Quote:
Originally Posted by freebeard
Thanks for taking the time, but
is ambiguous. Any drawings or pictures. Or just, how would the idler arm theory translate to a tricycle?
Old Mechanic -- Dig the pix. I do hope you use an equivalent grade for the four bolts that hold the axle beam, the holes in the square tube are sleeved and you plug the ends of that crossbar so it doesn't distort.
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I haven't examined how this would "translate" to a three wheeler. Body lean relative to the suspension is in the front on a three wheeler with two in front, and is the compression of one front spring and extension of the other. A very different thing than on a truck where you have two solid axles, and a frame, and the steering axle changes it's relation to the frame. On the three wheeler with rear steer, the rear wheel stays true with the body, and the front wheels do not. Thus you inherently do not have the problem of lean causing steering. The way I would approach the problem is as I have said. Use positive caster, and "rake" to put the contact patch of the steering tire forward of the kingpin axis so that centrifugal force, which is pulling toward the outside of the turn is acting to create a steering force toward center on the tire. Thus if you were to let go of the wheel in a turn, it would tend to steer toward center of it's own accord. Alternatively you could use a mass on a swing arm that you would be moving when you steered, and as the centrifugal force of your turn increased, that mass would want to swing toward the outside of the turn. Properly attached to the steering linkage, this would provide an increasingly strong force against you wanting to move the wheel back to center. This would be extremely simple............. A ten pound pendulum for example mounted on a longitudinal axis pivot with a small damper shock, and a linkage with a bell crank to change direction so it could be connected directly to the forward and backward moving drag link that connects to the rear wheel. I'm not good at drawing word pictures... but I can close my eyes and see exactly how that would work...........
I've been talking about this for years........... and haven't built one. I did learn some very interesting things about caster and rake building a flying machine with a tricycle stance. I actually have pieces left over including the kingpin and front wheel assembly, and a piece of frame that could be used that already has a 10 deg angled hole for the kingpin, so it could be used as original easily, or inverted to give 10 deg positive caster angle or 10 deg negative caster. The steering assembly with the wheel can easily be reversed to place the wheel forward or rearward of the kingpin steering axis. It would be interesting to build a one rear wheel steer setup out of this as everything is there to try 4 different configurations. I also have a seat that will attach. It's all based on a 2" aluminum square tube. With a front wheel drive assembly of some sort, it would make a good test bed.
Howard
Howard