Harmonic Reducer Output Bearings: SF & HF Size Chart

SF and HF output bearings

Listed by reducer size. H is the overall width, C the outer-ring width and B the inner-ring width. Cr and Cor are the basic dynamic and static radial load ratings in kN. Step dimensions and hole patterns are in the full tables below.

SF series ⌄

Sizes 14–65 · OD 55–210 mm · 8 sizes

Stepped outer ring, small bore

Model	d (mm)	D (mm)	H / C / B (mm)	Cr / Cor (kN)
SF-14	11 (9)	55	16.5 / 16 / 13.5	7 / 9.1
SF-17	10	62	16.5 / 16 / 13.5	7.6 / 10.7
SF-20	14	70	16.5 / 16 / 13.5	8.5 / 13.4
SF-25	20	85	18.5 / 18 / 16.5	13.8 / 21.6
SF-32	26	112	22.5 / 21.5 / 19	12.5 / 35.6
SF-40	32 (24)	126	24 / 22.5 / 21.5	17.6 / 33.9
SF-50	40 (32)	157	31 / 30 / 28	49.5 / 85
SF-65	52 (44)	210	39 / 37 / 35	74.6 / 133

8 models · values in brackets are the second bore listed for the same size · Request a quote →

HF series ⌄

Sizes 14–50 · bore 38–135 mm · 7 sizes

Large through bore for hollow-shaft designs

Model	d (mm)	D (mm)	H / C / B (mm)	Cr / Cor (kN)
HF-14	38	70	15.2 / 14.2 / 13.7	6.1 / 14
HF-17	47	80	17 / 16 / 16.4	9.4 / 16.1
HF-20	54	90	18.5 / 17.5 / 17.5	20.2 / 31.1
HF-25	68	110	20.7 / 18.7 / 19.7	28.5 / 45.2
HF-32	88	142	24.4 / 23.4 / 23.4	47.3 / 77.3
HF-40	108	170	30 / 29 / 28.5	35.5 / 71.2
HF-50	135	214	36 / 34 / 34.5	80.4 / 151.9

7 models · Request a quote →

Related ranges

RAU thin-section crossed roller bearings → Bore 10–200 mm, widths 5, 8 and 13 mm.
PRZ flexible bearings → Thin ball bearings for the wave generator cam of the same reducer.

Supply options (confirmed per inquiry)

Bore version, hole pattern, thread depth and seal side to your reducer drawing
Clearance or preload and rotation torque to your specification · Grease to your duty

Load ratings are catalog values for initial selection. The approved drawing and the inspection items agreed with the order define the supplied bearing.

Where the output bearing sits in a harmonic reducer

A harmonic reducer has three main parts: the wave generator (an elliptical cam with a flexible ball bearing), the flexspline and the circular spline. The output bearing is a crossed roller bearing with bolt holes in both rings. One ring is fixed to the housing side, the other turns with the output flange, so the bearing carries every external load on the output.

The output bearing and the flexible bearing do different jobs and are selected separately. The flexible bearing is on the PRZ flexible bearings page.

SF and HF: two structures

SF bearings have a small bore (10–52 mm) and a stepped outer ring. HF bearings have a large through bore (38–135 mm) for hollow-shaft designs, with two sets of holes in the outer ring. Both are listed by reducer size.

H is the overall width, C the outer-ring width and B the inner-ring width. D1, D2, d1, d2, d3, H2 and B1 are step and recess dimensions on the outline drawing, which we send with the quotation. Hole notes: 8-Φ3.5 means 8 through holes of 3.5 mm; 12-M3 (6) means 12 tapped M3 holes with a thread depth of 6 mm.

SF series: outline dimensions

All dimensions in mm. Values in brackets are the second bore listed for the same size.

Model	d	D	H	C	B	H2	D1	D2	d1	d2
SF-14	11 (9)	55	16.5	16	13.5	2.5	41.8	28	29.8	28.4
SF-17	10	62	16.5	16	13.5	2.5	49	34	36	33.8
SF-20	14	70	16.5	16	13.5	2.5	56.5	40	43	40.2
SF-25	20	85	18.5	18	16.5	2	67	51	55.3	52.6
SF-32	26	112	22.5	21.5	19	3	90	64	74	68.6
SF-40	32 (24)	126	24	22.5	21.5	2.5	105	86	86	81.2
SF-50	40 (32)	157	31	30	28	3	131.6	98	108	102.6
SF-65	52 (44)	210	39	37	35	4	176	130	138	132.6

SF series: mounting holes and load ratings

dm is the pitch circle of the outer-ring holes. dn and dL are the pitch circles of the two inner-ring hole sets. Values in brackets are the second option listed for size 14.

