KEY SIZE VERSUS SHAFT DIAMETER PER ANSI B17.1-1967 (R1998)

ANSI B17.1-1967 standard gives a uniform relationship between shaft sizes and key sizes for parallel and taper keys as shown in the following page.

The size of a key is determined by the diameter of the shaft at the point of location of the key, regardless of the number of different diameters on the shaft. The designer chooses an appropriate key length to carry the torsional load. Failure of the key can be by direct shear, or by bearing stress.

Square keys are preferred through 6-1/2 inch diameter shafts and rectangular keys are preferred for larger shafts.

Shaft diameters are listed for identification of various key sizes and are not intended to establish shaft dimensions, tolerances or selections.

Calculator:

INPUT PARAMETERS
Nominal shaft diameter [over - to (incl.)]

 


Shaft sizes and key sizes
RESULTS
Parameter Symbol Value Unit
Nominal shaft diameter [over - to (incl.)] --- --- inch
Nominal Key Size Width ---
Height Square Key H ---
Rectangular Key ---
Nominal Keyseat Depth Square Key H/2 ---
Rectangular Key ---

Definitions:

Key: A demountable machinery part which, when assembled into keyseats, provides a positive means for transmitting torque between the shaft and hub.

Keyseat: An axially located rectangular groove in a shaft or hub.

Sunk Key: A standard form of key with rectangular or square cross-section in which the key fits into the keyseats on the shaft and the hub.

Reference:
  • Oberg, E. , Jones ,F.D. , Horton H.L. , Ryffel H.H., (2016) . Machinery's Handbook . 30th edition.  Industrial Press Inc.
  • Oberg, E. , Jones ,F.D. , Horton H.L. , Ryffel H.H., (2012) . Machinery's Handbook . 29th edition.  Industrial Press Inc.
  • ANSI B17.1-1967, Keys and Keyseats