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Old 09-10-2013, 01:03 PM   #97 (permalink)
EcoModding Lurker
Join Date: Jan 2010
Location: Montana
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[QUOTE=freebeard;389621]owly -- It's novel to see people advocating for rear-steer, so I have some questions, if you don't mind.
  • Do you have a cite-able reference one could point to in discussions of the subject?
  • What was the top speed of the truck/loader?

I don't have any references.......... I built quite a few of the reverse truck loaders back in the 80's. At first they were a handful to drive....... worse if you didn't reverse the axle. Then I built one that was so wild you couldn't keep it on the road much over walking speed. That experience forced me to analyze what the problem was. As it turned out, when you turned right, the roll of the frame was actually causing the steering force to increase due to the angle of the drag link downward from the steering box to the axle. The solution was simple. I built an idler which was mounted low so that the drag link ran at a slight upward angle instead of a steep downward angle. After this, you could run at 50 mph with no problems. It was rock stable. Since that machine, ever one I built has had an idler except one that I put straight hydraulic steering on. The steering cylinder mount on that one is mounted just a bit low so it has the same effect....... as the body rolls it tends to steer very slightly back toward center.

The difference in stability on the wild one between before and after I put the idler on was stunning! It was every bit as stable as the truck I built it from at that point.

One very common system that has been used on many of these is a large idler under he frame, and the axle not reversed. It's terrible. Though the idler makes the drag link run more or less straight, the reverse caster makes them wild to control.

Note that the trucks originally have the steering box mounted very low, and quite close to the axle so the drag link is more or less straight. Reversing the vehicle makes this impossible obviously, but an idler in the same relative position would solve the problem.

The one where I originally solved the problem was built in 1981, and is still being used on a regular basis....... it was pretty high class. Had a full reversed cab, heater, windshield wipers, radio, the works, and used the original N series truck nose, with a truck cab backed up to it.

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