Grade averaging apparatus

Claim 2

An improved grade averaging apparatus for use with a road working machine having a frame supporting a work piece for working contact with a roadway surface, the frame supported by a drive assembly having at least one rear drive track connected to the frame and pivotable about a rear control axis, and the drive assembly having at least one forward steering drive track connected to the frame and pivotable about a forward control axis, the forward steering drive track supported to accommodate swivel rotation to steer the road working machine, and the elevation of the work piece determined by an elevation control device sensing an external elevation control reference, comprising: a bar member supported independently to the frame of the road working machine and having a forward end and a rear end, the rear end of the bar member pivotally connected to the rear drive track at a selected attachment point defining a rear elevation reference, the position of the rear elevation reference being constantly fixed relative to the rear control axis, the elevation of the rear elevation reference being indicative of the average grade of the roadway surface supporting the rear drive track; and bar connecting means supporting the forward end of the bar member and connected to the forward steering drive track for providing a pivot point between the forward end of the bar member and the forward steering drive track such that the pivot point defines a forward elevation reference the position of which is constantly fixed relative to the forward control axis throughout the range of swivel of the forward steering drive track, the elevation of the forward elevation reference being determined by the average grade of the roadway surface supporting the forward steering drive track, and the bar member providing the elevation control reference indicative of the average of the forward elevation reference and the rear elevation reference.

Claim 3

The apparatus of claim 1 wherein the bar connecting means comprises: a swivel plate assembly supported by the forward steering drive track and having a bearing surface; and bearing means attached to the forward end of the bar member for engaging the bearing surface of the swivel plate.

Claim 4

The apparatus of claim 2 wherein the bearing means is characterized as comprising a swivel ball assembly with at least one swivel ball in rolling engagement with the bearing surface of the swivel plate.

Claim 5

The apparatus of claim 3 wherein the swivel plate assembly is characterized as comprising: a mounting base supported by the forward drive track; and a platform member supported by the mounting base, a portion of the platform member forming the bearing surface which is generally horizontally disposed.

Claim 6

The apparatus of claim 4 wherein the platform member is generally curvilinearly shaped and provides a travel arc of contact with the swivel ball assembly when the front steering drive track is swivelled relative to the frame.

Claim 7

In combination with a road working machine having a frame supported by and pivotally connected to a forward steering drive track assembly and a rear drive track assembly along one side of the frame, the forward steering drive track assembly being connected to swivel relative to the frame to effect steering of the road working machine, and the elevation of the frame determinable by an elevation control device sensing an elevation control reference, the improvement comprising: a bar member providing the elevation control reference and having a first end and a second end; a bar connecting assembly characterized as comprising: a swivel plate assembly having a generally horizontally disposed bearing surface and supported by the forward steering drive track assembly; and bearing means attached to the first end of the bar member, the bearing means supported by the bearing surface, the swivel plate assembly being disposed so that the first end of the bar member is supported in a position that the front steering drive track assembly serves as a first walking beam, the second end of the bar member pivotally connected to the rear drive track assembly so that the rear drive track assembly serves as a second walking beam, the elevation control reference being the average elevation of the first and second ends of the bar member.

Claim 8

In combination with a road working machine having a frame supported by and pivotally connected to a forward steering drive track assembly and a rear drive track assembly along one side of the frame, the forward steering drive track assembly being connected to swivel relative to the frame to effect steering of the road working machine, and the elevation of the frame determinable by an elevation control device sensing an elevation control reference, the improvement comprising: a bar member providing the elevation control reference and having a first end and a second end; a bar connecting assembly characterized as comprising: a swivel plate assembly having a generally horizontally disposed bearing surface and supported by the forward steering drive track assembly; and bearing means attached to the first end of the bar member, the bearing means supported by the bearing surface, the swivel plate assembly being disposed so that the first end of the bar member is supported in a position that the front steering drive track assembly serves as a first walking beam, the second end of the bar member pivotally connected to the rear drive track assembly so that the rear drive track assembly serves as a second walking beam, the elevation control reference being the average elevation of the first and second ends of the bar member.

Claim 9

The apparatus of claim 6 wherein the bearing means is characterized as comprising a swivel ball assembly with at least one swivel ball in rolling engagement contact with the bearing surface of the swivel plate.

Claim 10

The apparatus of claim 7 wherein the swivel plate assembly is characterized as comprising: a mounting base supported by the front steering drive track assembly; and a platform member supported by the mounting base and containing the bearing surface.

Claim 11

The apparatus of claim 8 wherein the platform member is generally curvilinearly shaped to provide a travel arc that is passed under the swivel ball assembly during the swivel tracl of the front steering drive track assembly.

