Light bulb replacement for TYCO US1 Electric Trucking #3937 Department Of Highways Dump Truck

[biddle]

This video will show you how to bring your old lighted US1 Trucking Peterbilt or Dump truck back to life! I used the #3937 Department Of Highways Dump Truck in this video. I purchased it and soon discovered it had no light bulb at all! As you can see, this is easily fixed. We sell the bulbs on our website at https://tycous1trucking.com/replacement-repair-parts/#bulbs

 

[Tyco Trucking]

Also when installing the motor back, make sure the marked magnet goes down. If it is placed facing up the truck will run backwards.

 

[biddle]

Also when installing the motor back, make sure the marked magnet goes down. If it is placed facing up the truck will run backwards.

Funny when I did the Peterbilt cab video I mentioned this because I remember putting it in upside down once. I went to run both of my DOH trucks on the track and the other one's bulb had burned out lol. Now they both work again.

 

[Tyco Trucking]

That is a good repair video. I wondered if one of the wires on the lamp has a way to know the positive side of the lamp. It could just be bi-directional, but typically a DC bulb will have a power side and a ground side.

You may want next time to slide a piece of shrink tubing or something on the wires so they don’t touch any metal. That will cause a direct short and could weld the speed selector to the resistor winding in the terminal.

Messing with the terminals I found out that the voltage remains constant (at the output of the transformer) regardless of the speed level selected. It changes the amperage across the resistor to regulate speed.

You’ll need a sleeve on each wire because the voltage is switched from one rail to the other, which is what flipping the motor does, but permanently until it’s flipped correctly.

I looked at the Fire Engine because I noticed the light and bell doesn’t work when in reverse. Where the drive gear is, there is a spring behind the gear with a tab on the gear. The spring acts like a clutch, and it actually is timed to park the flashing nub TDC on the axle shaft to hold the conduit off the axle. The gear does rotate freely on the axle and until the tab interlocks the spring the axle won’t turn.

Why this is a feature I don’t know, unless as I said it keeps the positive voltage from going to the ground side of the bulb.

I’m going to have to pull out a 3911 and a multimeter and go through that again to understand it better. I got the gist but how reversing the truck affects the flow of power and ground through the chassis.

 

[biddle]

I wondered if one of the wires on the lamp has a way to know the positive side of the lamp.

You may want next time to slide a piece of shrink tubing or something on the wires so they don’t touch any metal.

The light works when the truck is going forward or reverse so it doesn't matter what side the bulb is soldered for polarity.