:.':"':::::::': '.' '.'.:..::: ~.:,Christy 650694w. Allison DivisionCarriers IA. General Motors Corp.Transmissions CraneInAutomatic Farm,Construction and Industrial Machinery Meeting Milwaukee, Wis. September 13-16,1965SOCIETY OFAUTOMOTIVE ENGINEERSDownloaded from SAE International by University of British Columbia, Sunday, August 19, 2018Automatic Transmissions In Crane Carriers A. W. Christy Allison Division General Motor s Corp. In automotive equipment, many new devices influencing productivit y have appeared, and the automatic transmission is rapidly becom­ ing one of these. Also, with emphasis on greater individual productivity, it has become necessary to broaden a man's skills. Auto­ matic transmissions have contributed im­ measurably to both of these factors in many types of applications. For example, several large utilities have obtained experience with them in line construction trucks, dump trucks, line stringers, tractors equipment or ware­ house trucks and other applications peculiar to public utility work. This experience with automatics has begun to provide data and re­ sults which are not only of interest to the utility industry but to other users of similar equipment in the construction industry. OPERATION AND DESCRIPTION Operation Fromthe user's point of view, this transmis­ sion migh t be first described by its most ob­ vious means of identification, the controls in the cab. In this group there are three indi­ vidual components providing driver control: (Figure 1) . Range Selector . Throttle Pedal . Retarder Pedal To evaluate and understand these results re­ quires a n explanation of how an automatic operates, a description of its components, and a discussion of typical applications and their relation to crane carriers. Since the Allison transmission is the only automatic available at this time for medium and heavy-duty ve­ hicles, the discussion of necessity will center around its design, features, performance, application, and use. Downloaded from SAE International by University of British Columbia, Sunday, August 19, 20182 Figure 2 Figure 3 Range Selector Through the range selector (Figure 2) the driver has the choice of several combinations of gears best suited for different driving and operating conditions: Neutral is the engine - starting position as well as the position for operating the PTO; the 3-6 position, normal driving range, is used for open road opera­ tion; the 3-5 range provides the three gears (3rd, 4th, and 5th) best suited for zero to 45 MPH operation; the 3-4 range gives the driver optimum control in heavy traffic operation (zero to 30 MPH); the 1-2 position, also called "creeper" range, is used for off-highway and steep grade operation. maticupshifting is obtained. This also raises the downshift points to obtain a "kickdown" effect. Throttle modulation, the over-control of upshifts and the kickdown shifting are ac­ complished by a linkage inter-connecting the throttle pedal, the engine fuel control lever, and the transmission throttle valve lever. Retarder Pedal Usually, on the left side of the floor of the cab, there is a treadl e with which the hydraulic Throttle Pedal With the choice of the desired selector range to provide the several gears best suited to the operating conditions encountered, the driver can modulate the shifting by the throttle pedal position which exercises control over the transmission's shift speeds. At full throttle (Figure 3), the transmission's shifts occur at speeds immediately under the engine governor setting as the engine develops its full output horsepower. At part throttle, lower shift speeds are required to coincide with the lower engine power level. In addition, by pushing the throttle pedal through a detent, a n overrule preventing auto-Figure 4 Downloaded from SAE International by University of British Columbia, Sunday, August 19, 20183 grade retarder is applied. This devic