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 entirelyvoluntary, and its applicability and suitability for any particular use, including any patent infringement arising therefro
2、m, 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 2004 SAE InternationalAll rights reserved. No part of this publication may be
3、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)Fax: 724-
4、776-0790Email: custsvcsae.orgSAE WEB ADDRESS: http:/www.sae.orgSURFACEVEHICLESTANDARDJ2469REAF.AUG2004Issued 1999-07Reaffirmed 2004-08Superseding J2469 JUL1999Clutch Application Powertrain Startability Rating Requirements for Truck and Bus ApplicationsForewordThis SAE Recommended Practice is present
5、ed in response to a need to standardize startabilitycalculation methods and requirements. Powertrain startability is a key factor in establishing a vehicle powertrainspecification that will operate efficiently and give long service life. The four primary factors which affect how long aclutch will la
6、st in a given truck are:a. Powertrain specification (engine, clutch, transmission, axle, and tires)b. Control of drivetrain torsional activityc. Driver technique (starting gear selection, engagement technique, driving habits)d. Clutch maintenance (adjustment, lubrication, protection from rust and co
7、ntamination)The powertrain specification is not only one of these primary factors, but it also can have a major effect on anotherfactor, driver technique. The final indicator of powertrain acceptability is the Startability Rating defined in thisdocument.TABLE OF CONTENTS1. Scope . 21.1 Purpose 22. R
8、eferences . 22.1 Applicable Documents 22.1.1 SAE Publications 23. Definitions. 24. Technical Requirements . 24.1 Powertrain Specification . 24.2 Powertrain Startability Rating . 3Copyright SAE International Provided by IHS under license with SAENot for ResaleNo reproduction or networking permitted w
9、ithout license from IHS-,-,-SAE J2469 Reaffirmed AUG2004-2-1. ScopeAlthough not limited to, these installations are normally used on trucks considered as Medium Duty(Class 6 and 7), as well as Heavy Duty (Class 8).1.1 PurposeThis SAE Recommended Practice defines powertrain application startability r
10、ating requirements forpull type single and twin plate truck clutches.2. References2.1 Related PublicationsThe following publications are provided for information purposes only and are not arequired part of this document. The following publications define the existing clutch system designconfiguratio
11、n used in trucks and buses.2.1.1 SAE PUBLICATIONSAvailable from SAE, 400 Commonwealth Drive, Warrendale, PA 15096-0001.SAE J373Housing Internal Dimensions for Single and Two Plate Spring Loaded ClutchesSAE J617Engine Flywheel HousingsSAE J1463Pull Type ClutchTransmission Installation DimensionsSAE J
12、1479Automotive Pull Type Clutch TerminologySAE J1731Pilot Bearings for Truck and Bus ApplicationsSAE J1806Clutch Dimensions for Truck and Bus ApplicationsSAE J1857Flywheel Dimensions for Truck and Bus Applications2.1.2 TMC PUBLICATIONSAvailable from The Maintenance Council, American Trucking Associa
13、tions, 2200 MillRoad, Alexandria, VA 22314.TMC RP 633 (T)Effects of Drivetrain Torsionals3. DefinitionsThe following specific terms as used in the document are defined as follows:a. Heavy-Duty (Class 8) TrucksA truck or tractor rated by the manufacturer and certified to the USfederal government to b
14、e for operation at a gross vehicle weight or a gross combination weight of14 969 kg (33 001 lb) and over.b. Medium-Duty (Class 6 and 7) TrucksA truck or tractor rated by the manufacturer and certified to theUS federal government to be for operation at a gross vehicle weight or a gross combination we
15、ight of8846 kg (19 501 lb) to 14 969 kg (33 000 lb).c. OEMOriginal Equipment ManufacturerThe term used to identify a vehicles manufacturer.4. Technical Requirements4.1 Powertrain SpecificationThe powertrain specification includes engine performance parameters, clutchsize, transmission gear ratios, a
16、xle ratio, tire size, powertrain configuration, and vehicle weight. The interactionbetween these factors can be characterized by a Startability Rating which will be defined in the next section. Abrief discussion of the powertrain specification factors follows:a. EngineCorrectly selecting and matchin
17、g an engine for a given application requires the considerationof many complex requirements and is beyond the scope of this document.b. ClutchClutches are primarily selected based on rated clutch torque capacity, which must be equal toor greater than the peak torque of the engine selected. In those c
18、ases where different sized clutchesare available for a given engine and torque rating, the larger clutch with more heat capacity will providelonger life. The clutch disc damper specification should be based on the need for torsional resonancevibration control.Copyright SAE International Provided by
19、IHS under license with SAENot for ResaleNo reproduction or networking permitted without license from IHS-,-,-SAE J2469 Reaffirmed AUG2004-3-c. TransmissionAs with engine selection, transmission selection is based on many complex factorssuch as torque capacity, number of gears, gear ratio steps, low
