Torque Required to turn a wheel

[lysolmax]

Hello,

I am trying to figure out how much weight a particular motor/wheel setup can handle.

I have an electric motor that puts out 6000ft*lb of torque, and is driving 44" wheels and needs to reach a maximum of 2RPM. Acceleration doesn't really matter so long as the wheels are able to get up to speed in a reasonable amount of time.

How much weight am I capable of handling on this setup?

 

[Mech_Engineer]

You limitations will be in the inertial of whatever wheel you are accelerating, and the load ratings for the bearings supporting the wheel. 6000 ft-lb of torque sounds like a lot, are you sure you're right on your number there?

 

[jack action]

Rolling Resistance + ma = Driving Force​

R_r W + \lambda W \frac{a}{g} \le \frac{T}{r}
W \le \frac{T}{\left(R_r +\lambda\ ^a/_g \right) r}
Where:

• $W$ = Weight (lb)
• $T$ = Wheel Torque (lb.ft)
• $R_r$ = Rolling Resistance Coefficient
• $\lambda$ = mass factor (= $\frac{m_e}{m}$; see http://hpwizard.com/rotational-inertia.html)
• $^a/_g$ = Acceleration (in g's)
• $r$ = Wheel Effective Radius (ft)

In any cases, the Driving Force will not exceed the available friction force ($\mu W$), thus:
W \le \frac{\mu W}{R_r +\lambda \ ^a/_g}
Or:
R_r +\lambda \ ^a/_g \le \mu

Where $\mu$ is the tire-road friction coefficient.

EDIT: Added mass factor.

 

[lysolmax]

You limitations will be in the inertial of whatever wheel you are accelerating, and the load ratings for the bearings supporting the wheel. 6000 ft-lb of torque sounds like a lot, are you sure you're right on your number there?

Yeah it should be. The mass value I'm hoping to get is somewhere around 100,000 lbs