Cast Iron Sheave

7/8 1.6 .80
BK27 2.70 2.10 2.50 2 s 13/16 1 1/16 13/32 5/32 1/2, 5/8, 3/4, 7/8, 1.6 .84
1 1.7
BK28 2.95 2.20 2.60 2 s 13/16 1 1/16 13/32 5/32 1/2, 5/8, 3/4, 7/8, 1.6 1.0
1, 1 1/8 1.9
BK30 3.15 2.40 2.80 2 s 13/16 1 1/16 13/32 5/32 1/2, 5/8, 3/4, 7/8, 1.6 1.2
1, 1 1/8 1.9
BK32 3.35 2.60 3.00 2 s 13/16 1 1/16 13/32 5/32 1/2, 5/8, 3/4, 7/8, 1.6 1.2
1, 1 1/8 1.9
BK34 3.55 2.80 3.20 2 s 7/8 1 5/32 13/32 1/8 1/2, 5/8, 3/4, 7/8, 1, 1 1/8 1.9 1.7
BK36 3.75 3.00 3.40 2 s 7/8 1 5/32 13/32 1/8 1/2, 5/8, 3/4, 7/8, 1, 1 1/8 1.9 1.9
BK40 3.95 3.20 3.60 2 s 7/8 1 5/32 13/32 1/8 1/2, 5/8, 3/4, 7/8, 1, 1 1/8 1.9 2.1
BK45 4.25 3.50 3.90 2 s 7/8 1 5/32 13/32 1/8 5/8, 3/4, 7/8, 1.6 2.1
1, 1.7
1/2, 1 1/8 1.9
BK47 4.45 3.70 4.10 2 s 7/8 1 5/32 13/32 1/8 5/8, 3/4, 7/8, 1.6 2.2
1, 1.7
1/2, 1 1/8 1.9
BK50 4.75 4.00 4.40 3 s 7/8 1 5/32 13/32 1/8 5/8, 3/4, 7/8, 1.6 2.5
1, 1.7
1/2, 1 1/8 1.9
BK52 4.95 4.20 4.60 3 s 7/8 1 5/32 13/32 1/8 5/8, 3/4, 7/8, 1.6 2.6
1, 1.7
1/2, 1 1/8 1.9
BK55 5.25 4.50 4.90 3 s 7/8 1 5/32 13/32 1/8 5/8, 3/4, 7/8, 1.6 3.0
1, 1.7
1/2, 1 1/8, 1 3/16 2.0
BK57 5.45 4.70 5.10 3 s 7/8 1 5/32 13/32 1/8 5/8, 3/4, 7/8, 1.6 3.1
15/16, 1, 1.7
1 1/8, 1 3/16 2.0
BK60 5.75 5.00 5.40 3 s 7/8 1 5/32 13/32 1/8 5/8, 3/4, 7/8, 1.6 3.4
1, 1.7
1/2, 1 1/8, 1 3/16 2.0
BK62 5.95 5.20 5.60 3 s 7/8 1 5/32 13/32 1/8 5/8, 3/4, 7/8, 1.6 3.6
15/16, 1, 1.7
1/2, 1 1/8, 1 3/16 2.0
BK65 6.25 5.50 5.90 3 s 7/8 1 5/32 13/32 1/8 5/8, 3/4, 1.6 3.9
1, 1.7
1 1/8 2.0
BK67 6.45 5.70 6.10 3 s 7/8 1 5/32 13/32 1/8 5/8, 3/4, 1.6 3.7
1, 1.7
1 1/8, 1 3/16 2.0
BK70 6.75 6.00 6.40 3 s 7/8 1 15/32 21/32 1/16 5/8, 3/4, 7/8, 1.6 4.6
15/16, 1, 1.7
1 1/8, 1 3/16, 1 1/4 2.0
1 7/16 2.5
BK72 6.95 6.20 6.60 3 lh 7/8 1 15/32 21/32 1/16 3/4, 1.6 4.4
1, 1.7
1 1/8, 2.0
1 3/8 2.5
BK75 7.25 6.50 6.90 3 lh 7/8 1 15/32 21/32 1/16 3/4, 1.6 4.6
1, 1 1/8, 1.9
BK77 7.45 6.70 7.10 3 lh 7/8 1 15/32 21/32 1/16 3/4, 1.6 5.1
1, 1 1/8, 1.9
1 3/8 2.5
BK80 7.75 7.00 7.40 3 lh 7/8 1 15/32 21/32 1/16 5/8, 3/4, 7/8, 1.6 5.4
1, 1 1/8, 1.9
1 3/16, 1 1/4, 2.2
1 3/8, 1 7/16 2.5
BK85 8.25 7.50 7.90 3 lh 7/8 1 15/32 21/32 1/16 3/4, 1.6 5.8
1, 1.7
1 1/8, 2.2
1 3/8, 1 7/16 2.5
BK90 8.75 8.00 8.40 3 lh 7/8 1 15/32 21/32 1/16 3/4, 7/8, 1.6 6.1
15/16, 1, 1.7
1 1/8, 1 3/16, 2.2
1 3/8, 1 7/16 2.5