20、gear ratios (forward and reverse), finaldrive ratio, shift pattern, weight, and startability (discussed later). The number of gears and gear ratiosteps are important for clutch life. It is essential that a comfortable start-up gear with acceptablestartability be available for any normally encountere
21、d vehicle operating weight and applicationcondition (see Startability). The correct start-up gear may vary with vehicle weight, starting grade, androad surface conditions. Selecting a higher gear for start-up will increase clutch engagement slip timeand may significantly reduce clutch life.d. AxleFi
22、nal drive ratio is usually selected to complement the transmission and engine choice and toallow attainment of maximum cruising speed with optimized fuel economy. The ratio has a great affecton clutch life and must be used to calculate vehicle startability.e. TiresSizes range over a broad spectrum a
23、nd have the effect of modifying the final drive ratio.However, tire size has a limited effect and is not a major factor in clutch life. The startability formulaincludes the tire size effect through inclusion of the tires revolutions per mile rating.f. Powertrain ConfigurationThe number of total axle
24、s and the number of driving axles affect vehicletractive effort and driveline overall efficiency. For the purpose of defining powertrain startability,powertrain configuration has a very limited effect and is not taken as a variable factor in calculations.g. Vehicle LoadingThis factor has a direct ef
25、fect on vehicle performance, clutch heat input at startupand the startability calculation.4.2 Powertrain Startability RatingPowertrain startability has the most significant effect on clutch life. Astartability factor is calculated which is based on energy (heat) which must be absorbed by a clutch du
26、ringvehicle starts. It is important that startability be determined in the normal start-up gear (which is notnecessarily the lowest ratio gear of the transmission.) The normal start-up gear is one that can be used to startthe vehicle comfortably without having to fuel up the engine. Driveline compon
27、ent suppliers have formulas forstartability which are used to assess the starting capability of a given powertrain specification. Traditionally,differences have existed between the startability formulas used by the different component manufacturers, butthe Equation 1 is recommended to be used as a s
28、tandard calculation method. This formula is in generalagreement with all manufacturers requirements.(Eq. 1)where:Te= Gross available engine torque during clutch engagement in lb-ftRt= Transmission normal starting gear ratioRa= Axle final drive ratioM = Driving tire revolutions per mileGW = Total gro
29、ss vehicle weight including towed trailers (if any) in poundsStartability, S must meet the following requirements depending on type of application:S = 16 minimum for General On-Highway usageS = 25 minimum for Moderate On/Off-Highway usageS = 30 minimum for Severe On/Off-Highway usageTe, the clutch e
30、ngagement engine torque is the torque available from the engine at idle rpm, the assumedengine speed during clutch engagement. The minimum required clutch engagement torque for any applicationcan be computed by using the appropriate value of S from the previous requirements and substituting it into
31、thefollowing rearrangement of the startability formula (see Equation 2):(Eq. 2)Startability STeRtRaM10.7 GW=Te10.7 GW SRtRaM=Copyright SAE International Provided by IHS under license with SAENot for ResaleNo reproduction or networking permitted without license from IHS-,-,-SAE J2469 Reaffirmed AUG20
32、04-4-A sample startability calculation for a typical Class 8 truck, is as follows:“Clutch Engagement Torque” = Te= 640 lb-ftTransmission starting ratio = Rt= 10.99Rear axle final drive ratio = Ra= 4.10Driving tire revolutions per mile = M = 500Gross vehicle loaded weight = GW = 80000 lbSTARTABILITY
33、Conclusion: Acceptable for General On-Highway Usage.PREPARED BY THE SAE TRUCK AND BUS CLUTCH SUBCOMMITTEE OF THESAE TRUCK AND BUS POWERTRAIN COMMITTEES640 10.99 4.10 50010.7 80000 16.84=Copyright SAE International Provided by IHS under license with SAENot for ResaleNo reproduction or networking per
34、mitted without license from IHS-,-,-SAE J2469 Reaffirmed AUG2004RationaleThis document has been reaffirmed to comply with the SAE 5-Year Review policy.Relationship of SAE Standard to ISO StandardNot applicable.ApplicationThis SAE Recommended Practice defines powertrain application startability ratin
35、g requirementsfor pull type single and twin plate truck clutches.Reference SectionSAE J373Housing Internal Dimensions for Single and Two Plate Spring Loaded ClutchesSAE J617Engine Flywheel HousingsSAE J1463Pull Type ClutchTransmission Installation DimensionsSAE J1479Automotive Pull Type Clutch Termi
36、nologySAE J1731Pilot Bearings for Truck and Bus ApplicationsSAE J1806Clutch Dimensions for Truck and Bus ApplicationsSAE J1857Flywheel Dimensions for Truck and Bus ApplicationsTMC RP 633 (T)Effects of Drivetrain TorsionalsDeveloped by the SAE Truck and Bus Clutch SubcommitteeSponsored by the SAE Truck and Bus Powertrain CommitteeCopyright SAE International Provided by IHS under license with SAENot for ResaleNo reproduction or networking permitted without license from IHS-,-,-
