# Questions tagged [pulleys]

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### Does "stacking" of thinner timing pulley and belts reduce "belt stretch", as using a wider belt would?

When wanting precise belt driven motion, it is desirable to reduce belt stretch by using a wider and/or stronger belt. Wider GT family can be quite expensive (hundreds of dollars) compared to thinner ...
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### Can I drive a pulley with two shaded pole motors using one motor at a time with different size pulleys for speed control?

Using two same RPM shaded pole motors, one with a one inch diameter motor and one with a two inch diameter. Using a DTDP switch to swap power from one pulley to the other. For a two speed rotation ...
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### Help on how to calculate motor drive torque for belt and pulley. To get a stepper motor

I need help to find 2 stepper motor for the x and y axis on gantry. The pulleys is 8mm. Force formula F=mgu m=mass g=gravity u=coefficient of friction (7kg)(9.81m/s2)(0.5) = 34 N Torque formula T=Fd t=...
1 vote
60 views

### Would this pulley system only halve the force?

TLDR: Is this only a 2:1 pulley system? Hi there, I’m trying to build a Murphy bed for my roommate. Long story short we’re using an electric hoist + pulley system to raise and lower the bed. The setup ...
41 views

### Clutch for rotating axis of mount used for astronomy

a short disclaimer that for me mechanical engineering is a hobby. Please be gentle with me, even if there may be an obvious answer. The main reason for asking here is that searching for the topic you ...
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 ...
43 views

### Can you calculate torque without any pulleys involved, and if so, how?

I'm trying to calculate the type of motor I need to turn something of a certain weight, so I feel the thing I'm trying to calculate is torque, but, when I research how to find torque, I find this &...
46 views

### Small belt transmission: Radius difference?

I am trying to make a pulley reduction system for my project. I need it to be as quiet as possible, so I am considering pulleys. My project also has limited space, so I am trying to have as small a ...
41 views

### XL timing belt missing Dimension!

I'm trying to design and 3d print a XL pulley. I think there is a missing dimension that I can't find in the spec tables. we've got pitch circle, teeth height, belt thickness... but I can't find ...
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1 vote
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### Bushed 3" V-belt pulley with unkeyed 3/4" shaft?

Shortly I will have two 3/4" unkeyed shafts needing 3" type-A V-belt pulleys, one each. They'll each have their own motor driving them, and will need to run to 5000 RPM and possibly higher ...
1 vote
276 views

### In an open belt drive, which angle of wrap should be taken for calculating tension in the belt?

An open belt drive with flat belt has different angle of wrap on the larger and smaller pulley. I have to calculate a tension in the pulley. We generally use the formulae Here θ is the angle of wrap. ...
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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
201 views

### How can you control the speed of a rope moving through a pulley?

I'm putting together a ceiling-mounted clothes rack. The rack is raised and lowered with rope and pulleys. If the rack is raised under full load and accidentally released, then the system could be ...
43 views

### Minimum pulley diameter at small scale

I am trying to design a musical locket which includes a slowly (28 rpm) rotating component. The two things that make this a challenge is: Very limited space. The motor and the reduction system should ...
197 views

I am in the process of building an antenna mast that can tilt from horizontal (down) to vertical (up). The mast (arm) is 360" and weighs a total of 105 lbs. I need to calculate the amount of ...
878 views

### Mechanical Advantage of 3 Pulley System

I am a physics teacher, but have found myself teaching engineering. I have come across the following pulley question, and am starting to doubt my own understanding of pulleys ! Until now the rule ...
48 views

### Rubik cube torque experiment - Correct equations and experiment set up?

Background I am attempting to experimentally find out the average torque required to rotate a single face of a Rubik cube. Little to no data is available as it varies from cube to cube. Some people ...
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789 views

### Endless synchronous belt problem

I have a motor coupled over a synchronous belt (AT5) to a bigger tooth wheel (1:4), and the problem comes up that the belt is moving up or down (depending on the rotation direction) until it reaches ...
57 views

### What would the tension in the cable be?

A subsequent question stemming from here A massless motor is attached to a massless pulley(the blue circle) with a fixed rotational inertia and they are all attached to a mass X (the green platform). ...
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### HTD3 tooth pulley design

I try to design a HTD3 pulley, but I don't know, how the teeth exactly should look like. I found the following specification: But this seems to be wrong, since I found some HTD3 STL files and ...
805 views

### Degrees of Freedom for Complex Pulley Systems

I'm trying to understand DOF clearly, but this pulley system has me doubting myself. When I try to determine the degrees of freedom, I sum the DOF of each object, and subtract the constraints. for ...
55 views

### How to pull on one side, while keeping an angle?

I have the following setup, consisting of a bar attached to another bar via a ball joint (indicated by a circle, and attached to the wall over a pulley with a weight at the end (the small "kg&...
60 views

### Use of pulleys in gearboxes

I'm designing a simple gearbox with some fairly strict space constraints. I was wondering if having a belt pulley inside of a custom gearbox is a serious issue for the belt. Would it get worn down ...
50 views

### Braking movement of a chain through a pulley or sheave

I am attempting to build a rotating climbing ladder, similar to the one below. The structural supports will be different, but the mechanism of chain (or cable) running in a loop over pulleys/sheaves ...
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### I'm looking for the simplest way to increase rotational speed from 120 to 5,000 rpm for a light duty device

I'm currently designing a device and want to increase speed from 120 to 5,000 rpm. Device is lightweight, hand operated, free spinning, low torque in/out. Picture a cheap fertilizer spreader from Home ...
439 views

### What makes a pulley that is rated for horizontal pulling different from a pulley rated for lifting?

I have a home project that involves lifting a platform with a cable that runs through a series of pulleys to redirect the cable. I'm selecting pulleys for the job and I see that some pulleys are rated ...
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### Is there any way to conserve energy for the following scenario of lifting weight?

