How to Grade a Road with a Motor Grader?
Like the other heavy equipment, motor grader is very different when it comes to operating it. On top of that, every road grading task is also very different wherein various things have to be kept in mind. Thus, it can be clearly stated that it surely takes time and patience to master the road grading job. Even the operators who are pro with motor graders have to keep on evolving themselves to produce better results.
What makes operation of motor graders a bit difficult is that this single equipment is highly versatile and can perform multiple tasks from mixing asphalt to grading shoulders. And each task generally requires different tricks and practices to get the best result. However, the general motor grader operating tips remain the same.
General operating tips
1. The materials should not be moved regularly as this can cause damage.
2. If there is good compaction, trimming becomes much easier. To make the blade steady, some weight can be put over it. This is better than being overly concerned with having material on the blade while trimming.
3. It is better to get familiar with all the blade movements which is made possible by the hydraulic controls, as they are suited to different tasks. Some cases may require a combination of some or even all of the blade movements. You should be fully aware of the settings and even the angles and heights.
4. A loose blade can be chosen for spreading loose material or spreading and a tight blade can be chosen for reshaping an area by cutting down into it. Most of the times, you will be needing these two options at different stages.
5. You should know that the moldboard can be lifted from both the sides so the blade is at a level height (for levelling an area etc), or you can have just one side raised, if your surface needs to be sloped.
Grading the road with the motor grader
The starting process
To begin with, in order to dress the road, some moisture is needed. Recent rains can do this task or the road should be made wet using water from a water tank. It should be ensured that there is good drainage. Another thing to be kept in mind is that the curves should have super elevation and road crown should be in straight sections.
Straights, slopes and bends
The wear surface should rise at about a three percent slope from the shoulder to the road centre in case of the straight road. Here, the gravel type and area’s rainfall should be taken into consideration. Curved roads need to be flat but with an incline that has a six per cent slope down to the inside of the corner.
The cutting edges should be trimmed with a torch so as to keep them absolutely straight. You need to check for any blade wear as then it would be needed to replace it so as to avoid any wear on the bottom of the moldboard.
The road crown should be shaped properly. If still there is moisture on the ground, you can cut lightly in the spring.
Ditches and surfaces
In case of hard and dry road surface, the cutting edge should be dragged along the surface, however, it should be set about 90 degrees to the surface.
In case of ditches, the soil and road type as well as the right of way should be considered. Generally, the rule is that they should be about five centimetres or two inches lower than the road wear surface.
The road surface should be elevated considerably in areas with high rainfall so as to avoid water running beneath the road. This can also cause potholes.
The right speed and modlboard angle should be chosen before starting the grading process. When the work is delicate, you need to be slow and when you have to remove rocks from a road surface, then you need to move fast. By making use of the various moldboard angles (between 10 to 45 degrees), you can make a smooth motion as against just bulldozing your way forward.
In the link bar, there are several holes or positions that allow the operator to choose as to how far offset the circle from the frames centre line. Generally, first and second holes should be used for cleaning shallow ditches and moving large windrows and combined with articulation to build narrow and flat-bottom ditches.
You should cut straight to the depth of a large pothole. Here, it is to be noted that loose material should not be filled in the pothole if you don’t want the pothole to form again. When you are performing road maintenance, then it’s best to have the centre-shift lock pin centred with the drawbar and circle also centred beneath the mainframe.
If you want the equipment to be stable, then the mainframe should either be straight or articulated only a little. By keeping the mainframe articulated towards the mouldboard’s toe at about 1 to 1.5 times the tyre width, the machine can be prevented from bouncing. When cutting washboard from a road’s surface, this really helps.
Cutting and moldboard position
Generally and as a rule of thumb, the moldboard top should be about five centimetres ahead of the cutting edge. This position can be adjusted according to the material and other variables. It should be clearly remembered that the depth of cut across the entire moldboard can be changed by tipping the moldboard forwards or backwards.
If we talk about the wheel position, then the top of the front wheels are generally leaned in the same direction that material comes off the moldboard. In cases, where the windrow becomes heavy, then the front wheels should be leaned in the direction of the windrow.
The front wheel should be kept in a vertical position when you are working on side slopes or ditches. The wheels should be leaned down the slope so as to ensure that the front-axle doesn’t reach its oscillating limit when you’re using articulation to work across a slope.
Learning about wheel leans is important as they can also help an operator make steering adjustments without taking his hands off the hydraulic controls.
You should be always careful when using the full rear tip as otherwise you can run into penetration problems. If cutting edges are worn, doing so could also damage the moldboard bottom or pivot area.
In a nutshell
Grading a road with the motor grader is not at all an easy task. Also, the style of every motor grader operator differs from the other. The general principle is that you start slow, keep your calm, understand the need of the job and then perform the task of road maintenance.
If as a contractor or constructor, you are assigned the task of grading roads and you are looking to buy a motor grader, then you should surely consider Mahindra Construction Equipment’s RoadMaster G75 and RoadMaster G90 motor graders that offer an affordable, un-compromised and mechanised grading solution.