Device for setting the inclination of the bucket in a bulldozer

Claim 1

Device for setting the inclination of a bucket of a bulldozer comprising a tiltable bucket, a bucket tilting cylinder piston assembly having a bottom side chamber and a head side chamber and connected to said bucket for tilting the same upwards when said bottom side chamber is pressurized by working fluid while said bucket is tilted downwards when said head side chamber is pressurized, a piston pump operatively coupled with said bucket tilting cylinder-piston assembly such that the head side chamber of said piston pump is pressurized when said bucket tilting cylinder-piston assembly moves to a position to tilt said bucket upwards to a predetermined position, the bottom side chamber thereof communicating with a sump of working fluid, an actuator cylinder-piston assembly with its head side chamBer communicating with the head side chamber of said piston pump, wherein the head side chamber of said actuator cylinder-piston is pressurized when the head side chamber of said piston pump is pressurized, a detent lever connected to said actuator cylinder-piston assembly said detent lever being moved by the movement of the piston of said actuator cylinder-piston assembly, an actuator valve having a movable spool therein and connected to a source of working fluid said actuator valve communicating with said head side chamber and said bottom side chamber of said bucket tilting cylinder-piston assembly for actuating said bucket tilting cylinder-piston assembly to tilt said bucket upwards and downwards by the actuation of said spool, a switching lever connected to said spool of said actuator valve said switching lever being engageable with said detent lever, an operating handle connected to said switching lever for actuating said switching lever such that, when said handle is operated to move said spool in a position for actuating said bucket tilting cylinder-piston assembly to tilt said bucket upwards, said detent lever is engaged with said switching lever for maintaining said spool in said position for tilting said bucket upwards, while, when said piston pump is actuated by said bucket tilting cylinderpiston assembly, said piston pump actuates said actuator cylinder-piston assembly such that said detent lever is disengaged from said switching lever thereby permitting said spool to move to the neutral position thereof for terminating the actuation of said bucket tilting cylinder-piston assembly to automatically set the inclination of said bucket, and a bypass valve having a movable throttle member therein, said bypass valve being connected between said head side chamber of said bucket tilting cylinder-piston assembly and said actuator valve, said bypass valve communicating with said head side chamber of said piston pump and said head side chamber of said actuator cylinderpiston assembly, said movable throttle member being adapted to be moved to a first position to shut off the communication of said head side chambers of said piston pump and said actuator cylinder-piston assembly with said bypass valve when said bottom side chamber of said bucket tilting cylinder-piston assembly is pressurized to tilt said bucket upwards thereby maintaining said head side chambers of said piston pump and said actuator cylinder-piston assembly in pressurized condition and said movable throttle member being adapted to move to a second position to establish the communication of said head side chambers of said piston pump and said actuator cylinder-piston assembly with said bypass valve thereby communicating said head side chamber of said piston pump with said head side chamber of said bucket tilting cylinder-piston assembly and communicating said head side chamber of said actuator cylinder-piston assembly with said sump of working fluid through said bypass valve, when the head side chamber of said bucket tilting cylinder-piston assembly is pressurized, whereby said head side chambers of said piston pump and said actuator cylinder-piston assembly are at all times in a pressurized condition.