05.19.08
Motors
Over the last few days, I’ve been working on a variety of small projects. First off, I picked up the traction motor from the local rebuilder. The owner checked everything out and powered up the motor to demonstrate it for me. It ran like a charm — no bad noises. The brushes and bearings are good and there is no problem with the wiring — even after havimg sat out in the Las Vegas summer heat for 15 years. In the next few days, I’ll disassemble it so that I can have the case media blasted and powder coated.
I’ve also been studying the electrical diagrams for the car, in anticipation of designing a new instrument panel. I need to understand how the car is wired before I can decide how many switches, circuit breakers, instruments, etc. I want to put on the panel.
I got stuck when I was reviewing the circuit for the headlight motor. I had assumed (in error, as it turns out) that some kind of reversing circuit was needed to raise and lower the headlight buckets. It turns out that the reversing is actually accompliahed by the mechanical linkage between the motor and the buckets’ torque tube. The motor actually runs in one direction only.
To figure this out, I needed to disassemble the motor to see how it works. So, I figured that I might as well rebuild it at the same time. It turned out to be a good thing that I did. The motor is mounted under the left side of the hood, right near the gap between the left side of the hood and the car body. There wan’t much of an attempt to keep water from leaking between this joint in the body panels and, as a result, the interior of the headlight motor had some pretty bad rusting. It took a while with a Dremel and a wire brush to clean up the inside of the motor. Also, one of the springs that keeps pressure on one of the carbon brushes had rusted in half. Luckily, I had another that was similar in size in my Hell Box.
My motor has two wires — a red one and a green one. It doesn’t have the black, black, red and green ones indicated on the car’s wiring diagram. After a bit of experimenting with a battery charger (used as a 12-volt power supply), I determined that the motor needs to be powered between the green wire and ground. One of the motor’s brushes is grounded inside the motor’s case. Powering the motor between the red wire and ground makes it run at a faster rate, so the red wire is not used. Powering the motor between the red and green wires (not using the ground connection) makes it run erratically. The motor also has an internal limit switch in the gear head which is not used.
At 12 VDC, the motor draws about 0.61 amps and runs at about 25 RPM. This seems a bit fast to me. A 180-degree rotation of the output shaft on the motor’s gear box is enough to raise (or lower) the headlight buckets. That puts the actuation time at just over one second. Granted, my speed test was with the motor unloaded. Once the motor is connected to the linkages, it will probably turn somewhat slower. Still, it looks like the headlights pop up and down pretty fast.
I also spent some time painting some of the smaller chassis parts yesterday (grease caps, U-bolts for the sub-chassis, washer plates for the CV joints, etc. The nice thing about living in Las Vegas is that the summer sun (it was over 105 degrees yestrday) gives a nice baked enamel finish to any parts that you paint outside.
