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 2016 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/J45_201608 SURFACE VEHICLE RECOMMENDED PRACTICE J45 AUG2016 Issued 1973-10 Revis
5、ed 2016-08 Superseding J45 MAY2009 Brake System Test Procedure - Snowmobiles RATIONALE This document is being revised to clarify the definition of Turf in section 3.8 and Test Surfaces in section 5.3.1 which will align this procedure with the surfaces specified in SAE J192, Maximum Exterior Sound Le
6、vel for Snowmobiles. In addition, the braces in Equations 3 and 4 where transposed to correctly match the appropriate equation to the unit of measure. 1. SCOPE This SAE Recommended Practice establishes a uniform procedure for the level surface testing of hand-operated brake systems on recreational n
7、oncompetitive snowmobiles. 1.1 Purpose This procedure offers a method of testing snowmobiles on turf. Turf is preferred over snow because test repeatability is more easily obtained. In addition, tests shall be conducted under winter conditions to ensure that the braking systems remain operative and
8、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 the brakes are applied. The purpose of the document is to establish brake system capabilities with regard to deceleration or stopping distance versus applied brak
9、e lever force, as affected by vehicle speed, brake temperature, and usage. 2. REFERENCES 2.1 Related Publications The following publications are provided for information purposes only and are not a required part of this SAE Technical Report. 2.1.1 SAE Publications Available from SAE International, 4
10、00 Commonwealth Drive, Warrendale, PA 15096-0001, Tel: 877-606-7323 (inside USA and Canada) or +1 724-776-4970 (outside USA), www.sae.org. SAE J44 Service Brake System Performance Requirements - Snowmobiles SAE J1282 Snowmobile Brake Control Systems SAE INTERNATIONAL J45 AUG2016 Page 2 of 7 3. DEFIN
11、ITIONS 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 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 s
12、topping time. Numerically equal to the initial vehicle speed divided by the stopping time. Does not denote instantaneous deceleration at some time during brake application. 3.3 AVERAGE DECELERATION Refers to the average of the previous decelerations over the required number of tests. 3.4 INITIAL VEH
13、ICLE SPEED Steady-state vehicle speed immediately prior to brake application. 3.5 STOP INTERVAL Distance or time between successive brake applications. 3.6 STOPPING DISTANCE Distance vehicle travels from position where brake is applied to position where vehicle comes to a stop. 3.7 STOPPING TIME Ela
14、psed time between initial brake application and when vehicle comes to a stop. 3.8 TURF A consistent and reasonably uniform grass covered surface. In this context, does not include root structure. 4. INSTRUMENTATION Instrumentation is required to make the following observations: a. Brake lever force
15、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 an 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%. 1For exam
16、ple, 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 (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 INTERNATIONAL J45 AUG2016 Page 3 of 7 f.
17、Current time with an accuracy of 30 s. 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 INSTRUCTIONS 5.1 Brake Assembly Brakes shall be prepared and adjusted in accordance with the vehicle manufacturers standard sp
18、ecifications. 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 weight, kg C = curb weight, kg, which is the weight of the vehicle with standard equipment, including maximum capacity of
19、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 weight of the vehicle with standard equipment, including maximum capacity of fuel and oil with a total accuracy within 5 l
20、b S = the vehicles designed seating capacity 5.3 Test Conditions 5.3.1 Test Surface 5.3.1.1 Turf Tests shall be conducted on a substantially level (not to exceed 1% grade) turf, free of visible droplets of water. The turf shall not exceed 76 mm (3 in) in height. When repeated testing results in visi
21、ble deterioration of the test surface, testing should be moved to a new, unused area. 5.3.1.2 Snow Covered Surface The surface of the ground shall be covered with a maximum of 75 mm (3 in) of loose snow over a base consisting of at least 75 mm (3 in) of snow sufficiently compacted to support the sno
22、wmobile without significant penetration. The hardness of the snow surface shall be verified prior to testing by traversing the snowmobile over the test lane at a steady speed as slow as clutch engagement will allow and verifying at least 25 mm of track lug penetration. A track with less than a 25 mm
23、 lug shall have full lug penetration. Lug height is to be determined by measuring from the track belt to the maximum lug height. SAE INTERNATIONAL J45 AUG2016 Page 4 of 7 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 Fo
24、rce 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 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. 5
25、.3.4 Test Speed Vehicles shall be tested at the specified speed for each test. If the specified speed cannot 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 th
26、e 64 km/h (40 mph) requirement would become 56 km/h (35 mph).) If the maximum achievable speed is less 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
27、. Also note and record any uncontrollable braking action causing the vehicle to lose stability, overturn, 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
28、 and 4. SVASVA22075.10386.0(Eq. 3)or TVATVA466.1278.0(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
29、) to the brake lever and note any indication of component or assembly failure. Brake lever may yield or bottom on adjacent element after track is locked. SAE INTERNATIONAL J45 AUG2016 Page 5 of 7 6.1.2 In order to allow for a general check of brakes, instrumentation, and vehicle operation, the follo
30、wing tests are to be run: 6.1.2.1 Conditions a. Stops required - 5 b. Stop interval - 0.8 km (0.5 mile) c. Initial vehicle speed - 48 km/h (30 mph) d. Brake lever force - Determine the brake lever force to obtain a deceleration of 3 m/s2(10 ft/s2). Figure 1 - Brake lever force 6.2 Burnish Procedure
31、Continue preburnish stops until stable brake performance is 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
32、 the vehicle to lose stability due to track skid, overturn, or swerve out of the test lane. SAE INTERNATIONAL J45 AUG2016 Page 6 of 7 6.3.1 Conditions a. Stops required - 4 at each speed b. Stop interval - 0.8 km (0.5 mile) c. Initial vehicle speed - 32 and 64 km/h (20 and 40 mph) d. Brake lever for
33、ce - As 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 lb) of brake lever force may be applied at any time. 6.4 Water Test 6.4.1 Preliminary Preparation Perform wetting of brakes prior to the test. a. Wetting time - 5 min minimum. b. Wetting
34、 procedure - Wet all friction elements of brake system with a fine water spray. 6.4.2 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 required - 1 b. Initi
35、al vehicle speed - 32 km/h (20 mph) c. Brake lever force - That previously established during 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
36、 stopping distance or time. If the time or distance measurements at every stop are not feasible 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. T
37、otal elapsed time from end of the first fade stop to end of last fade stop. 6.5.1.1 Conditions a. Stops required - 10 b. Stop interval - 1 min maximum c. Initial vehicle speed - 64 km/h (40 mph) or maximum vehicle speed, whichever is less SAE INTERNATIONAL J45 AUG2016 Page 7 of 7 d. Cooling speed -
38、Same as initial speed e. Brake lever force - That previously established during the effectiveness test to give a deceleration of not less than 6 m/s2(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
39、 locking the track. 6.5.2 Recovery Test Allow the brakes to cool and repeat effectiveness test at 64 km/h (40 mph). 6.6 Final Inspection After completion of all previous tests, disassemble the brakes, inspect, and record all pertinent observations. 7. NOTES 7.1 Revision Indicator A change bar (l) lo
40、cated 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 SNOWMOBILE TECHNICAL COMMITTEE
