Abstract A self-leveling linkage assembly for maintaining a bucket in a level condition and for preventing the bucket from being rolled rearwardly beyond a predetermined maximum rollback position as the lift arm for the bucket is moved to an extreme raised position. The self-leveling linkage assembly includes a control arm rotatably mounted to a tractor frame at a location forwardly of the lift arm pivot, a position link connected between the control arm and bucket, a control valve for actuating a bucket cylinder, and a linkage connected between the control valve and a manually operable control handle. If the bucket rolls back beyond a predetermined position, the position link causes the control arm to rotate which in turn actuates the control valve for the bucket cylinder thereby rolling the bucket to a level position. When the hydraulic system is inoperative and the lift arm is left in an extreme raised position, a portion of the control arm is adapted for engagement with the lift arm pivot to resist movement of the bucket rearwardly thereby preventing damage to the self-leveling linkage elements. Further, a spring relief assembly is provided in the control valve linkage to prevent the operator from interfering with the operation of the self-leveling linkage assembly.
In a material handling mechanism including at least one lift arm, pivot means securing said lift arm to a frame, a bucket pivotally supported on said lift arm, a lift cylinder for raising and lowering said lift arm, and a bucket cylinder for rolling said bucket forwardly or rearwardly relative to said lift arm, the improvement comprising: a self-leveling linkage assembly for maintaining the bucket in a level condition and for preventing the bucket from being rolled rearwardly beyond a predetermined maximum rollback position as the lift arm is moved to an extreme raised position, said self-leveling linkage assembly including a control arm rotatably mounted to said frame at a location forwardly of said lift arm pivot means, a position link connected between said control arm and said bucket, a control valve for actuating said bucket cylinder and said control valve including a linkage connected to a manually operable control handle, means for connecting said rotatable control arm to said control valve linkage, and said rotatable control arm including an anti-rollback portion which is engagable with said lift arm pivot means to act as a mechanical stop against bucket rollback beyond a predetermined maximum rollback position for preventing damage to said self-leveling linkage assembly.
Claim 2
Dependent Claim
204 words
In a material handling mechanism including at least one lift arm, pivot means securing said lift arm to a frame, a bucket pivotally supported on said lift arm, a lift cylinder for raising and lowering said lift arm, and a bucket cylinder for rolling said bucket forwardly or rearwardly relative to said lift arm, the improvement comprising: a self-leveling linkage assembly for maintaining the bucket in a level condition and for preventing the bucket from being rolled rearwardly beyond a predetermined maximum rollback position as the lift arm is moved to an extreme raised position, said self-leveling linkage assembly including a control arm rotatably mounted to said frame at a location forwardly of said lift arm pivot means, a position link connected between said control arm and said bucket, a control valve for actuating said bucket cylinder and said control valve including a linkage connected to a manually operable control handle, means for connecting said rotatable control arm to said control valve linkage, and said rotatable control arm including an anti-rollback portion which is engagable with said lift arm pivot means to act as a mechanical stop against bucket rollback beyond a predetermined maximum rollback position for preventing damage to said self-leveling linkage assembly.
Claim 3
Dependent Claim
48 words
The material handling mechanism as defined in claim 1 including a spring relief assembly mounted to said control valve linkage for preventing damage to said self-leveling linkage assembly when an operator applies more pressure to said control handle than is required for normal actuation of said control valve.
Claim 4
Dependent Claim
98 words
The material handling mechanism as defined in claim 2 wherein said spring relief assembly includes a housing having a first plate member fixed to one of its ends and a second plate member held at its other end by retainer means, a first member connected between said control handle and said first plate member, a second member connected between said second plate member and said control valve, and a compressible spring means mounted between said plate member which is deflected when more pressure is applied to said members than is required for normal actuation of said control valve.