AP-1200 ASPHALT PAVER Paving Operation Caterpillar

Positioning The Paver

The first step in starting the paving operation is to position the machine at the starting point. Drive the machine to the starting point and align it with the edge of the grade, curb, gutter, mat or other reference to be used. Position the steering indicator so that it and the steering reference are easily visible.

Adjusting The Screed For "Flying Screed" Operation

If a transverse joint is to be made with an existing mat, see "Transverse Joints" on page 4-23, otherwise:

1. Place a wooden block under the screed near each end of the screed. The blocks should be 25% thicker (depending on the mix) than the thickness wanted in the final compacted mat.

2. Lower the screed onto the blocks.

3. Check that the tow point is at approximately the same height as the bottom of the screed. If it is not, adjust the tow point height:

a. With the engine running, flip the tow point selector switch to "Manual".

b. Move the tow point control switch to "Up" or "Down" until the tow point pin can easily be removed.

c. Remove the pin.

d. Move the tow point control switch to "Up" or "Down" until the appropriate holes in the tow arm and grade control post are aligned.

e. Place the pin through the holes.

f. Remove the cylinder pin and raise the cylinder rod to the limit by holding the tow point control switch at "Up".

g. Repeat for the other side of the machine.

4. Turn the thickness control cranks until they are in the unloaded position (no load when the crank is turned either way).

5. Turn the thickness control cranks enough to raise the front of the screed 1/16 inch (1.59 mm) off the wooden blocks, about one complete turn.

6. If it is necessary to start the slab from near the base level, raise the screed, replace the wooden blocks with 1/4 inch (6.35 mm) thick strips, and lower the screed onto the strips. When the paver starts forward, the screed will leave a mat starting at a thickness of 1/4 inch (6.35 mm) and gradually increasing to full thickness.

7. Proceed to "Heating the Screed" on page 4-17.

Adjusting The Screed For Automatic Operation

If a transverse joint is to be made with an existing mat, see "Transverse Joints" on page 4-23, otherwise:

1. Place a wooden block under the screed near each end of the screed. The blocks should be about 25% thicker (depending on the mix) than the thickness wanted in the final compacted mat. If slope control is to be used, block the screed to the desired slope.

2. Lower the screed onto the blocks.

3. Check that the tow point is at approximately the same height as the bottom of the screed. If it is not, adjust the tow point height:

a. With the engine running, flip the tow point selector switch to "Manual".

b. If a tow point pin is present, move the tow point control switch to "Up" or "Down" until the tow point pin can easily be removed. Remove the pin.

c. Move the tow point control switch to "Up" or "Down" until the tow point is at approximately the same height as the bottom of the screed.

d. Flip the tow point selector switch back to "Auto".

e. Repeat the procedure for the other side of the machine.

4. Turn the thickness control cranks until they are in the unloaded position (no load when the crank is turned either way).

5. Turn the thickness control cranks enough to raise the front of the screed 1/16 inch (1.59 mm) off the wooden blocks, about one complete turn.

Adjusting The Grade Control System

After the paver is in position and the screed is adjusted, check that the grade control sensor mount is securely installed and then:

1. Position the grade control sensor mount so that the sensor is a minimum of 15 inches (38.1 cm) and a maximum of 3 feet (91.4 cm) in front of the leading edge of the screed.

2. Install the ski and/or skate, or right angle grid follower on the sensor shaft, if not already done (see page 4-8).

3. Adjust the spring at the right sensor hub so the right angle grid follower rides firmly against the stringline, or the ski and/or skate rides firmly on the reference surface.

4. With the ignition switch at "On", set the grade sensor switch at "Standby".

5. Adjust the position of the sensor mount and sensor until the needle in the meter is centered.

6. Loosen the jam nut, then turn the gain adjusting screw clockwise to the stop. Place a nickle between the reference and the follower, skate or ski. Turn the adjusting screw counterclockwise until the needle in the motor is in the red/white division. Tighten the jam nut.

7. Remove the nickel.

It may be necessary to further adjust the gain after paving is started. Turning the adjusting screw clockwise will increase the gain and make the system more sensitive. Turning the screw counterclockwise will decrease the gain and make the system more sluggish.

Adjusting The Slope Control System

1. After the screed is adjusted (see page 4-8) and with the ignition switch at "On", set the slope sensor switch at "Standby".

2. Adjust the remote setpoint until the needle in the slope sensor meter is centered. The slope sensor is now set to maintain the cross slope at which the screed is set.

Heating The Screed

Each screed heater is equipped with a single glow plug/fan switch and a fuel control valve. The standard 10-foot (3.05 meter) screed has two heaters and each 4.75-foot (1.45 meter) screed extension has an additional heater. Some 2-foot (0.61 meter) screed extensions also have an additional heater.

