Photos of full size mechanical signal and point operating equipment.
Compensators.
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Compensators. A compensator is a simple device consisting of two offset cranks and a fixed linkage which keeps the rodding run at the correct length as the ambient temperature changes. Rodding runs are made of metal rods, often inverted `U' channel but there are several types, the metal rodding will expand as the temperature rises and contract as it gets colder, yet it still has to operate over a fixed distance that does not change with temperature. By splitting the rodding run into two equal halves and fitting a compensator at the mid-point any expansion or contraction in the rodding due to temperature will be `taken up' in the compensator which effectively balances the length of the run keeping it at the required fixed length over a range of temperatures. The compensators in this photograph have been fitted below the level of the main rodding run. Note the short lengths of angled rod used to drop down below the rodding run level to the compensator cranks.
