Overhead crane and pulleys

In summary, the speaker is facing a problem with a system involving two winches, two moving pulleys, and a fixed pulley. They are lifting a 130-ton load using a steel cable and measuring the load at a load cell. However, while the load is rising, they only measure 30 tons instead of the expected 32.5 tons. When the load is lowered, the load cell measures 36.2 tons, and at rest, it measures 32.5 tons. The speaker is looking for a solution to adjust the safety relay to 110% of the nominal load, but the system's behavior is making it impossible.
  • #1
Marinel
13
0
The problem bellow is a real problem and I would like to get some ideas in order to overcome it.

As you can see in the attached doc, we have two winches ( drum 1 and 2 ) on the same shaft of motor M1, two moving pulleys ( 3 and 4 ) and a fixed pulley (5).
The load is 130 Tons, and we can measure that with a load cell at pulley 5 ( 32,5 Tons) after the lifting of the load.
But during the time as the load is rising we measure only 30 tons! Note that we have a cable of steel with 30mm diam. and the rising speed is about 1m/min.

When we lower the load, the load cell measures 36,2 Tons. and as soon it stops we get again 32m5 Tons.

When the load gets the floor than we read 0 Tons (of course!)

Can someone explain this? This is a real case and my problem is to adjust the safety relay to 110% of nominal load, which is impossible with this beahviour of the system!
 
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  • #2
Doc not attached to OP
 

1. What is an overhead crane and how does it work?

An overhead crane is a type of lifting equipment used in industrial and construction settings. It consists of a bridge or beam that runs along elevated tracks, allowing it to move horizontally across a space. Attached to the bridge are hoists and trolleys, which can lift and lower heavy objects. The crane is controlled by an operator who uses a pendant or remote control to move the hoist and trolley along the bridge.

2. What are the main components of an overhead crane?

The main components of an overhead crane include the bridge, which is the horizontal beam that moves along the tracks; the hoist, which is the lifting mechanism; the trolley, which moves along the bridge and carries the hoist; and the controls, which allow the operator to move and control the crane.

3. How is an overhead crane different from other types of cranes?

An overhead crane is different from other types of cranes because it is supported from above by a structure or building, rather than being mounted on the ground. This allows it to have a larger lifting capacity and to move objects horizontally and vertically with precision.

4. What are pulleys and how are they used in an overhead crane?

A pulley is a simple machine that consists of a wheel with a groove around its circumference. In an overhead crane, pulleys are used to change the direction of the force applied to the hoist. This allows the crane to lift and lower objects with less effort from the operator.

5. What safety precautions should be taken when operating an overhead crane?

When operating an overhead crane, it is important to follow all safety guidelines and procedures. This includes performing regular maintenance and inspections on the crane, ensuring that the load being lifted does not exceed the crane's capacity, and using appropriate personal protective equipment. Operators should also be properly trained and aware of potential hazards in the surrounding area.

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