System and method for fluid assisted shifting of mechanical transmissions
AssigneeEaton Corporation
InventorsGraeme A. Jackson, Alan J. Fielding
Life of this patent
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Abstract
A shifting mechanism for a mechanical transmission includes a selector shaft having associated shift forks for engaging or disengaging a selected gear ratio and a control rod directionally coupled to the selector shaft for positive rotation while allowing a predetermined relative axial translation. A cylinder assembly is operatively associated with the selector shaft and control rod to provide a fluid coupling which applies a force on the selector shaft in response to the relative translation between the selector shaft and the control rod to reduce the operator effort required to complete a gear shift.
Claims17
A shifting mechanism for a mechanical transmission having a plurality of selectable gear ratios, the shifting mechanism comprising:
- a selector shaft having a plurality of shift forks positioned thereabout, wherein rotation of the selector shaft selects one of the shift forks and translation of the selector shaft is operative to translate the selected shift fork to engage or disengage a selected gear ratio;
- a control rod directionally coupled to the selector shaft for positive rotation therewith while allowing a predetermined relative axial translation therebetween;
- a cylinder assembly operatively associated with the selector shaft and the control rod providing a fluid coupling therebetween to apply a force on the selector shaft in response to relative translation between the selector shaft and the control rod.
A shifting mechanism for a mechanical transmission having a plurality of gears defining gear ratios selectable via a shift lever and shift finger assembly, the shifting mechanism comprising:
- a shift bar housing;
- a selector shaft disposed within the shift bar housing, the selector shaft having a plurality of shift forks associated therewith each selectable by rotation of the selector shaft and axially translatable to engage or disengage a selected gear;
- a control rod concentrically disposed within the selector shaft and directionally coupled to the selector shaft via at least one pin passing through the control and the selector shaft wherein one of the control rod and selector shaft includes an axially elongated slot to provide positive rotation of the control rod and selector shaft while allowing a predetermined relative axial translation therebetween;
- a proportional valve assembly operatively associated with the selector shaft and the control rod providing a fluid coupling therebetween to apply a force on the selector shaft in response to relative translation between the selector shaft and the control rod.
A method for reducing operator effort during shifting of a mechanical transmission having a plurality of gears defining a plurality of selectable gear ratios, the transmission including a shift lever cooperating with a shift finger assembly which actuates a selector shaft having at least one shift fork selected by rotation of the selector shaft, the shift fork being translated in response to translation of the selector shaft to engage or disengage a selected gear ratio, the method comprising:
- coupling the selector shaft to a control rod such that the selector shaft rotates with the control rod while allowing a predetermined axial displacement therebetween;
- and
- fluidly coupling the selector shaft to the control rod to provide an additional force on the selector shaft while relative displacement of the control rod and selector shaft is between zero and the predetermined axial displacement.
Dependencies are inferred from the claim text.