Why Does the Load Measurement Vary with Crane Movement?

  • Thread starter Thread starter Marinel
  • Start date Start date
  • Tags Tags
    Crane Pulleys
AI Thread Summary
The discussion revolves around the inconsistent load measurements during crane movement, specifically when lifting and lowering a 130-ton load. While the load cell at the fixed pulley measures 32.5 tons when the load is stationary, it shows only 30 tons during the lift and 36.2 tons while lowering. This discrepancy raises concerns about adjusting the safety relay to 110% of the nominal load, as the fluctuating measurements complicate the process. Factors such as the dynamics of the winches, pulleys, and the steel cable's properties may contribute to these variations. Understanding these mechanics is crucial for addressing the measurement inconsistencies and ensuring safety compliance.
Marinel
Messages
13
Reaction score
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!
 
Last edited:
Physics news on Phys.org
Doc not attached to OP
 

Thread 'Derivation of Hamilton's Principle: Questions'

I have recently been really interested in the derivation of Hamiltons Principle. On my research I found that with the term ##m \cdot \frac{d}{dt} (\frac{dr}{dt} \cdot \delta r) = 0## (1) one may derivate ##\delta \int (T - V) dt = 0## (2). The derivation itself I understood quiet good, but what I don't understand is where the equation (1) came from, because in my research it was just given and not derived from anywhere. Does anybody know where (1) comes from or why from it the...
View full post »

Similar threads

Overhead crane and pulleys problem
Replies
6
Views
5K
Why Does a Crane's Load Cell Show Different Weights While Lifting and Lowering?
Replies
2
Views
3K
Pulley friction in a overhead crane
Replies
10
Views
4K
Why Does Pulley Require Less Work to Lift Mass?
Replies
6
Views
7K

Hot Threads

Recent Insights

Back
Top