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 reaffirmed, revised, or cancelled. SAE invites your written comments and suggestions. Copyright 2008 SAE International All rights reserved. No part of this publication m
3、ay 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: 724-776-4970 (outside USA)
4、 Fax: 724-776-0790 Email: CustomerServicesae.org SAE WEB ADDRESS: http:/www.sae.org J1729 REV. FEB2008 SURFACE VEHICLE RECOMMENDED PRACTICE Issued 1995-08 Revised 2008-02 Superseding J1729 AUG2001 Parking Brake Drawbar Pull Test ProcedureTruck and Bus RATIONALE This document has been updated in keep
5、ing with the five-year review process. The Brake Systems Subcommittee has sanctioned the following changes: a. Removed the parking brake drawbar pull test procedures from SAE J1626 and incorporate as appropriate into SAE J1729 and SAE J360. The SAE J1626 will only reference these two procedures as a
6、ppropriate when required. b. Added SAE J2503 as reference. c. Removed SAE J1626 specific section numbers based on the upcoming and ongoing revisions with this document. d. Revised Section 5.3 to agree with SAE J1626 burnish snub procedure changes with the transmission in the highest gear appropriate
7、 for 40 mph. e. Removed pressure-applied/mechanically locked actuators from Section 5.11. f. Changed title from Commercial Vehicle to Truck and Bus. g. Other editorial changes for clarity as appropriate. 1. SCOPE This SAE Recommended Practice provides a test method and instructions for measuring per
8、formance of parking brakes on air- or hydraulic-braked vehicles equipped with in-wheel or drive-line parking brakes. This procedure applies to truck-tractors, trailers, trucks and buses. 1.1 Purpose This document establishes a uniform procedure for determining retardation force capability of the par
9、king brakes of new truck-tractors, trailers, trucks and buses. 2. REFERENCES 2.1 Applicable Publications The following publications form a part of this specification to the extent specified herein. Unless otherwise specified, the latest issue of SAE publications shall apply. SAE J1729 Revised FEB200
10、8 - 2 - 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 J360 Truck and Bus Grade Parking Performance Test Procedure SAE J1452 Trailer Grade Parking Pe
11、rformance Test Procedure SAE J1626 Braking, Stability, and Control Performance Test Procedures for Air- and Hydraulic-Brake-Equipped Trucks, Truck-Tractors and Buses SAE J2503 Drawbar Pull Performance Criteria SAE J2115 Air Brake Performance and Wear Test Code Commercial Vehicle Inertia Dynamometer
12、2.1.2 Federal Publications Available from the Superintendent of Documents, U.S. Government Printing Office, Mail Stop: SSOP, Washington, DC 20402-9320. 49 CFR 571.105 Brake PerformanceHydraulic Brake Systems 49 CFR 571.121 Brake PerformanceAir Brake Systems 3. INSTRUMENTATION AND EQUIPMENT 3.1 Instr
13、umentation Required 3.1.1 Temperature Measuring Device 0 to 540 C (0 to 1000 F), to measure parking brake lining pad or shoe as per figure described in SAE J2115 and display monitor/recording brake lining temperature accurate to 5.6 C (10 F). 3.1.2 Load Cell 0 to 89 kN (0 to 20 000 lbf) capacity acc
14、urate to 445 N (100 lbf). 3.1.3 Pressure Gauge 0 to 900 kPa (0 to 130 lbf/in2) for air brake application pressure measurements. 3.1.4 Decelerometer 0 to 9.8 m/s2(0 to 32.2 ft/s2), to measure vehicle deceleration during burnish or establishing initial brake temperature (IBT). 3.1.5 Force Measuring De
15、vice 0 to 890 N (0 to 200 lbf), to measure park brake hand or foot application force. 3.1.6 Axle Weight Measuring Device 1.0% of indicated weight. 3.1.7 Device or method of measuring wheel rotation, 5% of indicated value once the parking brake has been applied. SAE J1729 Revised FEB2008 - 3 - 3.2 Eq
16、uipment Required 3.2.1 A device capable of providing a steady-state pull to the vehicle with park brake applied, at the required rate of 1.2 m/min (4 ft/min) or less. 4. VEHICLE INFORMATION AND DATA 4.1 Test Data Sheet 1 (Figures 1A and 1B) to be used as a work sheet during testing. 4.2 Vehicle info
17、rmation shall be documented as described in SAE J1626 Data Sheet Vehicle Information. 4.3 Vehicle Conditions To insure the accuracy and validity of results, the following conditions should be met: 4.3.1 On the brakes applied by the parking brake system, use new thermocouple lining and drums or discs
18、 of original equipment material and install in accordance with the vehicle manufacturers specifications. 4.3.2 Parking brake assemblies and actuation systems are to be installed, lubricated, adjusted, and inspected in accordance with the vehicle manufacturers specifications. 4.3.3 Tires must not be
