Figure 4 would probably tell a different story if you used the 415N load level rather than the 174 N. I expect the ball bearing block would look better. (for US readers, 415N is 93 lbf, 174N is 39 lbf)
I opted for the 174 N data because the I have no 415 N data for the thinnest line that give us total friction very close to the pure block friction. I have attached a 415 N plot. As you see there is still little difference between the ball bearing block and the plain bearing blocks.
It would be really nice if you could compare a ball bearing block to a plain bearing block of the same sheave diameter. Actually it would nice to see that comparison at several different sheave diameters. Also, it would be nice to see a comparison of a new ball bearing block to a used one.
Do you sponsor me?
:-)
/Martin