A pulley can be used to provide mechanical advantage while lifting weight. Suppose a combination pulley is made such that in order to lift something four times heavier, one can use the same force but ...
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43 views

### Exceed 'designed' speed ratio of timing belt

I'm trying to create a setup to transfer motion from a motor to a shaft that requires a much higher torque (bi-directional). The housing is about 6 inches long and the speed ratio needed will be ...
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1 vote
104 views

### What's a simple machine to lift and drop a 100 lbs weight repeatedly using an electric motor?

Essentially I have a 100 lbs. pile driver with an eyelet for lifting it on top. (It's on rails) I want to set up and automated machine to lift and drop the driver at a variable pace. Preferably I ...
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### How to make pivoting arms move symmetrically towards each other?

I have a basic design of two arms which need to be brought together. But I tried the design using a test setup and it did not work successfully. Here is a diagram of my design - What I observed is ...
1 vote
138 views

### calculation of tension in curved chain for chain fountain (Mould effect)

https://royalsocietypublishing.org/doi/10.1098/rspa.2013.0689 A chain of some sort goes upwards, turns in a half circle (according to the drawn diagram), and goes back down. Focusing on the half ...
181 views

### Calculating optimal angle on a rolling pulley wheel, which holds weight, on a horizontal cable

The 40 kg load on the rope accelerates from 0 to 50km / h in 6 seconds. The rope is tightened with a force of 500kg while the whole assembly is on it. The middle pulley is driven by a dc motor. I ...
1 vote
70 views

### Help me build a mechanical gizmo involving a pulley (I think)

Electrical engineer here. I'm looking to build an incredibly simple mechanism that in my mind involves kind of a pulley. Below is a diagram. So it's essentially like a mechanical servo. I would like ...
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1 vote
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### Springs on a pulley... When to use?

I saw a machine that fed a sheet of laminate through some rollers. The motor had a pulley attached to its shaft, and a spring connected to the pulley. Why not use a belt? Wouldnt the spring make it ...
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### Minimum required rolling friction between pulley and the rope

The 40 kg weight accelerates and runs on a rope from 0 to 50 km/h in 10 seconds. I want to calculate the minimum required rolling friction that I need (acceleration without slipping) to achieve ...
38 views

### Trying to visualize the resulting interaction between two pulleys

I'm trying to get an answer for something potentially quite simple, but I can't visualize it (nor do I have the parts yet to build it). It's for a little hobby project, but I'm slightly concerned I ...
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1k views

### How do you calculate the frictional losses in wire ropes over sheaves?

I am currently pulling a load with a wire rope that is moved through a system of sheaves, but had to replace a smaller wire rope cable (1/2") with a larger wire rope cable (3/4"). The sheave/wire ...
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1 vote
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### How can I couple two small parallel shafts offset a short distance from each other?

I have two parallel shafts, 3 millimetres in diameter and offset by 8 millimetres, both anchored in surrounding housing by ball bearings. When one shaft is rotated (via gear), I want the other shaft ...
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110 views

### Wire type for robotic tendon?

I'm working on a small project where an armature is actuated by a servo via a couple feet of tendon. The servo+tendon needs to be able to pull about 5-10 lbs. There will be springs at the endpoints to ...
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147 views

### choosing between v belt and round belt for fast RPM, low torque application

My pulleys are going to be rotated with a 1000-2000 RPM motor, with a constant RPM controlled by a hall effect sensor, there is going to be almost no torque as one of the pulleys just has a 100 gram ...
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### timing pulleys setup for children's pedal car

I want to convert my son's pedal car to electric. The car is meant for 3-6 year old children. So far I got the following: 50W, 3300 RPM electric motor with 8mm round shaft (no keyway or shaft groove)...
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1k views

### How to mount timing pulleys/belts for small DIY project

I'm building a rotating lamp for a small DIY project to learn about motors and timing belts/pulleys. As I am learning, finding parts that are small enough, fit a stepper motor shaft and reasonable ...
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352 views

### Belt tension to rotational force

This may be an obvious question, but here goes anyhow. If you have two pulleys (different diameters) with infinitely strong bearings and shafts, does increasing the belt tension have any effect on ...
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1 vote
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### Torque Required to Drive Capstan and Bow

I am trying to find the torque exerted on the shaft of a capstan and bow drive. In particular, the system I'm looking at has two wire rope pulleys, and two idler pulleys, and is used to drive a ...
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### How can i move a 5000 lb object with 1500 pound towing capacity?

I'm getting a shipping container delivered to my property that weighs about 5000 pounds. Once it's delivered I will need to re-position it. I'm thinking of trying to use a number of cylindrical logs, ...
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110 views

### How to fix sheared flats on a pulley?

On my belt sander, there is a small cast aluminum drive pulley/wheel about 1.25" diameter that slips over a 5/16" shaft. Two flats on the shaft mate with two flats inside the bore. The internal flats ...
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### Surprisingly Low Efficiency of Compound Machine [Project Help]

I'm working on a school project that requires us to build a compound machine with a mechanical advantage of 9. It should be able to lift a 10oz soup can three or more inches by using the weight of ...
943 views

### Mounting a timing pulley on a ball screw shaft

I have a pretty basic question. I need to install a timing pulley on a ball screw shaft (6mm): http://uk.rs-online.com/web/p/products/2816419/ The processed end (the pointy side) of the shaft is ...
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