HP or PWOER Loss between 2 different sized Pulleys?

[trillionex]

hello guys..!
i have one pulley of 8" (Driver) and another one 10" (Driven) he driver pulley is driven by 2Hp motor, so is there any equation or formula to calculate the Hp loss or power loss from 2Hp?

 

[cjl]

In the ideal case, there is no power loss. For a real situation, you'd need to know more to be able to figure out what the power loss was.

 

[trillionex]

so if 10' pulley is kept on load then it would get 25% less Hp then the input Hp at 8"pulley as it is 25% bigger in size?

 

[rcgldr]

Pulley size will affect torque and rate of rotation (trading one for the other), but will have little effect on power. Power losses are due to losses in the pulley bearings and friction with the belt.

 

[cjl]

so if 10' pulley is kept on load then it would get 25% less Hp then the input Hp at 8"pulley as it is 25% bigger in size?

Nope. The power would be the same, but the torque and rpm would change.

 

[russ_watters]

As said, ideally the power loss is zero regardless of the pulley size. Realistically, it is a few percent, depending on the configuration.

 

[trillionex]

Yaa russ the change is few percent but i wana calculate that few percent..

 

[cjl]

Then you need to know more than just the size difference. That will depend on the bearings and belt or cable used.

 

[trillionex]

Ok so suppose if 8" pulley is driven by 2 hp and 10" pulley has to also drive 2hp load then would 10" pulley will be able to drive that load with full 2hp or 1.75hp or 1.5hp?

 

[russ_watters]

Ok so suppose if 8" pulley is driven by 2 hp and 10" pulley has to also drive 2hp load then would 10" pulley will be able to drive that load with full 2hp or 1.75hp or 1.5hp?

You're not understanding: it could literally be anything below 2 hp in a real-world situation and it can't be calculated exactly, only estimated. If you have a real-world application and you need to know so you can select a motor, use 10% to be safe...and then increase the motor size by another 20% to be safer.

 

[trillionex]

You're not understanding: it could literally be anything below 2 hp in a real-world situation and it can't be calculated exactly, only estimated. If you have a real-world application and you need to know so you can select a motor, use 10% to be safe...and then increase the motor size by another 20% to be safer.

ok got it...i just needed to confirm that loss does occur and that also quite significant one...as u said it trades torque for rpm...others were saying that there is so little loss that it wuldnt even matter but i think that loss count matters

 

[russ_watters]

ok got it...i just needed to confirm that loss does occur and that also quite significant one...as u said it trades torque for rpm...others were saying that there is so little loss that it wuldnt even matter but i think that loss count matters

Right, but just so we're clear, trading torque for rpm is not loss.

 

[trillionex]

Yaa russ, thnx fr the help, appreciate it

 

[cjl]

ok got it...i just needed to confirm that loss does occur and that also quite significant one...as u said it trades torque for rpm...others were saying that there is so little loss that it wuldnt even matter but i think that loss count matters

What you don't seem to be understanding is that trading torque for RPM does not necessarily indicate a loss.