Tractor Testing; Drawbar; Allis Chalmers

"Test no. 397. Max. drawbar test. 37,556 lbs pull. A-C HD 19." Side view of Allis-Chalmers HD-19 crawler on the test track towing the Adams test car. The latter is towed separately from the 4 load tractors because of the lesser strength of its chassis. A large chain at the rear of the Allis-Chalmer tractor attaches it to a cylinder, which in turn is attached to the hitch and the load tractors. The cylinder provides Hydraulic Pressaure from which the actual force is derived