What pulling force does my PTO winch actually have

  • Context: Undergrad 
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SUMMARY

The discussion centers on the challenges faced by electricians when pulling underground power cables through concrete ducts using a rope tugger and double braided rope. The primary issue is the friction encountered at bends, which causes the rope to get stuck. To address this, the user plans to utilize a truck equipped with a PTO and a 30-tonne winch, which is expected to provide smoother power delivery and reduce rope stretch. Calculating the winch's pulling force at various RPMs is crucial for preventing damage and ensuring safe operation.

PREREQUISITES
  • Understanding of PTO (Power Take-Off) systems
  • Knowledge of winch specifications, including torque and horsepower ratings
  • Familiarity with rope types and their properties, specifically double braided rope
  • Basic principles of friction and tension in cable pulling
NEXT STEPS
  • Research the specifications of commercial winches, focusing on torque and pulling power ratings
  • Learn about calculating pulling force based on motor horsepower and gearing ratios
  • Explore the use of weak links in winching applications to prevent equipment damage
  • Investigate techniques for reducing friction in cable pulling, such as tapered transitions
USEFUL FOR

This discussion is beneficial for electricians, construction professionals, and anyone involved in cable installation or winching operations, particularly those facing challenges with friction and pulling force in confined spaces.

Smith_
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I am an electrician pulling underground power cables through concrete ducts.

We have had issues using a rope tugger and 7/8 double braided rope as seen here

It keeps getting stuck before certain bends in the duct towards the end when the rope is at its tightest and is pulling the most weight. The friction between the rope and duct must be amazing.

I believe it has to do with how the rope stretches under tension and the number of bends in the run. This wasnt a well engineered job and we are only a sub trade. So we have no choice but to try all angles.

We are about to bring out a truck with PTO and 30 tonne winch. I believe this will offer us the advantage of slow smooth power and almost no stretch in the line. This should in theory reduce the chances of the nose getting stuck (http://s4d8b89f6c462f.img.gostorego.com/809E82/cdn/media/s4d8b89f6c462f/HDD_Drilling_Parts/HDD_Swivels_and_Pullies/multiple-pulling-harnesses-collage.jpg

I am trying to calculate what the winch will output in terms of pulling force at a given rpm. (say idle to start) This would allow me to know when I am applying to much power, see with a rope and tugger you can tell when something is wrong. Tension will slowly build and will show on the unit. It has a gauge. The truck just pulls like a ox and could really do some damage if we don't have some means of knowing what its putting out.

Any help would be greatly appreciated

Thanks
 
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hi there
welcome to PF :)

the torque - pulling power of a winch ( if its a commercial one) should be readily available from the manufacturer

to work it out otherwise, you would need to know hp rating of the motor, gearing ratios etc

Dave
 
Can you buy or make a weak link (as used when winching a Glider) to ensure you don't break the draw rope?

I've never had to pull something that big through a duct but I usually wrap the transition between the draw rope and the cable with tape to produce a tapered transition between the two. Is there something like that that you put over the "nose" assembly?
 

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