Sighting Boards

Sighting boards are used to set up the level of the track which is generally referred to as the "top". They are usually used as a set of three boards. A common use is to carry out the lifting of sunken rail joints. Sighting boards can be clipped to the top of the rail. To raise a dipped joint the first and third boards are set up either side of the dipped rail and the second board is placed at the deepest point of the dip. The first board has a narrow slit through which the ganger peers. The central board in the dip has a screw adjustment and a scale. The rail in the dip is raised until the ganger calls out that the second board is in line with the third. (Dow A) The joint sleepers are then packed. Sighting boards are also used when setting up newly relaid track.

The FR uses sighting boards and a rail end straightener (RES). This is required because joints dipping through the vibration of the wheels on the rail joints can bend the rails ends. The purpose of the RES is to bend them back to straight. The RES is a special trolley which runs on the rails and has claws which can be closed under the rail ends. These are then raised by hydraulic jacks until the desired force is applied to bend the rails back up to straight. The "top" can then be checked with the sighting boards to check the joint has been put right.

References

Dow A (2014) The Railway: British track since 1804 page 305, Pen & Sword Books Ltd., 47 Church Street, Barnsley, South Yorkshire, S70 2AS, UK.