Motor

[sportysolution]

May someone help, i am not very good in decide a dc motor needed, so hope someone may help in my case.
From static analysis, i calculated horizontal force needed to lift a human weight using scissor lift is 2142N and using ACME power screw this force required 9.74Nm torque to lift at lowest position 24 degree and at highest position 61.81 degree needed 1.164Nm torque.

The weight to lift is 150kg to height 14cm at 14 second.
Anyone can teach me how to choose the DC motor required to lift?
How to calculate the highest rpm required?

From potential energy 150*9.81*0.14/14? to get power? Or using max torque* rad/sec= power?

It look like both will produce different answer? Can any one help me ?thanks a lot

 

[flash3780]

Bodine electric allows you to select a motor based on the required torque. Perhaps that would be helpful?

http://www.bodine-electric.com

You'll want to look at both required torque and power output, since the speed and load are both important. I would try to incorporate a safety margin as well... you never know when a 250lb guy carrying 100lb worth of stuff (cement, tools, whatever) is going to climb onto your lift.

As for the methodology for calculating energy, you have to consider the frictional power in your system that is lost to heat (screw threads, joints, etc). If you bookkeep the power properly, all methods for calculating power should balance out. Energy can't be created or destroyed, after all.

 

[sportysolution]

Thanks flash, so the power output and torque are the factor in choosing a motor,but how about the speed? how we can calculate it, how we know will it affordable to lift or to turn at the highest load condition?

thanks a lot