HOUSING-FILT 5144602 - Caterpillar

Principles of Operation
All asphalt pavers use the same principle. A tractor receives asphalt mix and distributes the mix in front of a screed that is being towed by the tractor. A tow arm is connected to each end of the screed and to a single point (called the tow point) on the tractor. The tow arms and the connected screed are free to rotate around the tow points.The elevation of the screed determines the depth or thickness of the mat left by the screed.The screed rides on the asphalt mix much the same way a boat rides in water or an airplane rides on air. The screed will rise or fall on the asphalt mix until the forces acting on the screed are balanced. The elevation of the screed will then be constant until something happens to put the forces out of balance. The screed will then rise or fall until the forces are again in balance.Some of the forces that act on the screed are:1. The reaction of the material under the screed to the weight of the screed.2. The towing force.3. The resistance to the towing force of the material ahead of the screed.The factors that affect these forces are:1. Changes in forward speed.2. Changes in material composition or temperature.3. Changes in material level ahead of the screed.4. Changes in the angle of attach of the screed.In order to produce the smoothest mat possible, all these changes must be avoided once the correct mat thickness and finish are obtained.Lighting The Screed Burners
The screed should be heated before first starting operation. The screed should also be heated if it cools during a long stop.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.
Fifteen Minutes Is The Maximum Heating Time Recommended.
1. Set the engine at a low speed but fast enough to charge the batteries while the glow plugs are operating. 2. Check that the fuel control valves are all closed. 3. Flip the fuel pump 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, release the heater switch to return to the "Fan" position. 7. Adjust the air damper as necessary. If the flame goes out, the damper is opened too wide. (An air damper may have to be completely closed to establish ignition in some cases.)8. Repeat the process for each heater.Burner Operating Precautions
While the burners are in operation:1. Keep an eye on all the burners to be sure they all remain lit. If a burner flame should blow out, a dangerous pool of fuel could accumulate.2. If a burner flame does blow out, shut the fuel control valve and leave