Thurs 4-16-2026 6:45 p.m.
Unfortunately, my work on the modified power truck was accomplished with some Tyco diesel power trucks which were in very poor (discarded) condition. On one truck, I had to repair the little fork / spring subassembly between the two brushes. I also had to repair the "u"-shaped retainer for the spring. The parts are made from Delrin (acetyl plastic). Delrin is slippery and repairing the parts is challenging. You cannot glue Delrin together. However, it is possible to melt and shape / graft Delrin as needed.
I accidently found out that new Jeeps have some kind of Delrin spacer which the manufacturer includes on the vehicles. I am not sure what the purpose is of the spacer, but some tend to fall off the vehicle and accumulate on the dealership parking lot. I harvested some of the spacers (white, gray and black) and use them for Delrin repair work. I think some street sweeper brushes have Delrin bristles. and I have a ladder-like piece of Delrin which I found somewhere.
The second Tyco diesel truck had no forks and spring between the brushes or "u"-shaped spring retainer. Therefore, I had to fabricate all of the necessary parts to get the truck up and running.
On the first modified power truck I made, I cut the phosphor-bronze electrical pick-up strip in two (laterally). The strip contacts the axles on the wheel sets and is located inside the power truck. I ended up splicing the two halves of the pick-up strip (the strip which I cut in two) with pieces of 0.005-inch thick soldered brass. Once the strip was re-assembled, I made an "S"-shaped cut through the length of the strip (start the cut on the side of the strip just before the semi-circular cut-out to clear the gears on the axles, cut down the middle of the strip and come out on the opposite side). This created two similar fork-like pieces of strip. Then I re-assembled the strip with top, middle and bottom pieces of vinyl electrical tape. The tape pieces insulate the two fork-like strip pieces from each other. I cut out two strips of 1/8-inch wide electrical tape and wrapped bands around the strip close to the gear cut-out locations on each end of the strip. I did this to hold the top / middle / bottom layers of tape together. It is not a good idea to put a band of tape around the middle of the strip because the armature can rub on the tape. (Note: You must be careful with the taping effort to separate the two fork-like pieces of strip, or the power truck subassembly may short out.)
I also had to solder a 1/8-inch-wide x 0.005 thick brass tab on one of the forks. The tab sticks out from the side of the fork directly across from the existing tab on the other fork. The new tab has to be bent upward like the tab on the opposite side. The two tabs need to be provided with some long wires which are soldered to the brass / graphite motor brushes. It is a good design because the strip can be pulled out of the way as needed for inspection and servicing of the motor commutator.
The only thing left to do is to flip one of the wheel sets around, re-assemble all the parts and test the modified power truck to see if it works. (Note: There are a couple of phosphor-bronze tabs which fit into slots on the retainer plate for the wheel sets. The tabs must fit into the slots, or the strip may contact the armature.
After rebuilding the second Tyco power truck, I still need to modify the electrical pick-up strip with an "S"-shaped cut and electrical tape and then flip the one wheel set around in the plastic truck chassis.