19、more than 20% worn, largest diameter specified for the vehicle at the test GVWR and inflated to the pressure specified by the vehicle manufacturer for the GVWR, measured cold (at the beginning of each test day). 4.3.4 For driveline type parking brakes, the rear axle ratio should be at the specified
20、manufacturer value to generate the highest torque in combination with 4.3.3 tire size during drawbar pull. 4.3.5 The vehicle is to be tested in the fully loaded condition. For the purposes of this test procedure, fully loaded shall be the manufacturers gross vehicle weight rating (GVWR) distributed
21、proportionately to individual axle weight ratings (GAWRs) per SAE J1626 Definitions. NOTE: FMVSS 121 allows the option of performing the grade holding test at LLVW and GVWR or the static retardation force parking brake test at GVWR. 4.3.5.1 Load vehicles to GVWR per SAE J1626. 4.3.5.2 Trailer Hook u
22、p trailer to tractor. Add ballast to trailer until weight of trailer and tractor equal trailer GAWR(s). Position ballast over trailer axle(s) to prevent wheel slide. If a wheel slides during test, load trailer axle to GAWR. Conduct burnish as described in Appendix A. 5. TEST CONDITIONS AND FACILITIE
23、S 5.1 Ambient air temperature must be between 0 and 38 C (32 and 100 F). 5.2 Wind velocity should not exceed 24 km/h (15 mph). 5.3 Unless otherwise specified, the transmission shall be in the highest gear appropriate for a speed of 40 mph during burnish snubs per SAE J1626. 5.4 All vehicle openings
24、(doors, windows, hood, etc.) must be closed except as required for instrumentation purposes. 5.5 The road surface used for vehicle parking brake conditioning shall be dry with a peak friction coefficient (PFC) less than 0.9 per SAE J1626, flat with no more than a 1% grade in all directions, includin
25、g crown for burnish snubs and initial brake temperature (IBT) conditioning. SAE J1729 Revised FEB2008 - 4 - 5.6 Automatic adjusters must remain activated for the duration of the test. 5.7 Unless otherwise specified, parking brakes can be adjusted per the vehicle manufacturers procedure. 5.8 Individu
26、al parking brake lining temperatures should be less than 95 C (200 F) when being adjusted or checked. 5.9 All park brake tests should be conducted on a dry, level, smooth Portland cement concrete surface or equivalent. 5.10 Initial Brake Temperature (IBT) For vehicles with a parking brake system tha
27、t utilizes friction elements of the service brake system, the lining temperature just prior to any parking brake test must be between 65 and 95 C (150 and 200 F). Temperature condition the lining material by conducting brake snubs from 64 to 32 km/h (40 to 20 mph) speed at 3 m/s2(10 ft/s2) decelerat
28、ion at 1.6 km (1 mile) intervals (If speed or deceleration is not attainable, run at maximum speed or deceleration). For hydraulic vehicles with a parking brake system that does not utilize the service brakes, the lining material temperature just prior to any parking brake test shall not be more tha
29、n 65 C (150 F) (when the temperature of components on both ends of an axle are averaged or the temperature of the driveline type parking brake material). Temperature condition the lining material per the vehicle manufacturers recommendation but not to exceed the 65 C (150 F) requirement per FMVSS 10
30、5. 5.11 With variable input systems, conduct the test to establish the applied manual effort or pressure required to lock the braked wheels and observe whether the braked wheels lock or roll. 5.12 With fixed input systems, determine the manual effort required to actuate the system control and observ
31、e whether the braked wheels lock or roll. 5.13 For vehicles having any equipment (such as driver-controlled interaxle differentials or multi-speed axles), which can be placed in or out engagement by the driver so as to vary either the number of axles braked or the amount of torque imposed on the par
32、king brake or brakes, conduct the test to determine parking performance under the condition that requires highest parking brake torque and under the condition that requires highest tire-to-road tractive force. It is suggested that all conditions be tested. 5.14 Parking brake systems employing servic
33、e brakes or those employing non-service brakes for which the manufacturer provides the purchaser with a published burnish procedure need not be tested before burnishing because of the difficulty in obtaining reliable and repeatable pre-burnish data. 5.15 Vehicles equipped with parking brake systems
34、employing cable or rod actuation of service brakes shall be allowed to roll between each pull and data reading. This will improve repeatability of results by allowing realignment between axle and actuation parts and by removing system hysteresis. 5.16 Air braked trucks with more than two axles shall
