Keys & keyways specification

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Keys and keyways secure the hub and shaft to prevent relative movement between a power transmitting shaft and an attached component.

Why do we need a Key & keyway?

To secure the hub and shaft and stop relative movement between a power transmitting shaft and an attached component, a key and the keyway combine to form a keyed joint. For instance, the power transmitting shaft is securely connected to gear drives, pulleys, or sprockets using keys.

Shaft keys_keyway examples
Shaft keys & keyway examples

Keyed joints are an essential component of shafts and couplings used in mechanical power transmission because they guarantee that the connection will transmit load, power, and rotation accurately and without slipping.

Dimensions and tolerances of metric keyways for parallel keys

Keys and keyways secure the hub and shaft to prevent relative movement between a power transmitting shaft and an attached component.

Read more  on how keys and keyways work and what types are available – Keys and Keyways

For example, Gear drives, Pulleys or Sprockets are connected securely using keys to the power transmitting shaft.

Dimensions and tolerances of metric keyways for parallel keys
Figure 1. Dimensions and tolerances of metric keyways for parallel keys (source:BS 4235-1:
1972)
ShaftKeyKey way
Nominal
Diameter 
SizeWidth ( b )Depth (t)Radius
( r )
NomFreeNormalClose/
Interference
Shaft
(t1)
Hub
(t2)
dShaft (H9)Hub (D10)Shaft (N9)Hub (Js9)Shaft/Hub (P9)
OverInclb x hMinMaxMinMaxMinMaxMinMaxMinMaxMinMaxMinMaxMinMax
682×220+0,025+0,02+0,06-0,029-0,004-0,012+0,012-0,031-0,006 1,21.31,01.10,080,16
8103×330+0,025+0,02+0,06-0,029-0,004-0,012+0,012-0,031-0,006 1,81.91,41.50,080,16
10124×440+0,03+0,030+0,078-0,0300-0,015+0,015-0,042-0,0122,52.61,81.90,080,16
12175×550+0,03+0,030+0,078-0,0300-0,015+0,015-0,042-0,0123,03.12,32.40,160,25
17226×660+0,03+0,030+0,078-0,0300-0,015+0,015-0,042-0,0123,53.62,82.90,160,25
22308×780+0,036+0,040+0,098-0,0360-0,018+0,018 -0,051-0,015 4,04.23,33,50,160,25
303810×8100+0,036+0,040+0,098-0,0360-0,018+0,018 -0,051-0,015 5,05.23,33,50,250,40
384412×8120+0,043+0,050+0,12-0,043-0,021+0,021-0,061-0,0185,05.23,33,50,250,40
445014×9140+0,043+0,050+0,12-0,043-0,021+0,021-0,061-0,0185,55.73,84,00,250,40
505816×10160+0,043+0,050+0,12-0,043-0,021+0,021-0,061-0,0186,06.24,34,50,250,40
586518×11180+0,043+0,050+0,12-0,043-0,021+0,021-0,061-0,0187,07.24,44,60,250,40
657520×12200+0,052+0,065+0,149-0,0520-0,026+0,026-0,074-0,0227,57.74,95,10,400,60
758522×14220+0,052+0,065+0,149-0,0520-0,026+0,026-0,074-0,0229,09.25,45,60,400,60
859525×14250+0,052+0,065+0,149-0,0520-0,026+0,026-0,074-0,0229,09.25,45,60,400,60
9511028×16280+0,052+0,065+0,149-0,0520-0,026+0,026-0,074-0,02210,010.26,46,60,400,60
11013032×18320+0,062+0,080+0,18-0,062-0,031+0,031-0,088-0,026 11,011.27,47,60,40,6
13015036×20360+0,062+0,080+0,18-0,062-0,031+0,031-0,088-0,026 12,012.38,48.70,71,0
15017040×22400+0,062+0,080+0,18-0,062-0,031+0,031-0,088-0,026 13,013.39,49.70,71,0
17020045×25450+0,062+0,080+0,18-0,062-0,031+0,031-0,088-0,026 15,015.310,410.70,71,0
20023050×28500+0,062+0,080+0,18-0,062-0,031+0,031-0,088-0,026 17,017.311,411.70,71,0
23026056×32560+0,0740,100+0,220-0,0740-0,037+0,037-0,106-0,03220,020.312,412.71,21,6
26029063×32630+0,0740,100+0,220-0,0740-0,037+0,037-0,106-0,03220,020.312,412.71,21,6
29033070×36700+0,0740,100+0,220-0,0740-0,037+0,037-0,106-0,03222,022.314,414.71,21,6
33038080×40800+0,0740,100+0,220-0,0740-0,037+0,037-0,106-0,03225,025.315,415.72,02,5
38044090×45900+0,0870,120+0,260-0,0870-0,043+0,043-0,124-0,03728,028.317,417.72,02,5
440500100×501000+0,0870,120+0,260-0,0870-0,043+0,043-0,124-0,03731,031.319.519.82,02,5

Table 01.Dimensions and tolerances of keyways for parallel keys (source: BS 4235-1:1972)

Woodruff keys specification

Woodruff_key_keyway
Woodruff_key_keyway
KeyKey way
SizeWidth ( b )Depth (t)Radius
( r )
NomNormalClose/
Interference
Shaft
(t1)
Hub
(t2)
Shaft (N9)Hub (Js9)Shaft/Hub (P6)
b x h1 x DMinMaxMinMaxMinMaxMinMaxMinMaxMinMax
1,0 x 1,4 x 41-0,029-0,004 -0,012+0,012 -0,0031-0,006 1,01,10,60,70,160,08
1,5 x 2,6 x 71,5-0,029-0,004 -0,012+0,012 -0,0031-0,006 2,02,10,80,90,160,08
2,0 x 2,6 x 72,0-0,029-0,004 -0,012+0,012 -0,0031-0,006 1,81,91,01,10,160,08
2,0 x 3,7 x 102,0-0,029-0,004 -0,012+0,012 -0,0031-0,006 2,93,01,01,10,160,08
2,5 x 3,7 x 102,5-0,029-0,004 -0,012+0,012 -0,0031-0,006 2,72,81,21,30,160,08
3,0 x 5,0 x 133,0-0,029-0,004 -0,012+0,012 -0,0031-0,006 3,84,01,41,50,160,08
3,0 x 6,5 x 163,0-0,029-0,004 -0,012+0,012 -0,0031-0,006 5,35,51,41,50,160,08
4,0 x 6,5 x 164,0-0,030-0,015+0,015-0,042-0,0125,05,21,81,90,250,16
4,0 x 7,5 x 194,0-0,030-0,015+0,015-0,042-0,0126,06,21,81,90,250,16
5,0 x 6,5 x 165,0-0,030-0,015+0,015-0,042-0,0124,54,72,32,40,250,16
5,0 x 7,5 x 195,0-0,030-0,015+0,015-0,042-0,0125,55,72,32,40,250,16
5,0 x 9.0 x 225,0-0,030-0,015+0,015-0,042-0,0127,07,32,32,40,250,16
6,0 x 9,0 x 226,0-0,030-0,015+0,015-0,042-0,0126,56,82,82,90,250,16
6,0 x 11,0 x 286,0-0,030-0,015+0,015-0,042-0,0127,57,82,83,00,250,16
8,0 x 11,0 x 288,0-0.036-0.018+0,018 -0.051+0,015 8,08,33,33,50,400,25
10,0×13,0x3210,0-0.036-0.018+0,018 -0.051+0,015 10,010,33,33,50,40,25

Table 02.Dimensions and tolerances of metric keyways for Woodruff keys