1、_ SAE Technical Standards Board Rules provide that: “This report is published by SAE to advance the state of technical and engineering sciences. The use of this report is entirely voluntary, and its applicability and suitability for any particular use, including any patent infringement arising there
2、from, is the sole responsibility of the user.” SAE reviews each technical report at least every five years at which time it may be revised, reaffirmed, stabilized, or cancelled. SAE invites your written comments and suggestions. Copyright 2013 SAE International All rights reserved. No part of this p
3、ublication may be reproduced, stored in a retrieval system or transmitted, in any form or by any means, electronic, mechanical, photocopying, recording, or otherwise, without the prior written permission of SAE. TO PLACE A DOCUMENT ORDER: Tel: 877-606-7323 (inside USA and Canada) Tel: +1 724-776-497
4、0 (outside USA) Fax: 724-776-0790 Email: CustomerServicesae.org SAE WEB ADDRESS: http:/www.sae.org SAE values your input. To provide feedback on this Technical Report, please visit http:/www.sae.org/technical/standards/J2535_201302 SURFACE VEHICLE RECOMMENDED PRACTICE J2535 FEB2013 Issued 2001-03 Re
5、vised 2013-02 Superseding J2535 DEC2006 Setting Preload in Heavy-Duty Wheel Bearings RATIONALE The changes are to correct the cornering values in Table 4 which were transposed for city delivery, to define Target Preload Setting and clarify the Preload setting procedure. 1. SCOPE This SAE Recommended
6、 Practice applies to the four primary, large volume applications in the class 7-8 heavy-duty market place, as specified in SAE J1842: a. “N” trailer axle b. “R” powered rear axle c. “FF / FG” nonpowered front axle d. “P” trailer axle This document applies to on-highway applications. It is not applic
7、able to those applications that exceed the GAWR ratings or the load line restrictions listed in columns “A,” “B,” and “C” of Table 1. Load lines are measured from the inboard bearing cup backface as shown in 3.4. This document establishes preload force values only. The methodology to obtain these fo
8、rce values must be determined by the fastener supplier and/or axle assembler. This document reviews the bearing system. It is NOT intended to prescribe (new or existing) axle and/or hub manufacturers ratings and/or specifications. 1.1 Purpose The purpose of this document is to list acceptable axial
9、bearing preload force values for conventional wheel-end components used in heavy-duty tractors and trailers. SAE J2535 Revised FEB2013 Page 2 of 7 The audience of this document is intended to be the axle and/or component engineers. The user should be aware of both the benefits and the risks of this
10、practice. a. Benefits - Bearing and seal life can be maximized when the bearings are adjusted to a light, controlled preload setting. b. Risks - The benefits of a light and controlled preload bearing setting are negated if bearing preload force is excessive. Care must be taken to ensure that preload
11、 force does not exceed the recommended amounts. Excessive preload can cause high operating temperatures, reduced lubricant life, reduced seal life, and premature bearing damage. Bearing lock-up and/or wheel-end assembly separation may occur if the preload force is excessive. A light preload bearing
12、setting should only be attempted if the entire bearing setting process is accurate and repeatable. For adjustment recommendations where bearing end-play is desired, refer to The Technology and Maintenance Council (TMC) Recommended Practice #RP-618. 2. REFERENCES 2.1 Applicable Documents The followin
13、g publications form a part of this specification to the extent specified herein. Unless otherwise indicated, the latest issue of SAE publications shall apply. 2.1.1 SAE Publication Available from SAE International, 400 Commonwealth Drive, Warrendale, PA 15096-0001, Tel: 877-606-7323 (inside USA and
14、Canada) or 724-776-4970 (outside USA), www.sae.org. SAE J1842 Disc Wheel Hub/Spoke Wheel and Axle Interface Dimensions - Commercial Vehicles SAE J393 Nomenclature-Wheels, Hubs, and Rims for Commercial Vehicles 2.1.2 TMC Publication Available from the Technology and Maintenance Council, American Truc
