Bellows Shaft Couplings | McMaster-Carr

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System of Measurement

Shaft Diameter

For Shaft Misalignment Type

Overall Length

Shaft Mount Type

Material

Maximum Torque

25 in·lbf to 49 in·lbf

50 in·lbf to 249 in·lbf

250 in·lbf or greater

Maximum Rotation Speed

10,000 rpm

Not Rated

Angular Misalignment Capability

Length

For Rotary Motion

Axial Misalignment Capability

Parallel Misalignment Capability

Torque

25 in·lbf to 49 in·lbf

50 in·lbf to 249 in·lbf

250 in·lbf or greater

REACH

Compliant

RoHS

Compliant

U.S.–Mexico–Canada Agreement (USMCA) Qualifying

Yes

DFARS Specialty Metals

Exempt

Export Control Classification Number (ECCN)

EAR99

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127 Products

High-Speed Precision Flexible Shaft Couplings

With a bellows between two hubs, these couplings handle all types of misalignment and are good for precision stepper and encoder motion-control applications. All have lightweight aluminum hubs and a stainless steel bellows for corrosion resistance. Couplings allow zero backlash (no play) and grip evenly around your shaft for a strong hold without marring the shaft. Tighten the clamping screws to secure.

						Misalignment Capability
	For Shaft Diameter	Overall Lg.	OD	Max. Rotation Speed, rpm	Max. Torque, in·lbf	Parallel	Angular	Axial	For Rotary Motion		Each
2024 Aluminum with 321 Stainless Steel Bellows



		1/8" × 1/8"	1 1/16"	19/32"	10,000	22	0.004"	1.5°	0.008"	Forward/Reverse, Start/Stop	6446K271	0000000


		3/16" × 3 mm	1 1/16"	19/32"	10,000	22	0.004"	1.5°	0.008"	Forward/Reverse, Start/Stop	6446K762	000000
		3/16" × 5 mm	1 5/16"	3/4"	10,000	40	0.004"	1.5°	0.01"	Forward/Reverse, Start/Stop	6446K769	000000
		1/4" × 1/4"	1 1/16"	19/32"	10,000	22	0.004"	1.5°	0.008"	Forward/Reverse, Start/Stop	6446K276	000000
		1/4" × 1/4"	1 5/16"	3/4"	10,000	40	0.004"	1.5°	0.01"	Forward/Reverse, Start/Stop	6446K313	000000
		1/4" × 1/4"	1 11/32"	1"	10,000	60	0.004"	1.5°	0.012"	Forward/Reverse, Start/Stop	6446K41	000000
		1/4" × 3/8"	1 11/16"	1 5/16"	10,000	120	0.006"	1.5°	0.016"	Forward/Reverse, Start/Stop	6446K89	000000
		1/4" × 3 mm	1 1/16"	19/32"	10,000	22	0.004"	1.5°	0.008"	Forward/Reverse, Start/Stop	6446K757	000000
		1/4" × 5 mm	1 1/16"	19/32"	10,000	22	0.004"	1.5°	0.008"	Forward/Reverse, Start/Stop	6446K759	000000
		1/4" × 5 mm	1 5/16"	3/4"	10,000	40	0.004"	1.5°	0.01"	Forward/Reverse, Start/Stop	6446K766	000000
		1/4" × 6 mm	1 1/16"	19/32"	10,000	22	0.004"	1.5°	0.008"	Forward/Reverse, Start/Stop	6446K761	000000


