# Questions tagged [mechanisms]

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43 views

### How to create a friction-based cable exercise machine?

What would be the best mechanism to create a friction based cable machine? The point of this machine to only have resistance to movement not when the cable's stationary and without the momentum of ...
29 views

### Working of planetary gear set in electric bicycle

For mid-drive electric bicycles where the motor is attached to the pedals, it provides helping torque which reduces the force that needs to be provided on the pedal. So, how does a planetary gear set ...
32 views

### How is energy in the hairspring restored in a mechanical watch?

I've read through the excellent guide to how mechanical watches work by Ciechanowski, but it leaves some questions unanswered. The main spring of the watch, when it loses energy, can of course be re-...
22 views

### To design the system of a rectangular small shaft moving in and out in a completely mechanical way without remote control

In my setup , I have designed a system in which a body will rotate and execute rectilinear motion down the screw along its thread . upon reaching the bottom most point I want to make a system in which ...
39 views

### Conical pulley system and transmission ratio (closed)

I tried asking this on other SE forum but i think this is the correct one: Basically our teacher has sent us quite a lot of exercises but I can't get past this one which says: a pulley cone consists ...
17 views

I'm wanting to see if it is possible to create a functional prop that includes two blades that spring out creating a circular quad blade. 2 blades would be fixed at opposite ends of the circular ...
19 views

### Piston that produces equal amounts of swing in a lever?

I am attempting to figure out an equation I've found for designing part of Walschaerts Valve Gear. The specific implementation isn't relevant here, because it's the math I'm after, but this is the ...
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### Calculate the required torque of a motor

I want to know how much torque I need for my engine. Imagine a wheel with a motor in the center. One like this: Let's say the wheel measures 400mm, weighs 10KG, what is the formula to make that ...
59 views

### Why were handcuffs ever made with a chain between them?

I've noticed that modern handcuffs are always attached directly to each other, without any "chain" of any length in between. I guess I can understand why that make them safer and more robust....
35 views

### One way locking mechanism linear movement

Sorry for the English in advance, it is not my native language :) I am working on a design which involves moving two steel plates in a horizontal linear motion together to clamp around a box. After ...
• 1
26 views

### Tension Arms In Watt Governors

I wonder why there is no tension acting at the arm connecting the flyball with the sleeve in Watt governors but it is only acting towards point P which is a pivot. Furthermore, the tension would act ...
29 views

### Which Pallet provides Impulse to the Anchor in an Escapement Mechanism?

I've been reading a lot about Escapement Mechanisms lately, and know that the escape wheel provides impulse to the anchor which helps the pendulum continue oscillating. But, I can’t understand (in ...
32 views

### Incremental rotation that snaps in place

I'm developing a board game and it needs a mechanism of incremental rotation in which the rotated object will snap to one of five possible angles. I have been trying to search for examples of ...
37 views

### Is it essential for two meshing gears to have even number of teeth?

Should the teeth of meshing gears be even rather than odd numbers? If not, which is better?
1 vote
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### Connection to periodically electrify equipment

I am designing a system where I have a set of 4 electrical components rotating in a circle. In the bottom stage, the electrical component is submerged in water. In the top stage, the electrical ...
35 views

### Modulating Output of a Pulley with Variable Inputs

I am working on a recreational project to take variable inputs and convert them to a constant output without substantially altering the force required to achieve such a task. The best way to visualize ...
33 views

### Best type of pin to use when two parts are rotating relative to each other?

[Edit 1]: Added material of components. I have a flywheel with a shaft connected to it. The shaft rotates with the flywheel, but also rotates relative to it, to give me a kind of camshaft motion if ...
34 views

### Retractable linear mechanism with a retractable drive for servo control

I am considering a mechanical system that is able to retract and extend via servo control but with the drive mechanism being retractable itself. Doing so I will be able to have a multiplied retracting ...
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### How to make a circle spin from the edges

I have an issue where I need to make a large wire through a bearing spin in 3" diameter circles, and have a weight hanging from the bottom of the wire. Essentially, I need a hole that moves in a ...
36 views

### Moving a Bushing in Circular Motion

I am trying to design some way of making a bushing move in a circle. Specifically, I want the center of the bushing to draw out a trajectory that is a 3" diameter circle. I do not want the ...
1 vote
94 views

### Is there a mechanism that allows this kind of piston/plunger movement?

I am trying to create a prototype for a gravity energy storage system, and I need to release potential energy stored in a heavy load of mass M, raised to a height *H. I intend to use the mass ...
23 views

### Is it possible to construct geared speed and torque dials?

Say you have a very complex completely mechanical machine, and you want to put a dial indicating rotation speed of the central drive shaft and its torque. But the machine is completely mechanical, and ...
• 103
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### Question about cam follower design

It's always said that jerk function should be smooth to avoid undesired vibrations. What exactly is the vibration in a cam follower mechanism and why is it important to avoid it?
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### What is this type of detent mechanism called?

