Design Guide

Operating Principle
Design Consideration
Installation
Specifications

Specifications

Linear Rotary Precision (LR) and Linear Rotary Super Precision (LRP)

Bearing No. Working Bore Outside Diameter Length
A LR LRP
Tolerance +0000 to Tolerance +0000 to Concentricity (T.I.R.) B Tolerance +0000 to C Tolerance +0000 to
6 0.3750 -0.0005 -0.0003 0.0005 0.6250 -0.0004 0.875 -0.015
8 0.5000 -0.0005 -0.0003 0.0005 0.8750 -0.0004 1.250 -0.015
10 0.6250 -0.0005 -0.0003 0.0005 1.1250 -0.0004 1.500 -0.015
12 0.7500 -0.0005 -0.0003 0.0005 1.2500 -0.0004 1.625 -0.015
16 1.0000 -0.0005 -0.0003 0.0005 1.5625 -0.0004 2.250 -0.015
20 1.2500 -0.0006 -0.0004 0.0010 2.0000 -0.0005 2.625 -0.020
24 1.5000 -0.0006 -0.0004 0.0010 2.3750 -0.0005 3.000 -0.020
32 2.0000 -0.0008 -0.0005 0.0015 3.0000 -0.0006 4.000 -0.020
40 2.5000 -0.0010 -0.0005 0.0015 3.7500 -0.0008 5.000 -0.025
48 3.0000 -0.0012 -0.0006 0.0015 4.5000 -0.0010 6.000 -0.030
64 4.0000 -0.0020 -0.0010 0.0020 6.0000 -0.0012 8.000 -0.040

 

Bearing No. Distance between retaining rings Retaining Ring Groove Dimensions Maximum Shaft Diameter Ball Diameter No. of Ball Circuits Bearing Weight (lbs)
D Tolerance Groove Width Groove Diameter LR LRP
6 0.562 0.010 0.039 0.593 0.3745 0.3747 1/16 6 0.05
8 0.875 0.010 0.046 0.770 0.4995 0.4997 5/64 7 0.07
10 1.000 0.010 0.056 1.057 0.6245 0.6247 3/32 7 0.15
12 1.062 0.010 0.056 1.178 0.7495 0.7497 3/32 8 0.22
16 1.625 0.010 0.068 1.500 0.9995 0.9997 1/8 8 0.45
20 1.875 0.010 0.068 1.886 1.2494 1.2496 5/32 9 0.93
24 2.250 0.015 0.086 2.255 1.4994 1.4996 5/32 9 1.45
32 3.000 0.015 0.103 2.880 1.9992 1.9996 7/32 9 2.85
40 3.750 0.015 0.120 3.562 2.4990 2.4995 9/32 9 5.95
48 4.500 0.015 0.120 4.310 2.9988 2.9994 5/16 9 10.00
64 6.000 0.020 0.139 5.745 3.9980 3.9990 7/16 9 23.20

 

Notes:

  1. The groove widths marked match standard retaining ring thicknesses.
  2. To order wipers - one end, add the suffix W, i.e. LR-W
  3. To order wipers - both ends, add the suffix WW, i.e. LR-WW
  4. For shaft to bearing selection a clearance of 0.0005 is recommended.
  5. Shaft diameters greater than specified could cause ball loss during insertion.

Chart 1 - Maximum Allowable Loads

Bearing No. Shaft Dia. Revolutions per minute
Linear Only 50 100 200 300 500 900 1200 1500 1800 2400 3650
LR-6 0.3750 70 61 48 39 33 29 23 21 20 18 17 15
LR-8 0.5000 185 161 128 102 89 76 61 56 52 48 44 39
LR-10 0.6250 283 246 195 156 136 116 93 85 79 74 68 59
LR-12 0.7500 325 283 224 179 156 133 107 98 91 85 78 68
LR-16 1.0000 450 392 311 248 216 185 149 135 126 117 108 95
LR-20 1.2500 600 522 414 330 288 246 198 180 168 156 144 126
LR-24 1.5000 935 813 645 514 449 383 309 281 262 243 224 196
LR-32 2.0000 1340 1166 925 737 643 549 442 402 375 348 322 281
LR-40 2.5000 1830 1592 1263 1018 878 750 604 549 512 475 439 --
LR-48 3.0000 2370 2062 1635 1304 1138 972 782 711 663 616 -- --
LR-64 4.0000 5285 4598 3647 2907 2537 2167 1744 1585 1480 -- -- --
 

Notes:

  1. Load ratings based on use with hardened shaft - Rockwell 60C.
  2. Based on travel life of 10 million inches.
  3. For speeds and loads not listed, consult Linear Rotary Bearings.