15、king Associations, 2200 Mill Road, Alexandria, VA 22314-5388, Tel: 703-838-1700, . TMC RP-618 Adjustment of Wheel Bearings SAE J2535 Revised FEB2013 Page 3 of 7 3. DEFINITIONS 3.1 END-PLAY An axial clearance between the bearings rolling elements and the races producing a measurable axial wheel-end m
16、ovement when a force is applied, first in one axial direction and then in the opposite direction, after oscillating the wheel-end. 3.2 PRELOAD A load resulting from an axial interference between the bearings rolling elements and races resulting in no discernible axial wheel-end movement when a force
17、 is applied, first in one axial direction and then in the opposite direction, after oscillating the wheel-end. 3.3 CONVENTIONAL WHEEL-END A wheel-end assembly that consists of a hub, an inboard seal, two single row tapered roller bearings, and fastening hardware (Figure 1). Conventional wheel-ends u
18、se the spindle fastening hardware to establish bearing setting and can not be categorized as unitized, pre-adjusted, or other system that attempts to automatically control bearing adjustment. 3.4 LOAD LINE The distance from the inboard bearing cup backface to the center of the tire(s) contact (Figur
19、es 2 and 3) which directly influences the relative wheel bearing load distribution. 3.5 TARGET PRELOAD SETTING The preload force value that is the optimium level of adjustment from which the final wheel bearing adjustment can be achieved. FIGURE 1 - CONVENTIONAL WHEEL END SAE J2535 Revised FEB2013 P
20、age 4 of 7 4. PRELOAD SETTINGS Target and maximum preload force values can be found in columns “D” and “E” in Table 1. Suppliers and/or axle assemblers developing a preload methodology should take care to ensure that their fastener adjustment methodology never results in a final setting that exceeds
21、 the maximum value listed in column “E” and to ensure their prescribed adjustment procedure will result in achieving a light, controlled preload setting Maximum GAWR shown is for calculation purposes and actual GAWR rating for each type of axle should be obtained from the axle manufacturer. TABLE 1
22、- PRELOAD SETTINGS SAE Configuration “A” Maximum GAWR (Gross Axle Weight Rating) N (lbs) “B” Minimum Load Line(1)mm (in) “C” Maximum Load Line(1)mm (in) “D” Target Preload Force N (lbf) “E” Maximum Preload Force N (lbf) “N” trailer axle 111 220 (25 000) 23.1 (0.91) 52.3 (2.06) 2 220 (500) 4 450 (1 0
23、00) “R” powered rear axle 133 470 (30 000) 46.2 (1.82) 75.2 (2.96) 2 220 (500) 4 450 (1 000) “FF / FG” nonpowered front axle 65 390 (14 700) 24.9 (0.98) 42.9 (1.69) 1 110 (250) 2 220 (500) “P” trailer axle 113 450 (25 500) 48.8 (1.92) 78.0 (3.07) 2 220 (500) 4 450 (1 000) FIGURE 2 - NONPOWERED FRONT
24、 1Load line position is measured from the inboard bearing cup backface, the sign convention is explained in Figures 2 and 3. SAE J2535 Revised FEB2013 Page 5 of 7 FIGURE 3 - TRAILER OR POWERED REAR 5. METHOD USED TO DETERMINE OPTIMUM PRELOAD (FOR REFERENCE ONLY) To determine an optimum preload range
25、 for heavy-duty wheel bearings, it is necessary to calculate the life of the bearings across a specified range of preload values. The bearing life calculations require a set of constants, a duty cycle, and wheel-end design data. Table 2 shows the assumptions that were held constant for each of the w
26、heel-end preload calculations. TABLE 2 - CONSTANTS Application Definition Value used for Condition Vehicle Center of Gravity(2)1 969 mm (77.5 in) Track Width 1 816 mm (71.5 in) Tire Radius 508 mm (20.0 in) Bearing Spread See SAE J1842 Lubrication Type(3)Oil Wheel Hub Stiffness(3)Infinite Two duty cy
27、cles were used to determine the target and maximum preload for each of the axle configurations. The line-haul duty cycle simulates a vehicle operating under conditions where little turning is involved. The city-delivery duty cycle simulates a vehicle operating under more frequent turning conditions.
