These are used with Steel Trough sleepers and C.S.T-9 sleepers. A taper of 1 in 32 is provided on either side of key so that keys can be driven from either direction. They are manufactured from a special rolled section. The keys are 190 mm in length and a gauge variation of +-3 mm can be adjusted by altering the length of drive. The performance of a key drive depends on the elastic characteristic of the Jaw and taper of the key. With wear in the components, the key may work loose and need the use of a liner.