Chart 2 - Shaft Selection Chart

Standard AISI C-1060 Steel hardened to Rockwell 58/63C or 440C.  Stainless steel shafts hardened to Rockwell 50/55C are charted below.  Shafting can be supplied up to 12 feet long or can be cut to any length.  Special tolerances, dimensions or end matching will be promptly quoted.

All units in inches, except where noted.

Nominal Diameter* Tolerance Code Tolerances Weight per inch (lb) Min. Depth of Hardness
3/8 A 0.3735 / 0.3740 0.031 0.040
B 0.3740 / 0.3745
1/2 A 0.4985 / 0.4990 0.055 0.060
B 0.4990 / 0.4995
R 0.4998 / 0.5000
5/8 A 0.6235 / 0.6240 0.086 0.060
B 0.6240 / 0.6245
R 0.6248 / 0.6250
3/4 A 0.7485 / 0.7490 0.125 0.060
B 0.7490 / 0.7495
R 0.7498 / 0.7500
1 A 0.9985 / 0.9990 0.222 0.080
B 0.9990 / 0.9995
R 0.9998 / 1.0000
1 1/4 A 1.2485 / 1.2490 0.348 0.080
B 1.2490 / 1.2495
R 1.2498 / 1.2500
1 1/2 A 1.4984 / 1.4969 0.500 0.080
B 1.4989 / 1.4994
R 1.9997 / 2.0000
2 A 1.9980 / 1.9987 1.391 0.100
B 1.9987 / 1.9994
R 1.9997 / 2.0000
2 1/2 A 2.4977 / 2.9983 1.391 0.100
B 2.4985 / 2.4993
R 2.4995 / 2.5000
3 A 2.9974 / 2.9983 2.003 0.100
B 2.9983 / 2.9992
R 2.9994 / 3.0000
4 A 3.9964 / 3.9976 3.560 0.100
B 3.9976 / 3.9988
R 3.9991 / 4.0000

*For other sizes and tolerance, consult Linear Rotary Bearings.

Bearing Selection

  • Chart 3 - Load Correction Factor (Kl) vs. Travel Life in Millions of Inches
  • Chart 4 - Load Correction Factor (Kh) vs. Shaft Hardness - Rockwell "C"

Sizing Example

A pick and balance machine requires two linear rotary bearings.  Total load is 800 lbs.  Maximum rotation is 300 RPM.  Shafts are to be hardened to Rc 55C.  Travel life is required to be 25,000,000 inches.

Calculations:

Load bearing = 800 lbs / 2 = 400 lbs. @ 300 RPM

Shaft hardness RC 55: from Chart 4 we obtain a load correction factor Kh = 0.76

Load factor for 25,000,000 inches: from Chart 3 we obtain Kl = 0.75

Factored load capacity = 400 / (Kh * Kl) = 400 / (0.76 * 0.75) = 702 lbs.

From Chart 1, we obtain for 702 lbs. @ 300 RPM a Linear Rotary bearing rated at 878 lbs. (LR-40)

Calculate margin of safety = (878 / 702) - 1 = 25%

NOTE: Means of measuring inches of travel = Shaft diameter (inches) x 3.1416 x Revolutions + Linear Inches Travel

Shaft Selection

Because of its inherent geometric configuration, the linear rotary bearing has no inner race.  Therefore, to take full advantage of its superior characteristics, proper shaft selection is mandatory.  Under "Design Guidelines" correct diameters were suggested.  To achieve the full rated life cycle and smooth operation, the shaft shoud be AISI C-1000 steel case hardened to Rockwell 58-63C or from 440 Stainless Steel, case hardened to Rockwell 50-55C.  If shaft hardness cannot be met, see Chart 4 for the reduction factor.

Lubrication

The lubrication factor is a function of speed, linear plus rotary, where applicable.  The faster the ball movement, the less viscous the oil required.  It is theoretically possible to use no lubricant at high speeds.  The load factor must also be considered.  It is suggested that a light machine oil be used, if only to prevent corrosion.

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Last Updated: 19 October 2009