28、 Tables 3 and 4 show the corresponding duty cycles. 2Vehicle Center of Gravity refers to the theoretical point of mass for the vehicle where forces act. It is measured vertically from the ground and is needed for vehicle dynamics calculations that affect bearing life. 3Lubrication type and wheel hub
29、 stiffness have minimal effect on the calculated preload values. SAE J2535 Revised FEB2013 Page 6 of 7 TABLE 3 - LINE HAUL DUTY CYCLE Condition Vertical Acceleration (g) Horizontal Acceleration (g) Percent Distance Straight Road 1.0 0.00 95% Right Turn 1.0 0.15 2.5% Left Turn 1.0 0.15 2.5%TABLE 4 -
30、CITY DELIVERY DUTY CYCLE(4)Condition Vertical Acceleration (g) Horizontal Acceleration (g) Percent Distance Straight Road 1.0 0.00 70% Right Turn 1.0 0.15 13% Left Turn 1.0 -0.15 13% Right Turn 1.0 0.25 2% Left Turn 1.0 -.025 2% The axle weights were determined using ratings given by various axle ma
31、nufacturers. Typical load line limits were calculated from a collection of data for current hubs, disc wheels, and outboard mounted brake drums. Minimum and maximum dimensions from component features contributing to the load line were summed. Table 5 shows minimum and maximum axle weights and load l
32、ine values used for each wheel-end calculation. Each wheel-end was analyzed using each combination of axle weight, load line, and duty cycle. Preload targets and maximum values were established based on bearing system life versus preload force for each SAE configuration. Several bearing manufacturer
33、s used their own calculation programs to calculate the optimum preload forces. The values published in this document were agreed upon by the contributing bearing manufacturers. The inputs used to analyze the preload forces were accumulated for the purpose of this work alone; the data should not be e
34、xtrapolated to other calculations without consulting your bearing manufacturer. The maximum and minimum axle weights in Table 5 are for the calculation purposes and are not necessarily axle load ratings for use. Consult the axle manufacturer for specific approved axle ratings. 4This duty cycle was s
35、elected to evaluate frequent turning conditions. It is not intended to be used as a newly established or standardized duty cycle. SAE J2535 Revised FEB2013 Page 7 ofTABLE 5 - MINIMUM AND MAXIMUM AXLE WEIGHTS AND LOAD LINES SAE Configuration Bearing Cup Spacing mm (in) Minimum Axle Weights N (lbf) Ma
36、ximum Axle Weights N (lbf) Minimum Load Line Positions(5)mm (in) Maximum Load Line Positions(5)mm (in) “N” trailer axle 85.1 (3.35) 75 630 (17 000) 111 220 (25 000) 23.1 (0.91) 52.3 (2.06) “R” powered rear axle 109.5 (4.31) 75 630 (17 000) 133 470 (30 000) 46.2 (1.82) 75.2 (2.96) “FF / FG” nonpowere
37、d front axle 85.9 (3.38) 44 490 (10 000) 71 180(6)(16 000) -24.9 (-0.98) 42.9 (1.69) “P” trailer axle 114.3 (4.50) 75 630 (17 000) 133 470(6)(30 000) 48.8 (1.92) 78.0 (3.07) 6. NOTES 6.1 Marginal Indicia A change bar (l) located in the left margin is for the convenience of the user in locating areas
38、 where technical revisions, not editorial changes, have been made to the previous issue of this document. An (R) symbol to the left of the document title indicates a complete revision of the document, including technical revisions. Change bars and (R) are not used in original publications, nor in documents that contain editorial changes only. PREPARED BY THE SAE TRUCK AND BUS WHEEL COMMITTEE 5Load line position measured from the inboard bearing cup backface. 6These values exceed the axle GAWR shown in Table 1. They were used for calculation purposes only.
