8 mm Gears | McMaster-Carr

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About Roller Chain and Sprockets

Designed to meet ISO 606 and DIN 8187 international dimensional standards, these sprockets are for use with compatible ISO and DIN roller chain. They come machined to the shaft diameter size listed and are machinable up to the maximum shaft diameter size.

For technical drawings and 3-D models, click on a part number.

For ISO 05B Roller Chain (8 mm Pitch)
Number of Teeth	For Shaft Dia., mm	For Max. Shaft Dia., mm	OD, mm	Overall Wd., mm	Hub Dia., mm	Material	Specifications Met		Each
8	6	8	24	12	13	Steel	DIN 8187, ISO 606	0000000	000000
9	6	8	26.6	12	15	Steel	DIN 8187, ISO 606	0000000	00000
10	8	11	29.2	12	17	Steel	DIN 8187, ISO 606	0000000	00000
11	8	11	31.7	13	18	Steel	DIN 8187, ISO 606	0000000	00000
12	8	12	33.5	13	20	Steel	DIN 8187, ISO 606	0000000	00000
13	8	20	36.7	13	23	Steel	DIN 8187, ISO 606	0000000	00000
14	8	15	39.9	13	25	Steel	DIN 8187, ISO 606	0000000	00000
15	8	18	42	13	28	Steel	DIN 8187, ISO 606	0000000	00000
16	8	19	45	14	30	Steel	DIN 8187, ISO 606	0000000	00000
17	8	20	47.6	14	30	Steel	DIN 8187, ISO 606	0000000	00000
18	8	22	50	14	30	Steel	DIN 8187, ISO 606	0000000	00000
19	8	24	52.5	14	30	Steel	DIN 8187, ISO 606	0000000	00000
20	8	25	55	14	30	Steel	DIN 8187, ISO 606	0000000	00000
21	8	25	57.5	14	35	Steel	DIN 8187, ISO 606	0000000	00000
22	8	25	60	14	35	Steel	DIN 8187, ISO 606	0000000	00000
23	8	17	62	14	35	Steel	DIN 8187, ISO 606	00000000	00000
24	8	17	64.6	14	35	Steel	DIN 8187, ISO 606	00000000	00000
25	8	25	67.5	14	35	Steel	DIN 8187, ISO 606	0000000	00000
26	10	22	69.5	16	40	Steel	DIN 8187, ISO 606	0000000	00000
28	10	22	74.8	16	40	Steel	DIN 8187, ISO 606	0000000	00000
30	10	30	80.5	16	40	Steel	DIN 8187, ISO 606	0000000	00000

Idler Sprockets for Metric Roller Chain

Keep constant tension on your drive with these sprockets that press against your metric ISO roller chain to take up slack and reduce wear and vibration. They rotate freely on built-in ball bearings, which are double sealed to keep dirt out, and are for use with roller chain tensioners. All come with a finished bore that fits directly onto your shaft—no need for machining. These sprockets meet ISO 606, which is an international standard for dimensions and materials.

For technical drawings and 3-D models, click on a part number.

						Bearing
Number of Teeth	For Shaft Dia., mm	OD, mm	Overall Wd., mm	Hub Dia., mm	Material	Type	Material	Specifications Met		Each
For ISO 05B Roller Chain (8 mm Pitch)
23	16	62	18	40	Steel	Ball	Steel	ISO 606	0000000	000000

Timing Belt Idler Pulleys

Add these free-spinning pulleys to your timing belt setup to minimize vibration and keep belts from wearing out. The needle bearing at the center of these pulleys is lined with small, cylindrical rollers that reduce friction as they rotate. This bearing allows both the pulley and the shaft it’s mounted on to spin independently. Made from iron or steel, these pulleys are strong and wear-resistant. The black oxide coating protects the pulleys from corrosion in dry environments.

Curved teeth have more surface contact with belts than traditional trapezoidal teeth, which allows you to apply more torque without damaging belts. These teeth fit together seamlessly to prevent backlash, or unwanted movement of the belt on the pulley, for a smooth, quiet cycle. They are also known as curvilinear belt pulleys.

For technical drawings and 3-D models, click on a part number.

