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 2009 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 SURFACE VEHICLE RECOMMENDED PRACTICE J45 MAY2009 Issued 1973-10 Revised 2009-05 Superseding J45 FEB2003 Brake System Test ProcedureSnowmobiles RATIONALE This document is being revised to remove obsolete references in
5、 Section 2. 1. SCOPE This SAE Recommended Practice establishes a uniform procedure for the level surface testing of hand-operated brake systems on recreational noncompetitive snowmobiles. 1.1 Purpose This procedure offers a method of testing snowmobiles on turf. Turf is preferred over snow because t
6、est repeatability is more easily obtained. In addition, tests shall be conducted under winter conditions to ensure that the braking systems remain operative and that the vehicle has no undue tendency to lose stability, overturn, or swerve out of a test lane 1.2 m (4 ft) wider than the vehicle when t
7、he brakes are applied. The purpose of the document is to establish brake system capabilities with regard to deceleration or stopping distance versus applied brake lever force, as affected by vehicle speed, brake temperature, and usage. 2. REFERENCES 2.1 Related Publications The following publication
8、s are provided for information purposes only and are not a required part of this document. 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 J44 Service
9、 Brake System Performance RequirementsSnowmobiles SAE J1282 Snowmobile Brake Control Systems SAE J45 Revised MAY2009 Page 2 of 7 3. DEFINITIONS 3.1 Brake Lever Force A steady force applied in a direction normal to the handle grip in the plane of rotation of the hand brake lever at a distance no more
10、 than 25.4 mm (1 in) from the end of the control lever. Refer to 5.3.3. 3.2 Deceleration Average rate of change of vehicle speed during stopping time. Numerically equal to the initial vehicle speed divided by the stopping time. Does not denote instantaneous deceleration at some time during brake app
11、lication. 3.3 Average Deceleration Refers to the average of the previous decelerations over the required number of tests. 3.4 Initial Vehicle Speed Steady-state vehicle speed immediately prior to brake application. 3.5 Stop Interval Distance or time between successive brake applications. 3.6 Stoppin
12、g Distance Distance vehicle travels from position where brake is applied to position where vehicle comes to a stop. 3.7 Stopping Time Elapsed time between initial brake application and when vehicle comes to a stop. 3.8 Turf A consistent and reasonably uniform grassy surface. In this context, does no
13、t include root structure. 4. INSTRUMENTATION Instrumentation is required to make the following observations: a. Brake lever force with an accuracy of 5%. b. Specified vehicle speed with an accuracy of 3 km/h (2 mph).1c. Actual vehicle speed with an accuracy of 2 km/h (1 mph).2d. Stop interval with a
14、n accuracy of 0.1 km (0.05 mile) on distance, 5 s on time. e. Stopping distance or stopping time with an accuracy of 5%. f. Current time with an accuracy of 30 s. 1For example, if a test calls for an initial vehicle speed of 32 km/h (20 mph), a speed less than 29 km/h (18 mph) or more than 35 km/h (
15、22 mph) is not acceptable. 2For example, a recorded actual speed of 34 km/h (21 mph) should be accurate within 2 km/h (1 mph). SAE J45 Revised MAY2009 Page 3 of 7 g. Ambient temperature with an accuracy of 0.5 C (1 F). h. Deceleration (optional)may be useful as a guide or indicator. 5. GENERAL INSTR
16、UCTIONS 5.1 Brake Assembly Brakes shall be prepared and adjusted in accordance with the vehicle manufacturers standard specifications. 5.2 Vehicle Test Weight Tests shall be conducted with the vehicle loaded to a test weight as determined by Equations 1 or 2: W = C + 75(2)S (Eq. 1) where: W = test w
17、eight, kg C = curb weight, kg, which is the weight of the vehicle with standard equipment, including maximum capacity of fuel and oil with a total accuracy within 2 kg S = the vehicles designed seating capacity or W = C + 165(5)S (Eq. 2) where: W = test weight, lb C = curb weight, lb, which is the w
18、eight of the vehicle with standard equipment, including maximum capacity of fuel and oil with a total accuracy within 5 lb S = the vehicles designed seating capacity 5.3 Test Conditions 5.3.1 Test Surface Tests shall be conducted on a substantially level (not to exceed 1% grade), dry turf. The turf
19、shall not exceed 76 mm (3 in) in height. The coefficient of sliding friction between the test surface and the loaded vehicle with its track locked should be established to be within the range of 0.55 to 0.75. When repeated testing results in visible deterioration of the test surface, testing should
20、be moved to a new, unused area. 5.3.2 Ambient Air Treatment Ambient air temperature for all tests shall be between 7 and 27 C (20 and 80 F). 5.3.3 Brake Lever Force The brake force shall be applied in a manner equivalent to that shown in Figure 1. The effective brake lever force shall be applied at
