1.1 THE BASICS OF FITS
• 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
1.1.1 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
1.1.2 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
1.1.3 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