# Motor Torque Requirements (Hub Motor)

1. Sep 2, 2009

### elsikre

Hi !
I really hope that someone can help me with this one. It should actually be straight forward, but somehow these calculations really just … Well, perhaps I am just making things way too complicated so I really need a fresh view on things, so I really like to hear some of your inputs, thx.

The task is actually a homebuilding project. A small trailer with 2 wheels in the front and a freewheel at the rear. Each front wheel has an mounted hub motor (not yet chosen). From a standstill the trailer will accelerate, drive 100 meter at designated speed, then stop, turn around and drive back. I need to estimate how much torque each hub motor can give, able to do this travel. The travel will first be in a parking lot and afterwards repeated on a grass field. Boiled down to this:

1) To know how much torque needed in each motor (both during acceleration and during continous driving)
2) To estimate how many amps each of the hub motor will consume during this travel (assuming 24V)

Data:
m(total) = 50 kg
r(front.wheel) = 0.1 m
v(trailer) = 3 m/s
a(trailer) = 1 m/s^2
n(motor) = 0.6
V(motor) = 24 V
Thanks