Screw threads

GENERAL INFORMATION

03-11

Split pins

Always fit new split-pins of the correct size for the 
hole in the bolt or stud.

Screw threads

General
Metric threads to ISO standards are used.

Damaged nuts, bolts and screws must always be 
discarded. Cleaning damaged threads with a die or 
tap impairs the strength and  closeness of fit of the 
threads and is not recommended.

Always ensure that replacement bolts are at least 
equal in strength to  those replaced.

Castellated nuts must not be slackened to accept a 
split-pin, except in  recommended cases when this 
forms part of an adjustment.

Do not allow oil or grease to enter blind threaded 
holes. The hydraulic action on screwing in the bolt or 
stud could split the housing.

Always tighten a nut or bolt to the recommended 
torque figure. Damaged or corroded threads can 
affect the torque reading.

To check or re-tighten a bolt or screw to a specified 
torque figure, first loosen a quarter of a turn, then 
retighten to the correct torque figure.

Oil thread lightly before tightening to ensure a free 
running thread, except in the case of threads treated 
with sealant/lubricant, and self-locking nuts.