Calculation of Starting torque for Hoist load

[Rakshith]

Dear friends:

Please explain how to develop a torque v/s speed characteristics of given hoist load. Especially i would like to know how to calcuate starting torque for given hoist load.

Sri

 

[monkeydog]

Sri,
Do you mean torque required from a motor?
Static load (torque) after you have establised the gear or pulley configuration would be straight forward, right? Or am I missing something?
Motor wise there is an in-rush current for just the motor to start, and that you should get from the motor manufacturer.

 

[Rakshith]

Hi Monkeydog:

Thank you very much for your reply. Basically i am looking for characteristics of Hoist load, but not the motor. Here i am trying to develop torque v/s speed charactristics of Hoist load, then i will try select a motor for given hoist load.

Thanks
Sri

 

[sacem1]

Not so easy, for hoists the most difficult part of the calcs is the number of loaded starts per hour that the motor will be able to handle without suffering an overload, that's why different classes of service are given by hoist manufacturers for their different equipment.

Besides that the power absorved will be dependend on the speed the load is going to be raised.

Do not forget the braking load calcs also, they are also criticall

SACEM1