OD:	Outside diameter of bearing ( inches )
ID:	Inside diameter of bearing ( inches )
OH:	Overall height of bearing ( inches )
OBC, IBC:	Denotes outer and inner race bolt circle diameters ( inches )
# of Holes:	Number of mounting holes in a given race. Suffix of "N" denotes unequal spacing Suffix of "O" denotes equal spacing with one hole removed for the loading plug.
Bolt:	Denotes bolt diameter ( inches ). Threaded holes are designated by diameter and pitch. Metric bolts are designated by "M" prefix followed by diameter ( mm ).
Tooth:	Denotes tooth form. FS is Fellow Stub; ST is Stub; FD is Full Depth; MOD is Module and SP is Special tooth form.
PD:	Denotes the theoretical operating pitch diameter of the gear ( inches ).

Note: All bearings listed are 4-point contact ball styles except those with an "R" prefix. These models are Series R, crossed roller designs.

External Gear

				Mounting Holes						Gear Data					Capacity Data
	Outline Dimensions			Outer race			Inner race
Model	OD	ID	OH	OBC	# Holes	Bolt	IBC	# Holes	Bolt	Tooth	PD	Module	# Teeth	Face	Moment	Thrust	Radial	Tooth
R621A1	640	472	56	585	28	M12 x 1.5	498	32	12	MOD	630	6	105	46	48,808	448,550	179,420	32,199
817A3	525	323	57.2	475	20	16	370	20	16	MOD	515	5	103	50.8	75,774	896,952	179,390	29,254
R1032A4	979	717	100	893	18	20	753	30	20	MOD	968	8	121	65	389,720	2,367,816	947,126	60,413
1244A4	1280	987	78	1191	32	M20 x 1.5	1035	36	20	MOD	1260	10	126	71	749,911	3,345,153	386,265	68,515
1251A2	1460	1176	114	1370	40	20	1215	40	20	MOD	1440	10	144	85	1,251,006	4,838,176	558,664	102,012
1257A6	1600	1305	90	1505	26	M16 x 2	1345	30	20	MOD	1580	10	158	71	1,574,810	5,412,091	624,934	85,957
1287A1	2386	2083	87	2274	42	20	2127	42	20	MOD	2352	12	196	78	3,591,222	8,160,446	942,287	113,339
12102A1	2776	2485	90	2673	40	20	2527	40	20	MOD	2736	12	228	77	5,031,123	9,637,143	1,112,801	112,520
1532A8	948	698	102	885	24	M20 x 2.5	737	24	20	MOD	936	6	156	89	490,745	3,025,593	605,118	91,470
1570A1	1988	1648	101.6	1870	60	20	1702	62	20	MOD	1960	14	140	89	2,868,288	8,030,557	927,288	148,225
1739A3	1160	838	114	1067	30	22	889	32	22	MOD	1140	10	114	102	1,021,468	5,222,809	603,078	120,310
2054A4	1590	1206	126	1464	40	24	1260	42	24	MOD	1570	10	157	114	2,258,706	8,292,258	957,507	146,979
2258A1	1649.2	1296	165	1543	54	M24 x 3	1349.4	53-O	M24 x 3	MOD	1624	14	116	152	2,952,704	10,098,086	1,166,026	266,804
25108A1	3060	2544	165	2887	60	30	2673	60	30	MOD	3024	18	168	152	11,775,327	21,332,375	2,463,250	306,923
30106A1	3000	2505.5	200	2851	72	32	2565.4	72	32	MOD	2960	20	148	190	13,265,140	24,565,099	2,836,533	469,364

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Module:	Denotes the module of gear.
# of teeth:	Number of teeth in the gear
Face:	Face width of the gear (mm)
Capacity:	Raceway capacity (Moment, Thrust and Radial) are based upon the Theoretical Stress Limit Static Load rating for a single axis. See page 2-6 for additional information. Contact Avon Bearings Engineering for analysis of combined loading applications. Note: Bolts may be the limiting factor from a capacity standpoint. Tooth capacity denotes the Tangential Tooth Capacity based upon the Lewis equation and including a 4:1 saftey factor over the tensile strength of the steel.
Moment:	Denotes moment capacity of raceway, single-axis (Newton-meters).
Thrust:	Deontes thrust or axial capacity of raceway, single-axis (Newtons).
Radial:	Denotes radial capacity of raceway, sigle-axis (Newtons).
Tooth:	Denotes tangential tooth capacity (Newtons).