Drawbar support for leveling circle frame on road graders

Claim 2

In grading machines having an earth working blade, a circle frame member for mounting said blade for rotation about an upright axis, a main frame, and means for connecting said circle frame to said main frame comprising a drawbar member attached at one end thereof to said circle frame, means between said circle frame and said main frame to raise and lower said circle frame and first pivot means attaching the other end of said drawbar member to said main frame, said drawbar member including two drawbar portions, means forming a second pivot connection between said drawbar portions adjacent the first pivot means, and having a pivot axis generally transverse to the direction of movement of the road grader, and means interconnecting the two pivoted drawbar portions to control the angular relationship between the two pivoted drawbar portions to level said circle frame at different depth positions of said circle frame.

Claim 3

The combination specified in claim 1 wherein said two drawbar portions comprise a main portion and a link portion, a lever arm fixedly attached to said link portion and extending outwardly therefrom, and said means to control the angular relationship comprising a hydraulic cylinder positioned between said lever arm and said main portion to control the angular relationship between said link portion and said main portion.

Claim 4

The combination specified in claim 1 wherein said means to control the angular relationship comprises mechanical means for adjusting the angular position between said two drawbar portions comprising a screw threaded member attached to a first of said drawbar portions about a second pivot axis, and attached to a second of said drawbar portions through threadably adjustable means.

Claim 5

The combination specified in claim 3 wherein the points of attachment of said screw thread member are positioned in a plane spaced from the axis of pivot between said two drawbar portions.

Claim 6

The combination specified in claim 2 wherein said link portion comprises a stub shaft member, and the connection between said main frame and said drawbar comprises a ball attached to one end of said link, bearing means to pivotally mount said stub shaft member to the main portion of said drawbar about a substantially transverse axis with respect to the direction of movement of said grader.

Claim 7

The combination of claim 5 and said means to control the angular relationship Further comprising a servo valve controlling said hydraulic cylinder, and a servo valve controller having an actuating lever, a second link, means mounting a first end of said second link to said main frame, and means mounting a second end of said second link to said drawbar so that said second link and stub shaft link form parallel link members, means to connect said second end of said second link to said actuator whereby movement of said drawbar tends to change the diagonal distance relationship of the pivots of said stub shaft and second link respectively, said controller and servo valve and hydraulic cylinder in direction to tend to retain said relationship by pivoting said stub shaft about transverse axis of mounting the main portion of said drawbar.

Claim 8

In a road grader having a main frame, means for supporting said main frame for movement along the earth surface, said main frame having a forward portion, an earth working blade, means to rotatably mount said earth working blade with respect to said main frame including a drawbar connecting said earth working blade to the forward portions of said main frame, said drawbar comprising two portions, a first portion being connected to said main frame and a second portion being connected to said earth working blade, means to pivotally mount said two portions together about an axis substantially transverse to the direction of movement of said main frame, hydraulic cylinder means to control the angular relation of said two portions about said transverse axis with respect to each other and thereby control the height of said second portion with respect to the main frame, one end of said hydraulic cylinder means being attached to a first of said portions, and a second end of said hydraulic cylinder means being attached to a second of said portions, control means on said road grader for said hydraulic cylinder, means on said frame to sense changes of depth of cut of said working earth blade, said means to sense controlling said control means to adjust said hydraulic cylinder means to change the relationship of said two portions as a function of the changes in depth of cut of the earth working blade.

Claim 9

In a road grader having a main frame, means for supporting said main frame for movement along the earth surface, said main frame having a forward portion, an earth working blade, means to rotatably mount said earth working blade with respect to said main frame including a drawbar connecting said earth working blade to the forward portions of said main frame, said drawbar comprising two portions, a first portion being connected to said main frame and a second portion being connected to said earth working blade, means to pivotally mount said two portions together about an axis substantially transverse to the direction of movement of said main frame, hydraulic cylinder means to control the angular relation of said two portions about said transverse axis with respect to each other and thereby control the height of said second portion with respect to the main frame, one end of said hydraulic cylinder means being attached to a first of said portions, and a second end of said hydraulic cylinder means being attached to a second of said portions, control means on said road grader for said hydraulic cylinder, means on said frame to sense changes of depth of cut of said working earth blade, said means to sense controlling said control means to adjust said hydraulic cylinder means to change the relationship of said two portions as a function of the changes in depth of cut of the earth working blade.

Claim 10

The road grader of claim 7 wherein said means to sense comprises a link, means to mount said link on said main frame, at location other than the connection of the drawbar to the main frame, and wherein said control means includes an activatable element, said link being connected to said element.

