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 ther
2、efrom, 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 2015 SAE International All rights reserved. No part of this
3、publication 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: +1 724-776-49
4、70 (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/J294_201506 SURFACE VEHICLE RECOMMENDED PRACTICE J294 JUN2015 Issued 1972-07 Rea
5、ffirmed 2015-06 Superseding J294 MAY2011 Service Brake Structural Integrity Test Procedure - Vehicles Over 4500 kg (10 000 lb) GVWR RATIONALE J294 has been reaffirmed to comply with the SAE five-year review policy. 1. Scope This SAE Recommended Practice establishes a method of testing the structural
6、 integrity of the brake system of all new trucks, buses, and combination vehicles designed for roadway use and falling in the following classifications: a. Truck and BusOver 4500 kg (10 000 lb) GVWR b. Combination vehicleTowing vehicle over 4500 kg (10 000 lb) GVWR The test consists of two distinct
7、tests: a Structural Endurance Test followed by a Structural Ultimate Strength Test. NOTEThese two tests originated from separate procedures, and were combined in this Recommended Practice. Each test can be considered to be an independent evaluation of the service brakes structure. Based on time avai
8、lable, cost limitations, and the desired evaluation and historical data available, either of these tests could be considered as a complete evaluation of the brakes structure. 1.1 Purpose The main purpose of the document is to evaluate the structural integrity of a vehicles braking system. However, o
9、ther areas such as the steering or suspension system may also be evaluated during the test provided that the criteria and procedure detailed as follows are not modified in any way. For repeatability, it is recommended that a brake apply device be utilized whenever possible, since it would eliminate
10、the variations in application times and efforts of different operators. 2. References 2.1 Applicable Publications The following publications form a part of the specification to the extent specified herein. Unless otherwise indicated the lastest revision of SAE publications shall apply. 2.1.1 SAE PUB
11、LICATIONS Available from SAE, 400 Commonwealth Drive, Warrendale, PA 15096-0001. SAE J2115Brake Performance and Wear Test CodeCommercial Vehicle Inertia Dynamometer SAE J1404Service Brake Structural Integrity RequirementsVehicles Over 4500 kg (10 000 lb) GVWR SAE J1626Braking, Stability, and Control
12、 Performance Test Procedures for Air- and Hydraulic-Brake-Equipped Trucks, Truck-Tractors and Buses 2.2 Related Publications The following publications are provided for information purposes only and are not a required part of this document. 2.2.1 FMVSS PUBLICATIONS Available from the Superintendent
13、of Documents, U.S. Government Printing Office, Washington, DC 20402. FMVSS 105Hydraulic and Electric Brake Systems FMVSS 121Air Brake Systems 3. Equipment 3.1 Brake Apply Device (Optional but recommended for hydraulic braked vehicles) 3.2 Calibrated Speedometer and Odometer 3.3 Service (Application)
14、 Pressure Gauges 3.4 Pedal Force Transducer (Hydraulic Brakes) 3.5 Stop Counter 3.6 Decelerometer (U-tube or Equivalent) 3.7 Ambient Temperature Gage 3.8 Recording Equipment Pedal force versus time for hydraulic braked vehicle, brake chamber pressure versus time for air brake vehicles. 3.9 Tire Pres
15、sure Gage 3.10 Wheel Alignment Equipment (When steering and suspension system are also tested) _ SAE INTERNATIONAL Reaffirmed J294 JUN2015 2 of 73.11 Torque Wrench 3.12 Direct Reading Temperature Instrument (Brake lining temperature) 4. Test Preparation 4.1 Calibrate instrumentation as required and
16、note calibration on data sheet. 4.2 Install new brake drums and/or rotors, brake assemblies and fasteners to the manufacturers specifications, except all brake fasteners shall be at minimum specified torque on one side of the vehicle and at maximum specified torque on the other side. Record torque v
17、alues. Record pertinent brake parameters and specifications. 4.3 Adjust brakes per manufacturers specifications. 4.4 (Optional) Check wheel geometry of all axles and adjust to manufacturers mean specifications and record. 4.5 Vehicle test weight to be Gross Vehicle Weight Rating (GVWR) or Gross Comb
