[EricH]

Originally Posted by yash101

A castor can easily make it possible to push the load. However, I am guessing that I may reach 400 pounds or more! At that weight, an assisting system will help.

I routinely move a lot (capital "a lot") more than that with just another person on the other end of the cart to steer that end (and push). No assistance device needed.

If the cart didn't have wheels, you would have a problem. But 400 lb on wheels with 1-2 people handling it? You don't need assistance from a drive system.