Points (or switches) are a very important part of any railway, whether it be a rural junction or a mainline station. The controlling of these points is the responsibility of the signalman, who would pull leavers in sequence to throw the point left or right depending on the intended direction of the locomotive.
Different Types of Point Motors
For model railway use there are lots of different ways to throw points. In the early days modellers used wire in a tube, inserting a length of piano wire through a metal or plastic tube and attaching it to a tie-bar on the point. The wire was then pulled and pushed to throw the point in the required direction.
Solenoid point motors use two solenoids connected to a suitable power supply to pull a pin towards them. This pin is attached to the tie bar and throws the switch in the required direction.
Solenoid motors come in all shapes and sizes and can be used both above, or under the baseboard depending on the design of the layout (and the motor). Point motors mounted under the board can be easily hidden out of sight, but above mounted motors can be used over joints and hard to reach areas where an under board motor will not fit. I would always recommend installing a Capacitor Discharge Unit to ensure efficient point throwing.
Wiring a point motor normally consists of three wires - a Common, which provides power to the motor, and two switch wires which when activated complete the circuit to either throw the point motor pin left or right.
Frequently Asked Questions
Q: Why does point motor makes a buzzing sound during operation?
A: This sound is made when the 16v supply is being pulled across the solenoid. It is perfectly normal but can be overcome by adding a Capacitor Discharge Unit into the circuit.
Q: How many points can I run off a capacitor discharge unit?
A: You can use one capacitor discharge unit to wire up the whole layout, but actual operation you will be limited to up to three at a time.
Q: What switches do I need to operate my Hornby points?
A: As the Hornby motors are solenoids you can use any of the switching methods described in the article.
Q: Can I operate more than one point motor with one switch to create a crossover from track 1 to track 2?
A: Yes, all you would need to do is locate the wires that throw the point motors in the direction you want and wire them into one half of the switch (Left Switch wire) and attach the others to the other side (Right Switch wire)
Q: What power supply do I need to power my point motors?
A: Solenoid motors can take a 16v AC supply but if you wire them up with a Capacitor Discharge Unit in the circuit they can take up to 24v AC. Personally, I always use a 16v supply with a Capacitor Discharge Unit connected to the transformer output to give a nice positive thump across.