The GMC CCKW

How the army arrived it it for the CCKW was to use the maximum grade that a fully loaded and equipped vehicle can climb at constant speed on a smooth concrete course when operated in a specific gear range. A lot of work went into perfecting these men of war that we now play in.

These wartime test courses for the CCKW were at Aberdeen Proving Ground, Ft Holibird, Detroit Arsenal and at the General Motors Proving Ground.
Vintage Video has filmstrips for sal that depict wartime testing. I will have a 54 minute filmstrip available and for sale in the near future about WWII Military Tire production, that is if it includes nice pictures of WWII trucks. I have to first take it and view it at north Historic Film, and then have it converted to modern method of viewing.

According to Aberdeen personnel who gave me the tour a number of years ago, they have the gradibility hill with different grades up to 65 percent. The test vehicle must climb 1/2 way up the grade, stop, and have the parking brake set. The driver then gets out, walks around the vehicle and resumes his climb!

I have been on the hill. You can barely crawl up the 65 percent grade yourself!

There is a large curved steel plate at the top of the this (roadways are concrete) so that they can run a steel cable from the test vehicle over the top to a vehicle of equal or greater weight on the other side so that if something fails on the test vehicle, it won't go screaming down the hill backwards.

Thanks Doc, that is interesting.