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Control Methods

DocRef: JC24a

Control and Switching of Pointwork

For more information on construction of points Building Pointwork

Specific examples of each control method can be accessed via links in the sections below.

Depending upon the location of your trackwork, indoors or outdoors but under cover, or unprotected in the garden, the choices will differ.

The three principal methods are;

  • The simple mechanical using levers and rods.
  • The electro-mechanical using solenoids or motors or servo powered with either simple switches or digital control.
  • The pneumatic control which requires a source of compressed air.

If you are working indoors, then all of the above methods may be used without any concerns as to weather-proofing. Pneumatic is the most expensive option and the expense and complexity of it is not justifiable since its main advantage is that it is impervious to damp.

Moving outside, proofing against damp becomes a serious issue, even in a protected situation, humidity and consequent damp can cause rapid corrosion.

Plain mechanical linkage, using levers and rod, is the "basic" and cheap option, with little maintenance required.

Examples of suitable levers are available from;

For more information Mechanical Control

Electrical installations require protection both from potential corrosion and the ingress of damp which may cause current leakage and short circuits. Electronic components, such as motors and circuit boards, are especially prone to deterioration if not adequately protected.

As to commercially available point motors, (e.g. LGB), there have been mixed reports as to durability outside. Some have not experienced problems but one user, who lives in the driest part of Australia, said that several LGB motors had failed from corrosion after just a couple of years! It has been suggested that opening the casing of the motors and packing with grease will help but then you "void" the warranty. Another problem with some solenoid-type motors is that they are not "self-latching" and may require some kind of supplementary "over-centre" springing arrangement to hold the setting and prevent the switch blades moving.

For more information Electromechanical Control

Servo motors as used in radio control applications, are available in waterproof versions and are not particularly expensive, see Hobby King for options, but they do require a digital controller, e.g. Mega Points , both to program them and for operational purposes. The digital control boards will need to be weather-proofed and there are limitations upon the distances over which the signal, between the control board and the servo, can be carried reliably. One important factor with servo motors is that they will quickly burn out if subjected to continuous loading. In the context of point operation, this means that your pointwork must move freely, without exerting any resistance to movement or attempt at "self-centring". This can be the case if the switch blades are not pivoted but "sprung" in some way, as is the case with Cliff Barker track if the cast tie-bars are used to hold the switch blades.

For more information Servo control

Pneumatic operation Over the years, several US-based suppliers have offered very similar systems under a variety of names (e.g. EZ-Air) but the only current supplier is Sunset Valley Railroad . They have distributors in various countries, the current sole UK agent being Anything Narrow Gauge . This is probably the most expensive option, but for outdoor use it is claimed you can "fit and forget". All the components are rust proof but are not the simplest to install. All joints must be airtight and you need a compressor with a reservoir. Another advantage is that distance is no object. There are no problems with stiff mechanical linkages or voltage and signal "dropout" since the air pressure in the pipe system is constant. One concern which I do have is that the plastic pipework could be vulnerable to rodent, e.g. squirrel, damage and for that reason I recommend that as much of the pipework as is practicable should be encased in conduit but, having said that, the same observation can be made in respect of electrical wiring!

For more information Pneumatic Control

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