# Trying to find force on a chain.

TokerM
I am trying to find out how much force is being transferred into a drive chain. Here's the info as I was given:

Motor: 150HP
RPM: 1750
Gearbox information:
ratio: 39:44 Input HP 223 Output shaft to sprocket 6" dia.
Sprocket 20" dia. Top of tooth to bottom of root 1-3/8" 4" pitch of chain
No other sprockets connected.

Am I correct in assuming there is some extraneous info in there? As in, the input HP on the gearbox, I think that's a max number they may have pulled off the id plate?

What we're looking for is the tonnage of the bench.

## Answers and Replies

TokerM
Is it that I'm not giving enough information? If so, what more information is needed? I'm not an engineer by trade, I'm a mechanical designer, so I don't know what calculation to look up. Can someone at least point me in the right direction here?

Pkruse
Pwr & rpm give you torque at the motor. Multiply that by the gear ratio to get torque at the gear box output shaft. Divide that by the radius of the first sprocket to get max tension in the chain. If you have the gear box efficiency, then reduce the number by that amount, otherwise assume 95%.

This is the max chain tension. Actual tension is determined by the load if it is less.

Last edited: