Return to neutral device for a hydraulic apparatus

A hydraulic drive device, comprising:

• a housing;
• a rotatable cylinder block disposed in the housing and having a plurality of pistons disposed therein, and a movable swash plate engaged to the pistons for controlling the output of the cylinder block;
• a first return member disposed in the housing and having a first end about which the first return member is pivotable, and a second end;
• a bias member engaged to the second end of the first return member to provide a return force thereto;
• a second return member pivotally engaged to the first return member between the first and second ends of the first return member, the second return member comprising at least a first contact arm positioned to contact a first stop on the swash plate, whereby the first contact arm provides a return force to the swash plate when the swash plate is stroked in a first direction;
• and
• an adjustment mechanism engaged to the first end of the first return member for adjusting the position of the first return member, wherein a portion of the adjustment mechanism extends outside the housing to permit external adjustment.

A return to neutral mechanism for use with a movable swash plate disposed within a housing, the return to neutral mechanism comprising:

• a return assembly for providing a return force to the swash plate when the swash plate is stroked in at least a first direction, the return assembly comprising a first return member disposed in the housing and permitted to rotate about a first end of the first return member;
• and
• an adjustment mechanism for adjusting the position of the first return member, the adjustment mechanism comprising:
• a rotatable bearing member extending through an opening in the housing so that a first end of the rotatable bearing member is accessible outside the housing;
• a shoulder disposed at a second end of the rotatable bearing member and inside the housing, wherein rotation of the rotatable bearing member causes the shoulder to rotate;
• and
• an off-center protrusion disposed on the shoulder and engaged to the first return member, whereby the first return member rotates about the off-center protrusion thereby adjusting the position of the first return member with respect to the swash plate.

A return to neutral mechanism for use with a movable swash plate disposed within a housing, the mechanism comprising:

• a first return member having a first end pivotally secured in the housing, and a second end, whereby the first return member is permitted to rotate about the first end;
• a bias member secured to the second end of the first return member to provide a force to the first return member;
• and
• a second return member engaged to the first return member at a point between the first and second ends of the first return member, the second return member comprising a single contact arm positioned to contact a stop on the swash plate, whereby the second return member provides a return force to the swash plate through the stop when the swash plate is stroked in a first direction, and the second return member does not provide any return force to the swash plate when the swash plate is stroked in a second direction.

A return to neutral mechanism for use with a movable swash plate disposed within a housing, the mechanism comprising:

• a first return member having a first end pivotally secured in the housing, and a second end, whereby the first return member is permitted to rotate about a first axis adjacent the first end;
• a bias member secured to the second end of the first return member to provide a bias force to the first return member;
• a second return member engaged to the first return member at a point between the first and second ends of the first return member to be rotatable about a second axis adjacent the point and parallel to the first axis, the second return member comprising at least a first contact arm positioned to contact a first stop on the swash plate, whereby the first contact arm provides a return force to the swash plate through the first stop when the swash plate is stroked in a first direction;
• and
• the second return member further comprising a protuberance and the first return member further comprising a pocket shaped to receive the protuberance, to permit the second return member to pivot with respect to the first return member.

A return to neutral mechanism for use with a movable swash plate disposed within a housing, the mechanism comprising:

• a first return member having a first end pivotally secured in the housing, and a second end, whereby the first return member is permitted to rotate about a first axis adjacent the first end;
• a bias member secured to the second end of the first return member to provide a bias force to the first return member;
• and
• a second return member engaged to the first return member at a point between the first and second ends of the first return member to be rotatable about a second axis adjacent the point and parallel to the first axis, the second return member comprising at least a first contact arm positioned to contact a first stop on the swash plate, the first contact arm comprising a curved surface, and the first stop comprising a pocket shaped to receive the curved surface, and the first contact arm provides a return force to the swash plate through the first stop when the swash plate is stroked in a first direction.

A return to neutral mechanism for use with a movable swash plate disposed within a housing, the mechanism comprising:

• a first return member having a first end pivotally secured in the housing, and a second end, whereby the first return member is permitted to rotate about a first axis adjacent the first end;
• a bias member secured to the second end of the first return member to provide a bias force to the first return member;
• and
• a second return member secured to a side surface of the first return member, the second return member comprising at least a first contact arm positioned to contact a first stop on the swash plate, whereby the first contact arm provides a return force to the swash plate through the first stop when the swash plate is stroked in a first direction.