9 votes
Accepted

Mechanical Advantage of 3 Pulley System

The tension on the rope is everywhere the same and its equal to F. So if you did a free body diagram on the following system by sectioning along the ropes: what you get from the equilibrium is $4F =...
NMech's user avatar
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5 votes

Tower crane with a cabin on ground level

The crane operator at the top of the tower doesn't just have a view of the load being lifted. He/she can see the entire surrounding area and take account of any potential hazardous situations that ...
alephzero's user avatar
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5 votes

Endless synchronous belt problem

Use a ruler or straight edge and place it across the diameter of the pulley nearest you. Check for parallel on the other pulley. If the flanges are the same width then align the pulleys. Figure 1. An ...
Transistor's user avatar
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5 votes

Endless synchronous belt problem

Use flanged backside idlers and flangeless or single flanged pulleys. From Gates -
Phil Sweet's user avatar
  • 4,755
4 votes
Accepted

Is twisted belt configuration a good practice?

The twist introduces a sideways torque, making the belt align non-uniformly, stretch and compress non-uniformly, and rub against any stops that prevent it from falling off (or be prone to fall off in ...
SF.'s user avatar
  • 6,105
3 votes
Accepted

Belt tension to rotational force

Your intuition is correct in "real life", but incorrect within the specific parameters laid out in your question. In "real life" (where your intuition rightly stems from), the extremely tight belt ...
Jonathan R Swift's user avatar
3 votes

Tower crane with a cabin on ground level

It is not trivial to replace human vision with a camera in this sort of situation. it is difficult to reproduce good depth perception with cameras the human eye can change focus quickly and ...
Chris Johns's user avatar
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3 votes

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

Idea 1: Adjust the pulley attachment position so that it is in line with the pulling force. If this is a rowing machine, then maybe use 2 pulleys like this: Idea 2: Use a linear bearing to prevent ...
Drew's user avatar
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3 votes

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

Another idea would be to at some point have the rope move through a pulley and the pulley has an inefficient propeller attached to it. As the speed increases, so the does the air resistance thus ...
fred_dot_u's user avatar
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3 votes

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

An eddy current brake is easy to build and might suit this purpose. Simply attach a largish aluminum disk to the pulley and place some powerful fixed magnets close to it near the outside where the ...
Drew's user avatar
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3 votes
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Bushed 3" V-belt pulley with unkeyed 3/4" shaft?

Here are four shaft connection methods. Figure 1. Image source: PTI International. I've used something like the Adaptor style successfully. The ones I used had a slot cut on the shaft clamp. The ...
Transistor's user avatar
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3 votes
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Will this pulley system work?

Yes. If the motor moves to the right by distance $x$ then the inner left pulley most move the same distance. This will increase the length of the fixed end by $x$ and the length of the top left ...
Transistor's user avatar
  • 10.7k
2 votes

Tower crane with a cabin on ground level

From 1924 to 1932 Sydney Harbour Bridge was constructed. It used two creeper cranes on both sides of the arch during construction to hoist people & materials. The crane operators couldn't see ...
Fred's user avatar
  • 9,637
2 votes

How to make a pulley system with a mechanical advantage of 0.5

What you need is a block-and-tackle, namely a gun-tackle. Source The general trick to determine advantage is how many verticals you have bearing the load (other than the end you are pulling from). ...
Wasabi's user avatar
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2 votes

Is twisted belt configuration a good practice?

Twisting the belts increases the angle of wrap, or arc of contact, that the belt has with the pulleys - ie the belt has a greater contact area with each pulley. Generally, the greater the angle of ...
Fred's user avatar
  • 9,637
2 votes

Torque and Speed of a DC Motor with Pulleys and Wheels

Maximum speed is affected by air drag, rolling resistance and power of the motor. The force pushing the skate is simple to calculate: $$ f_a = k_m{ P \over v }$$ Where $P$ is the power output of ...
fededevi's user avatar
  • 131
2 votes

Two-way pulley system considering inertia of pulleys

The first step in a problem like this is to draw the relevant free body diagrams. You sort of did this in the top left diagram, but not really. What you want to do is to split each mass and inertia ...
Daniel K's user avatar
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2 votes

Surprisingly Low Efficiency of Compound Machine [Project Help]

I have a few suggestions when it comes to managing forces: Try putting the angle of the ramp and the angle of the cord in the same value. This will reduce the force required to pull it up as the ...
Jem Eripol's user avatar
2 votes

Wire type for robotic tendon?

I have successfully used a non-stretch polymer known by various names such as Dyneema, GelSpun or Spectra for a similar purpose. It is easily purchased from most fishing supply stores. The material ...
Donald Gibson's user avatar
2 votes

How to make pivoting arms move symmetrically towards each other?

There are many ideas which have worked for different gears like this drafting compass with a threaded shaft and a roller: And this pantograph. . -
kamran's user avatar
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2 votes

How to make pivoting arms move symmetrically towards each other?

I can think of two options: 1) have the arms connected by gears at the pivot point - when one is moved so will the other, in fact one could be fixed... 2) connect the arms with a threaded rod (needs ...
Solar Mike's user avatar
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2 votes
Accepted

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

Consider a small element of chain with length $dl$ at the top of the arc. Its mass is $\lambda\,dl$. It is curved through an angle $dl/2r$ on each side of the vertical. So the downward force on it ...
alephzero's user avatar
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2 votes

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

The simplest way to achieve this in my mind, is with two gears - one should have a drum attached with the rope wound around, and the other has the arm attached. One benefit of this method, is that ...
Jonathan R Swift's user avatar
2 votes

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

Most of my experience is with various blocks and pulleys on sailboats, and I can see one significant difference between the two McMaster pulleys you linked to: The sheave of the lifting pulley has a ...
Ward - Trying Codidact's user avatar
2 votes

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

From what I see, in order to measure the torque you should have put the side view. See below and imagine that the blue line around the face is the rope. From that view its possible to see if your ...
NMech's user avatar
  • 24.3k
2 votes
Accepted

Small belt transmission: Radius difference?

I would estimate The radius to be a bit larger than 4 mm. How much, depends on the friction and stiffness of your belt. Similar to continuously variable transmission, CVT. If the belt is stiff enough ...
kamran's user avatar
  • 22.4k
2 votes

Collecting a released rope with a proper speed

Simplest method: torque-limiting clutch. I have one on my electric screwdriver. Less simple but even finer control: torque sensor with feedback to the motor winding speed.
Carl Witthoft's user avatar
2 votes
Accepted

Collecting a released rope with a proper speed

This is similar to a low-tension rewinder application used for filaments and films / webs. The simplest solution would be to run a rewinder motor in constant torque mode. This could be achieved with a ...
Transistor's user avatar
  • 10.7k
2 votes
Accepted

Would the reduction ratio of a pulley drive also be applied to a compound pulley?

The size of the sheaves doesn't matter to pulley systems. Pulleys gain advantage by multiplying the constant tension of the rope by the pulley advantage. Gears and belts give an advantage to the ...
Tiger Guy's user avatar
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