BK95 9.25 8.50 8.90 3 lh 7/8 1 15/32 21/32 1/16 3/4, 1.6 7.0
1, 1.7
1 1/8, 2.2
1 3/8 2.5
BK100 9.75 9.00 9.40 3 lh 7/8 1 15/32 21/32 1/16 3/4, 7/8, 1.6 7.4
15/16, 1, 1.7
1 1/8, 1 3/16, 1 1/4 2.2
1 3/8, 1 7/16 2.5
BK105 10.25 9.50 9.90 3 lh 7/8 1 15/32 21/32 1/16 1, 1.7 8.0
1 3/8, 1 7/16 2.5
BK110 10.75 10.00 10.40 3 sp 7/8 1 15/32 21/32 1/16 3/4, 1, 1.7 8.5
1 1/8, 1 3/16, 2.2
1 3/8, 1 7/16 2.5
BK115 11.25 10.50 10.90 3 sp 7/8 1 15/32 21/32 1/16 1, 1.7 8.9
1 7/16 2.5
BK120 11.75 11.00 11.40 3 sp 7/8 1 15/32 21/32 1/16 3/4, 1, 1.7 10.0
1 3/16, 2.2
1 7/16 2.5
BK130 12.75 12.00 12.40 3 sp 7/8 1 15/32 21/32 1/16 3/4, 1, 1.7 10.8
1 1/8, 1 3/16, 1 1/4 2.2
1 7/16 2.5
BK140 13.75 13.00 13.40 3 sp 7/8 1 15/32 21/32 1/16 3/4, 1, 1.7 12.1
1 3/16, 1 7/16 2.2
BK160 15.75 15.00 15.40 3 sp 7/8 1 15/32 21/32 1/16 1, 1.7 14.4
1 1/8, 1 3/16, 1 1/4 2.2
1 7/16 2.5
BK190 18.75 18.00 18.40 3 sp 7/8 1 15/32 21/32 1/16 1, 1.7 21.3
1 3/16, 1 1/4, 2.2
1 7/16 2.5
BK
6-10 .2362-.3937 High +.027 mm High +.0010 *
Low +.005 mm Low +.0001 * 1/2 +.002
10-18 .3937-.7087 High +.033 mm High +.0013 * 1/2 3/4 +.003
Low +.006 mm Low +.0020 * 3/4 1 +.003
18-30 .7087-1.1811 High +.040mm High +.0016 * 1 1 1/2 +.004
Low +.007mm Low +.0003 *
30-50 1.1811-1.9685 High +.048mm High +.0019 *
Low +.009mm Low +.0003 *
50-80 1.9685-3.1496 High +.056mm High +.0022 *
Low +.010mm Low +.0003 *
80-120 3.1496-4.7244 High +.066mm High +.0026 *
Low +.012mm Low +.0004 *
120-180 4.7244-7.0866 High +.077mm High +.0030 *
Low +.014mm Low +.0005 *
180-250 7.0866-9.8425 High +.087mm High +.0034 *
Low +.015mm Low +.0005
Bore Size Bore Size Key Tolerances
Nominal Nominal Key Width Range
Dimension Dimension G8 Tolerance G8 Tolerance
(mm) (inches) (mm) (inches) > < inches
* Note: Beginning Jan. 2004 all fixed bore and adjustable sheaves
are installed with 5/16-18 Knurled Set Screw!
MasterDrive Bore/Keyway Specifications
Standard Key Dimensions
Shaft Dia. Keyseat W x D
Dimensions Diameters Dimensions Hub Series
Part Pitch Dia Average
No. O.D. 4L or A 5L or B Type F L P C Stock Bores in. M Weight
s = solid, lh = lighting hole, sp = spoked

Cast Iron Sheaves - Light Duty
Bored-to Size, One Groove
BK24 to BK190
for 4L or A, 5L or B Belts. See pages

Cast Iron Sheaves - Light Duty
Bored-to Size, One Groove