21、a point no more than 25.4 mm (1 in) from the end of the control lever in a direction normal to the hand grip and in the plane of rotation of the control lever. SAE J45 Revised MAY2009 Page 4 of 7 5.3.4 Test Speed Vehicles shall be tested at the specified speed for each test. If the specified speed c
22、annot be obtained, the test speed shall be the greatest achievable speed evenly divisible by 8 km/h (5 mph). (For example: if 61 km/h (38 mph) is the maximum speed achievable, the test speed for the 64 km/h (40 mph) requirement would become 56 km/h (35 mph).) If the maximum achievable speed is less
23、than 8 km/h, the test speed shall be 5 km/h (3 mph). 5.4 Test Observations 5.4.1 During all phases of testing, any unusual performance such as grab, noise, or track skid is to be noted and recorded. Also note and record any uncontrollable braking action causing the vehicle to lose stability, overtur
24、n, or swerve out of a test lane 1.2 m (4 ft) wider than the width of the vehicle. 5.4.2 Using stopping distance or stopping time as the test methods, deceleration shall be determined by Equations 3 and 4. g184g184g185g183g168g168g169g167=SV0386.0ASV075.1A22(Eq. 3) or g184g185g183g168g169g167=TV278.0
25、ATV466.1A (Eq. 4) where: A = deceleration, m/s2(ft/s2) V = initial vehicle speed, km/h (mph) S = stopping distance, m (ft) T = stopping time, s 6. TEST PROCEDURE The test procedure shall conform to the following: 6.1 Preburnish Check 6.1.1 Apply 400 N (90 lb) to the brake lever and note any indicati
26、on of component or assembly failure. Brake lever may yield or bottom on adjacent element after track is locked. 6.1.2 In order to allow for a general check of brakes, instrumentation, and vehicle operation, the following tests are to be run: 6.1.2.1 Conditions a. Stops required5 b. Stop interval0.8
27、km (0.5 mile) c. Initial vehicle speed48 km/h (30 mph) d. Brake lever forceDetermine the brake lever force to obtain a deceleration of 3 m/s2(10 ft/s2). SAE J45 Revised MAY2009 Page 5 of 7 FIGURE 1 - BRAKE LEVER FORCE 6.2 Burnish Procedure Continue preburnish stops until stable brake performance is
28、achieved or 80% lining contact is obtained. 6.3 Effectiveness Test Conduct the test and record the actual brake lever force and stopping distance or time for each initial vehicle speed. Stay alert for any hazardous condition which may cause the vehicle to lose stability due to track skid, overturn,
29、or swerve out of the test lane. 6.3.1 Conditions a. Stops required4 at each speed b. Stop interval0.8 km (0.5 mile) c. Initial vehicle speed32 and 64 km/h (20 and 40 mph) d. Brake lever forceAs required to give not less than 6 m/s2(20 ft/s2) or the minimum for a locked track. No more than 111 N (25
30、lb) of brake lever force may be applied at any time. SAE J45 Revised MAY2009 Page 6 of 7 6.4 Water Test 6.4.1 Preliminary Preparation Perform wetting of brakes prior to the test. a. Wetting time5 min minimum. b. Wetting procedureWet all friction elements of brake system with a fine water spray. 6.4.
31、2 Test Start the test not more than 1 min after wetting brakes. Conduct the test under the following conditions and record stopping distance versus brake lever force. 6.4.2.1 Conditions a. Stops required1 b. Initial vehicle speed32 km/h (20 mph) c. Brake lever forceThat previously established during
32、 the effectiveness test 6.3.1d. d. Deceleration shall be at least 3 m/s2(10 ft/s2). 6.5 Fade and Recovery Test 6.5.1 Fade Test Conduct the test under the following conditions and record brake lever force and stopping distance or time. If the time or distance measurements at every stop are not feasib
33、le due to course layout, it is permissible to limit measurements to every other stop providing the last stop is recorded. Also record the following: a. Ambient air temperature at beginning of fade test. b. Total elapsed time from end of the first fade stop to end of last fade stop. 6.5.1.1 Condition
34、s a. Stops required10 b. Stop interval1 min maximum c. Initial vehicle speed64 km/h (40 mph) or maximum vehicle speed, whichever is less d. Cooling speedSame as initial speed e. Brake lever forceThat previously established during the effectiveness test to give a deceleration of not less than 6 m/s2(
35、20 ft/s2) from 64 km/h (40 mph). If track locks before obtaining 6 m/s2(20 ft/s2), then reduce the brake lever force to the maximum obtainable without locking the track. 6.5.2 Recovery Test Allow the brakes to cool and repeat effectiveness test at 64 km/h (40 mph). SAE J45 Revised MAY2009 Page 7 of
36、7 6.6 Final Inspection After completion of all previous tests, disassemble the brakes, inspect, and record all pertinent observations. 7. NOTES 7.1 Marginal Indicia A change bar (I) located in the left margin is for the convenience of the user in locating areas where technical revisions, not editori
37、al 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 SNOWMOBILE TECHNICAL COMMITTEE
