Solenoid Operated Start Gate Notes

This information applies only to EARLY versions of SuperTimer II. As part of our continuing committment to Pinewood Derby Timer improvement, later versions include an extended peg (replacing the brass tab), stronger solenoid and an automatic gate latching mechanism.

See the CURRENT VERSION Pinewood Derby Timer Start Gate pictures in the online user's manual.


Many users have successfully installed and operated the solenoid operated start gate, but a few have had problems that look like the solenoid doesn’t work. After working with those users and analyzing their comments, we have prepared the following as a guide to successful installation and operation. The drawing below illustrates a side view of a typical start gate.

pinewood derby timer

The most important part of the above drawing is the area labelled by SPACE. This space need only be the thickness of a piece of paper but it must be a SPACE from front to back and from left to right across the entire Start gate. If the Start gate in the normally closed condition hits the Track, that interference puts great sideways pressure on the Plunger to Tab connection which forces the Plunger sideways making it very difficult to retract.

You can eliminate any interference in a number of ways depending on where the interference is:

  1. Move or bend the Tab.
  2. Remount or shim the Hinge.
  3. Shave or file the Start gate.
Further sideways pressure is put on the Plunger by a too strong rubber band and the load of the cars. In general, the rubber band should be long and weak, just enough to pull the gate below the track.

You can make the Solenoid stronger by insuring that the clearance between a fully retracted Plunger and the Tab is at a minimum. The further the plunger has to travel the weaker it is when it starts.

You can make the sideways pressure on the solenoid plunger much less by increasing the distance from the center of rotation of the gate (eg. hinge pin) to the solenoid. This is done by adding wood between the bar and the tab or using a long flattened nail instead of the tab or other creative means. In the current revision we use a peg from the SuperTrack starting gate instead of the brass tab. The peg rests on top of the plunger instead of in the middle slot.

More ideas are available on the SuperTrack Start Gate Detail page.

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