18、ination Weight Rating (GCWR) within 2%. Each axle should be loaded to the Gross Axle Weight Rating (GAWR) 5%. However, if the sum of the GAWR exceeds the GVWR 5% or GCWR 5%, the load should be distributed over each axle in proportion to the GAWR/GAWR SUM ratios 5%. If so desired, this test can be ru
19、n at a 10% overload. NOTEIn comparing test results between different vehicles or components, only tests with like loading should be compared. 4.6 Install the tires and wheels offered by the manufacturer which produce the largest moment of inertia effect for the vehicle. Tires must be in good conditi
20、on with a minimum of 6 mm (1/4 in) tread at all times during the test. Set tire pressure per manufacturers specifications for GAWR. 4.7 Install plug-type thermocouple in the most heavily loaded shoe or outboard pad of each brake per SAE J2115. 4.8 For those vehicles which are equipped with power (ai
21、r or hydraulic) or power assist brake actuation, the reserve pressure should be set at the vehicle manufacturers maximum recommended cut-out pressure. 5. General Notes 5.1 All tests are conducted on a 12 ft (+0/-2 in.) wide level (no more than 1% grade in all directions, including crown), straight r
22、oadway having a peak friction coefficient (PFC) of 0.9 (dry Portland cement concrete or equivalent surface). _ SAE INTERNATIONAL Reaffirmed J294 JUN2015 3 of 7Where vehicles are equipped with a wheel slip brake control system as standard equipment, the control system should be disabled during the te
23、st. Any automatic adjusting devices supplied as standard equipment should be left operational. Automatic adjustment may be disabled if overadjustment occurs, provided operational de-adjustment is prevented. 5.2 Spike Brake Application 5.2.1 A spike brake application for hydraulic braked vehicles is
24、accomplished by applying 668 N (150 lb) of force on the service brake control in less than 0.3 s. See Figure 1 for a typical spike brake application curve. Maintain pedal force of 668 N 89 N (150 lb 20 lb) after vehicle has stopped and is motionless. FIGURE 1TYPICAL SPIKE BRAKE APPLICATION 5.2.2 A s
25、pike brake application for air brake vehicles is accomplished by a full pedal application such that the air pressure build-up at the brake valve delivery port reaches 585 kPa (85 psi) in no more than 0.2 s from the start of pedal movement. 5.3 All brake applications are to be made in neutral or with
26、 clutch disengaged. 5.4 Driving speed between all brake applications to be at the subsequent test speed +5/-0 km/h (+3/-0 mph). Acceleration to all test speeds is to be moderate. _ SAE INTERNATIONAL Reaffirmed J294 JUN2015 4 of 75.5 During all phases of this procedure, note and record any unusual br
27、aking or handling characteristics of the vehicle, including excessive pedal travel, brake noise, and wheel slide. 6. Procedure 6.1 Preburnish Check In order to allow for a general check of instrumentation, brakes, and vehicle function, the following stops are to be run noting pedal force or line pre
28、ssure for stop. a. Number of stops10 b. Speed48 km/h (30 mph) c. Deceleration3 mpsps (10 fpsps) d. Interval1.6 km (1 mile) 6.2 Burnish 6.2.1 Burnish the brakes by making 500 snubs between 64 km/h (40 mph) and 32 km/h (20 mph) at a deceleration rate of 3 mpsps (10 fpsps). Except where an adjustment i
29、s specified, after each brake application accelerate to 64 km/h (40 mph) and maintain that speed until making the next brake application at a point 1.6 km (1 mile) from the initial point of the previous brake application. If the vehicle cannot obtain a speed of 64 km/h (40 mph) in 1.6 km (1 mile), c
30、ontinue to accelerate until the vehicle reaches 64 km/h (40 mph) or until the vehicle has traveled 2.4 km (1.5 miles) from the initial point of the previous brake application, whichever occurs first. NOTEThis test can be completed after an FMVSS-105 or 121 test (SAE J1626) without replacing the brak
31、e hardware and fasteners (and no additional burnish). 6.2.2 The brakes may be adjusted three times during the burnish, in accordance with the manufacturers recommendations. Manual and automatic adjustment brakes shall be manually adjusted after burnish at a lining temperature of less than 65 C (150
