121(20G) Types (Clutches and brakes)

These are open-mounted clutches and brakes that have through-shaft constructions of clutch and brake outside a light alloy drum.Power is output from the input hub continuously to the output shaft. The output shaft is braked when clutch current is shut off and the brake is energized in response. The construction holds up well under radial loads due to a wide bearing span, so it can be used under high tension when mounted with V pulleys, spur gears or the like. Thanks to the through-shaft construction, output is available at both ends of the shaft, so many mechanism layouts are possible, including using both ends in split driving or mounting a detection disc or the like on one end.

Specifications

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121 (20G) Types

[Specifications]

Model	Size	Dynamic friction torque Td ［N・m］	Static friction torque Ts ［N・m］	Coil (at 20℃)				Heat resistance class	Max. rotation speed ［min^-1］	Rotating part moment of inertia J ［kg・m²］	Total work performed until readjustment of the air gap ET ［J］	Armature pull-in time ta ［s］	Torque build-up time tp ［s］	Torque decaying time td ［s］	Mass ［kg］
Model	Size	Dynamic friction torque Td ［N・m］	Static friction torque Ts ［N・m］	Voltage ［V］	Wattage ［W］	Current ［A］	Resistance ［Ω］	Heat resistance class	Max. rotation speed ［min^-1］	Rotating part moment of inertia J ［kg・m²］		Armature pull-in time ta ［s］	Torque build-up time tp ［s］	Torque decaying time td ［s］	Mass ［kg］
121-06-20G	06	5	5.5	24 DC	11	0.46	52	B	3000	1.43×10^-4	36×10⁶	C: 0.020/B: 0.015	C: 0.041/B: 0.033	C: 0.020/B: 0.015	1.5
121-08-20G	08	10	11	24 DC	15	0.63	38	B	3000	4.23×10^-4	60×10⁶	C: 0.023/B: 0.016	C: 0.051/B: 0.042	C: 0.030/B: 0.025	2.7
121-10-20G	10	20	22	24 DC	20	0.83	29	B	3000	1.42×10^-3	130×10⁶	C: 0.025/B: 0.018	C: 0.063/B: 0.056	C: 0.050/B: 0.030	5.5
121-12-20G	12	40	45	24 DC	25	1.04	23	B	3000	4.18×10^-3	250×10⁶	C: 0.040/B: 0.027	C: 0.115/B: 0.090	C: 0.065/B: 0.050	9.6
121-16-20G	16	80	90	24 DC	35	1.46	16	B	3000	1.34×10^-2	470×10⁶	C: 0.050/B: 0.035	C: 0.160/B: 0.127	C: 0.085/B: 0.055	18.5
121-20-20G	20	160	175	24 DC	45	1.88	13	B	2500	4.13×10^-2	10×10⁸	C: 0.090/B: 0.065	C: 0.250/B: 0.200	C: 0.130/B: 0.070	35
121-25-20G	25	320	350	24 DC	60	2.50	9.6	B	2000	1.02×10^-1	20×10⁸	C: 0.115/B: 0.085	C: 0.335/B: 0.275	C: 0.210/B: 0.125	64

*The dynamic friction torque, Td, is measured at a relative speed of 100 min-1. Depending on the initial torque characteristics, break-in to condition the engaging surfaces may also be required.

[Dimensions]

Size	Dimensions of part																		Dimensions of shaft
Size	A1	A2	B1	B2	C	D	E	F	G	H	J1	J2	K	L	M	N	Z1	Z2	Q1	Q2	S1	S2	U1	U2	V1	V2	X1	X2	W1, 2
6	52.5	75	80	90	55	80	27.5	53	2.6	95	65.5	40.5	105.5	181	47	33	13.5	6.5	25	20	11	38	12.5	39.5	M4×0.7, length: 8	3-M4×0.7, length: 4	3-120°	60°	4
8	65	90	90	105	65	100	27.5	61	2.6	115	78.5	48.5	126.5	217	57	37	13.5	6.5	30	25	14	45	16	47	M4×0.7, length: 8	3-M4×0.7, length: 6	3-120°	60°	5
10	80	110	110	130	80	125	32.5	72	3.2	142.5	98	62	154	270	72	47	15.5	9	40	30	19	55	21	57	M6×1, length: 11	4-M4×0.7, length: 8	4-90°	45°	5
12	105	135	140	160	90	150	35	81	3.2	165	121	73.5	184	330	92	52	20	11.5	50	40	24	64	27	67	M6×1, length: 11	4-M4×0.7, length: 8	4-90°	45°	7
16	135	160	175	185	112	190	43	97	4.5	207	149	90	221	399	113	62	24.5	11.5	60	50	28	75	31	78	M6×1, length: 11	6-M5×0.8, length: 8	6-60°	30°	7
20	155	200	200	230	132	230	45	109	6	247	187	117	276	504	142	74.5	28	14	80	60	38	90	41.5	93.5	M10×1.5, length: 17	4-M6×1, length: 12	4-90°	45°	10
25	195	240	240	270	160	290	47.5	124	20	305	238	154	334	632	183	101.5	28	14	110	70	42	115	45.5	118.5	M10×1.5, length: 17	8-M6×1, length: 12	8-45°	22.5°	12

*The input/output shaft keyways are old JIS standard class 2 while the key is old JIS standard class 1. Note that the keyway dimensions of the unit hub part do not conform to JIS standards. Check them on the dimensions table above.

*When inserting pulleys or the like onto input/output shafts, use the supplied insertion set.

*The 121-25-20G base is a casting.