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2、rom, 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 2009 SAE International All rights reserved. No part of this publication ma
3、y 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.orgSURFACEVEHICLESTANDARDJ299 JAN2009 Issued 1972-08Revised 2009-01 Superseding J299 SEP1993 Stopping Distance Test Procedure RATIONALEThis document has been modified based upon the normal review process to assure that th
5、e document recognizes current equipment, instrumentation and procedures. The document was formerly a Recommended Procedure that is being converted to a Standard in recognition of its use by industry for more than 30 years. Fifth wheel measuring device was removed to acknowledge use of other devices
6、for measuring speed and stopping distance. Speed and stopping distance maximum error were adjusted to correlate and be representative of current practice. 1. SCOPE This SAE Standard provides a method for determining stopping distances of all motor vehicles with any type of brake system. 1.1 Purpose
7、This code provides the test procedure and instructions to determine motor vehicle stopping distances on any level road surface from any desired initial vehicle speed. It allows the user to impose test conditions specified by any source and designates the preferred instrumentation and techniques for
8、achieving the accuracy that is practical with current equipment.2. REFERENCES There are no referenced publications specified herein. 3. DEFINITIONS 3.1 Motor Vehicle Every device which is self-propelled and equipped with driver controls in, upon, or by which any person or property is or may be trans
9、ported or drawn upon a highway or upon natural terrain, excepting devices moved by human or animal power or used exclusively upon stationary rails. 3.2 Start of Brake Application The initial movement of the brake system control. 3.3 Stopping Distance The distance traveled by a motor vehicle from the
10、 start of a brake application to the point at which the motor vehicle stops. SAE J299 Revised JAN2009 Page 2 of 33.4 Initial Stopping Speed The speed of the motor vehicle at the start of brake application. 3.5 Instrumentation System Delay The time between the start of brake application and the start
11、 of stopping distance readout. 4. INSTRUMENTATION AND EQUIPMENT All instrumentation and equipment used in this test procedure must maintain required accuracy throughout the test period. 4.1 Speed Measuring Device A device that not only monitors vehicle speed, but also makes an instrumented recording
12、 of actual initial stopping speed. Error must not exceed 0.5% of the actual speed. 4.2 Stopping Distance Measuring Instrumentation The distance measuring device is to be triggered at the point at which brake application can be detected and data acquisition begun without false triggering but in any e
13、vent not to exceed 22 N (5 lb) and/or first movement of 2.0 mm (0.07 in) of travel of the center of the brake pedal pad, the tip of the brake treadle, or the tip of the brake control handle (initial movement). Total instrumentation system delay shall not exceed 20 milliseconds. Error of distance mea
14、suring instrumentation shall not exceed 0.5% of actual distance. 5. MOTOR VEHICLE PREPARATION 5.1 Perform motor vehicle and brake system preparation required to conform to specific desired test conditions. Record these conditions and operations. 5.2 Install and calibrate instrumentation. Record pert
15、inent instrumentation information. 6. TEST PROCEDURE The following test sequence shall be conducted at the test site: 6.1 Attain a speed sufficiently above the desired initial stopping speed to allow the driver to perform operations in 6.2 and 6.3 and still comply with the requirements of 6.4. Howev
16、er, this speed shall not exceed desired initial stopping speed by more than 12 km/h (7.5 mph). 6.2 Release throttle. 6.3 If the stop is to be made in neutral or with clutch disengaged, perform the desired operation(s). 6.4 At the desired initial stopping speed, apply the brake control at the desired
17、 rate to any required limit(s) and maintain braking at the desired limit(s) until the motor vehicle reaches a full stop. The limit(s) shall be determined by the specific desired conditions and may be wheel skid, pedal force, deceleration, pressure, brake control movement, vehicle control, lane bound
18、aries, or a combination of these. NOTE: For vehicles with standard transmission, if stop is made in gear, the clutch should be disengaged when vehicle speed is reduced to below 16 km/h (10 mph) or as engine nears idle speed, whichever is the greater vehicle speed.SAE J299 Revised JAN2009 Page 3 of 3
19、6.5 Record measured stopping distance and actual initial vehicle stopping speed plus wind velocity, wind direction, road grade (if other than level), vehicle direction, road surface data, vehicle data, test conditions, etc. 6.6 Repeat 6.1, 6.2, 6.3, 6.4 and 6.5 as many times as specified for each se
20、t of conditions. 7. DISTANCE CORRECTION FORMULA FOR SMALL INITIAL STOPPING SPEED ERRORS This correction can only be made if actual initial vehicle stopping speed is visibly recorded as recommended in 4.1. Stopping distance corrections for initial speed errors greater than 3.2 km/h (2 mph) are invali
21、d due to inaccuracy. See Equation 1. ScSmVd2Va2-=(Eq. 1) where:Vd= desired initial vehicle stopping speed, km/h (mph) Va= actual initial vehicle stopping speed, km/h (mph) Sm= measured stopping distance, m (ft) Sc= calculated stopping distance from Vd, m (ft) 8. NOTES 8.1 Marginal Indicia A change b
22、ar (I) 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) 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 ROAD TEST PROCEDURES STANDARDS COMMITTEE