Claim 11

A drawbar leveler for a road grader having a main frame, a drawbar, means comprising a ball joint connection connecting said drawbar to the forward portion of the main frame of said road grader, a grader blade and circle frame, means to connect the drawbar to the grader blade and circle frame at a rear portion of the drawbar, said drawbar comprising two sections between said circle frame and said ball joint including a first section connected to the circle frame and a second section connected to the ball joint, means forming a pivot between said first and second sections about a substantially transverse axis adjacent the forward portion of said drawbar, lever means on one of said sections and a support on the other section, and means to control the angular relationship of the two sections about said pivot comprising an extendable and retractable actuator connected between said lever means and said support respectively, and control means on said road grader responsive to changes in the vertical position of said circle frame to control said actuator to thereby change the angle between said two sections about said pivot and the vertical position of the portion of said first section adjacent said pivot with respect to said ball joint.

Claim 12

A drawbar leveler for a road grader having a main frame, a drawbar, means comprising a ball joint connection connecting said drawbar to the forward portion of the main frame of said road grader, a grader blade and circle frame, means to connect the drawbar to the grader blade and circle frame at a rear portion of the drawbar, said drawbar comprising two sections between said circle frame and said ball joint including a first section connected to the circle frame and a second section connected to the ball joint, means forming a pivot between said first and second sections about a substantially transverse axis adjacent the forward portion of said drawbar, lever means on one of said sections and a support on the other section, and means to control the angular relationship of the two sections about said pivot comprising an extendable and retractable actuator connected between said lever means and said support respectively, and control means on said road grader responsive to changes in the vertical position of said circle frame to control said actuator to thereby change the angle between said two sections about said pivot and the vertical position of the portion of said first section adjacent said pivot with respect to said ball joint.

Claim 13

The combination of claim 9 wherein said control means includes a parallelogram linkage including a first link portion pivoted at its opposite ends on the axes of movement of said second section and a second link pivoted at a first end adjacent said frame and at a second end with respect to said draWbar on means permitting the second link to move parallel to said first link portion during pivoting of said drawbar, said control means further including means to sense changes in position of said second end of said second link relative to said drawbar as the drawbar pivots when the vertical position of said circle frame is changed.

Claim 14

The combination of claim 10 wherein said means to control the angular relationship between said drawbar sections comprises a hydraulic cylinder, a servo valve controlling said cylinder, and means to control said servo valve including a movable feedback means sensitive to the position of said second end of said second link to actuate the servo valve in direction to restore a desired relationship between the second end of said second link and said drawbar.

Claim 15

In an earth working machine having an earth working blade, a drawbar member, means to connect said earth working blade to said drawbar for rotation about an upright axis, means between said drawbar and said main frame to raise and lower said earth working blade, first pivot means attaching a leading end of said drawbar member to said main frame, said drawbar member including first and second drawbar portions, means forming a second pivot connection between said drawbar portions adjacent the first pivot means, said second pivot connection defining a pivot axis generally transverse to the direction of movement of the earth working machine, means interconnecting the two pivoted drawbar portions to control the angular relationship between the two pivoted drawbar portions to level said drawbar at different depth positions of said earth working blade, and servo control means including a feedback sensor to control the means interconnecting the pivoted drawbar portions to maintain one of said drawbar portions at a reference relationship with respect to the main frame.

Claim 16

In an earth working machine having an earth working blade, a drawbar member, means to connect said earth working blade to said drawbar for rotation about an upright axis, means between said drawbar and said main frame to raise and lower said earth working blade, first pivot means attaching a leading end of said drawbar member to said main frame, said drawbar member including first and second drawbar portions, means forming a second pivot connection between said drawbar portions adjacent the first pivot means, said second pivot connection defining a pivot axis generally transverse to the direction of movement of the earth working machine, means interconnecting the two pivoted drawbar portions to control the angular relationship between the two pivoted drawbar portions to level said drawbar at different depth positions of said earth working blade, and servo control means including a feedback sensor to control the means interconnecting the pivoted drawbar portions to maintain one of said drawbar portions at a reference relationship with respect to the main frame.

Claim 17

In an earth working machine having a main frame and an earth working blade, means mounting said blade for rotation about a substantially upright axis for rotational movement in a generally horizontal plane including a drawbar member and having two portions, said means mounting said blade to said main frame having a first pivot connection to said main frame and a second pivot connection between said two portions of said means mounting said blade, means interconnecting said two portions to control the position of said two portions to maintain said blade oriented for rotation substantially in a horizontal plane regardless of changes of depth of cut of said blade, and control means for said means interconnecting said two portions including a servo system having a feedback sensor to sense deviation of said blade from its desired orientation and for operating said means interconnecting said two portions portion to return said blade in its desired orientation.

Claim 18

In an earth working machine having a main frame and an earth working blade, means mounting said blade for rotation about a substantially upright axis for rotational movement in a generally horizontal plane including a drawbar member and having two portions, said means mounting said blade to said main frame having a first pivot connection to said main frame and a second pivot connection between said two portions of said means mounting said blade, means interconnecting said two portions to control the position of said two portions to maintain said blade oriented for rotation substantially in a horizontal plane regardless of changes of depth of cut of said blade, and control means for said means interconnecting said two portions including a servo system having a feedback sensor to sense deviation of said blade from its desired orientation and for operating said means interconnecting said two portions portion to return said blade in its desired orientation.