Singapore legislation

Regulation 73

Locking of nuts

All moving parts of a vehicle and all parts subject to severe vibration which are connected by bolts or studs and nuts shall be fastened by —

(a)

lock nuts;

(b)

nuts and efficient spring;

(c)

lock nut washers;

(d)

castellated nuts and split pins; or

(e)

some other efficient device,to prevent their working or coming loose.