Automatic screed control for asphalt pavers

Claim 2

In combination with a paving machine having a screed vertically positioned by leveling arms in accordance with changes in grade determined by a gradeline extending taut between grade rods substantially parallel to the direction of movement of the paving machine, a control system for varying the position of the screed in response to changes in grade and slope including poweroperated means connected to the leveling arms for vertical and pivotal displacement of the screed, a follower device pivotally supported by at least one of the leveling arms about a pivotal axis transverse to the direction of movement of the paving machine for contact with the gradeline, and grade-signalling means for energizing the power-operated means in response to pivotal displacement of the follower device by the gradeline relative to the leveling arms, said grade-signalling means including a detecting device connected to the follower device for developing a signal and relay means connected to the poweroperated means for delaying energization thereof following said signal.

Claim 3

The combination of claim 1 including gravity-operated switch means connected to the power-operated means for energization thereof in response to relative displacement of said leveling arms and switch-mounting means for pivotally adjusting the position of the switch means relative to the leveling arms.

Claim 4

The combination of claim 2 wherein said power-operated means includes a solenoid valve-controlled fluid piston device pivotally mounted to each of the leveling arms, a fixed pivot assembly slidably and pivotally supporting each of the leveling arms, a lever member pivotally mounted by the pivot assembly and connected to the piston device and a link element interconnecting the lever member and each of the leveling arms.

Claim 5

The combination of claim 3 wherein said follower device comprises an elongated housing fixed to said one of the leveling arms, angularly adjustable bracket means secured to said housing, a follower lever pivotally mounted by the bracket about said pivotal axis, a follower contact pivotally mounted by the lever about a substantially vertical axis in close lateral spaced relation to the gradeline, torsion spring means biasing the follower contact to a position engaging the gradeline, and means connected to the follower contact for preventing pivotal movement thereof below the gradeline in response to displacement of the follower contact by a grade rod out of contact with the gradeline.

Claim 6

The combination of claim 4 wherein the switch-mounting means includes a supporting arm pivotally mounted by the leveling arms below the gravity-operated switch means, and remotely controlled drive means operatively connected to the switch means for incremental displacement thereof in opposite directions. 6. The combination of claim 2 wherein the switch mounting means includes a supporting arm pivotally mounted by the leveling arms below the gravity-operated switch means, and remotely controlled drive means operatively connected to the switch means for incremental displacement thereof in opposite directions.

Claim 7

The combination of claim 1 wherein said power-operated means includes a solenoid valve-controlled fluid piston device pivotally mounted by each of the leveling arms, a fixed pivot assembly slidably and pivotally supporting each of the leveling arms, a lever member pivotally mounted by the pivot assembly and connected to the piston device and a link element interconnecting the lever member and each of the leveling arms.

Claim 8

The combination of claim 7 wherein said follower device comprises an elongated housing fixed to said one of the leveling arms, angularly adjustable bracket means secured to said housing, a follower lever pivotally mounted by the bracket about said pivotal axis, a follower contact pivotally mounted by the lever about a substantially vertical axis in close lateral spaced relation to the gradeline, torsion spring means biasing the follower contact to a position engaging the gradeline, and means connected to the follower contact for preventing pivotal movement thereof below the gradeline in response to displacement of the follower contact by a grade rod out of contact with the gradeline.

Claim 9

The combination of claim 1 wherein said follower device comprises an elongated housing fixed to said one of the leveling arms and displaceable therewith relative to the other of the leveling arms, angularly adjustable bracket means secured to said housing, a follower lever pivotally mounted by the bracket about said pivotal axis, follower contact pivotally mounted by the lever about a substantially vertical axis in close lateral spaced relation to the gradeline, torsion spring means biasing the follower contact to a position engaging the gradeline, and means connected to the follower contact for preventing pivotal movement thereof below the gradeline in response to displacement of the follower contact by a grade rod out of contact with the gradeline.

Claim 10

The combination of claim 9 including gravity-operated switch means connected to the power-operated means for energization thereof in response to changEs in slope of said pivotal axis of the follower device and switch-mounting means for pivotally adjusting the position of the switch means relative to the leveling arms.

Claim 11

In combination with a paving machine having a screed vertically positioned by leveling arms in accordance with changes in grade determined by a gradeline extending taut between grade rods substantially parallel to the direction of movement of the paving machine, a follower device pivotally supported by at least one of said leveling arms comprising an elongated housing fixed to said one of the leveling arms, angularly adjustable bracket means secured to said housing, a follower lever pivotally mounted by the bracket about a pivotal axis, a follower contact pivotally mounted by the lever about a substantially vertical axis in close lateral spaced relation to the gradeline, torsion spring means biasing the follower contact to a position engaging the gradeline, means connected to the follower contact for preventing pivotal movement thereof below the gradeline in response to displacement of the follower contact by a grade rod out of contact with the gradeline and switch means actuated by the follower lever for vertically adjusting one of the leveling arms.

Claim 12

In combination with a paving machine having a screed vertically positioned by leveling arms in accordance with changes in grade determined by a gradeline extending taut between grade rods substantially parallel to the direction of movement of the paving machine, a follower device pivotally supported by at least one of said leveling arms comprising an elongated housing fixed to said one of the leveling arms, angularly adjustable bracket means secured to said housing, a follower lever pivotally mounted by the bracket about a pivotal axis, a follower contact pivotally mounted by the lever about a substantially vertical axis in close lateral spaced relation to the gradeline, torsion spring means biasing the follower contact to a position engaging the gradeline, means connected to the follower contact for preventing pivotal movement thereof below the gradeline in response to displacement of the follower contact by a grade rod out of contact with the gradeline and switch means actuated by the follower lever for vertically adjusting one of the leveling arms.

