FITTING LOCK TO A KNOTT-AVONRIDE COUPLING HEAD
1.	Move the catch in direction of arrow ‘a’ and handle in direction of arrow ‘b’ until roll pin is exposed.
2.	Using a suitable drift remove roll pin. Do not drill.
3.	The original catch can now be removed. Retain spring for use with the lock. Discard the 2 washers and the plastic blank
4.	Locate lock into catch, secure with special nut. Position locking cam by tightening screw position - shown in fig.2. Replace spring into catch under locking cam (see fig.2) and place assembly in position on coupling body.
5.	Line up catch holes and insert new roll pin.
Check all parts are secure and test locking mechanism operates freely