What's involved when installing point motors?

If you're not electrically minded, the thought of installing solenoid point motors to your layout for the first time can be a little bit scary but don't worry because when you have done it once, it's really quite easy.

The circuit you'll have to create to install point motors consists of a power supply, a CDU (Capacitor Discharge Unit), a momentary pulse switch and the solenoid point motor. Starting with the power supply, this traditionally comes from the auxiliary port on a controller, 16v AC or 12v DC auxiliary ports are both fine but given a choice, 16v AC will provide more oomph which is always nice to have. If you do not have an auxiliary port on your controller, you could consider using a separate dedicated controller or a type of CDU that plugs directly into the wall. 

The next component required is the CDU. The purpose of this device is to amplify the power received from your auxiliary port to a level that will move your turnout's point blades competently and reliably. The amplified power will be stored in the CDU until you require the points to be changed.

Next in the circuit, you will need to install a 'momentary pulse switch'. This type of switch is required rather than a regular two-way toggle switch because your point motor does not require a constant supply of power to operate. The switch looks like a regular toggle switch but has its resting position in the middle (which is its isolated mode). A quick push to the left or right will allow a pulse of strong power to pass through the circuit to move your points from one side to the other.

This brings us to the point motor and the need for the first two components. Solenoid point motors operate by using two electromagnets (one placed on either side of the device). A short, sharp pulse of electricity provided by the switch and CDU will magnetise the selected side resulting in the device's drawbar being attracted to one side or the other respectively and the point blades will move. Only a short burst of power is required because once the blades have moved into position, no further movement or pressure is required and the momentary pulse switch is the best way of achieving this. The amplified power provided by the CDU is needed to ensure the magnetic pull created is strong enough to ensure a positive and reliable movement of the point blades every time.

The last thing to consider when installing point motors is how the motor attaches to the turnout. This is done using the thin metal bar which protrudes from the point motor and connects to the turnout's drawbar through a hole in the baseboard. This is a very effective and unobtrusive way of installing point motors with very little evidence of their presence thanks to the motor being hidden beneath the baseboard, however, if no hole was drilled in the baseboard prior to fixing the turnout in place, you will be left with the unenviable choice of either lifting the track or trying to drill a hole from underneath without damaging the turnout.