SAE TECHNICAL PAPER SERIES The Engineering Sociefy *A =For Advancing Mobility Land Sea Air and Space, Development of a Hydraulic Retarder for the Allison AT545R Transmission Timothy J. Cooney Joel E. Mowatt Allison Transmission Division General Motors Corporation International Truck & Bus Meeting and Exposition Winston-Salem, North Carolina November 13-1 5,1995 400 COMMONWEALTH DRIVE, WARRENDALE, PA 15096-0001 U.S.A. Downloaded from SAE International by University of New South Wales, Saturday, August 25, 2018The appearance of the ISSN code at the bottom of this page indicates SAE's consent that copies of the paper may be made for personal or internal use of specific clients. The consent is given on the condition, however, that the copier pay a $7.00 per article copy fee through the Copyright Clearance Center, Inc. Operations Center, 222 Rosewood Drive, Danvers, MA 01923 for copying beyond that permitted by Sections 107 or 108 of the U.S. Copyright Law. This consent does not extend to other kinds of copying such as copying for general distribution, for advertising or promotional purpos- es, for creating new collective works, or for resale. SAE routinely stocks printed papers for a period of three years following date of publi- cation. Direct your orders to SAE Customer Sales and Satisfaction Department. Quantity reprint rates can be obtained from the Customer Sales and Satisfaction Department. To request permission to reprint a technical paper or permission to use copyrighted SAE publications in other works, contact the SAE Publications Group. All SA E papers, standards, and selected books are abstracted adn indexed in the Global Mobility Database. No part of this publication may be reproduced in any form, in an electronic retrieval system or otherwise, without prior written permission of the publisher. ISSN 01 48-71 91 Copyright 1995 Society of Automotive Engineers, Inc. Positions and opinions advanced in this paper are those of the author(s) and not nec- essarily those of SAE. The author is solely responsible for the content of the paper. A process is available by which discussions will be printed with the paper if it is published in SAE transactions. For permission to publish this paper in full or in part, contact the SAE Publications Division. Persons wishing to submit papers to be considered for a presentation or publication through SAE should send the manuscript or a 300 word abstract of a proposed manu- script to: Secretary, Engineering Activity Board, SAE. Printed in U.S.A. 90-1 203DlPG Downloaded from SAE International by University of New South Wales, Saturday, August 25, 2018Development of a Hydraulic Retarder for the Allison AT545R Transmission Timothy J. Cooney Joel E. Mowatt Allison Transmission Division General Motors Corporation ABSTRACT With the introduction of the AT545R, Allison Transmission completes its family of transmission integral retarders. These retarders, as an auxiliary braking system to vehicle service brakes, will now be available with all commer- cial on-highway and off-highway transmission models. The AT545R has a retarder located on the input side of the trans- mission that is designed for auxiliary braking for downhill speed control. This 160-hp retarder has a two-stage capacity that, in conjunction with selection of the appropriate gear ranges, can be used to tailor desired retardation performance to particular duty cycles. The design, development and perfor- mance of the AT545R are targeted for school busses and motorhomes, though many other users will find distinct vehi- cle control advantages with this low cost, compact retarder. The development from concept through production implemen- tation will be discussed in this paper. INTRODUCTION Throughout the mountainous areas of the United States, indeed throughout the world, drivers are increasingly demand- ing secondary vehicle retardation systems. From the Appalachians a