Talking about construction, such as roads, buildings or bridges, it certainly cannot be separated from heavy equipment.
In the construction world there are various kinds of heavy equipment such as excavators, loaders, cranes, scrapers, bulldozers, asphalt pavers and many more. In this article, we will discuss about bulldozers in more detail about how they work.
Bulldozer is a heavy construction equipment used for leveling the land or other materials. The distribution referred to here is different from the asphalt distribution process.
The process of equalizing the land using a bulldozer is to flatten the contours of the soil or material by plowing it with a ripper so that the soil surface becomes “loose”, then leveled using a blade.
There are several types of bulldozers on the market. In order for a bulldozer to work optimally, it requires knowledge on how to operate it.
The following is an explanation about step by step in general in operating a bulldozer which is divided into 2 parts, which are basic operating techniques and operating techniques.
Basic Operation Technique
1. Starting the Machine
- Make sure the ignition switch with the battery is on.
- Position the directional selector lever in the neutral position.
- Set the governor switch to the low idle position.
- Activate the parking brake (up arrow) and release the parking brake lock (down arrow).
- Position the hydraulic control lever in the holding position.
- Position the engine key on the on position. When the engine key is in the on position, the monitoring system will perform a function test automatically.
- When the test is complete, turn the engine ignition key to the start position (to the right) to start the engine.
2. After the Engine Starts
Please note: To avoid engine damage, if the engine oil pressure gauge still does not respond after 10 seconds, stop the engine immediately.
- Let the machine run at low speed for about 5 minutes.
- Keep the hydraulic and transmission system lubrication surfaces between the ADD and FULL lines.
- The battery charge indicator should be off. If the engine is still running, the indicator light is still on, please turn off the engine immediately and repair it immediately.
- Hydraulic lubrication on warm transmission, immediately set hydraulic control lever to medium engine speed (1300 rpm).
- Watch for abnormal noise and vibration, and observe the readings of all measuring instruments.
- During operation, try to periodically check the warning lights and indicators.
- Check hydraulic oil tank. The surface must be between the ADD and FULL lines.
3. Testing the Brakes
Brake testing is carried out through the following procedure:
- Ensure that there are no unauthorized persons in the vicinity of the equipment.
- Perform brake function test in a dry and level place.
- Use a seat belt.
The steps in brake testing are as follows:
- Start the engine.
- Pick up all attachments.
- Depress the service brake pedal (arrow in the image below).
- Release the parking brake.
- While holding the service brake, put the 2-speed transmission in the forward position.
- Use the finger wheel to reduce and set the movement speed to the lowest speed
- Increase engine speed gradually to maximum. However, the condition of the engine still does not move.
- Move the direction selector lever to neutral.
- Reduce engine speed and apply the parking brake.
4. Unit Preparation
Operation preparation here are the steps that must be done before performing basic operations. This basic operation begins once the engine is ready to run, which means the engine and systems and all components of the bulldozer must be fully powered on and warmed up.
Heating (working temperature) is about 70 to 90°C. The pre-operation steps include activities that must be performed before starting the engine or preparing to start the engine until the engine is started and ready to run.
5. Running the Machine
- To avoid accidents, keep people out of the vicinity of the unit.
- Condition to keep the unit in a controlled state at all times.
- Know the unit size to maintain a safe distance.
- Reduce unit speed, if you are moving in tight spaces.
- Set the right gear before descending the descent.
- Do not shift gears while on the descent.
- Adjust the driver’s seat.
- Fasten the seat belt.
- Lift the blade and ripper until it feels safe to walk.
- Step on the service brake pedal.
- Release the parking brake.
- Turn the shift lever forward (number 5 in the figure below) to start the unit.
- Release the service brake, then increase engine speed as needed.
- Run the unit to get a clear view.
6. Change Direction and Speed
Please note that shifting transmission gears with high engine speed can be done on bulldozers with a PowerShift transmission system. However, for the sake of operator comfort and to optimize the life of the power train components, it is recommended to stop the bulldozer before making a change of direction.
- Press the decelerator pedal.
- Neutralize transmission.
- Press the brake pedal to stop the engine.
- After the engine has stopped, change direction by turning the lever (number 1 in the image below) backwards to start the engine again.
- Release the service brake.
- Increase engine speed by releasing the decelerator pedal.
- Push the gear selector switch (number 2 in the image above) up or down to raise or lower gears
Operation Technique
1. Transmission Gear Selection
Selection of the correct transmission gear can maximize the work to be done. For this reason, the use of gear must be adjusted to the load conditions. With a certain load, the unit will operate faster in first gear than in higher gear (see Figure 2).
