19.5.3 Choice of Pin Type
The choice of pin depends on the circumstances of use.
Countersunk pins are used where the heads of other types might be an obstruction, as when passing over a sheave or when the shackle has to pass close to fixed structures.
For general use, and where there is no tendency for the pin to unscrew and the shackle can be observed in use, screwed pins with eye and collar are very satisfactory and easily manipulated.
For permanent installations or where there is an inherent tendency for the pin to unscrew or when the shackle cannot be observed, pins comprising bolt, nut and split cotter pin are recommended. When maximum security is required but for other reasons this type of pin is not suitable, then reference should be made to the manufacturer or Competent Person who will advise on alternative arrangements.
The forelock pin is not a preferred type. Its advantage is ease of assembly, but it should only be considered for specialised applications.