Gearbox adaptor

A gearbox comprising:

• a casing defining a longitudinal axis comprising a wall and at least one passage through the wall having a section extending substantially perpendicularly to the longitudinal axis of the casing;
• a hub defining a longitudinal axis comprising a central portion, at least one annular recess, and at least one passage, the hub being coaxially disposed with the casing;
• at least one piston positioned at least partially within the at least one annular recess of the hub;
• an interior passage located between the at least one piston and the central portion of the hub in fluid communication with the at least one passage of the hub;
• a fluid supply source for supplying fluid through the at least one passage of the casing and the at least one passage of the hub to the interior passage in an inwardly flow direction to pressurize a first face of said at least one piston so as to move said at least one piston in a first direction;
• at least one gear locatable on a shaft adjacent said hub;
• at least one clutch pack positioned between said at least one piston and said at least one gear, part of said at least one clutch pack being engaged with said hub and a different part of said clutch pack being engageable with said at least one gear;
• wherein said at least one gear is freely rotatable relative to said shaft, and said at least one clutch pack being located and arranged such that movement of said at least one piston in said first direction inter-engages said parts of said at least one clutch pack to drivingly engage said at least one gear with said shaft.

A gearbox for sequentially rotating a plurality of gears mounted on a gear shaft comprising a hub, two pistons each comprising an outside diameter arid an inside diameter, and two clutch packs mounted inside a casing between two gears;

• a fluid supply source for selectively supplying fluid to one of the two pistons to pressurize one side of said piston;
• wherein each clutch pack comprises a first pack part in rotational relationship with the hub and a second pack part in rotational relationship with one of the gears;
• wherein when fluid pressurizes one side of one of the pistons, the piston moves in a first direction to push the first pack part to matingly engage the second pack part to then cause the gear, to which the second pack part is in rotational relationship, to be in rotational relationship with the hub;
• and
• wherein pressurized fluid passes through a passage in a wall of the casing and a passage in the hub and flows towards the piston from the outside diameter portion of the piston towards the inside diameter portion of the piston.