35、 disable parking brake chambers on those axles other than the test axle per FMVSS 121. 5.17 Method of Conducting Parking Brake Retardation Force Test NOTE: For air brake vehicles, the following procedures apply only to vehicles equipped with conventional spring-applied, air-release parking brake sys
36、tems from which air is exhausted after actuation of the parking brake control. 5.17.1 Test Preparation 5.17.1.1 Install instrumentation and equipment based on the type of parking brake system as described in Section 3. 5.17.1.2 Install new thermocouple lining and drums/discs. Lining grind and surfac
37、e finish of drums/discs, including all other brake components must be within vehicle manufacturers specifications. SAE J1729 Revised FEB2008 - 5 - 5.17.1.3 Adjust brakes to vehicle manufacturers specifications. Where applicable, measure and record pushrod travel with only service brakes applied at 6
38、20 kPa (90 psi +0,-5 psi) at chamber. 5.17.1.4 Adjust vehicle weight to appropriate load condition as per test sequence, if required. 5.17.1.5 For vehicles with a parking brake system that does not utilize the service brakes, burnish brakes as described in 6.1.1. 5.17.1.6 For vehicles with a parking
39、 brake system that utilize friction elements of the service brake system, burnish the brakes as described in 6.2.1. 5.17.1.7 Install/prepare drawbar pull device, load cell, and wheel or driveline parking brake rotation measuring device or method. 5.17.1.8 For hydraulic brake vehicles, install force
40、transducer for park brake foot and/or hand control applied efforts. 5.17.1.9 For vehicles having any equipment (axle differential locks or multi-speed axles) which is driver-controlled, the test must be conducted in the condition which requires the highest parking brake torque. 5.17.2 Test Procedure
41、 5.17.2.1 Temperature condition the parking brake lining material based on vehicle type per 5.10. 5.17.2.2 Position vehicle on a dry level Portland cement concrete or equivalent surface in line with pull cable or equivalent device. Connect pull cable and force measuring device so that cable is level
42、 within 5 degrees. 5.17.2.3 Mark circumference of tire(s) on braked wheel(s) at point of tire/ground contact or driveline parking brake at one point on the drum or disc contact and at 90, 180, and 270 degrees from that point. 5.17.2.4 For air brake vehicles, disable spring brake chambers on axle(s)
43、other than the axle being tested. 5.17.2.5 Charge air brake system reservoirs to compressor governor cutout pressure. 5.17.2.6 Place driver selected equipment in desired condition as identified in Section 5.17.1.9. 5.17.2.7 With vehicle at rest and transmission in neutral, actuate brakes as follows:
44、 5.17.2.7.1 Air-Braked Vehicle Apply and hold service brakes by using maximum treadle (pedal) travel with system at compressor cut-out pressure. Apply parking brake(s). Release service brakes after parking brake control is at the fully-applied position. 5.17.2.7.2 Hydraulic-Braked Vehicle Apply and
45、hold service brakes with 667 N (150 lbf) force. Apply parking brake(s). Release service brakes after parking brake control is at the fully-applied position. Hydraulic brake vehicles with a GVWR 4536 kg (10 000 lb) apply up to a maximum of 667 N (150 lb) to the park brake foot control or 556 N (125 l
46、b) to the hand control parking brake. If the vehicle does not remain stationary, reapplication of the service brakes to hold the vehicle stationary, with reapplication of the force to the parking brake control at the level specified as appropriate for the vehicle being tested may be used twice to at
47、tain a stationary position per FMVSS 105. 5.17.2.8 Turn off engine. 5.17.2.9 For variable input systems, record the minimum applied effort or pressure to lock the braked wheels. For fixed input systems, record the applied effort or pressure and observe if the braked wheels are rolling or locked. Obs
48、erve vehicle performance whether brake locks and wheel slides, etc. If the system is a cable or rod actuated service brake, allow vehicle to roll between each reading as noted in 5.15. SAE J1729 Revised FEB2008 - 6 - 5.17.2.10 Pull vehicle forward at a maximum rate of 1.2 m/min (4 ft/min) until the
49、wheel or driveline parking brake rotates 90 degrees. Record force in the data sheet of Figures 1A and 1B. 5.17.2.11 Release brakes and re-apply as in 5.17.2.7.1 or 5.17.2.7.2. Repeat 5.17.2.10 until wheels have rotated 360 degrees. 5.17.2.12 Record peak drawbar force in 90 degrees of wheel rotation until wheels have rotated 360 degrees. 5.17.2.13 Repeat all steps in 5.17.2 for each test condition of driver selecte
