in a device with a fixed gear ratio?

Electric motors typically only operate well at high speeds, and compared to something like an internal combustion engine, relatively low torque. Fixed gear ratios are used to cope with this inherent ...
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### What is the mechanical element that holds a worm gear shaft in place called?

Not only does the shaft have a "bearing" surface but the ends of the shaft also need something to "bear" against due to the "thrust" of the shaft in either direction. So I would add the term "thrust ...

### What is the use of gears in a device with a fixed gear ratio?

A given mass of copper and iron can only produce so much torque : increasing torque further would require more current which means (a) the increased magnetic flux saturates the iron and (b) the I^2R ...
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### Transform/change/convert rotation axis

The go-to solution is bevel gears. They are used when the shafts would intersect and allow the same ratios as normal gears. You can also make one of the gears a crown gear so the other gear can be a ...
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