		1/4" × 6 mm	1 5/16"	3/4"	10,000	40	0.004"	1.5°	0.01"	Forward/Reverse, Start/Stop	6446K767	000000
		1/4" × 8 mm	1 5/16"	3/4"	10,000	40	0.004"	1.5°	0.01"	Forward/Reverse, Start/Stop	6446K772	000000
		1/4" × 8 mm	1 11/32"	1"	10,000	60	0.004"	1.5°	0.012"	Forward/Reverse, Start/Stop	6446K782	000000
		1/4" × 10 mm	1 11/32"	1"	10,000	60	0.004"	1.5°	0.012"	Forward/Reverse, Start/Stop	6446K785	000000
		5/16" × 1/4"	1 5/16"	3/4"	10,000	40	0.004"	1.5°	0.01"	Forward/Reverse, Start/Stop	6446K315	000000
		5/16" × 5/16"	1 5/16"	3/4"	10,000	40	0.004"	1.5°	0.01"	Forward/Reverse, Start/Stop	6446K316	000000
		3/8" × 1/4"	1 11/32"	1"	10,000	60	0.004"	1.5°	0.012"	Forward/Reverse, Start/Stop	6446K563	000000
		3/8" × 3/8"	1 11/32"	1"	10,000	60	0.004"	1.5°	0.012"	Forward/Reverse, Start/Stop	6446K565	000000
		3/8" × 3/8"	1 11/16"	1 5/16"	10,000	120	0.006"	1.5°	0.016"	Forward/Reverse, Start/Stop	6446K613	000000
		3/8" × 3/8"	2 1/32"	1 5/8"	10,000	250	0.01"	2°	0.02"	Forward/Reverse, Start/Stop	6446K43	000000


		3/8" × 6 mm	1 11/32"	1"	10,000	60	0.004"	1.5°	0.012"	Forward/Reverse, Start/Stop	6446K779	000000
		3/8" × 8 mm	1 11/32"	1"	10,000	60	0.004"	1.5°	0.012"	Forward/Reverse, Start/Stop	6446K781	000000
		3/8" × 10 mm	1 11/32"	1"	10,000	60	0.004"	1.5°	0.012"	Forward/Reverse, Start/Stop	6446K783	000000
		1/2" × 1/4"	1 11/32"	1"	10,000	60	0.004"	1.5°	0.012"	Forward/Reverse, Start/Stop	6446K566	000000
		1/2" × 1/4"	2 1/32"	1 5/8"	10,000	250	0.01"	2°	0.02"	Forward/Reverse, Start/Stop	6446K45	000000
		1/2" × 3/8"	1 11/32"	1"	10,000	60	0.004"	1.5°	0.012"	Forward/Reverse, Start/Stop	6446K568	000000
		1/2" × 3/8"	1 11/16"	1 5/16"	10,000	120	0.006"	1.5°	0.016"	Forward/Reverse, Start/Stop	6446K615	000000
		1/2" × 3/8"	2 1/32"	1 5/8"	10,000	250	0.01"	2°	0.02"	Forward/Reverse, Start/Stop	6446K44	000000
		1/2" × 1/2"	1 11/32"	1"	10,000	60	0.004"	1.5°	0.012"	Forward/Reverse, Start/Stop	6446K569	000000
		1/2" × 1/2"	1 11/16"	1 5/16"	10,000	120	0.006"	1.5°	0.016"	Forward/Reverse, Start/Stop	6446K616	000000


		1/2" × 1/2"	2 1/32"	1 5/8"	10,000	250	0.01"	2°	0.02"	Forward/Reverse, Start/Stop	6446K46	000000
		1/2" × 1/2"	2 13/32"	2"	10,000	400	0.01"	2°	0.02"	Forward/Reverse, Start/Stop	6446K861	000000
		1/2" × 6 mm	1 11/32"	1"	10,000	60	0.004"	1.5°	0.012"	Forward/Reverse, Start/Stop	6446K776	000000
		1/2" × 8 mm	1 11/32"	1"	10,000	60	0.004"	1.5°	0.012"	Forward/Reverse, Start/Stop	6446K777	000000
		1/2" × 8 mm	1 11/16"	1 5/16"	10,000	120	0.006"	1.5°	0.016"	Forward/Reverse, Start/Stop	6446K789	000000
		1/2" × 10 mm	1 11/16"	1 5/16"	10,000	120	0.006"	1.5°	0.016"	Forward/Reverse, Start/Stop	6446K787	000000
		1/2" × 10 mm	2 1/32"	1 5/8"	10,000	250	0.01"	2°	0.02"	Forward/Reverse, Start/Stop	6446K794	000000
		1/2" × 15 mm	2 1/32"	1 5/8"	10,000	250	0.01"	2°	0.02"	Forward/Reverse, Start/Stop	6446K795	000000
		5/8" × 3/8"	1 11/16"	1 5/16"	10,000	120	0.006"	1.5°	0.016"	Forward/Reverse, Start/Stop	6446K618	000000
		5/8" × 3/8"	2 1/32"	1 5/8"	10,000	250	0.01"	2°	0.02"	Forward/Reverse, Start/Stop	6446K911	000000


