36

The soft clicking sound you hear when coasting is the pawl going over the ratchet as in the picture below.


26

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 freely. They are either several spring-loaded ballbearings that self deploy when the outer ring turns faster and recoil when it turns slower than the inner ring. ...


10

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.


9

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 leading the bike, sometimes the pedals will turn very slowly due to the friction of ratchets. Image borrowed from https://www.notubes.com/technology/neo-...


8

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 good, for the reasons you describe. Your misconception, however, seems to be that a "rigid" bumper would not do these things. The bumper, and indeed ...


6

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 parts seem to go by a lot of names, but Phil Sweet's comment led me down the track to get where I am. An IPB, "illustrated parts breakdown," of a reel mower ...


6

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. Operator initially only has to see that they are one layer deep. Use of multiple belts runing side by side at different speeds and textures may be able to ...


6

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-Winding-Machine-with-Digital/. A bicycle speedometer may also work directly on the bobbin shaft. Set the wheel circumference to 1000 mm and you'll get 0.001 km for a ...


5

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 airplane, with the wings and tail now gone.


5

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 line. The crucial dimensions are in a 2:4:5 ratio (or 1:2:2.5 in the animation linked above) This is an improvement on the earlier (by about a century!) James ...


5

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 circuit as a third switch. Here's a diagram that shows what I mean:


5

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 simulator only shows how the thing would work given measurements but does not help you into placing the joints that you need. In your case one of the simpler ...


5

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) Alternating gear (blue) Output gear (orange) The alternating gear and output gears can be identical, and the sum of the numbers of teeth of the alternating and ...


5

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 search, done in the US, resulted in primarily US sources, one of which lists a set that can handle 300 volts and 15 amps.


5

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


5

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/B01DNLRAUA/ Just attach the magnet to part of your jig that's spinning, and mount the sensor so that it will pass close by during each revolution. I built a ...


5

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 spring (instead of gravity), so - at least in theory - you could turn it upside down.


5

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 transmission with a controller that sets the ratio according to the output speed. Any version that has a controllable ratio could be hooked to a simple pid ...


5

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 of bolts (source linearmotiontips) To my understanding (from the context of the question) the main differences that you are likely to find between the ...


4

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 overpressure could penetrate the site. See the pipe loops over the Launch Control Equipment Building? Those are the delay loops for ventilation air. BLAST-...


4

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). Once you can do this I would say you are in the 95th percentile of linkage design ability. Most non mechanical engineers do not have the ability to calculate or ...


4

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 itself when held horizontally.


4

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 geometry you can choose any two points as the start and end and the distance between them will always be equal fractions of the total. Obviously in this particular ...


4

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 into the optical gate, stops the film there for a brief instant while the light shines through it, and then pulls the next frame of film in, stops it, etc. This ...


4

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 become colored (red, green or blue). There is a mirror for each pixel and it direct light to the projecting lens or to an absorber depending on if the pixel ...


4

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. As for controlled caliper force, one could use a scissor mechanism with a hook on the bottom which could be loaded by the desired weights as per the schematic ...


4

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 medium grey linkages (60mm) is equal to the radius of the red circle (50mm), plus some clearance (10mm). Note how the distance from the centre of the red circle ...


4

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 the finer the pitch and therefore precision will be, but at the cost of reduced load capacity. Just keep the rod lubricated and you shouldn't have issues.


3

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 between the teeth. Obvious examples of devices which use sliding friction are brakes and friction clutches, these will have a limited wear life depending on the ...


3

It's just a fancy rolling cycloidal drive (not that that being simple makes it any less cool). It really bothers me that all the available articles only compare it to harmonic drives when it only bears a passing resemblance to them. Probably because it's owned by Harmonic Drive LLC. The bearing races can be abstracted as wire ring races that have been bent ...


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