Work tool assembly for machine system and method of operating same

A work tool assembly comprising:

• a left vertically extending mount;
• a right vertically extending mount;
• a linkage including a left link assembly coupled to the left vertically extending mount and including a left hinge joint, a right link assembly coupled to the right vertically extending mount and including a right hinge joint, and a carrier coupled to the left hinge joint and the right hinge joint;
• a work tool coupled to the carrier;
• the linkage is adjustable among a plurality of linkage positions in a vertical operating range including a raised linkage position, a lowered linkage position, and a middle linkage position;
• the left hinge joint and the right hinge joint define an axis, and the work tool having an angular orientation about the axis that is dependent upon the position of the linkage in the vertical operating range, and being pivotable about the axis from a tucked orientation at the raised linkage position, to a service orientation at each of the middle linkage position and the lowered linkage position;
• a first angle is defined between the work tool and a horizontal plane, and the first angle has a larger size in the service orientation and a smaller size in the tucked orientation;
• each of the left link assembly and the right link assembly includes an upper link and a lower link connected via the respective left hinge joint and right hinge joint, and the upper link and the lower link in each of the left link assembly and the right link assembly being pivotable in the vertical operating range about an upper link axis and a lower link axis, respectively;
• and
• the upper link and the lower link in each of the right link assembly and the left link assembly together define a larger acute angle at the raised linkage position, and a smaller acute angle at the lowered linkage position, and wherein the smaller acute angle is less than 5°.

A method of operating a work tool assembly comprising:

• adjusting a linkage in a work tool assembly in a vertical operating range between a lowered linkage position and a raised linkage position;
• pivoting a work tool having an angular orientation that is dependent upon the position of the linkage in the vertical operating range at a reduced pivoting ratio in a ground-penetrating lower portion of the vertical operating range ending at the lowered linkage position;
• maintaining the work tool at a service orientation in the ground-penetrating lower portion of the vertical operating range;
• pivoting the work tool at a greater pivoting ratio in an upper portion of the vertical operating range ending at the raised linkage position;
• and
• positioning the work tool at a tucked orientation when the linkage is at the raised position;
• wherein an angle defined between the work tool and a horizontal plane is varied to a lesser relative extent based on the reduced pivoting ratio, and the angle is varied to a greater relative extent based on the greater pivoting ratio;
• the linkage is positionable at a parallel linkage position between the lowered linkage position and the raised linkage position, and the angle varies 2° or less between the parallel linkage position and the lowered linkage position.

A machine system comprising:

• a machine including a front machine end, a back machine end, and a plurality of ground-engaging propulsion elements;
• a work tool assembly coupled to the back machine end and including a linkage projecting rearwardly of the machine, a work tool, and a hinge joint coupling the work tool to the linkage and defining an axis;
• the linkage is adjustable among a plurality of linkage positions in a vertical operating range including a raised linkage position, a lowered linkage position, and a middle linkage position;
• the work tool having an angular orientation about the axis that is dependent upon the position of the linkage in the vertical operating range, and being pivotable about the axis from a tucked orientation at the raised linkage position, to a service orientation at each of the middle linkage position and the lowered linkage position;
• the work tool is pivotable about the axis at a greater pivoting ratio between the raised linkage position and the middle linkage position, and at a reduced pivoting ratio between the middle linkage position and the lowered linkage position;
• and
• one of the plurality of linkage positions includes a parallel linkage position, and wherein the work tool includes a tool surface extending to a terminal tip, and an angle defined between the tool surface and a horizontal plane varies 2° or less between the parallel linkage position and the lowered linkage position.