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 2017 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: +1 724-776-4970
4、 (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:/standards.sae.org/J2686_201710 SURFACE VEHICLERECOMMENDED PRACTICEJ2686 OCT2017 Issued 2012-03 Reaffirmed 2017-10 S
5、uperseding J2686 MAR2012 Brake Drum Qualification Recommended Practice RATIONALE J2686 has been reaffirmed to comply with the SAE Five-Year Review policy. 1. SCOPEThis SAE Recommended Practice is intended for qualification testing for brake drums used on highway commercial vehicles with air brakes u
6、sing an inertia-dynamometer procedure. This Recommended Practice consists of two distinct tests: Part A - durability and speed maintenance test, and Part B - heat check drag sequence test. Each test can be considered to be an independent evaluation of the brake drum which tests different properties.
7、 1.1 Purpose This document establishes uniform inertia-dynamometer procedures to determine the integrity and durability when the brake drum is subjected to various functional modes. 2. REFERENCES2.1 Applicable Documents The following publications form a part of this specification to the extent speci
8、fied herein. Unless otherwise indicated, the latest issue of SAE publications shall apply. 2.1.1 SAE Publications Available from SAE International, 400 Commonwealth Drive, Warrendale, PA 15096-0001, Tel: 877-606-7323 (inside USA and Canada) or 724-776-4970 (outside USA), www.sae.org. SAE J294 Servic
9、e Brake Structural Integrity Test Procedure - Vehicles Over 4500KG (10 000 LB) GVWR SAE J2115 Brake Performance and Wear Test Code - Commercial Vehicle - Inertia Dynamometer 2.2 Related Publications The following publications are provided for information purposes only and are not a required part of
10、this SAE Technical Report. 2.2.1 Federal Motor Vehicle Safety Standard (FMVSS) Publication Available from the Superintendent of Documents, U. S. Government Printing Office, Washington, DC 20402 49CFR571 Code of Federal Regulations Sec. 571.121 Standard No. 121 (Revised as of October 1, 2009) - Air B
11、rake Systems - Trucks, Buses and Trailers 3. INERTIA-DYNAMOMETER The dynamometer must have provisions for the following: Electronic console capable of controlling the test sequence and recording data automatically through the entire test. Inertia capabilities with minimum increments to obtain any re
12、quired inertia within + 2%. Constant pressure within 13.8 kPa ( 2 psi) from 138 kPa to 827 kPa (20 to 120 psi). Constant torque control within 136 Nm (100 ftlb). Temperature control within 6C ( 10F). Time control within 1 second for repetitive cycles. Speed control within 1.61 km/h (1 mph). Permanen
13、t recording of pressure, torque, temperature, shaft speed, and time. Simultaneous direction of air uniformly and continuously over the brake drum at a velocity of (11 1) m/s; (2,200 200) ft/min at (15-38) C; (60-100) F. 4. DEFINITIONS 4.1 BRAKE RETARDATION FORCE Brake torque / SLR 4.2 BRAKE TORQUE T
14、est weight SLR deceleration rate / Acceleration due to gravity 4.3 CAM TORQUE Air chamber size air pressure slack adjuster moment arm 4.4 CYCLE TIME Time interval from the beginning of one brake application to the beginning of the next 4.5 GAWR Gross Axle Weight Rating SAE INTERNATIONAL J2686 OCT201
15、7 Page 2 of 6_ 4.6 IBLT Initial brake lining temperature 4.7 IBDT Initial brake drum temperature 4.8 SLR Static loaded radius of the tire 4.9 Test Material Provide three new brake drums representative of production or sample lot and two brake assemblies for each test as follows: 4.9.1 Use one brake
16、drum and one set of brake lining(s) for the initial burnish and durability and speed maintenance test (Part A, paragraph 5.4). 4.9.2 Use the second brake drum with unburnished brake lining(s) for the “Heat Check Drag Sequence” (Part B, paragraph 5.5). The brake lining(s) used for Part B can be the s
17、ame as that used for Part A or can be different. 4.9.3 Use the third brake drum to burnish additional brake lining(s) if needed for part A only. 4.10 Thermocouples Install two thermocouples in the lead shoe as close to the center of the rubbing area as possible, embed the primary thermocouple (IBLT)
18、 1.0 mm (0.040 in) below the friction surface, install the secondary thermocouple for backup embedded 3.0 mm (0.12 in) below the friction surface, located as shown in SAE J2115 Figures 2 and 3. Install two thermocouples in the durability drum (Part A), 120 degrees apart; embed the primary (IBDT) and
19、 secondary thermocouples 1.0 mm (0.04 in) from the inside diameter in the center of the rubbing area (drill through from outside diameter) as shown in SAE J2115 Figures 3 and 4. 5. PROCEDURE 5.1 Brake Drum Test Procedure description The test consists of two different types of evaluations: 5.1.1 Part
20、 A 5.1.1.1 Durability section in which the brake drum is subjected to deceleration loads from various speeds. 5.1.1.2 Grade simulation section to evaluate the durability of drum when subjected to speed maintenance brake applications encountered on descents of various grades. 5.1.2 Part B - Drag simu
