the more we know....

Please explain the quest by anonymously posting the answers you think are unreasonable. That would be professionally correct. Also bear in mind that the answers could have been compromised by the original questions so we need to see those as well.

Software apart: have you asked the clients why they specify using higher values for starting?

What do the lagging people say on the subject?■

Originally Posted by louispanjang

answers could have been compromised by the original questions

Questions are a burden to others, answers are a prison for oneself. ■

Originally Posted by Marco M

Running coefficient of friction versus Accelerating coefficient of friction

Hello,

.......why the coefficient of friction for lagged pulleys vaires between accelerating and running conditions?

..........................

Thanks,

Marco

Will it be related to Newton's law?

Rgds, ■

Many years ago some very bright people, at then Hewitt-Robins, did testing on pulley lagging on a laboratory drum. They found that for a short period of the operating life the transmission of the drive could sustain more slip without apparent degradation. Since slip occurs anyway, they deduced for the short starting vs. running cycle, the drive could be engineered with a higher slip criteria.

The coefficient was arbitrarily raised by 0.05 units. This became the internal standard back in the 1950's. When H-R gave CEMA the body of the original CEMA manual, back in the 1960's, no one questioned the criteria. It has stuck in acceptance mode ever since.

Others have questioned the data and have also came to accept it. Ask an old H-R employee, maybe Frank Loeffler was with them then. Most have gone into retirement. ■