36.1 THE BASICS OF FITS

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A set of reasonable fits is suggested below,

shafts rotating under 600 rpm with ordinary loads; >RC5

shafts rotating over 600 rpm with heavy loads; < RC5

shafts sliding freely; approx. LC

push fits with keyed shafts and clamp, no fitting; LT

parts assmemble with some basic fitting; LN

Permanent assembly with no freely moving parts; FN1

permanent assembly with severe loading effects; FN3

permanent assembly with press needed for assembly; FN5

36.1.1 Clearance Fits

A clearance fit always has a gap between the two mating parts.

The diagram below shows a clearance fit between a shaft and a hole

36.1.2 Transitional Fits

This type of fit may result in interference, or clearance

This type of fit can be used for items such as snap fits

The figure below illustrates this condition for a hole shaft pair

36.1.3 Interference Fits

Interference fits always overlap and are used mainly for press fits where the two parts are pushed together, and require no other fasteners

The figure below shows an interference fit for a hole shaft pair