SAE TECHNICAL PAPER SERIES The MT643R-An Automatic Transmission with Retarder for the Latin American Market f imothy J. Cooney Allison Transmisson Paulo Mauali General Motors- Allison Transmission VI International Mobility Technology Conference and Exhibit Sio Paulo, Brazil October 27-29, 1997 400 Commonwealth Drive, Warrendale, PA 15096-0081 U,S.A. Tel: (724) 776-4841 Fax: (724) 776-5760 Downloaded from SAE International by University of New South Wales, Sunday, August 26, 2018The appearance of the ISSN code at the bottom of this page indicates SAE's consent that coples of the paper may be made for personal or internal use of specific clients. This 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 U.S. Copyright Law. This consent does not extend to other kinds of copytng such as copying for general distribution, for advertising or promotional purposes, for creating new collective works, or for resale. SAE routinely stocks printed papers for a period of three years following date of publication. Direct your orders to SAE Customer Sales and Satisfaction Department. Quantity reprlnt rates can be obtained from the Customer Sales and Satisfact~on Department. To request permission to reprint a technical paper or permission to use copyrighted SAE publications in other works, contact the SAE Publications Group. GUWW MOBIUTY a4TAB4SE All SAE papers, standards, and selected books are abstracted and indexed in the Global Mobility Database. No part of th~s publicatron may be reproduced In any form, In an electronic retrieval system or othetw~se, w~thout the prlor written permlsslon of the publisher ISSN 0148-7191 Copyright 1997 Society of Automotive Engineers, Inc. Positions and opinions advanced in this paper are those of the author(s) and not necessarily 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 Group. Persons wishing to submit papers to be considered for presentation or publication through SAE should send the manuscript or a 300 word abstract of a proposed manuscript to: Secretary, Engineering Meetings Board, SAE. Downloaded from SAE International by University of New South Wales, Sunday, August 26, 2018The MT643R - An Automatic Transmission with Retarder for the Latin American Market Timothy J. Cooney Allison Transmission Division of General Motors Corporation Paulo Roberto Cassoli Mauali General Motors do Brasil - Divisgo Allison Transmission Copyright Q 1997 Society of Automotive Engineers, Inc ABSTRACT The Allison MT643R is a fully automatic transmission with integral input retarder that has been designed and developed for the Latin American city bus market. This transmission provides a cost effective manner to integrate secondary braking into an automatic transmission to lower overall life cycle costs for the city bus. It provides the ease of operation of the fully automatic transmission while providing a system that will enhance vehicle braking and safety while saving on brake system repairs - all in one package. The MT643R has a 250 horsepower input retarder which has a two- stage capacity that, in conjunction with the gear multiplication through the drivetrain as the transmission downshifts, allows for tailoring of the retardation performance to very specific duty cycles. This paper will discuss the design, development, and specific product launch of the MT643R into the Latin American marketplace. INTRODUCTION The Latin America city bus market is one of the most severe in the world. With its high density start & stop traff