Anyone need to run drawbar pull on their tractor

This vehicle was powered with twin 500hp Ford gas engines. Each engine had dual 4 barrel carburetors and it had an electric drive similar to a locomotive. There's also a loadcell on the
front for measuring drawbar pull in pounds. We could monitor temperatures of the test vehicle too since the temperatures were read on a Fluke recorder in the M7.

The M7 and 3 trailers would easily hold 100,000 pounds of drawpull. The trailers had an electric
drive too and were controlled from the M7.

I would bet the Nebraska Test Lab would have like to have had this vehicle for their tests. Hal

I gave a D8 operator quite a surprise, this summer and I didn't have the largest 8 wheeler out there. He pulled me out of deep mud. He was driving on hard ground with me in tow, mainly to get rid of mud before we unhooked. I thought for the fun of it I'll step on brakes, I stopped him, he went for the heavy gears and rpm, I did the same and much to his surprise, he went for a backwards drive.

A rule of thumb for 4 wheel drive vehicles is that they should pull around 80% of their weight on drawbar pull.

The M7, M9 and the 3 big trailers all had chain drive. This was taken from the WW2 Recovery vehicle known as the M26 Draggin Wagon. The electric drive and the Ford engines were used in the T23 electric tank and were used on both the M7 and M9.

These vehicles were made in CA by a company known as the Knuckey Truck Co. They built the M26 during WW2 and were awarded a contract in 1945 after the war was over. Another company in Seattle WA known as Pacific Car and Foundry also built the the M26's since there was such a demand for them. You can see pictures of the M26 and the T23 by clicking on "Keyword" and typing in M26
or T23 Tank. I was told Mr Knuckey didn't have an engineering degree, but he must of had some good ones working for him. I think GE was involved in the electric drive since they had a contract on T23. APG bought a new heavy field dynanmometer known as the M18 in the late 70's and it was powered with the 1600 hp EMD engine
that was part of GM at that time. It would tow an M1 tank 45 miles an hour like it wasn't on behind. Hal

On some vehicles like your Farmall tractors that have the engine speed governed you won't be able to change the rpm since the governor cuts in to recover. We ran these by road speed starting at the max rs. We would drop the road speed by one mph until the max drawbar pull is obtained. The vehicle may start to lose traction and the pull will fall off. We would not go any lower in rs here. On the higher gears we ran by road speed
too, but we would quit when the drawbar pull dropped off. You don't want to overload your clutch by stalling your test vehicle and having the clutch smoking. The M7 has a calibrated 5th wheel for measuring road speed too. Hal