To start the heaters:

1. Start the engine and set it at "Slow".

2. Close the fuel control valves.

3. Flip the screed fuel switch to "On".

4. Hold the heater switch for one heater at "Glow Plug" and allow the glow plug to warm up 10 to 15 seconds.

5. Open the selected fuel control valve.

6. When the fuel ignites, return the heater switch to "Fan".

7. Adjust the air damper as necessary.

8. Repeat the process for each heater.

The length of time the heaters should be left on will depend on the ambient temperature and the asphalt mix to be used. Normally the screed will not require heating for more than 10 minutes. Care must be used to not overheat the screed or the screed may warp.

To shut the screed heaters down:

1. Close the fuel control valves.

2. Flip the fuel switch to "Off".

3. Allow the fans to blow air through the combustion chambers for about ten minutes to clear out any remaining fumes and then flip the heater switches to "Off".

Receiving First Load Of Asphalt

Before the first load of asphalt is received, a final check should be made to be sure the conveyors and screed vibrators are working properly: move each feeder switch to "Override" and check for proper conveyor travel, then move the compactor switch to "Override" and check for vibrator operation. (The engine must be running and the power switch at "Stop".)

1. Have the truck back toward the paver until the truck wheels contact the push roll. If a quick hitch push roll is installed, be sure the hitch is opened until the truck is in position and then move the hitch switch to "Close".

NOTE: ONCE PAVING HAS STARTED, NEVER ALLOW A TRUCK TO BUMP THE PAVER OR MARKS WILL BE LEFT ON THE FINISHED SURFACE.

2. Have the truck start dumping.

3. Hold the feeder switches at "Override" to move the initial material back and spread it across the front of the screed.

4. When the head of asphalt is about half way up the screw conveyor at the outer edges, return the feeder switches to "On".

Starting To Pave

1. Check that the console selector switch is properly positioned.

2. Check the following switches for position:

Power Switch - "Stop".

Compactor Switch - "On".

Feeder Switches - "On".

Grade Sensor Switches - "Run" or "Standby" as appropriate.

Slope Sensor Switch - "Run" or "Standby" as appropriate.

Park Brake Switch - "Off".

3. Set the travel speed control at "O".

4. Set the engine speed selector switch at "Fast".

5. When all personnel are ready, flip the power switch to "Run" and bring the paver up to speed with the travel speed control. The machine will start forward and the screed will ride off the wooden blocks or strips onto the asphalt.

NOTE: BE SURE THE TRUCK BRAKES ARE RELEASED.

6. Adjust the vibrators as needed.

7. Check the head of material at the screw conveyor and adjust the feeder control paddles and/or flow gates as necessary.

NOTE: NEVER EMPTY THE ASPHALT FROM THE SCREW CONVEYORS TO THE POINT THAT THE AUTOMATIC FEEDER CONTROL DOES NOT FUNCTION OR THE SCREW CONVEYOR WILL MOVE ALL THE ASPHALT TO THE ENDS OF THE SCREED.

8. Check the mat thickness at several places across the mat and make any required adjustments to the thickness controls. Turning the controls clockwise will raise the rear of the screed and decrease the mat thickness.

NOTE: DO NOT OVERCONTROL. ALLOW AT LEAST THREE TOW ARM LENGTHS OF TRAVEL FOR AN ADJUSTMENT TO TAKE EFFECT BEFORE MAKING ANOTHER ADJUSTMENT. NEVER TURN THE THICKNESS CONTROLS MORE THAN 1/4 TURN AT A TIME.

IF SLOPE CONTROL AND/OR GRADE CONTROL ARE BEING USED, MAKE ANY CORRECTIONS TO MAT THICKNESS OR SLOPE WITH THE ADJUSTABLE SENSOR MOUNT OR THE REMOTE SETPOINT, NOT WITH THE THICKNESS CONTROLS. USE CARE NOT TO OVERCONTROL THESE CONTROLS EITHER. TURNING THE CRANK ON A SENSOR MOUNT CLOCKWISE WILL RAISE THE SENSOR AND DECREASE THE MAT THICKNESS.

Setting Paver Speed

The best asphalt mats are produced when the paver is operated continuously after it has been properly set up and adjusted. The best paving speed is, therefore, just slightly faster than the rate that the plant can supply the asphalt, provided that it is not too fast for the paver to properly lay the type of asphalt being used. Paving just slightly faster than the asphalt can be supplied allows for time consuming tasks such as raking joints.

If it becomes necessary to speed up the operation to clear out a group of waiting trucks, the mat thickness and finish should be watched closely. It may be necessary to adjust the thickness controls or grade control to maintain the mat thickness at the higher speed. It may also be necessary to adjust the screed lead crown and/or the vibrator speed to maintain the proper mat finish.