I'm trying to find out what this common rotary detent mechanism is actually called. I see them in all sorts of cheap plastic toys, and I'd like to see if I can find them for sale, but I don't know ...
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1 vote
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### Animatronic Eye Mechanism - Eye Socket Spring Tension

I am building an animatronic eye mechanism that will ultimately be moved via servo motors for a project I am working on. It is comprised of the following components: Eye Plate - 3mm thick Acrylic ...
54 views

### Rotate - Mechanism that changes direction

I have a square plate (8x8 cm) that I want to turn it 90 degrees clockwise and after 90 degrees counterclockwise as you can see in the picture. Each rotate will happened after a second delay and fast (...
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### mechanism design for matrix of adjustable direction pointer

I need to construct a matrix of light pointers, each one aims in specific direction, and each pointer direction will be adjusted thousands times, size is flexible could be millimeters or centimeter ...
146 views

### Mechanism to control spring release

okay so I’m trying to build a tennis ball launcher for my school so we can showcase it- my teacher helped me get motors and stuff setup similar to this image. Question: How would I include a spring so ...
40 views

### Summing Displacements of two Cranks and Sliders

Is there a linkage mechanism allowing the summation of the throws of two crank and slider mechanisms oriented next to one another in order to control an output slider with a motion equal to the summed ...
58 views

### Designing a grabber

I designed a grabber for grabbing strings and yarns. the movement that I need is straight up and down to grab a piece of yarn. I wanted to know if this model (in the video) works in real life or not. ...
64 views

### Question about theory of machines (kinematic diagrams)

Can I draw this part of kinematic diagram in this way, knowing that bolded W is a point of interest. so is my drawing true also? (my lines are in red and black(not bolded black))?
65 views

### Determining range of projectile

Lets say i am using a counterweight and a weight on the other end of an arm (that i want to launch like a trebuchet)- im not sure how to find the formula between the range of motion and the weight (...
231 views

### What is a line launcher

Okay, so I think that a line launcher is a device used in rescues? What I’m unsure please about is how they work, like the Batman grapple gun (is that a line launcher) or like a line launcher gun ...
32 views

### Finding MEMS Accelerometer Nonlinearity Coefficient from %FSR Specification

I want to predict the maximum output error from nonlinearity for the working range of a MEMS accelerometer. I am given in the accelerometer spec sheet a nonlinearity value of 1% FSR for a ±40 g range. ...
57 views

### Automated Opening and Closing of hinge

I am trying to design a mechanism that puts tension on a string. The purpose is to dip this string in a solution for a stipulated amount of time, and once the time is up, the string is pulled back up! ...
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1 vote
106 views

I want to move a small tool table/bed linearly, so I'm designing its mechanism. Fairly simple, it's going to have 2 rails and a lead screw. Browsing the web I find that locally the shortest ...
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1k views

### Mechanical mechanism that regulates gear's rotational velocity

Please do note that I am a civil engineer not a mechanical engineer. I have a gear that rotates at a speed that varies with time. Usually, it rotates at speeds higher than the desired speed. Is there ...
53 views

### Can tubes for fits & tolerance be purchased or only manufactured?

I'm currently designing a steel structure for a gym machine. I want to assemble two rectangular tubes, one being able to slide inside the other, for height adjusting. I intend to use a spring ball pop ...
1 vote
77 views

### Self locking ramp with cylinder

Does anyone know any known applications with a stopping ramp that is acctuated with a cylinder and is self locking in its top position. That means that the force on the ramp doesn't load the cylinder, ...
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1 vote
353 views

### Ideas for mechanism for quick reciprocating motion - a 'truly' mechanical switch

I need a mechanism to switch the vertical position of an assembly in as square a profile as possible - i.e. a normal crank mechanism produces a sine wave profile, to explain myself better. I've seen ...
46 views

### Stiffness of spring pendulum from position, velocity, and acceleration

I'm working on a problem for which I have an external tool that integrates the equations of motion of a complex 'pendulum-like' mechanism (multiple beams, torsion springs and dampers, actuation, etc., ...
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1k views

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

I need to create several spools of enameled copper wire, each one rolled on a 3D printed bobbin and with a certain number of turns. In total, there will be several thousands of turns, and I want to ...
• 131
224 views

### Why does this thing that is not a screw have a screwdriver slot?

I am (partially) disassembling an old sewing machine to clean it up. While removing the bobbin winder, I found this thing that has a screwdriver slot, but it isn't a screw. This is the part: It came ...
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42 views

### Lab Jack with Bi-Dimensional Movement

I just bought a lab jack like this one: Its purpose is to change its height without loosing its rigidity by using the so called: scissors mechanism I was wondering if there is a similar device like ...
• 101
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### How can I cheaply tilt a 700 lb cactus?

We got some heavy rain last week and a 4.5 ft tall barrel cactus fell over. Assuming most of it is water, it probably weighs about 700 lb. I've read that if I moisten the soil, take care with the ...
1 vote
183 views

### Is there a formula that relates the two angles in a crank rocker?

I'm working on a mechanism that requires a crank rocker - is there a formula that relates the angle (to some fixed reference; horizontal, vertical, whatever) of the driving "crank" to the ...
• 113
1 vote
83 views

### What happens to a mechanical watch when the stem is fully pulled out?

Related to the question: Why would anyone “pull the stem out and stop the wristwatch at night or when not wearing it” in the context of mechanical watches? When the stem of either a mechanical wrist ...
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1 vote
83 views

### Why would anyone "pull the stem out and stop the wristwatch at night or when not wearing it" in the context of mechanical watches?

I read this the other day while discussing mechanical pocket and wrist watches: Plus it is common practice to pull the stem out and stop the wristwatch at night or when not wearing it. You then have ...
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### Belt Drive Shaft - What Profile is This?

I'm trying to source a similar extruded aluminum round profile, that I can attach a belt to, as in the pic below. The shaft will turn and pull on that belt. I looked at the 80-20 extrusions and ...
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1 vote
Two-mass rotational system has the following form and is represented in following structural diagram. where $\tau_e$, $\omega_1$ and $J_m$ - motor torque, angular velocity and moment of inertia \$\...