Claim 13

In combination with a paving machine having a screed vertically positioned by leveling arms in accordance with changes in grade determined by a gradeline extending taut between grade rods substantially parallel to the direction of movement of the paving machine, a control system for varying the position of the screed in response to changes in grade and slope including power-operated means connected to the leveling arms for vertical and pivotal displacement of the screed, a follower device pivotally supported by at least one of the leveling arms about a pivotal axis transverse to the direction of movement of the paving machine for contact with the gradeline, grade-signalling means connected to the follower device for energizing the power-operated means to change the position of one of the leveling arms, and gravity-operated switch means connected to the power-operated means for changing the position of the other leveling arm in response to changes in slope of said pivotal axis of the follower device, said follower device comprising an elongated housing fixed to said one of the leveling arms, angularly adjustable bracket means secured to said housing, a follower lever pivotally mounted by the bracket about said pivotal axis, and a follower contact pivotally mounted by the lever about a substantially vertical axis.

Claim 14

In combination with a paving machine having a screed vertically positioned by leveling arms in accordance with changes in grade determined by a gradeline extending taut between grade rods substantially parallel to the direction of movement of the paving machine, a control system for varying the position of the screed in response to changes in grade and slope including power-operated means connected to the leveling arms for vertical and pivotal displacement of the screed, a follower device pivotally supported by at least one of the leveling arms about a pivotal axis transverse to the direction of movement of the paving machine for contact with the gradeline, grade-signalling means connected to the follower device for energizing the power-operated means to change the position of one of the leveling arms, and gravity-operated switch means connected to the power-operated means for changing the position of the other leveling arm in response to changes in slope of said pivotal axis of the follower device, said follower device comprising an elongated housing fixed to said one of the leveling arms, angularly adjustable bracket means secured to said housing, a follower lever pivotally mounted by the bracket about said pivotal axis, and a follower contact pivotally mounted by the lever about a substantially vertical axis.

Claim 15

The combination of claim 12 wherein said grade-signalling means comprises a casing mounted by the bracket means in an angularly adjusted position about the pivotal axis, a cam actuator connected to the follower lever, and a pair of signal-establishing switches engageable by the cam actuator.

Claim 16

In combination with a paving machine having a screed vertically positioned by leveling arms in accordance with changes in grade determined by a gradeline extending taut between grade rods substantially parallel to the direction of movement of the paving machine, a control system for varying the position of the screed in response to changes in grade and slope including power-operated means connected to the leveling arms for vertical and pivotal displacement of the screed, a follower device pivotally supported by at least one of the leveling arms about a pivotal axis transverse to the direction of movement of the paving machine for contact with the gradeline, and grade-signalling means connected to the follower device for energizing the power-operated means in delayed response to pivotal displacement of the follower device by the gradeline relative to the leveling arms, said grade-signalling means comprising a casing mounted by said one of the leveling arms in an angularly adjusted position about the pivotal axis, a cam actuator connected to the follower device, a pair of signal-establishing switches engageable by the cam actuator, and time delay relay means electrically connecting the switches to the power-operated means for energizing the same.

Claim 17

In combination with a paving machine having a screed vertically positioned by leveling arms in accordance with changes in grade determined by a gradeline extending taut between grade rods substantially parallel to the direction of movement of the paving machine, a control system for varying the position of the screed in response to changes in grade and slope including power-operated means connected to the leveling arms for vertical and pivotal displacement of the screed, a follower device pivotally supported by at least one of the leveling arms about a pivotal axis transverse to the direction of movement of the paving machine for contact with the gradeline, and grade-signalling means connected to the follower device for energizing the power-operated means in delayed response to pivotal displacement of the follower device by the gradeline relative to the leveling arms, said grade-signalling means comprising a casing mounted by said one of the leveling arms in an angularly adjusted position about the pivotal axis, a cam actuator connected to the follower device, a pair of signal-establishing switches engageable by the cam actuator, and time delay relay means electrically connecting the switches to the power-operated means for energizing the same.

Claim 18

The combination of claim 14 wherein said follower device comprises an elongated housing enclosing the time delay relay means and fixed to said one of the leveling arms, angularly adjustable bracket means secured to said housing, a follower lever pivotally mounted by the bracket about said pivotal axis, a follower contact pivotally mounted by the lever about a substantially vertical axis in close lateral spaced relation to the gradeline, torsion spring means biasing the follower contact to a position engaging the gradeline, and means connected to the follower contact for preventing pivotal movement thereof below the gradeline in response to displacement of the follower contact by a grade rod out of contact with the gradeline.

Claim 19

In a paving machine having a pair of screed-leveling arms pivotally interconnected by a transverse beam and power-operated means for adjusting the positions of the leveling arms, grade-sensing means mounted by one of the leveling arms for developing a signal in response to variation in grade, signal control means connected to the power-operated means for adjusting the position of said one of the leveling arms in delayed response to said signal and angle-sensing means mounted on the transverse beam and connected to the power-operated means for adjusting the position of the other of the leveling arms to maintain a preset lateral tilt of the beam.

Claim 20

In a paving machine having a pair of screed-leveling arms pivotally interconnected by a transverse beam and power-operated means for adjusting the positions of the leveling arms, grade-sensing means mounted by one of the leveling arms for developing a signal in response to variation in grade, signal control means connected to the power-operated means for adjusting the position of said one of the leveling arms in delayed response to said signal and angle-sensing means mounted on the transverse beam and connected to the power-operated means for adjusting the position of the other of the leveling arms to maintain a preset lateral tilt of the beam.