Prior to 1925 most dumps were graviity dumps where the dump box was cantilever over the rear of the frame so that when the lever was released the weight of the load raised the box. The box pivot was forward of the load centerline. I know in 1935 "Gar-Wood Industries" from Detroit, MI was making a dump hoist Type F4C Hoist that had two rollers on a cross shaft attached to a horizontally mounted hydraulic cylinder that pushed on two 1/4 round "wedges" mounted to the dump box. I have a picture of it.


34 & 35 trucks are the greatest