Metric—Press-Fit Mount

With Two Flanges

With Two Flanges and a Hub

With Two Flanges and Without a Hub

For GT Belt Trade Size
For Max. Belt Wd., mm	OD, mm	Number of Teeth	Teeth Shape	Pitch, mm	For Shaft Dia., mm	Dia., mm	Bore Type	Inside Wd., mm	Outside Wd., mm	Overall Wd., mm	Pitch Dia., mm	Number of Flanges	Fabrication	Material	Bearing Type	Hub Dia., mm		Each
20	90	32	Curved	8	20	80.12	Plain	20	31.5	46.23	81.48	2	Machined	Black-Oxide Iron	Needle Roller	69.85	0000000	0000000
30	100	36	Curved	8	30	90.3	Plain	30	48	48	91.67	2	Machined	Black-Oxide Iron	Needle Roller	__	0000000	000000
For GT2 Belt Trade Size
21	90	32	Curved	8	20	79.88	Plain	21	31.5	45.97	81.48	2	Machined	Black-Oxide Iron	Needle Roller	69.85	0000000	000000
62	100	36	Curved	8	30	90.07	Plain	62	73.91	91.19	91.67	2	Machined	Black-Oxide Iron	Needle Roller	79.5	0000000	000000

High-Strength Corrosion-Resistant HTD Timing Belt Pulleys

Move belts forward and backward or stop and start them in precise positions, especially in areas where rust is a concern. The curved teeth on these high-torque drive (HTD) pulleys have more surface contact with belts than traditional trapezoidal teeth, which allows you to apply more torque without damaging belts. These teeth fit together seamlessly to prevent backlash, or unwanted movement of the belt on the pulley, for a smooth, quiet cycle. These pulleys are often used in 3D printing, machine tool drives, robotics, and other applications where precision is essential. They are also known as curvilinear belt pulleys.

Pair pulleys with an HTD timing belt that has the same pitch. The width of your belt should not be larger than the maximum belt width listed.

Stainless steel pulleys can be wetted repeatedly without rusting or staining.

Bushing-mount pulleys grip the shaft more securely than press-fit pulleys, but require a quick-disconnect (QD) bushing or a split-tapered bushing (not included).

For technical drawings and 3-D models, click on a part number.

Stainless Steel—Press-Fit Mount

For 20 mm Max. Belt Wd.
OD, mm	Number of Teeth	Pitch, mm	For Shaft Dia.	Bore Type	Inside Wd., mm	Outside Wd., mm	Overall Wd., mm	Pitch Dia., mm	Number of Flanges	Fabrication	Hub Dia., mm		Each
65.08	22	8	1/2"	Plain	22.35	28.58	44.45	54.66	2	Machined	41.28	0000000	0000000
For 30 mm Max. Belt Wd.
65.08	22	8	1/2"	Plain	31.75	38.1	53.98	54.66	2	Machined	41.28	0000000	000000
69.85	24	8	1/2"	Plain	31.75	38.1	53.98	59.74	2	Machined	46.04	0000000	000000
74.6	26	8	1/2"	Plain	31.75	38.1	57.15	64.846	2	Machined	50.8	0000000	000000

