Abstract: An engine delivers torque to a transmission drive shaft through a flywheel and a damper. The damper includes a drive plate attached to the flywheel which is in turn mounted on the engine crankshaft. The damper has two driven plates which are fixed on the transmission drive shaft. The drive plate and driven plates have openings for retaining springs through which torque is transmitted from the drive plate to the driven plates. The flywheel has a plurality of arcuate segments equally spaced apart around a peripheral edge to form a plurality of windows. One of the driven plates has a plurality of radially extending fingers each extending into one of the windows so that gaps exist between each finger and two adjacent arcuate segments. As torque is transmitted through the damper the springs are compressed and the fingers move in the windows.

Abstract: In a tractor transmission system having electro-hydraulically actuated powershift clutches and a forward/reverse coupler mechanically coupled to a forward/reverse lever, a dump button is provided on the lever for releasing powershift clutch pressure. The forward/reverse coupler is uncoupled from the transmission input and output shafts when the button is depressed. An operator may shift between forward and reverse gears by depressing the button and shifting the lever. Upon release of the dump button, a microprocessor performs a control algorithm during which it senses engine speed and ground speed, computes acceleration/deceleration, and controls the clutch pressure of one of the powershift clutches to provide smooth acceleration in the direction selected by the shift lever. The arrangement is particularly suited for shuttle shift (forward/reverse) operations but may be used to provide smooth acceleration from a stopped position.

Abstract: A powershift transmission having input, center and output clutch sections, each section including a plurality of clutches, is arranged to have a high and a low range of input/output speed ratios with some of the lower ratios of the high range being substantially equal to some of the higher ratios of the low range. During upshifting the shift sequence is 1L, 2L, . . . (N-2)L, (N-1)L, NL, 3H, 4H, . . . NH and during downshifting the sequence is NH, (N-1)H . . . 2H, 1H, (N-2)L . . . 2L, 1L wherein ratios (N-1)L and NL are substantially equal to 1H and 2H, respectively, L represents the low range, H represents the high range and N represents the number of gear ratios within each range. The arrangement avoids the need for simultaneous clutch swaps in all three clutch sections and reduces the number of shifts requiring simultaneous clutch swaps in the center and output clutch sections.

Abstract: In a powershift transmission having electro-hydraulic clutches for selectively connecting an input shaft in driving relationship with an output at any one of a plurality of output to input shaft speed ratios, creeper gear speeds, less than those obtained by selecting the lowest output to input shaft speed ratio, are obtained by placing the transmission in the lowest gear (forward or reverse) and controlling the output shaft speed by automatically controlling clutch slippage. Any one of a plurality of forward or reverse creeper gear speeds may be selected by operation of a gearshift lever. The speeds of the input and output shafts are sensed and a microprocessor responds to the sensed shaft speeds and the selected creeper gear speed to control slipping of the clutch. In one embodiment the output shaft speed is controlled to a specific speed value independent of the input shaft speed. In a second embodiment, the output shaft speed is controlled to obtain a specific ratio of output to input shaft speed.

Abstract: In a powershift transmission system the output shaft and driveline unwind and then wind up during shifting under load as the torque applied to the shaft through a first clutch is reduced and the torque applied to the shaft through a second clutch is increased. The degree of winding or unwinding is dependent on the load being driven by the shaft and is manifested as an apparent increase or decrease in the rate of rotation of the output shaft as measured at the transmission end of the shaft. The rate of rotation of the transmission output shaft is sensed during shifting and the second clutch pressure is controlled in accordance with the sensed rate of rotation so that the second clutch pressure varies according to the load. The arrangement reduces sudden accelerations under no-load conditions but permits near optimum clutch pressures at heavier loads.

Abstract: A method of controlling an inching clutch in response to movement of an inching clutch pedal between up and down positions in a power shift transmission comprises, for clutch pedal positions below a limiting position, applying to the clutch a control signal which is non-linearly dependent upon the position of the pedal and, for clutch pedal positions above the limiting position, applying to the clutch a control signal which linearly increases with time and is entirely independent of clutch pedal position. Within one range of clutch pedal positions below the limiting position, the magnitude of the control signal applied to the clutch is constant when a high gear speed ratio has been selected, and varies linearly with the clutch pedal position when a low gear speed ratio has been selected. Within a range of pedal positions adjacent the fully down position, the control signal remains constant regardless of the position of the pedal.

Abstract: In a microprocessor controlled power shift transmission system having hydraulically actuated clutches, compensation is provided to offset the effects of centrifugal force on the fluid in the clutch piston cavity, these effects causing a variation in the response of a clutch to a clutch actuation signal. A table of compensation values is provided for each clutch which may be inched. Engine or input speed and vehicle or output speed are sensed to derive an address for addressing the table of an active clutch. The compensation value read from a table is used to modify a modulation value and the modulation value is then used to generate an actuation signal which is applied to the active clutch. If the piston cavity of a clutch is mounted on a member which is in direct drive connection with the input or output shaft of the transmission then the table is addressed by an address derived from the input speed or the output speed, respectively.

Abstract: In a power shift transmission system, two tables of values are established for modulating a clutch actuation, signal. When a clutch pedal is depressed below a limit position, both tables are accessed to obtain a pair of values, and the value which will result in the lower clutch pressure is used to modulate the actuation signal. One table is accessed in accordance with clutch pedal position and the other table is accessed in accordance with the selected gear speed ratio and engine speed. The arrangement prevents overheating of the clutch by the energy applied to it as a result of stalling the engine immediately after clutch inching.