		5/8" × 1/2"	1 11/16"	1 5/16"	10,000	120	0.006"	1.5°	0.016"	Forward/Reverse, Start/Stop	6446K619	000000
		5/8" × 1/2"	2 1/32"	1 5/8"	10,000	250	0.01"	2°	0.02"	Forward/Reverse, Start/Stop	6446K912	000000
		5/8" × 1/2"	2 13/32"	2"	10,000	400	0.01"	2°	0.02"	Forward/Reverse, Start/Stop	6446K862	000000
		5/8" × 5/8"	1 11/16"	1 5/16"	10,000	120	0.006"	1.5°	0.016"	Forward/Reverse, Start/Stop	6446K621	000000
		5/8" × 5/8"	2 1/32"	1 5/8"	10,000	250	0.01"	2°	0.02"	Forward/Reverse, Start/Stop	6446K47	000000
		5/8" × 5/8"	2 13/32"	2"	10,000	400	0.01"	2°	0.02"	Forward/Reverse, Start/Stop	6446K863	000000
		5/8" × 10 mm	1 11/16"	1 5/16"	10,000	120	0.006"	1.5°	0.016"	Forward/Reverse, Start/Stop	6446K791	000000
		5/8" × 12 mm	2 1/32"	1 5/8"	10,000	250	0.01"	2°	0.02"	Forward/Reverse, Start/Stop	6446K803	000000
		5/8" × 20 mm	2 13/32"	2"	10,000	400	0.01"	2°	0.02"	Forward/Reverse, Start/Stop	6446K813	000000
		3/4" × 3/8"	2 1/32"	1 5/8"	10,000	250	0.01"	2°	0.02"	Forward/Reverse, Start/Stop	6446K913	000000

