A shift interlock for a multi-speed transmission controlled by a speed lever and a directional lever is disclosed which prevents inadvertent operation of the directional control feature while the transmission is in the high gear ratios. The interlock is comprised of a pair of lock pins disposed between a first and second shift rod and having a length longer than the distance separating the shift rods. Each shift rod defines a plurality of grooves thereabout to receive the lock pins. One rod is movable in a first or a second direction to urge at least one of the lock pins into one of the annular grooves of the second rod to prevent reciprocation of the second shift rod. The second shift rod is reciprocable only with the first shift rod in the neutral position.
In an arrangement for mounting gear shift means in a gearbox, a number of selector shafts carry axially movable selector forks for operating a number of clutches for putting alternative gears in mesh while forming different gear ratios for the gearbox. An integrally implemented bearing bracket is removably attached to and enclosed in the gearbox housing and is formed with bearings for the selector shafts, so that these are at least partially carried by the bearing bracket. With the bearing bracket designed as a separate unit, the machining during manufacture and the configuration and manufacturing of the housing will be simplified, thereby reducing the risk of having to reject an entire housing due to incorrect manufacture.
The compound detent mechanism (104) for a manual change gear transmission (10) of the type wherein engagement and disengagement reverse gear is controlled by a first shift rail (58) and engagement and disengagement of the lowest forward speed is controlled by an adjacent second shift rail (56) is provided. Detent mechanism (104) is carried by the shift block assembly (88) associated with the first shift rail and includes a first piston (132) resiliently blocking transverse alignment of a shift element with the contact surfaces (96, 98) associated with the second shift rail (56) associated with the lowest forward speed and a second piston element (114) resiliently blocking shifter element transverse alignment with the contact surfaces (100 and 102) associated with the first shift rail (58) associated with the reverse speed ratio.
A compound transmission defining main and auxiliary gearboxes includes an auxiliary shift rail extending into both gearboxes for effecting joint interlock of the two units. The auxiliary shift rail includes an interlock bracket for actuation of a shift interlock element contained within the main gearbox. In a preferred embodiment, the bracket contains a pair of recesses disposed for engaging an interlock plunger, the recess having an angularly offset axis, perpendicular to but not intersecting the axis of the auxiliary shift rail. In another preferred embodiment, the bracket couples the auxiliary shift rail with a second axially spaced shift rail whereby axial movement of the auxiliary shift rail effects like movement of the second shift rail, the latter rail containing a pair of interlock plunger-receiving recesses.
A neutral sensing assembly for a multiple shift rail (60B, 62B, 64B) shift bar housing assembly (70) is provided. The neutral sensing assembly utilizes a single two-position sensing (112, 114) and a relatively simply shaped neutral sensing bar (104) extending generally transverse to the axes (80, 82, 84) of the shift rails and interacting with neutral sensing notches (60C, 62C, 64C) for displacing the neutral sensing bar (FIG. 4 and 6) sufficiently to actuate the sensing upon axial displacement of any of the shift rails sufficient to cause the transmission (10) to be engaged in a not neutral condition.
A shift control mechanism (10) for use in cooperation with a shift bar housing assembly (16) of a change gear transmission of the type comprising a shift bar housing (14) in which a plurality of axially moveable shift rails (18, 20, 22 and 24) are mounted is provided. The shift control mechanism includes a control housing (12) in which a shift yoke (64) is pivotably mounted for pivotal movement about a pivot axis (68) in a direction (Y--Y) transverse the axes of the shift rails. A shift lever (48) carrying a shift finger (52) at one end thereof and a shift knob (56) at the other end thereof is pivotably mounted in the shift yoke about an independent pivot axis (62) for pivotal movement in the direction (X--X) parallel the axes of the shift rails relative to the shift yoke and control housing. The shift yoke defines a slot or gap (82) having a transverse width (80) greater than the transverse width (38) of any one of the shift rails but less than the combined transverse width of two of the shift rails through which the shift finger is pivotably moveable in the direction parallel the axes of the shift rails to provide a positive interlock mechanism. The shift yoke carries stops (98) and (100) for engagement with the outer shift rails (18 and 24) to limit pivotal movement of the shift lever and shift yoke and to provide positive indication of correct selection of the outer two shift rails (18 and 24). A spring biased detent mechanism (110) cooperates with a notched contact surface (112) to provide a feel for proper selection of the inner two shift rails (20 and 22).