Abstract: A microprocessor controlling a shuttle shift transmission may be programmed while the gearshift lever is in neutral to preselect a forward and reverse gear into which the transmission is shifted when the gearshift lever is moved to a forward or reverse position. The microprocessor may also be programmed so that, in shifting between forward and reverse, the forward and reverse gears selected differ by a preprogrammed amount. The microprocessor may be programmed to control vehicle deceleration by selecting gears in the transmission so that the transmission and/or the vehicle engine become a load for decelerating the vehicle. In a diagnostic mode, the microprocessor executes a routine to develop a clutch calibration value which may later be used to insure uniformity of clutch operation in different vehicles, or in the same vehicle over a period of time. The normal speed ratio matching which normally takes place when shifting gears may be manually overriden by operator manipulation of the gearshift lever.

Abstract: A microprocessor controlling a shuttle shift transmission may be programmed while the gearshift lever is in neutral to preselect a forward and reverse gear into which the transmission is shifted when the gearshift lever is moved to a forward or reverse position. The microprocessor may also be programmed so that, in shifting between forward and reverse, the forward and reverse gears selected differ by a pre-programmed amount. The microprocessor may be programmed to control vehicle deceleration by selecting gears in the transmission so that the transmission and/or the vehicle engine become a load for decelerating the vehicle. In a diagnostic mode, the microprocessor executes a routine to develop a clutch calibration value which may later be used to insure uniformity of clutch operation in different vehicles, or in the same vehicle over a period of time. The normal speed ratio matching which normally takes place when shifting gears may be manually overridden by operator manipulation of the gearshift lever.

Abstract: A microprocessor controlling a shuttle shift transmission may be programmed while the gearshift lever is in neutral to preselect a forward and reverse gear into which the transmission is shifted when the gearshift lever is moved to a forward or reverse position. The microprocessor may also be programmed so that, in shifting between forward and reverse, the forward and reverse gears selected differ by a preprogrammed amount. The microprocessor may be programmed to control vehicle deceleration by selecting gears in the transmission so that the transmission and/or the vehicle engine become a load for decelerating the vehicle. In a diagnostic mode, the microprocessor executes a routine to develop a clutch calibration value which may later be used to insure uniformity of clutch operation in different vehicles, or in the same vehicle over a period of time. The normal speed ratio matching which normally takes place when shifting gears may be manually overridden by operator manipulation of the gearshift lever.

Abstract: A power shift transmission having a ratio matching feature whereby the disengagement of the transmission by moving the gearshift lever to the neutral position or by depressing the clutch pedal initiates a routine in the microprocessor controlling the operation of the transmission to calculate the ratio of the rotation of the input and output shafts of the transmission and select the gear most closely matching the calculated ratio is disclosed wherein the ratio matching routine can be manually overridden by signalling a gear change with the gearshift lever. The override feature for the ratio matching routine can be permanent for each disengagement of the transmission or temporary for the running of a timer for a predetermined length of time.

Abstract: A power shift transmission is operably controlled by a microprocessor that will effect a deceleration of the vehicle at relatively high speeds by effecting a downshifting of the transmission in response to a sensing of the rate of rotation of the output shaft such that the gears in the transmission are selected so that the transmission and/or the vehicle engine becomes a load for decelerating the vehicle. The microprocessor does not effect a downshifting of the transmission whenever the sensed rate of rotation of the output shaft would cause an overspeeding of the engine in the lower gear. The microprocessor runs a strategy determination check prior to entering a high speed deceleration routine to determine if a more efficient deceleration routine would be more effective, as based upon the pre-sensed rate of rotation of the output shaft.

Abstract: A control mechanism for an electronically controlled power shift transmission is disclosed wherein the shift pattern for the control mechanism includes an upshift and downshift path of movement for each of the forward, neutral, and reverse positions through which the control lever is movable. The control lever is biased toward a no-shift sub-position for each position of movement of the lever. A latching mechanism engageable when the control lever is in the neutral position does not restrict movement of the lever between the upshift and downshift subpositions.

Abstract: A microprocessor controlling a shuttle shift transmission may be programmed to effect a calibration of the final drive clutches in the transmission so that the microprocessor can efficiently effect engagement of each respective said clutch by applying the proper hydraulic pressure to cause proper engagement thereof. This method of calibrating the final drive clutches in the transmission includes braking the output shaft of the transmission so that any engagement of the selected final drive clutch being calibrated will cause a load to be applied to the engine. The hydraulic pressure is then incrementally increased until the engine RPM's decrease because of the load being placed on the engine. The value of this engagement hydraulic pressure is stored in the microprocessor for use when effecting engagement of the selected clutch during operation of the transmission. Service indicators are programmed into the microprocessor should the selected clutch not be capable of being calibrated.

Abstract: A microprocessor controlling a shuttle shift transmission may be programmed while the gearshift lever is in neutral to preselect a forward and reverse gear into which the transmission is shifted when the gearshift lever is moved to a forward or reverse position. The microprocessor may also be programmed so that, in shifting between forward and reverse, the forward and reverse gears selected differ by a pre-programmed amount. The microprocessor may be programmed to control vehicle deceleration by selecting gears in the transmission so that the transmission and/or the vehicle engine become a load for decelerating the vehicle. In the method of decelerating the tractor from relatively high vehicle speeds, the transmission is disconnected from the engine and then locked by simultaneously engaging two clutches for the simultaneous engagement of two gear ratios. A modulation of the final clutch set permits the inertial energy of the tractor to be dissipated.