21、lation section to evaluate resistance to heat check formation and propagation. SAE INTERNATIONAL J2686 OCT2017 Page 3 of 6_ 5.2 Burnish 5.2.1 Burnish the brake lining(s) for Part A as described in SAE J2115 paragraph 6.1. 5.3 Brake Performance 5.3.1 Adjust brakes per manufacturers specifications if
22、required. 5.3.2 Conduct the TP 121D brake performance as described in SAE J2115 paragraph 6.2. 5.4 Part A - Durability and Speed Maintenance Test 5.4.1 Test Loop Each test loop shall consist of a Durability Sequence per item 5.4.2, a Speed Maintenance Sequence per item 5.4.3, and a Cool-Down Sequenc
23、e per item 5.4.4. If faults occur, warm the brake drum by performing the next brake cycle until IBDT is achieved and then resume the test. If mechanical or structural failure occurs apart from the brake drum, replace the component(s), reburnish if needed and resume the test. 5.4.2 Durability Sequenc
24、e 5.4.3 Grade Speed Maintenance Sequence Perform all brake applications at a constant deceleration level with a brake pressure limit of 586 kPa (85 psi). Cool-down the drum to the IBDT by rotating at 8 km/h (5 mph). Cycles Initial speed Final speed Retardation level Drag-on time IBDT (Drum) Cycle ti
25、me 1 88.5 km/h (55 mph) 88.5 km/h (55 mph) 0.028 g 35 sec 66C (150F) 70 sec 2 88.5 km/h (55 mph) 88.5 km/h (55 mph) 0.028 g 35 sec - 70 sec 5 88.5 km/h (55 mph) 88.5 km/h (55 mph) 0.037 g 35 sec - 75 sec 2 88.5 km/h (55 mph) 88.5 km/h (55 mph) 0.019 g 35 sec - 70 sec 1 88.5 km/h (55 mph) 88.5 km/h (
26、55 mph) 0.030 g 40 sec - - 5.4.4 Cool Down the brake drum to IBDT by rotating the brake drum at 8 km/h (5 mph). 5.4.5 Run a maximum of 50 test loops or until test suspension occurs per paragraph 6. Cycles Initial speed Final speed Retardation level Pressure IBDT (Drum) Cycle time 1 48.3 km/h (30 mph
27、) 0.8 km/h (0.5 mph) 0.745 g 827 kPa (120 psi) maximum 93C (200F) - 1 80.5 km/h (50 mph) 0.8 km/h (0.5 mph) 0.621 g 827 kPa (120 psi) maximum 93C (200F) - 2 96.6 km/h (60 mph) 0.8 km/h (0.5 mph) 0.528 g 827 kPa (120 psi) maximum 93C (200F) - 1 113 km/h (70 mph) 0.8 km/h (0.5 mph) 0.373 g 827 kPa (12
28、0 psi) maximum 93C (200F) - SAE INTERNATIONAL J2686 OCT2017 Page 4 of 6_ 5.4.6 Inspection 5.4.6.1 Every 5 test loops or as specified by the test requestor, conduct a visual inspection to check drum for cracks and photograph. 5.4.6.2 Replace lining(s) as needed with lining(s) burnished on a separate
29、brake drum 5.4.6.3 Reset lining thermocouples at every inspection or as needed. 5.5 Part B Heat Check Drag Sequence 5.5.1 Heat check drag sequence 5.5.2 Heat check drag sequence (Part B) is run with a new brake drum, unburnished brake lining(s), and limited by maximum brake pressure input of 138 kPa
30、 (20 psi). 5.5.3 Inspect the brake drum and brake lining(s) every 50 drag cycles. 5.5.4 Repeat until test suspension occurs per paragraph 6 or 250 cycles whichever occurs first 6. TEST SUSPENSION DEFINITION When any of the following criteria is met, terminate the test and report to the project engin
31、eer: 6.1 Non-compliance to FMVSS performance requirements as described in SAE J2115 appendix A. 6.2 Crack of 25 mm (1.0 in) through the outer wall of the brake drum. 6.3 Heat checks merging together across the braking surface of the brake drum 6.4 Crack through the open end of the brake drum. 6.5 In
32、ability to meet the retardation levels of the Durability Sequence (5.4.2) with a maximum pressure of 827 kPa (120 psi) or the Grade Speed Maintenance Sequence (5.4.3) with a maximum brake pressure input of 586 kPa (85 psi). 7. TEST REPORT 7.1 Generate a test report including summary data for test lo
33、op number, speed, torque, pressure, deceleration, drum temperature, lining temperature. The test report header information must include brake size, brake type, lining manufacturer and part number, slack adjuster manufacturer and size, and brake chamber manufacturer and type. The brake drum informati
34、on must include the part number, initial and final weight, initial and final surface finish, amount of balance correction required and method of achieving balance. The brake lining information must report the beginning and final lining and shoe weight and brake lining replacement schedule if any. 7.
35、2 Document any finding related to paragraph 6 with measurements or digital pictures. 7.3 Document any replaced or repaired components that occurred during the test. Cycles Initial Speed Final Speed Retardation Level Drag Time IBDT (Drum) Cycle Time - 112.7 km/h (70 mph) 112.7 km/h (70 mph) 0.06 g 60
36、 sec 66C (150F) SAE INTERNATIONAL J2686 OCT2017 Page 5 of 6_ 8. NOTES 8.1 Marginal Indicia A change bar (l) located in the left margin is for the convenience of the user in locating areas where technical revisions, not editorial changes, have been made to the previous issue of this document. An (R)
37、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 FOUNDATION BRAKE COMMITTEE OF THE SAE TRUCK AND BUS BRAKE AND STABILITY CONTROL STEERING COMMITTEE SAE INTERNATIONAL J2686 OCT2017 Page 6 of 6_