Model	dm	Outer-ring holes	dn	Inner-ring holes	dL	Inner-ring holes (dL)	Cr (kN)	Cor (kN)	Mass (kg)
SF-14	49	8-Φ3.5	23	6-M4	17 (14.5)	6-M4 (M3)	7	9.1	0.15
SF-17	56	10-Φ3.5	27	6-M5	19	6-M5	7.6	10.7	0.24
SF-20	64	12-Φ3.5	32	8-M6	24	8-M5	8.5	13.4	0.2
SF-25	79	16-Φ3.5	42	8-M8	30	8-M6	13.8	21.6	0.45
SF-32	104	16-Φ4.5	55	8-M10	40	8-M10	12.5	35.6	0.9
SF-40	117	20-Φ5	68	8-M10	50	8-M10	17.6	33.9	2.8
SF-50	147	16-Φ5.5	84	8-M14	60	8-M14	49.5	85	4.6
SF-65	198	20-Φ6.5	110	8-M16	80	8-M16	74.6	133	9.6

HF series: outline dimensions

All dimensions in mm. dm is the pitch circle of the outer-ring holes.

Model	d	d3	D	H	C	B	B1	d1	d2	dm
HF-14	38	36	70	15.2	14.2	13.7	5	57	53	64
HF-17	47	44.2	80	17	16	16.4	6.5	68.1	64	74
HF-20	54	51.3	90	18.5	17.5	17.5	7	78	72.6	84
HF-25	68	66	110	20.7	18.7	19.7	7.5	94.8	90	102
HF-32	88	84	142	24.4	23.4	23.4	8	123	117.6	132
HF-40	108	106	170	30	29	28.5	9.5	148	142.6	158
HF-50	135	129	214	36	34	34.5	11	188	182.6	200

HF series: mounting holes and load ratings

Outer-ring holes are listed in two sets: through holes and tapped holes on the side opposite the seal. Inner-ring tapped holes are listed for each side. A dash means no holes on that side.

Model	Outer-ring holes	Outer-ring tapped holes (opposite seal)	dn	Inner-ring tapped holes (opposite seal)	Inner-ring tapped holes (seal side)	Cr (kN)	Cor (kN)	Mass (kg)
HF-14	8-Φ3.5	2-M3 (10)	44	12-M3 (6)	—	6.1	14	0.11
HF-17	12-Φ3.5	4-M3 (10)	54	20-M3 (6)	—	9.4	16.1	0.36
HF-20	12-Φ3.5	4-M3 (6)	62	16-M3 (6)	4-M3 (6)	20.2	31.1	0.44
HF-25	12-Φ4.5	4-M3 (6)	77	16-M4 (8)	4-M3 (6)	28.5	45.2	0.7
HF-32	12-Φ5.5	4-M4 (8)	100	16-M5 (8)	4-M4 (8)	47.3	77.3	1.57
HF-40	12-Φ6.6	6-M4 (8)	122	16-M6 (10)	4-M5 (10)	35.5	71.2	2.4
HF-50	12-Φ9	6-M5 (10)	154	16-M8 (12)	8-M5 (10)	80.4	151.9	4.5

How to match a replacement

Give the complete reducer designation and the bearing marking, if any.
Check the bore version: several SF sizes list two bores.
Check the hole pattern: pitch circle, number of holes, thread size, thread depth and which side the seal is on.
Check the widths H, C and B and the step dimensions against your housing and output flange.
Send the reducer drawing or a sample bearing when anything does not match.

Reducer size alone does not fix the bearing. Two bearings for the same size can differ in bore, holes or seal side.

Frequently asked questions

Are SF and HF bearings interchangeable?

No. They are different structures with different bores, widths and hole patterns. Choose the series that matches your reducer type, then check the drawing.

Does NLHB supply harmonic reducer bearings?

Yes. NLHB provides supply and customization support for the SF and HF output bearings in these tables and for PRZ flexible bearings. Send the reducer designation and drawing.

Can the hole pattern or bore be changed?

Send your drawing. Bore, hole pattern, threads and seal side are reviewed against your design before quoting.

Can the load ratings be used to rate the reducer?

No. Cr and Cor are bearing ratings. The allowable output load of the reducer also depends on the bearing span, the mounting and the gear set, so use the reducer data for reducer selection.

Do you also supply the flexible bearing for the wave generator?

Yes. See the PRZ flexible bearings page and include the cam drawing in your inquiry.

Need a specific model in this line?

Send the part number, dimensions or drawing. We confirm specs, supplier status and lead time before quoting.

Request a Quote

Harmonic Reducer Output Bearings