36 votes

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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  • 361
26 votes

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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  • 21k
10 votes
Accepted

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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  • 373
9 votes
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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 ...
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8 votes
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Rigid bumpers vs shock absorber bumpers

To answer your later questions first: Isn't it good for the car that its bumper dissipates some energy in collision so that the time of impact increases, therefore reducing impact force? Yes, it is ...
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6 votes
Accepted

What is this captive screw and barrel nut adjustment assembly called? Picture attached

I never quite found exactly what I'm looking for, but I did come close, so I'll post what I've got. If anyone ever does have a better answer, please post it and I'll accept that one as correct. The ...
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  • 3,525
6 votes

What can be the mechanism used in devising a machine that can arrange the dishes properly to make the cleaning faster in the messes/hotels

Some of this depends on how tough the dishes are. While taking a lot of room, I can see possibilitiles in a conveyer sorter. Concept one: Dishes are dumped onto a conveyer that is on a sideways slant....
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6 votes

Reliable mechanism for counting the number of rotations of a shaft?

Figure 1. A coil winder using a hand-drill, magnet (on the handle), reed switch and pedometer. Image source (and more details) [Instructables](https://www.instructables.com/DIY-Hand-Driller-Coil-...
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  • 8,229
5 votes
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What is this contraption?

It looks like it might be a air-powered propeller. You pump up the bottle with air, and the high pressure is used to run a air motor that spins the propeller. This might have been part of a toy ...
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  • 11.2k
5 votes
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How this radio knob converting a rotation into a straight-linear motion?

Chebyshev Link Motion. (cognate form known as the Lambda Motion) It's a classic, also sometimes seen in its original form using circular motion to provide a 6th order approximation to a straight ...
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  • 1,580
5 votes

How can I modify a pair of two-way switches so that the circuit can also be opened or closed remotely using a device?

You don't really want an "external case" to mechanically switch one of the existing switches. What you really want is a DPDT relay that your Arduino (or whatever) controls, and wire that into the ...
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  • 6,749
5 votes
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4 bar mechanism simulator

Reading your question leads me to belive that you are not really after a simulator at all! Instead you are looking for a mechanism synthesis method, which allows you to design the mechanism. A ...
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  • 3,395
5 votes

Is there a mechanism that can turn circular motion into alternating circular motion?

One solution is to use a system with a ring gear that only has teeth on half of its inner circumference, like conceptually shown in the following image: There are three gears: Ring gear (red) ...
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  • 1,272
5 votes

Switch at the back of a battery eliminator

It's difficult to be certain, but I suspect what you have is commonly known as a spring speaker clip. Using those terms in your search engine to find one that has listing for maximum and voltage. My ...
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  • 6,192
5 votes
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A latch that’s easy to open under lateral pressure

How about a levered latch like this (very rough sketch) showing the catching tooth above the self latching spring and the pivot point.
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  • 13.9k
5 votes

Reliable mechanism for counting the number of rotations of a shaft?

There are cheap off-the-shelf devices to do this. I've used one for exactly what you're doing. Search "Digital Counter" https://smile.amazon.com/DIGITEN-Digital-0-99999-Proximity-Magnetic/dp/...
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  • 1,553
5 votes

Mechanical mechanism that regulates gear's rotational velocity

To my understanding the Hartnell governor is a variation that might be applicable to your needs. Figure : HArtnell Governor source mechoholic Essentially it moves the sleeve against a compression ...
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  • 22.6k
5 votes

Mechanical mechanism that regulates gear's rotational velocity

There are multiple things going on here. Your question indicates you have a variable input speed but want a constant output speed. The answer to this on its own would be a continuously variable ...
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  • 4,668
5 votes
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Does lead screw's thread have to be trapezoidal?

It's not exactly clear to me what you mean by trapezoidal thread rod. Like you noticed Metric threads are also trapezoidal (just like ACME with slightly difference face angels). Figure : Common types ...
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  • 22.6k
5 votes
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Is it essential for two meshing gears to have even number of teeth?

The recommendation is quite the opposite. The teeth of meshing gears are, where possible, chosen to be odd or, better again, primes so that a bad tooth doesn't keep hitting the same point on the ...
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  • 8,229
4 votes
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Is there a pressure relief mechanism that operates faster than sound in a material?

They are called blast valves. You need a delay loop in the pipe so the trigger can get ahead of the shock wave. Our interest was in closing off ventilation air conduits before the nuclear weapon's ...
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  • 3,425
4 votes

what college level teaches mechanical linkage design?

It all depends on how complicated the linkage is. For many simple linkages all you need to know is trigonometry (sin, cos, tan) and torque/moment equilibrium (Force x Distance = Force x Distance). ...
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  • 7,469
4 votes
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What is this linear movement mechanism called?

The head probably moves by rack and pinion or a hidden timing belt. The cable management is done by a cable carrier. It works by having each joint only have a limited rotation so that it can support ...
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4 votes
Accepted

What is the mechanism of the blades movement

One way to achieve this is by a series of 4 bar linkages The above is used for marking out equally spaced points on a line of arbitrary length. Pretty simple and elegant. By virtue of the ...
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4 votes

What is the reason for the intermittent motion and blocking of light during change of frame in Conventional projector?

if the film was fed smoothly past the lens and bulb, your eye wouldn't see a series of pictures- all you'd see would be a continuous blurry smear. So instead, the projector pulls one frame of film ...
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4 votes

How is mechanism used in modern projector different from intermittent mechanism used in conventional one?

Modern digital projector use a technique called DLP(digital light processing). They use an array of micromirorrs in order to point the white light source(often a bulb) that goes through a filter to ...
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4 votes

Mechanism for controlling the clamping force

The bicycle disk as shown is inherently prone to shimmying and spiraling into an increasing flutter. I have an Ebike with a very similar disk brake and I have learned my lesson to be cautious with it. ...
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  • 21k
4 votes
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Rotation around an axis outside of the mechanism

The design that you illustrated is pretty much correct. See below: In order for the end to move along a circular path, you want a four-bar-linkage with equal length arms. Note how the length of the ...
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4 votes

Does lead screw's thread have to be trapezoidal?

You can use regular threaded rod as a lead screw. The size and pitch (and grade) of the thread will determine your precision but 0.5 mm seems overkill for furniture positioning. The smaller the screw ...
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  • 2,402
3 votes
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Applications with combination of high friction and low wear?

As mentioned in the comments you don't actually want high friction between gear teeth, the tooth profiles are designed to roll over each other indeed the ideal is to minimise any sliding friction ...
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