32、F). 6.2.3 Check brake and vehicle function by making three stops from 48 km/h (30 mph) at 3 mpsps (10 fpsps) and 93 C 14 C (200 F 25 F) for the hottest brake; record pedal force or line pressure. 6.2.4 For hydraulic brakes, make a service brake application at 667 N (150 lb) pedal force and hold for
33、30 s, or for air service brakes, make a full service application and hold for 3 min with the engine off. Record pedal position and service pressure at beginning and end of application. 6.3 Structural Endurance Test Any automatic adjusting devices supplied as standard equipment should be left operati
34、onal. Automatic adjustment may be disabled if overadjustment occurs, provided operational de-adjustment is prevented. 6.3.1 PERFORM 80 CYCLES OF THE FOLLOWING: 6.3.1.1 24 complete stops from 80 km/h (50 mph) at 3.7 mpsps (12 fpsps) deceleration at 4.8 km (3 mile) intervals. _ SAE INTERNATIONAL Reaff
35、irmed J294 JUN2015 5 of 76.3.1.2 1 reverse spike stop from 8 to 16 km/h (5 to 10 mph) estimated. 6.3.1.3 1 maximum effort (without wheel lock) stop from 80 km/h (50 mph). 6.3.2 All stops are with full rock-back. After the first, and after every 24th 3.7 mpsps (12 fpsps) stop, record line pressure, p
36、edal force (hydraulic brake), deceleration rate, initial and final temperatures. Record driver comments on brake operation. Check brake adjustment if 3.7 mpsps (12 fpsps) cannot be maintained. Adjust brakes per manufacturers specifications after 20, 40, 60, and 80 cycles. Record brake adjustments pe
37、rformed throughout the test. 6.3.3 Check brake and vehicle function by making three stops from 48 km/h (30 mph) at 3 mpsps (10 fpsps) and 93 C 14 C (200 F 25 F) for the hottest brake; record pedal force or line pressure. 6.3.4 For hydraulic brakes, make a service brake application at 667 N (150 lb)
38、pedal force and hold for 30 s, or for air service brakes, make a full service application and hold for 3 min with the engine off. Record pedal position and service pressure at beginning and end of application. 6.4 Inspection 1 6.4.1 (Optional) Check and record wheel geometry of all axles. 6.4.2 Chec
39、k and record torque of all brake fasteners. 6.4.3 Inspect all components of the brake system. 6.4.4 Reassemble and adjust brakes per manufacturers specifications. Manual and automatic adjustment brakes are to be manually adjusted as specified at a lining temperature of less than 65 C (150 F). Automa
40、tic adjustment may be disabled provided operational de-adjustment is prevented. 6.5 Structural Ultimate Strength Test 6.5.1 Make fifty 32 to 0 km/h (20 to 0 mph) forward spike stops, each forward spike stop to be followed by a reverse spike stop from 8 to 16 km/h (5 to 10 mph) estimated. Initial bra
41、ke temperature for each spike stop should be 93 C 14 C (200 F 25 F) for the hottest brake. All stops are with full rock-back. 6.5.2 Check brake and vehicle function by making three stops from 48 km/h (30 mph) at 3 mpsps (10 fpsps) and 93 C 14 C (200 F 25 F) for the hottest brake; record pedal force
42、or line pressure. 6.5.3 For hydraulic brakes, make a service brake application at 667 N (150 lb) pedal force for hydraulic brakes and hold for 30 s, or for air service brakes, make a full service application and hold for 3 min with the engine off. Record pedal position and service pressure at beginn
43、ing and end of application. _ SAE INTERNATIONAL Reaffirmed J294 JUN2015 6 of 76.6 Inspection 2 6.6.1 (Optional) Check and record wheel geometry of all axles. 6.6.2 Check and record torque of all brake fasteners. 6.6.3 Inspect all components of the brake system. 7. Acceptance Criteria 7.1 Reference S
44、AE J1404. 8. Notes 8.1 Marginal Indicia The change bar (l) located in the left margin is for the convenience of the user in locating areas where technical revisions have been made to the previous issue of the report. An (R) symbol to the left of the document title indicates a complete revision of the report. PREPARED BY THE SAE TRUCK AND BUS FOUNDATION BRAKE SUBCOMMITTEE OF THE SAE TRUCK AND BUS BRAKE COMMITTEE _ SAE INTERNATIONAL Reaffirmed J294 JUN2015 7 of 7
