Grading a road with a Motor Grader

Road grading consists of using a motor grader to restore the driving surface and drainage attributes to roads. Motor graders are used globally when constructing new roads or upgrading existing ones. As with all heavy equipment usage, using the right parts for the job is paramount. When it comes to road maintenance, the operator of the grader is generally the most experienced and skilled on the job site. His task is to use the best available grading equipment, using the most effective and efficient techniques.

What are the primary uses of a motor grader?

The two most common uses for motor graders are:

  • Smoothing surfaces, soil levelling and moving small quantities of earth.
  • Preparation of the final layer of a new road before the asphalt is laid.

In both instances, whether the driving path is tar, gravel or a natural road surface, the desired smoothness and shape are determined by removing irregularities and redistributing the gravel or earth. The key to achieving the best result, whether on rural or urban road projects, is the use of the correct grader blade. Assessing the type of ground or surface establishes which blade(s) should be used.

Using different types of grader blades

  • Soft ground – A thin blade with a sharp edge is recommended as little to no downward pressure is needed.
  • Reshaping roads – A thin, flat blade is suitable to cut and reshape roads and to cutting ditches. This reduces future road maintenance requirements and provides increased flexibility.
  • Covering potholes and wheel ruts – A serrated blade penetrates the ground and loosens more material for distribution over potholes and wheel ruts. This speeds up the job and reduces future maintenance.
  • Good mix of surface material for a roadbed – A corrugated style blade is most practical for grading through vegetation and different types of soils. This provides a good mix of surface material by allowing flow through the holes in the blade.
  • Redistribute and mix base, or sub-materials – A flat or curved blade will mix the base, or sub-base materials as the material rolls along the face of the blade for redistribution evenly across the road.
%focuskw Grading a road with a Motor Grader

Common Issues with Grader Blades


Crowning occurs when the cutting-edge moulds and changes to the profile of the road that is being graded. Some operators may make use of a narrower and/or thinner cutting edge when extreme crowning is in play. Using shorter blades may allow more play in the blades which allows for rotation inside out and inverted to maximise usage and wear.


Understanding the penetration requirements for the project will go a long way to selecting the correct thickness of blade. A thinner one may be a better option for harder, higher impact surfaces to penetrate the material more easily, whereas a thicker blade is better for such surfaces as the blade will take longer to wear.


Blading a road at the wrong angle can make a project easier or harder. Each application has a specific range which maintains the sharpness of the edge and offers the best penetration. Making sure that a good understanding of what the best angles are for the surface in the project is very important when making an assessment before starting out.

Komatsu motor graders help operators improve their technique

There are many unique features on Komatsu motor graders, one of which is the dual mode transmission, which utilises both a torque converter and a direct drive clutch to achieve high tractive effort, inching ability, high ground speeds and low fuel consumption. Inexperienced operators will find this of great benefit to improving their skills.

Finally, the hydraulics integrate extremely well with the latest grade control system for precision operation.

Komatsu is a global leader in the supply of Japanese-engineered mining, construction, earthmoving and utility equipment in Southern Africa. The MoJo Motor Industries (MMI) Team comes with over fifty-four years of combined experience in the automotive, construction and mining equipment sales and support. MMI is the official Komatsu dealer for Zimbabwe. Please direct all your pre-sales or equipment enquiries on motor graders to our friendly staff.

This article was produced by Kerry Langford, with input from the Komatsu Technical Specialist for Africa Operations, Mr Edwin Hewitt.


Komatsu America. (n.d.). Retrieved from

Komatsu Chile. (n.d.). Retrieved from

Komatsu South Africa. (n.d.). Retrieved from