Three Position Signals

Three Position Upper Quadrant signals at Whitemoor Yard

Three Position Upper Quadrant signals at Whitemoor YardTwo three-position signals were provided at Whitemoor Hump when the marshalling yard opened in the 1930s. Their purpose was rather different to the originally intended function when this type of signal was introduced in the early 1900s.

In this photograph, taken in late days, only one arm survives. The bracket signals (which were conventional upper quadrant arms) used to read to the Engine Line.

The three position arms were used to indicate to the shunt engine driver the required speed to propel wagons over the hump.

Arm raised at 45Arm raised at 90If the arm was raised to 45º, the driver should propel at medium speed, whereas if it was at 90º (vertical), the driver should propel at normal speed.

The signals were power operated by switches controlled by the shunting staff.

Close up view of three-position signal armA close-up view of the arm shows the three lenses in the spectacle.

The original pattern arm would have tapered down slightly towards the spectacle, but here a replacement standard arm has been fitted.