1300162, OPR, HYSTER, Hyster2, SRM

//-->.pos {position:absolute; z-index: 0; left: 0px; top: 0px;}INTRODUCTIONSlideTB9-1The T7 Powershift Transmission is essentiallythe two-speed brother of the T3 and T6 Single-SpeedPowershift Transmissions and may be installed in anyof the following lift trucks:••SpaceSaver models S125-150AChallenger models H60-70-80C, andH110-130-150FThese larger capacity lift trucks are fre-quently required to operate with long-er travelcycles than smaller trucks. As a result, a two-speedtransmission, which permits a greater speed rangethan a single-speed transmission, is essential forefficient operation. This textbook describes thattransmission. The designation “T7” is taken fromthe serial number prefix assigned to allS125-150A/ H60-80C / H110-150 F Two-SpeedPowershift Transmissions.SST Textbook T-1C describes the T6Powershift Transmission used in S30-50C/S60-80B/S100B lift trucks (referred to as the S30/60/100Single-Speed Powershift Transmission).SST Text-book TC2 describes the T3 Single-Speed PowershiftTransmission used in S20-30A/H20-30E lift trucks.Since there are many similarities between the T7 andthe T3/T6 Transmissions, you will find many similari-ties between this Textbook and SST Textbooks T-1C and TC2.If you are thoroughly familiar with T-1C andTC2, you may wish to skip over the sections dealingwith the torque converter and the directional engag-ing unit. If you have not been through T-1C or TC2,however, we recommend that you study this text in itsentirety.Figure 1. The T7 Powershift TransmissionTHE TRANSMISSION DESCRIBEDSlideTB9-2The T7 Powershift Transmission may be de-fined as a two-speed, constant-mesh, hydraulic - con-trolled transmission. See Figure l.Two-speed means that the transmission hastwo speed ranges for forward travel and two speedranges for reverse travel.Constant-mesh means that the output gearsare continuously engaged and do not shift, slide, orchange their relative position in any way.Hydraulic-controlled means that thetransmission’s directional and speed range engagingsystems (clutch packs) are actuated by hydraulic oilunder pressure. The driver controls the hydraulic sys-tem with two levers mounted to the truck’s steeringcolumn. One lever is used to select direction of travel,the other lever is used to select the speed range.A truck equipped with a T7 Powershift Trans-mission is also fitted with an inching pedal, extendingfrom the left side of the floorplate. “Inching” is theability of a truck to move at low speeds while main-taining high engine RPM. Initial depression of the inch-ing pedalcauses the transmission to begin to slip. Con-tinued depression gradually applies the service brakesuntil, with the inching pedal fully depressed, the trans-mission is fully disengaged from the drive wheels andthe brakes are fully applied.By coordinating the inchingpedal with thethrottle pedal, the driver can slowly maneuver in tightquarters yet have high engine speed to operate thehydraulic hoist system or other accessories. (The pedalto the right of the inching pedal operates the servicebrakes only.)The transmission is also equipped with a neu-tral start switch so that the engine cannot be startedunless the directional control lever is in neutral. TheT7 Powershift Transmission is comprised of four ba-sic elements. They are the;••••Torque ConverterDirectional Engaging Unit and GearsHigh-Low Engaging Unit and GearsHydraulic SystemThis textbook will describe the operation ofeach of these elements.THE TORQUE CONVERTERBefore we describe the torque converter, let’sfind out just what “torque” is.What is Torque ?Torque is an applied force. The word “twist”can usually be substituted for “torque” without chang-ing the meaning. Torque is determined by multiplyingthe applied force by the radius of the part being forced(which is simply a lever arm). The result is expressedin pound-feet.Don’t confuse a pound-foot with a foot-pound. A foot-pound is the amount of energy ex-pended in lifting a one-pound mass a distance of onefoot against the pull of gravity. A pound-foot is theforce generated when one pound of energy is appliedto a lever arm one foot long. Foot-pounds indicateEnergy; pound-feet indicate Torque.SlideLet’s determine Torque from a sample prob-TB9-3lem. The force exerted against the piston in an engineis 400 pounds. The throw of the crankshaft is 3 inches.See Figure 2. How much torque is produced?•Force (400 pounds) x Radius (3 inches or0.25 feet) 100 pound-feet of “twistingforce” or torque.Torque is not power. Power is a measure ofthe rate of work, which means that time is a factor.Time is not a factor of torque - only force and dis-tance. Torque can be present whether motion is pro-duced or not.SlideA torque converter multiplies torque. In otherTB9-4words, it increases the twisting force from the engine.In addition, a torque converter provides a fluid con-nection between the engine and the transmission. SeeFigure 3.Figure 2. TorqueFigure 3. The Torque Converter

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