Stainless Steel—Bushing Mount

For 20 mm Max. Belt Wd.
OD, mm	Number of Teeth	Pitch, mm	ID	Bore Type	For Bushing Style	Inside Wd., mm	Outside Wd., mm	Overall Wd., mm	Pitch Dia., mm	Number of Flanges	Fabrication		Each
70	26	8	1.374"	Finished	Quick Disconnect Style JA	22.35	28.58	28.58	62.22	2	Machined	0000000	0000000
80.17	28	8	1.625"	Finished	Split Tapered Style H	22.35	28.58	28.58	71.3	2	Machined	0000000	000000
84.94	30	8	1.625"	Finished	Split Tapered Style H	22.35	28.58	28.58	76.4	2	Machined	0000000	000000
95.25	34	8	1.871"	Finished	Quick Disconnect Style SH	22.35	28.58	28.58	86.59	2	Machined	0000000	000000
110.34	40	8	1.871"	Finished	Quick Disconnect Style SH	22.35	28.58	28.58	101.854	2	Machined	000000	000000
120.65	44	8	2.187"	Finished	Quick Disconnect Style SDS	22.35	28.58	28.58	112.04	2	Machined	0000000	000000
130.99	48	8	2.187"	Finished	Quick Disconnect Style SDS	22.35	28.58	28.58	122.22	2	Machined	0000000	000000
150.8	56	8	2.187"	Finished	Quick Disconnect Style SDS	22.35	28.58	28.58	141.224	2	Machined	0000000	000000
For 30 mm Max. Belt Wd.
78.49	28	8	1.625"	Finished	Split Tapered Style H	33.32	38.1	38.1	71.3	2	Machined	0000000	000000
84.94	30	8	1.625"	Finished	Split Tapered Style H	31.75	38.1	38.1	76.4	2	Machined	0000000	000000
90.48	32	8	1.625"	Finished	Split Tapered Style H	31.75	38.1	38.1	81.48	2	Machined	0000000	000000
95.25	34	8	1.871"	Finished	Quick Disconnect Style SH	31.75	38.1	38.1	86.59	2	Machined	000000	000000
110.34	40	8	1.871"	Finished	Quick Disconnect Style SH	31.75	38.1	38.1	101.854	2	Machined	0000000	000000
120.65	44	8	2.187"	Finished	Quick Disconnect Style SDS	31.75	38.1	38.1	112.04	2	Machined	0000000	000000
130.99	48	8	2.187"	Finished	Quick Disconnect Style SDS	31.75	38.1	38.1	122.22	2	Machined	0000000	000000
150.8	56	8	2.187"	Finished	Quick Disconnect Style SDS	31.75	38.1	38.1	142.6	2	Machined	0000000	000000
For 50 mm Max. Belt Wd.
95.25	34	8	1.871"	Finished	Quick Disconnect Style SH	53.98	60.33	60.33	86.59	2	Machined	0000000	000000
100	36	8	1.871"	Finished	Quick Disconnect Style SH	53.98	60.33	60.33	91.67	2	Machined	0000000	000000
110.34	40	8	1.871"	Finished	Quick Disconnect Style SH	53.98	60.33	60.33	101.854	2	Machined	0000000	000000

High-Strength HTD Timing Belt Pulleys

These HTD (high torque drive) pulleys have a curved tooth shape that provides higher strength than trapezoidal teeth. Select a pulley with a maximum belt width that’s the same or larger than your timing belt width.

Press-fit mount pulleys come machined to the for shaft diameter size and are machinable up to the for maximum shaft diameter size.

Bushing-mount pulleys grip the shaft more securely than pulleys that press fit. Quick-disconnect (QD) bushings and split-tapered bushings sold separately.

For technical drawings and 3-D models, click on a part number.

Press-Fit Mount

For 20 mm Max. Belt Wd.
For Belt Trade Size	OD, mm	Number of Teeth	Pitch, mm	For Shaft Dia.	For Max. Shaft Dia.	Bore Type	Inside Wd., mm	Outside Wd., mm	Overall Wd., mm	Pitch Dia., mm	Number of Flanges	Fabrication	Material	Hub Dia., mm		Each
H8M	65.03	22	8	1/2"	1.188"	Plain	22.23	28.58	44.45	56.032	2	Machined	Black-Oxide Iron	41.28	00000000	000000
For 30 mm Max. Belt Wd.
H8M	65.03	22	8	1/2"	1.188"	Plain	31.75	38.1	53.98	56.032	2	Machined	Black-Oxide Iron	41.28	00000000	00000
H8M	70.11	24	8	1/2"	1 1/4"	Plain	31.75	38.1	53.98	61.112	2	Machined	Black-Oxide Iron	46.02	00000000	00000
H8M	74.93	26	8	1/2"	1 1/4"	Plain	31.75	38.1	57.15	66.217	2	Machined	Black-Oxide Iron	50.8	00000000	00000

