Wire rope / block efficiency

[Philrock]

I want to calculate the efficiency of a wire rope / block system. There will be 4 or 5 sheaves on both upper and lower blocks, therefore 8 or 10 rope parts. There will also be several routing sheaves between the last block sheave and the winch. Because of the large number of sheaves, friction losses will be important. In one arrangement I looked at, the rope pull at the winch was more than twice the pull at the dead end.

The U.S. Steel Tiger Brand Wire Rope Engineering Handbook gives a fairly elaborate procedure for calculating the tension increase as a rope passes over a sheave. One of the parameters in their procedure is "C, a constant depending on the wire rope." They give a C value for only one rope construction: 6 x 19.

Where can I get a C value for 6 x 37 IWRC rope? - or a similarly thorough procedure that includes all the necessary information for that rope type?

 

[chicopee]

See if you can get your hands on Shapiro's"Cranes and Derricks" as it will go over some of the questions that you may have. I have a copy but I am out of town for a week. I believe that the "C" value is based on wire rope flexibility. The more wires in the wire rope, the more flexible it will be. 6x37 is more flexible that 6x19.

 

[BrianE22]

My Macwhyte Cable Book has a section on it (see enclosed).

 

[BrianE22]

Hmm, nothing enclosed on previous email. I'll try again