Gear change for an industrial vehicle provided with an integrated control unit

Claim 1

A gear change comprising an external box, an input shaft, an output shaft, a plurality of transmission stages in cascade in said box comprising a plurality of pairs of gears which are selectively engaged by sliding coupling members and defining a plurality of transmission ratios within each transmission stage and further defining, in combination with one another stages, an overall transmission ratio; between said input shaft and said output shaft, means for selecting gears to be engaged in at least one of said transmission stages in accordance with a selected transmission ratio between the input and output shafts, respective means for engaging and disengaging gears in each of said transmission stages, and an integrated control unit including at least first fluid actuator means for controlling said means for selecting gears in said one of said transmission stages, second fluid actuator means for controlling said respective means for engaging and disengaging gears in said one of said transmission stages, and valve means for actuating said first and second actuator means, wherein said sliding coupling members include control rods for respective transmission stages, said second actuator means comprising a respective fluid actuator for each transmission stage connected to a corresponding control rod of the respective transmission stage to shift said control rod and thereby engage the gears of the respective transmission stage in accordance with the selected transmission ratio, said first fluid actuator means being operative on said control rod of said at least one transmission stage to displace said control rod independently of said second actuator means for enabling the gears of said at least one transmission stage to be engaged when said control rod is shifted by the respective fluid actuator of the second actuator means, said control rod of said one transmission stage being longitudinally slidable along an axis by said second fluid actuator means to selectively engage and disengage the gears of said one transmission stage, said means for selecting gears in said at least one transmission stage being mounted on said control rod of said at least one transmission stage and undergoing displacement with said control rod in accordance with the displacement of said control rod by said first actuator means, to cause said control rod to engage the selected gear pair when the control rod undergoes longitudinal sliding by said second actuator means along said axis.