# Fixed end hydrualic cylinder with a pulley on top

• gjshafer
In summary, the conversation discusses the use of a hydraulic cylinder with a pulley to double the lifting height. The pulley needs to have a diameter larger than the width of the cylinder and the teeth must be able to support the load. However, the pulley diameter does not affect the lifting ratio, which is achieved through the use of simple machines and the cylinder's stroke. The conversation also mentions the importance of clearance and non-axial loads in the design of the pulley and cylinder.
gjshafer
I am using a hydraulic cylinder with a pulley on top. The bottom of the cylinder is fixed and the top has the pulley mounted on it free to rotate. I am trying to double the lifing height of the cylinder. The cylinder stroke is 24inches and I need to make if lift something from the ground up to 48inches. I am using a chain that one end is connected to the base of the cylinder, the chain is draped over the pulley and back down to the ground where it is attached to the object I am lifting up 48 inches. I am trying to figure out how to determine what diameter pulley to use to double the lifting height of the cylinder. Any help at all would be greatly appreciated.

Thanks,
Glen

Such an arrangement has been used in a number of hoist and jacks. I also think it has been used in some hydraulic elevators, but probably no longer.

The pulley needs to have a diameter greater than the width of the cylinder plus any chain guides, load rails, etc. Then the teeth need to be sized to carry the load and of course fit a chain that can handle the load. Typically speed is not an issue. Non-axial loads, due to asymmetries in the load support and guidance also would play a factor, although probably more in the pulley's attachment and the cylinder's guide bushing.

Ok, thanks for the information, but doesn't the pulley diameter have an effect on the ratio in which it doubles the cylinder? I guess that's what I'm truly asking is how can I size the pulley? Like you said it obviously has to be bigger than the width of the cylinder but how can I find the diamter to achieve the ratio lifting height of 2:1?

It only needs to be as large as required for clearance. Diameter means nothing as far as ratio goes.

Ok, so what is giving the cylinder a 2:1 lifting height? We already use this application else where so I know it works. The initial cylinder stroke is 24 inches and the object that is lifted, is lifted from the ground to the its stopping point of 48 inches from the ground. How is the cylinder doubling its lifting height if the pulley diameter has nothing to do with it? The engineer that designed this application is no longer here so I am just trying to understand how it works for future applications. Any help on this is greatly appreciated

Look up pulleys in simple machines.

## 1. What is a fixed end hydraulic cylinder?

A fixed end hydraulic cylinder is a mechanical device that uses fluid pressure to create force and movement. It consists of a cylindrical barrel, a piston, and a rod that extends from one end. The end of the cylinder where the rod is attached is fixed in place.

## 2. How does a fixed end hydraulic cylinder work?

When fluid, usually oil, is pumped into the cylinder, it pushes against the piston, which in turn pushes the rod outwards. The fixed end of the cylinder prevents the rod from moving inwards. As the rod moves, it creates linear motion and can be used to lift or move heavy objects.

## 3. What is the purpose of a pulley on top of a fixed end hydraulic cylinder?

The pulley on top of a fixed end hydraulic cylinder is used to change the direction of the force created by the cylinder. It allows the force to be applied at a different angle, making it useful in applications where the force needs to be applied horizontally instead of vertically.

## 4. What are some common uses for fixed end hydraulic cylinders with a pulley on top?

Fixed end hydraulic cylinders with a pulley on top are commonly used in industrial settings for lifting and moving heavy loads. They are also often used in construction equipment, such as cranes and excavators, and in agricultural machinery, such as tractors and harvesters.

## 5. Are there any safety precautions to consider when using a fixed end hydraulic cylinder with a pulley on top?

Yes, it is important to follow proper safety procedures when using any type of hydraulic equipment. This includes regular maintenance and inspections, using the correct fluid and pressure levels, and following manufacturer instructions. It is also important to wear appropriate personal protective equipment and to never exceed the weight limit of the equipment.

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