Arrangement for inhibiting range shifting in a transmission

A method of retrofitting a transmission to inhibit axial movement of a range clutch in the transmission, the transmission comprising a main shaft and an output shaft, the range clutch being movable on the output shaft between a high range position and a low range position to modify a main shaft rotational speed to at least one different output shaft rotational speed, and a plurality of selectable gears comprising a forward gear and a reverse gear for providing different speed ratios between an input shaft and the main shaft, the main shaft rotating in a main shaft forward rotational direction and in a main shaft reverse rotational direction when coupled to the input shaft and in the forward gear and in the reverse gear, respectively, the output shaft rotating in an output shaft forward rotational direction and in an output shaft reverse rotational direction when coupled to the main shaft rotating in the main shaft forward rotational direction and in the main shaft reverse rotational direction, respectively, wherein the range clutch is adapted to be moved to the high range position and the low range position by positioning a range shift valve in a high range shift valve position and a low range shift valve position, respectively, so that a source of hydrostatic pressure is adapted to communicate with a high range chamber and a low range chamber, respectively, of a range cylinder, the high range chamber and the low range chamber being defined by a piston movable in the range cylinder, the piston being connected to the range clutch, the method comprising:

• providing a sensor arrangement to sense at least one of reverse rotational direction and potential reverse rotational direction of at least one of the main shaft and the output shaft and send a signal to a controller when at least one of reverse rotational direction and potential reverse rotational direction of the at least one of the main shaft and the output shaft is sensed;
• providing an openable and closable range shift inhibitor valve for opening and closing flow communication between the source of hydrostatic pressure and the one of the high range shift valve chamber and the low range shift valve chamber;
• and
• programming the controller to output a signal in response to the sensor arrangement signal, the controller signal controlling opening and closing of the range shift inhibitor valve.