The use of a higher gear turns out to be slowing down the bulldozer’s movement, in such conditions, the operator is advised to return to using a lower gear.
2. Blade Tilts Right
Bulldozers with blades that have angle adjustment are ideal for wide digging, ditch filling or side ditching while still operating the unit (moving forward), for example used for cutting cliffs and dumping cut material into cliffs.
3. Displacing Direct (Straight Dozing)
For good eviction results, keep the cutting depth. Fully fill the blade with cut material and push it into the dump.
- Keep the engine at high rpm (high idle).
- Try not to slip.
- If forced to turn with a load carrying conditions, use a tilt blade (don’t use steering).
If the job you are doing is grading work, fill the blade to the brim, the result will be even more than half filling the blade.
4. Displacing in the Groove (Slot Dozing)
Slot dozing is a displacing operation technique by trapping material in a trench. With this, more material (soil) can be transported, due to the resistance of the trench walls (see Figure 4).
Start the eviction from the end of the dump, then run the bulldozer backwards (as in figure A). This will result in decreased eviction and the material will be brought to a more even place.
Meanwhile, the eviction method as shown in Figure B is considered less efficient, because the bulldozer will carry the load in climbing conditions, and it is difficult to make grooves.
If the eviction is carried out in several parallel trenches, the remaining embankments should be evicted from the rear (Figure 5). This allows the operator to maintain the depth of the trench. The thickness of the embankment should be no more than 30% of the blade width.
5. Displacing on the Slope
If forced to carry out evictions on sloping land, still prioritize safety so that the bulldozer does not overturn. If the unit slips to the side, immediately rotate the bulldozer so that the front is facing the descent.
Start working from the highest part to the lower part. Dispose of displaced material downwards to improve balance. Do not cut the bottom of the cliff too much because it will sharpen the cliff.
6. Climb and Descend the Slope
If forced to carry out evictions on sloping land, still prioritize safety so that the bulldozer does not overturn. If the unit slips to the side, immediately rotate the bulldozer so that the front is facing the descent.
Start working from the highest part to the lower part. Dispose of displaced material downwards to improve balance. Do not cut the bottom of the cliff too much because it will sharpen the cliff.
7. Hoarding the Abyss
To push the waste material from the dump truck, place the bulldozer perpendicular to the dump.
Push the material into the ravine while leaving the material on the edge as a levee. Watch out for materials falling from the truck.
8. Create a V Shape Trench
Place the tip of the blade in the center of the trench. Be careful of soft soil. Do the eviction until you get the desired depth.
9. Land Clearing
- Remove dry branches, then cut off the roots opposite the direction of the fall.
- Cut the roots on the left and right of the tree.
- Approach the tree slowly until the blade sticks to the tree, then push the tree while lifting the blade. Build an embankment in front of the tree if a higher bulldozer is needed.
- Stop the pushing process when the tree starts to fall.
10. Dismantling the Stump
Make sure that the tree roots are cut off, then lift the blade as you push.
11. Push Scraper
- Adhere the blade evenly to the push block.
- Keep the bulldozer speed to not exceed the scrapper speed.
- Try to always push in a straight line.
- Condition the Blade not to hit the tire.
- Avoid lifting the back of the scrapper.
- When loading is complete, push the scrapper out of the loading bay.
12. Ripping
- Use a low transmission gear (first gear) when plowing.
- Use the decelerator to adjust the traction to avoid slipping.
- Do the plowing as deep as possible without causing the track to slip.
- The size of the lump is determined by the depth and width of the groove.
Note: Lift the ripper before backing off and avoid turning while the shank is still embedded.
- Multiple Plow (Multi Shank Ripper)
- Multiple plows are expected to be more productive for use on hard, solid and loose rock
- Multiple plows with one plow in the middle are not meant for high yields
- There may be a specific purpose where the plow rods are placed at the edge of the beam. In this case the operator must be careful to place the plow rod in the shortest position and operate the bulldozer carefully. The ripper beam is not designed to run at full power when the plow bar is placed on the edge
- Caterpillar multiple plows are not designed for deep plow
- If you need deep plowing, use a single plow
- Hard soil, hard surface, loam, shale or cemented gravel are suitable for using a three stick plow. Use multiple plows to break the material to the desired size without creating track slip
This is an explanation regarding the steps in operating a bulldozer starting from the initial operation to how to use the correct operating technique.
The explanation above is based on a brief guide for bulldozer operators from the Ministry of Public Works and Public Housing (PUPR).