text: Sure... To do this, you need to examine the yield strength of all joints of the cart and what they are rated for.  (For example, Find out what kind of load is placed on the axle and then choose an axel that can withstand that weight...)  The maximum weight that you can hold on the cart is the maximum weight that the WEAKEST link of your cart can withstand.\n\n(Conservatively, one also introduces some factor of safety here. Multiply the maximum yield of the weakest link by a factor of 80-90% to give you some wiggle room in case you dynamically load -- i.e. drop weight on the cart.)