Bushing Mount

For 12 mm Max. Belt Wd.
For Belt Trade Size	OD, mm	Number of Teeth	Pitch, mm	ID	Bore Type	For Bushing Style	Inside Wd., mm	Outside Wd., mm	Overall Wd., mm	Pitch Dia., mm	Number of Flanges	Fabrication	Material		Each
R8M	74.6	26	8	1.346"	Finished	Quick Disconnect Style JA	14.66	21.01	33.71	66.218	2	Machined	Black-Oxide Steel	00000000	0000000
R8M	80.16	28	8	1.574"	Finished	Split Tapered Style H	14.66	21.01	30.54	71.298	2	Machined	Black-Oxide Steel	00000000	000000
R8M	84.94	30	8	1.574"	Finished	Split Tapered Style H	14.66	21.01	30.54	76.403	2	Machined	Black-Oxide Steel	00000000	000000
R8M	90.48	32	8	1.574"	Finished	Split Tapered Style H	14.66	21.01	30.54	81.483	2	Machined	Black-Oxide Steel	00000000	000000
For 20 mm Max. Belt Wd.
H8M	74.93	26	8	1.375"	Finished	Quick Disconnect Style JA	22.23	28.58	28.58	66.217	2	Machined	Black-Oxide Iron	00000000	00000
H8M	80.01	28	8	1.625"	Finished	Split Tapered Style H	22.23	28.58	28.58	71.297	2	Machined	Black-Oxide Iron	00000000	00000
H8M	85.09	30	8	1.625"	Finished	Split Tapered Style H	22.23	28.58	28.58	76.403	2	Machined	Black-Oxide Iron	00000000	00000
H8M	97.03	34	8	1.871"	Finished	Quick Disconnect Style SH	22.35	28.7	28.7	86.588	2	Machined	Black-Oxide Iron	00000000	00000
H8M	109.99	40	8	1.871"	Finished	Quick Disconnect Style SH	22.35	28.7	28.7	101.854	2	Machined	Black-Oxide Iron	0000000	00000
H8M	120.91	44	8	2.187"	Finished	Quick Disconnect Style SDS	22.35	28.7	28.7	112.039	2	Machined	Black-Oxide Iron	00000000	00000
H8M	131.07	48	8	2.187"	Finished	Quick Disconnect Style SDS	22.35	28.7	28.7	122.224	2	Machined	Black-Oxide Iron	00000000	00000
H8M	151.13	56	8	2.187"	Finished	Quick Disconnect Style SDS	22.35	28.7	28.7	142.595	2	Machined	Black-Oxide Iron	00000000	000000
For 22 mm Max. Belt Wd.
R8M	74.6	26	8	1.346"	Finished	Quick Disconnect Style JA	24.64	30.99	43.69	66.218	2	Machined	Black-Oxide Steel	00000000	000000
R8M	80.16	28	8	1.574"	Finished	Split Tapered Style H	24.64	30.99	40.52	71.298	2	Machined	Black-Oxide Steel	00000000	000000
R8M	84.94	30	8	1.574"	Finished	Split Tapered Style H	24.64	30.99	40.52	76.403	2	Machined	Black-Oxide Steel	00000000	000000
R8M	90.48	32	8	1.574"	Finished	Split Tapered Style H	24.64	30.99	30.99	81.483	2	Machined	Black-Oxide Steel	00000000	000000
For 30 mm Max. Belt Wd.
H8M	80.01	28	8	1.625"	Finished	Split Tapered Style H	31.75	38.1	38.1	71.297	2	Machined	Black-Oxide Iron	00000000	00000
H8M	85.09	30	8	1.625"	Finished	Split Tapered Style H	31.75	38.1	38.1	76.403	2	Machined	Black-Oxide Iron	00000000	00000
H8M	89.92	32	8	1.625"	Finished	Split Tapered Style H	31.88	38.23	38.23	81.483	2	Machined	Black-Oxide Iron	00000000	00000
H8M	97.03	34	8	1.871"	Finished	Quick Disconnect Style SH	31.88	38.23	38.23	86.588	2	Machined	Black-Oxide Iron	00000000	00000
H8M	109.99	40	8	1.871"	Finished	Quick Disconnect Style SH	31.88	38.23	38.23	101.854	2	Machined	Black-Oxide Iron	0000000	00000
H8M	120.91	44	8	2.187"	Finished	Quick Disconnect Style SDS	31.88	38.23	38.23	112.039	2	Machined	Black-Oxide Iron	00000000	00000
H8M	131.07	48	8	2.187"	Finished	Quick Disconnect Style SDS	31.88	38.23	38.23	122.224	2	Machined	Black-Oxide Iron	00000000	00000
H8M	151.13	56	8	2.187"	Finished	Quick Disconnect Style SDS	31.88	38.23	38.23	142.595	2	Machined	Black-Oxide Iron	00000000	000000
For 50 mm Max. Belt Wd.
H8M	97.03	34	8	1.871"	Finished	Quick Disconnect Style SH	54.1	60.45	60.45	86.588	2	Machined	Black-Oxide Iron	0000000	000000
H8M	100.08	36	8	1.871"	Finished	Quick Disconnect Style SH	54.1	60.45	60.45	91.668	2	Machined	Black-Oxide Iron	0000000	000000
H8M	109.99	40	8	1.871"	Finished	Quick Disconnect Style SH	54.1	60.45	60.45	101.854	2	Machined	Black-Oxide Iron	0000000	000000

High-Strength Ultra-Quiet Timing Belt Pulleys

Teeth are curved and set in an offset pattern for high strength with 25% less operating noise than pulleys and belts with trapezoidal teeth. Select a pulley with a maximum belt width that’s the same or larger than your timing belt width.