3/4" × 1/2"	2 1/32"	1 5/8"	10,000	250	0.01"	2°	0.02"	Forward/Reverse, Start/Stop	6446K914	000000
3/4" × 1/2"	2 13/32"	2"	10,000	400	0.01"	2°	0.02"	Forward/Reverse, Start/Stop	6446K864	000000
3/4" × 5/8"	2 1/32"	1 5/8"	10,000	250	0.01"	2°	0.02"	Forward/Reverse, Start/Stop	6446K915	000000
3/4" × 5/8"	2 13/32"	2"	10,000	400	0.01"	2°	0.02"	Forward/Reverse, Start/Stop	6446K865	000000
3/4" × 3/4"	2 1/32"	1 5/8"	10,000	250	0.01"	2°	0.02"	Forward/Reverse, Start/Stop	6446K916	000000
3/4" × 3/4"	2 13/32"	2"	10,000	400	0.01"	2°	0.02"	Forward/Reverse, Start/Stop	6446K866	000000
3/4" × 10 mm	2 1/32"	1 5/8"	10,000	250	0.01"	2°	0.02"	Forward/Reverse, Start/Stop	6446K799	000000
3/4" × 12 mm	2 13/32"	2"	10,000	400	0.01"	2°	0.02"	Forward/Reverse, Start/Stop	6446K815	000000
3/4" × 25 mm	3 1/4"	2 1/4"	10,000	530	0.012"	2°	0.03"	Forward/Reverse, Start/Stop	6446K821	000000
7/8" × 1/2"	2 13/32"	2"	10,000	400	0.01"	2°	0.02"	Forward/Reverse, Start/Stop	6446K867	000000
7/8" × 5/8"	2 13/32"	2"	10,000	400	0.01"	2°	0.02"	Forward/Reverse, Start/Stop	6446K868	000000
7/8" × 3/4"	2 13/32"	2"	10,000	400	0.01"	2°	0.02"	Forward/Reverse, Start/Stop	6446K869	000000
7/8" × 7/8"	2 13/32"	2"	10,000	400	0.01"	2°	0.02"	Forward/Reverse, Start/Stop	6446K871	000000
1" × 1/2"	2 13/32"	2"	10,000	400	0.01"	2°	0.02"	Forward/Reverse, Start/Stop	6446K872	000000
1" × 5/8"	2 13/32"	2"	10,000	400	0.01"	2°	0.02"	Forward/Reverse, Start/Stop	6446K873	000000
1" × 3/4"	2 13/32"	2"	10,000	400	0.01"	2°	0.02"	Forward/Reverse, Start/Stop	6446K874	000000
1" × 7/8"	2 13/32"	2"	10,000	400	0.01"	2°	0.02"	Forward/Reverse, Start/Stop	6446K875	000000
1" × 1"	2 13/32"	2"	10,000	400	0.01"	2°	0.02"	Forward/Reverse, Start/Stop	6446K876	000000
1" × 15 mm	2 13/32"	2"	10,000	400	0.01"	2°	0.02"	Forward/Reverse, Start/Stop	6446K807	000000
1" × 20 mm	3 1/4"	2 1/4"	10,000	530	0.012"	2°	0.03"	Forward/Reverse, Start/Stop	6446K826	000000
1 1/4" × 30 mm	3 1/4"	2 1/4"	10,000	530	0.012"	2°	0.03"	Forward/Reverse, Start/Stop	6446K829	000000
5 mm × 3 mm	27.3 mm	15 mm	10,000	22	0.1 mm	1.5°	0.2 mm	Forward/Reverse, Start/Stop	6446K634	000000
5 mm × 5 mm	27.3 mm	15 mm	10,000	22	0.1 mm	1.5°	0.2 mm	Forward/Reverse, Start/Stop	6446K636	000000
5 mm × 5 mm	33.2 mm	19.1 mm	10,000	40	0.1 mm	1.5°	0.25 mm	Forward/Reverse, Start/Stop	6446K644	000000
6 mm × 4 mm	27.3 mm	15 mm	10,000	22	0.1 mm	1.5°	0.2 mm	Forward/Reverse, Start/Stop	6446K638	000000
6 mm × 5 mm	27.3 mm	15 mm	10,000	22	0.1 mm	1.5°	0.2 mm	Forward/Reverse, Start/Stop	6446K639	000000
6 mm × 5 mm	33.2 mm	19.1 mm	10,000	40	0.1 mm	1.5°	0.25 mm	Forward/Reverse, Start/Stop	6446K646	000000
6 mm × 6 mm	27.3 mm	15 mm	10,000	22	0.1 mm	1.5°	0.2 mm	Forward/Reverse, Start/Stop	6446K641	000000
6 mm × 6 mm	33.2 mm	19.1 mm	10,000	40	0.1 mm	1.5°	0.25 mm	Forward/Reverse, Start/Stop	6446K647	000000
8 mm × 4 mm	33.2 mm	19.1 mm	10,000	40	0.1 mm	1.5°	0.25 mm	Forward/Reverse, Start/Stop	6446K648	000000
8 mm × 5 mm	33.2 mm	19.1 mm	10,000	40	0.1 mm	1.5°	0.25 mm	Forward/Reverse, Start/Stop	6446K649	000000
8 mm × 6 mm	33.2 mm	19.1 mm	10,000	40	0.1 mm	1.5°	0.25 mm	Forward/Reverse, Start/Stop	6446K651	000000
8 mm × 6 mm	34.2 mm	25.4 mm	10,000	60	0.1 mm	1.5°	0.3 mm	Forward/Reverse, Start/Stop	6446K662	000000
8 mm × 8 mm	33.2 mm	19.1 mm	10,000	40	0.1 mm	1.5°	0.25 mm	Forward/Reverse, Start/Stop	6446K652	000000
