It looked to me like his cars were guided by the slot and had a piece of brass tubing suspended below the front that rubbed the electric rails on each side.. No doubt his rails were just bare, small gg wire. I think he shows his small cars had a piece of wire that ran in the slot as a guide. Not any kind of wiper that ran against a raised rail.
Maybe I am not seeing it clearly.
In the video you can see the down turned wire in his early cars that guided the car by running in the slot. I don't see any kind of rail that it ran against. While not a flush braid or rail, it sure looks like a flush mounted small wire on either side of the slot that carried the power to the brass wipers under the car. I don't see much rail car, but a whole different type of system.
I will have to see better pictures to change my mind about this being the earliest slot type system. I think it clearly shows that the cars got power from conductors on each side of the slot.
Have you been fortunate to see this in person? I wonder if it is on display somewhere?
If his setup was a rail design first, than he was first with that system, too? 1942.
Commander Wallis, in his words. "However, the surface wire guidance was sometimes subject to damage when the little cars spun out of control. I soon replaced it with a slot cut in a sheet of plywood track, the slot being made by use of a dentist's drill driven by an electric motor adapted from a Gunsight Aiming Point camera. A pin forward of the steering axis of the "offside" front wheel would engage in the slot and steer the front wheels as the car moved forward. This "pin following a slot" system was far superior to the first experiment, in that the cars could swing round completely without any damage to the track or the car."
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