Press-fit mount pulleys come machined to the for shaft diameter size and are machinable up to the for maximum shaft diameter size.

Bushing-mount pulleys grip the shaft more securely than pulleys that press fit. Quick-disconnect (QD) bushings and split-tapered bushings sold separately.

For technical drawings and 3-D models, click on a part number.

Press-Fit Mount

For 16 mm Max. Belt Wd.
OD, mm	Number of Teeth	Pitch, mm	For Shaft Dia.	For Max. Shaft Dia.	Bore Type	Outside Wd., mm	Overall Wd., mm	Pitch Dia., mm	Fabrication	Material	Hub Dia., mm		Each
44.45	18	8	1/2"	7/8"	Plain	17	29	46	Cast	Magnesium-Phosphate-Coated Iron	38.7	0000000	0000000
For 32 mm Max. Belt Wd.
62.23	25	8	1/2"	1 3/8"	Plain	33	49	64	Cast	Magnesium-Phosphate-Coated Iron	53.5	0000000	000000

Bushing Mount

For 16 mm Max. Belt Wd.
OD, mm	Number of Teeth	Pitch, mm	ID	Bore Type	For Bushing Style	Outside Wd., mm	Overall Wd., mm	Pitch Dia., mm	Fabrication	Material		Each
69.85	28	8	1.625"	Finished	Split Tapered Style H	17	17	71	Cast	Magnesium-Phosphate-Coated Iron	0000000	0000000
90.43	36	8	1.871"	Finished	Quick Disconnect Style SH	17	17	92	Cast	Magnesium-Phosphate-Coated Iron	0000000	000000
For 32 mm Max. Belt Wd.
100.59	40	8	1.871"	Finished	Quick Disconnect Style SH	33	33	102	Cast	Magnesium-Phosphate-Coated Iron	0000000	000000
120.91	48	8	2.187"	Finished	Quick Disconnect Style SDS	33	33	122	Cast	Magnesium-Phosphate-Coated Iron	0000000	000000

Ultra-High-Strength Poly Chain Timing Belt Pulleys

Curved teeth with a high pitch provide superior load distribution and reduce wear. They mount with a bushing for a more secure grip on the shaft than set screws. Bushing is not included. Select a pulley with a maximum belt width that’s the same or larger than your timing belt width.

For technical drawings and 3-D models, click on a part number.

Bushing Mount

For 12 mm Max. Belt Wd.
OD, mm	Number of Teeth	Pitch, mm	ID	Bore Type	For Bushing Style	Inside Wd., mm	Outside Wd., mm	Overall Wd., mm	Pitch Dia., mm	Number of Flanges	Fabrication	Material		Each
66.04	22	8	1.386"	Finished	Taper-Lock Style 1008	15.24	22.35	22.35	56	2	Machined	Black-Oxide Steel	0000000	0000000
101.6	36	8	2.25"	Finished	Taper-Lock Style 1610	18.29	25.4	25.4	92	2	Machined	Black-Oxide Steel	0000000	000000
124.46	45	8	2.75"	Finished	Taper-Lock Style 2012	14.48	21.59	31.75	115	2	Machined	Black-Oxide Steel	0000000	000000
For 21 mm Max. Belt Wd.
66.04	22	8	1.386"	Finished	Taper-Lock Style 1008	23.37	30.48	30.48	56	2	Machined	Black-Oxide Steel	0000000	000000
101.6	36	8	2.25"	Finished	Taper-Lock Style 1610	23.37	30.48	30.48	92	2	Machined	Black-Oxide Steel	0000000	000000
124.46	45	8	2.75"	Finished	Taper-Lock Style 2012	24.64	31.75	31.75	115	2	Machined	Black-Oxide Steel	0000000	000000
For 36 mm Max. Belt Wd.
89.99	32	8	1.875"	Finished	Taper-Lock Style 1210	40.89	42.24	47.2	81.48	2	Cast	Black-Oxide Iron	00000000	000000
100.03	36	8	2.25"	Finished	Taper-Lock Style 1610	40.89	42.24	47.2	91.67	2	Cast	Black-Oxide Iron	00000000	000000
127.13	45	8	2.75"	Finished	Taper-Lock Style 2012	40.89	42.24	47.2	114.58	2	Cast	Black-Oxide Iron	00000000	000000