8 mm × 8 mm	34.2 mm	25.4 mm	10,000	60	0.1 mm	1.5°	0.3 mm	Forward/Reverse, Start/Stop	6446K663	000000
8 mm × 8 mm	43.2 mm	33.3 mm	10,000	120	0.15 mm	1.5°	0.4 mm	Forward/Reverse, Start/Stop	6446K685	000000
10 mm × 6 mm	34.2 mm	25.4 mm	10,000	60	0.1 mm	1.5°	0.3 mm	Forward/Reverse, Start/Stop	6446K654	000000
10 mm × 8 mm	34.2 mm	25.4 mm	10,000	60	0.1 mm	1.5°	0.3 mm	Forward/Reverse, Start/Stop	6446K655	000000
10 mm × 10 mm	34.2 mm	25.4 mm	10,000	60	0.1 mm	1.5°	0.3 mm	Forward/Reverse, Start/Stop	6446K653	000000
10 mm × 10 mm	43.2 mm	33.3 mm	10,000	120	0.15 mm	1.5°	0.4 mm	Forward/Reverse, Start/Stop	6446K664	000000
10 mm × 10 mm	51.7 mm	41.3 mm	10,000	250	0.25 mm	2°	0.5 mm	Forward/Reverse, Start/Stop	6446K686	000000
12 mm × 10 mm	51.7 mm	41.3 mm	10,000	250	0.25 mm	2°	0.5 mm	Forward/Reverse, Start/Stop	6446K687	000000
12 mm × 12 mm	34.2 mm	25.4 mm	10,000	60	0.1 mm	1.5°	0.3 mm	Forward/Reverse, Start/Stop	6446K657	000000
12 mm × 12 mm	51.7 mm	41.3 mm	10,000	250	0.25 mm	2°	0.5 mm	Forward/Reverse, Start/Stop	6446K688	000000
14 mm × 10 mm	43.2 mm	33.3 mm	10,000	120	0.15 mm	1.5°	0.4 mm	Forward/Reverse, Start/Stop	6446K669	000000
14 mm × 10 mm	51.7 mm	41.3 mm	10,000	250	0.25 mm	2°	0.5 mm	Forward/Reverse, Start/Stop	6446K689	000000
14 mm × 12 mm	43.2 mm	33.3 mm	10,000	120	0.15 mm	1.5°	0.4 mm	Forward/Reverse, Start/Stop	6446K671	000000
14 mm × 14 mm	51.7 mm	41.3 mm	10,000	250	0.25 mm	2°	0.5 mm	Forward/Reverse, Start/Stop	6446K692	000000
14 mm × 14 mm	61.3 mm	50.8 mm	10,000	400	0.25 mm	2°	0.5 mm	Forward/Reverse, Start/Stop	6446K712	000000
15 mm × 14 mm	43.2 mm	33.3 mm	10,000	120	0.15 mm	1.5°	0.4 mm	Forward/Reverse, Start/Stop	6446K676	000000
15 mm × 14 mm	51.7 mm	41.3 mm	10,000	250	0.25 mm	2°	0.5 mm	Forward/Reverse, Start/Stop	6446K695	000000
16 mm × 8 mm	43.2 mm	33.3 mm	10,000	120	0.15 mm	1.5°	0.4 mm	Forward/Reverse, Start/Stop	6446K684	000000
16 mm × 10 mm	43.2 mm	33.3 mm	10,000	120	0.15 mm	1.5°	0.4 mm	Forward/Reverse, Start/Stop	6446K679	000000
16 mm × 10 mm	51.7 mm	41.3 mm	10,000	250	0.25 mm	2°	0.5 mm	Forward/Reverse, Start/Stop	6446K697	000000
16 mm × 15 mm	61.3 mm	50.8 mm	10,000	400	0.25 mm	2°	0.5 mm	Forward/Reverse, Start/Stop	6446K718	000000
16 mm × 16 mm	43.2 mm	33.3 mm	10,000	120	0.15 mm	1.5°	0.4 mm	Forward/Reverse, Start/Stop	6446K683	000000
16 mm × 16 mm	51.7 mm	41.3 mm	10,000	250	0.25 mm	2°	0.5 mm	Forward/Reverse, Start/Stop	6446K701	000000
16 mm × 16 mm	82.2 mm	57.2 mm	10,000	530	0.3 mm	2°	0.75 mm	Forward/Reverse, Start/Stop	6446K737	000000
20 mm × 12 mm	51.7 mm	41.3 mm	10,000	250	0.25 mm	2°	0.5 mm	Forward/Reverse, Start/Stop	6446K703	000000
20 mm × 14 mm	51.7 mm	41.3 mm	10,000	250	0.25 mm	2°	0.5 mm	Forward/Reverse, Start/Stop	6446K704	000000
20 mm × 20 mm	61.3 mm	50.8 mm	10,000	400	0.25 mm	2°	0.5 mm	Forward/Reverse, Start/Stop	6446K726	000000
20 mm × 20 mm	82.2 mm	57.2 mm	10,000	530	0.3 mm	2°	0.75 mm	Forward/Reverse, Start/Stop	6446K736	000000
25 mm × 12 mm	61.3 mm	50.8 mm	10,000	400	0.25 mm	2°	0.5 mm	Forward/Reverse, Start/Stop	6446K727	000000
25 mm × 20 mm	82.2 mm	57.2 mm	10,000	530	0.3 mm	2°	0.75 mm	Forward/Reverse, Start/Stop	6446K742	000000
30 mm × 25 mm	82.2 mm	57.2 mm	10,000	530	0.3 mm	2°	0.75 mm	Forward/Reverse, Start/Stop	6446K741	000000
30 mm × 30 mm	82.2 mm	57.2 mm	10,000	530	0.3 mm	2°	0.75 mm	Forward/Reverse, Start/Stop	6446K734	000000

