# Would this motor be able to lift 150 lbs?

Would this motor lift me? 150 lbs or so?

http://www.superdroidrobots.com/shop/item.asp?itemid=722

Its for my walking chair, it will be chained to a shaft and the shaft will have about 150 lbs (NOT static load) or so of force to deal with.

Thanks :)

We need a few more details

We need a few more details before we can find the maximum output force. What are the diameters of the motor and shaft sprockets that mesh with the chain? What is the torque or torque arm length between the shaft and the load?

Τ=F*d, where T=torque, F=force tangent to the torque axis, and d=distance between the torque axis and the force. So far we’ve got the input torque and output force, but no distance values.

Hmm… I’m not certain how

Hmm… I’m not certain how to read these… but here’s the full specs:

http://www.superdroidrobots.com/product_info/IG32RGMb.gif (just the motor)

Thank you

The dimensions of the motor

The dimensions of the motor aren’t important unless you drive a belt/chain/rope directly off the output shaft. If both chain sprockets are the same diameter, then the drive shaft will have the same torque applied to it that the motor can output (ie: 12kg-cm nominally, up to 36kg-cm).
Unlike the linear actuators from your other chair, a motor cannot produce a linear force by itself - it needs a wheel, screw drive, arm, winch, or something along those lines to convert the torque into a force. The dimensions of the converter are absolutely critical to determine the force output for a given torque.

150lbs is ~68kg, so for the motor to lift this weight at the rated torque of 12kg-cm the converter will need a characteristic length of 12kg-cm/68kg=0.176cm. This is even smaller than the output shaft itself, so it’s not really going to work unless you gear the motor down even further.

So those are your options; add an even larger gearbox onto the output shaft, or find a bigger motor. I’d suggest finding a more powerful gearmotor, double gearboxes are pretty horrible.

the sprocket on the motor is

the sprocket on the motor is much smaller than the one on the shaft. i dont know if it will make too much of a diference, but yeah…

i honsetly can’t afford a much bigger motor that that. i may have to double up gearboxes…

thanks for the thorough answer too

and BTW, how would an electric bike motor work? what is the lowest possible RPM? ( or if anyone else knows, i may just post this question seperate)

The torque on the drive

The torque on the drive shaft will be higher than the motor torque - it’ll be 12kg-cm*(shaft sprocket diameter/motor sprocket diameter).

thank you very much! but i

thank you very much! but i have found a motor with 200 in-lbs… just right.

thanks for the equations too… i will be using them soon.