Claim 12

In combination with a road working machine having a frame drivingly supported by a forward steering drive track assembly and by first and second rear drive track assemblies pivotally connected to the frame, the frame supporting a work piece for working engagement with the surface of a roadway, the improvement comprising: a swivel plate assembly having a generally horizontally disposed bearing surface and supported by the forward steering drive track assembly and disposed so that the forward steering drive track assembly serves as a first walking beam, the elevation of the bearing surface indicative of the average grade of the roadway surface supporting the forward steering drive track assembly; and a bar member disposed along a first side of the frame and having a first end and a second end, the first end bearingly supported by the bearing surface of the swivel plate assembly and the second end of the bar member pivotally connected to the first rear drive track assembly so that the first rear drive track assembly serves as a second walking beam, the elevation of the bar member being indicative of the average elevation of the first and second walking beams.

Claim 13

In combination with a road working machine having a frame drivingly supported by a forward steering drive track assembly and by first and second rear drive track assemblies pivotally connected to the frame, the frame supporting a work piece for working engagement with the surface of a roadway, the improvement comprising: a swivel plate assembly having a generally horizontally disposed bearing surface and supported by the forward steering drive track assembly and disposed so that the forward steering drive track assembly serves as a first walking beam, the elevation of the bearing surface indicative of the average grade of the roadway surface supporting the forward steering drive track assembly; and a bar member disposed along a first side of the frame and having a first end and a second end, the first end bearingly supported by the bearing surface of the swivel plate assembly and the second end of the bar member pivotally connected to the first rear drive track assembly so that the first rear drive track assembly serves as a second walking beam, the elevation of the bar member being indicative of the average elevation of the first and second walking beams.

Claim 14

The apparatus of claim 10 further comprising: elevation control means supported by the frame and contacting the bar member for providing a first elevation control signal in response to the elevation of the bar member; rear hydraulic means connecting the frame to the first rear drive track assembly for establishing the elevation of a rear portion of the frame in response to the first elevation control signal; averaging means supported along a second side of the frame for providing a second elevation control reference indicative of a selected reference surface along the second side; second elevation control means supported by the frame and contacting the averaging means for providing a second elevation control signal in response to the second elevation control reference; and forward hydraulic means connecting the frame to the forward steering drive track assembly for establishing the elevation of a forward portion of the frame in response to the second elevation control signal.

Claim 15

In combination with a road working machine having a frame supporting a work piece for working contact with a roadway surface, the frame supported by a drive assembly having at least one rear drive track connected to the frame and pivotable about a rear control axis, and the drive assembly having at least one forward steering drive track connected to the frame and pivotable about a forward control axis, the forward steering drive track supported to accommodate swivel rotation to steer the road working machine, and the elevation of the work piece determined by an elevation control device sensing an external elevation control reference, the improvement comprising: a bar member having a forward end and a rear end, the rear end of the bar member pivotally connected to the rear drive track at a selected attachment point defining a rear elevation reference being constantly fixed relative to the rear control axis, the elevation of the rear elevation reference being indicative of the average grade of the roadway surface supporting the rear drive track; and bar connecting means supporting the forward end of the bar member and connected to the forward steering drive track for providing a pivot point between the forward end of the bar member and the forward steering drive track such that the pivot point defines a forward elevation reference the position of which is constantly fixed relative to the forward control axis throughout the range of swivel of the forward steering drive track, the elevation of the forward elevation reference being determined by the average grade of the roadway surface supporting the forward steering drive track, and the bar member providing the elevation control reference indicative of the average of the forward elevation reference and the rear elevation reference, the bar connecting means comprising: a swivel plate assembly supported by the forward steering drive track and having a bearing surface; and bearing means attached to the forward end of the bar member for engaging the bearing surface of the swivel plate.

Claim 16

In combination with a road working machine having a frame supporting a work piece for working contact with a roadway surface, the frame supported by a drive assembly having at least one rear drive track connected to the frame and pivotable about a rear control axis, and the drive assembly having at least one forward steering drive track connected to the frame and pivotable about a forward control axis, the forward steering drive track supported to accommodate swivel rotation to steer the road working machine, and the elevation of the work piece determined by an elevation control device sensing an external elevation control reference, the improvement comprising: a bar member having a forward end and a rear end, the rear end of the bar member pivotally connected to the rear drive track at a selected attachment point defining a rear elevation reference being constantly fixed relative to the rear control axis, the elevation of the rear elevation reference being indicative of the average grade of the roadway surface supporting the rear drive track; and bar connecting means supporting the forward end of the bar member and connected to the forward steering drive track for providing a pivot point between the forward end of the bar member and the forward steering drive track such that the pivot point defines a forward elevation reference the position of which is constantly fixed relative to the forward control axis throughout the range of swivel of the forward steering drive track, the elevation of the forward elevation reference being determined by the average grade of the roadway surface supporting the forward steering drive track, and the bar member providing the elevation control reference indicative of the average of the forward elevation reference and the rear elevation reference, the bar connecting means comprising: a swivel plate assembly supported by the forward steering drive track and having a bearing surface; and bearing means attached to the forward end of the bar member for engaging the bearing surface of the swivel plate.