High-Misalignment Precision Flexible Shaft Couplings

Specially designed ridges allow these bellows couplings to compensate for more misalignment than other precision couplings—useful for low-torque, high-precision applications such as instrumentation and motion control. They also allow zero backlash (no play) and never need lubrication. Couplings are nickel and stainless steel so they can be used in mildly corrosive environments. Fasten to your shaft by tightening the set screws, which bite into the shaft to hold it.

						Misalignment Capability
	For Shaft Dia.	Overall Lg.	OD	Max. Rotation Speed	Max. Torque, in·lbf	Parallel	Angular	Axial	For Rotary Motion		Each
303 Stainless Steel and Nickel



		0.12"	35/64"	1/4"	Not Rated	0.7	0.007"	7°	0.023"	Forward/Reverse, Start/Stop	59925K83	0000000


		3/16"	37/64"	3/8"	Not Rated	1.6	0.009"	6°	0.03"	Forward/Reverse, Start/Stop	59925K88	000000
		3/16"	1 3/64"	3/8"	Not Rated	0.7	0.066"	17°	0.09"	Forward/Reverse, Start/Stop	59925K85	000000
		1/4"	47/64"	1/2"	Not Rated	6.1	0.01"	5°	0.038"	Forward/Reverse, Start/Stop	59925K92	000000
		1/4"	27/32"	1/2"	Not Rated	4.7	0.018"	9°	0.059"	Forward/Reverse, Start/Stop	59925K91	000000
		1/4"	1 3/32"	1/2"	Not Rated	3.1	0.044"	12°	0.082"	Forward/Reverse, Start/Stop	59925K89	000000
		1/4"	1 3/32"	3/4"	Not Rated	13.1	0.026"	7°	0.067"	Forward/Reverse, Start/Stop	59925K94	000000
		1/4"	1 11/32"	3/4"	Not Rated	9.9	0.046"	9°	0.096"	Forward/Reverse, Start/Stop	59925K93	000000
		5/16"	1 1/8"	1"	Not Rated	26.3	0.02"	5°	0.067"	Forward/Reverse, Start/Stop	59925K97	000000
		5/16"	1 41/64"	1"	Not Rated	14.2	0.068"	11°	0.149"	Forward/Reverse, Start/Stop	59925K96	000000