Not quite a direct connection to this discussion but related on some level. Some running conventional locos may even find it useful. Forty plus years ago, long before TMCC I built a layout that had very little level track. It was either going up or going down except for some reverse loops that were flat. You simply had to ride the throttle continuously. Too little throttle and trains would stall going up hill too much and they ran off curves on downhill grades. One day I was over in Dads shop when he was cleaning up. I went over thinking he would throw out some really good tinker toys. One of his discarded treasures was a box with 15-20 mercury switches inside. When I got home, sitting next to my work bench and going through my booty I hit on an idea. I had a prewar 201 switcher that I had put a string of back to back diodes in series with the commutator because the thing would start running at a lower voltage than the e-unit took to cycle and once the e-unit drum finally came into position the loco would lurch forward. So the diodes raised the amount of track voltage needed to run the motor to more than needed to cycle the e-unit and once the e-unit was engaged the throttle could be further increased and the loco would ease away. While sitting on my work bench stool the idea of using one of dads mercury switches to jumper around the diodes when the loco was going up a grade just popped into my head. So, the next evening I figured a way to mount the switch in the loco on a piece of spring brass with an adjustment screw for fine tuning. To be honest, the system does not work if you try and back up a hill, but Lionel trains did not back up hills very well to begin with at that time. In it's essence you hook between 3 and 5 diodes together in a string then make a second string like the first. Now wire them up parallel + on the first string to - on the second string , connected at both ends. You can accomplish the same thing twisting the diodes together back to back in pairs and hook 3-5 of those pairs together. Next you will take your mercury switch connections and hook one to each end of your string of diodes. Then disconnect one of the wires going to the motor brushes, doesn't matter which one and connect your string of diodes and your mercury switch between the motor brush and the wire you took off the brush guide. You want the contact end of the mercury switch toward the rear of the loco so when the loco starts up hill the mercury rolls to the rear and closes the circuit , thus jumpering around your diodes. I found that it worked best if the glass tub when the loco was sitting on level track was tilted down toward the front of the loco enough to keep the mercury from flowing to the contacts upon start up. Another trick I found was to rotate the glass tube so one of the contacts was higher than the other this made sure that a small surge of mercury that only contacted the lower conductor did not complete the circuit No jackrabbit starts either. J
