Prototype Considerations For Signals
Of course I am referring to Semaphore Signals, specifically British ones:
Upper Quadrant Signals
When the signalman pulls the signal 'off',you would not expect there to be much bounce as he is working against both the weight of the signal arm and the balance weight but this is not necessarily the case.
However, when returning the signal to danger then,no matter how careful the signalman does it, the weight of the signal arm will induce bounce, this can of course vary in amount and amplitude, gradually decaying as the arm settles.
Lower Quadrant Signals
Here the picture is slightly different. When the signalman pulls the signal arm off, the weight of the signal arm dropping to clear induces bounce (a good example of this was in the opening sequence of 'The Land Girls').
When returning the arm to danger, the signalman is working against the weight of the arm, though this should be more than matched by the balance weight. So unless, the signalman is careless there is little or no bounce.
Signal-arms operated by cable rather than rod, are liable to exhibit more bounce than those operated by rod.
Speed of operation is also a consideration, normally, a return to Danger would be quicker than when 'pulling-off'’.
The type of signal post also has an impact, tubular types being less stiff than wooden ones, flex more and induce more bounce.
Solutions for the Modeller
Over the years, there have been many and varied mechanical mechanisms proposed and written about but all have been, prone to over complication, requiring constant adjustment.
For some time there has been an alternative solution based around Radio Control Servos, not only can they be used for signal control but also for points as they are both quiet and powerful. However, you cannot use them as they come, life is just not that simple, unfortunately, as they have too much throw. This is where the microprocessor comes in to drive the servo-motors.
How does it work? With my system, you connect the boards up to their power source and suitable on/off toggle switches for the servo control.
