South Africa still has a fair number of gravel roads, both public and private. With proper maintenance, gravel roads offer a cheaper and quicker road building option that is ideal for rural areas and farms.
Maintenance on gravel roads needs to be done at regular intervals to prevent displaced gravel, washboarding and potholes but with the right guidelines, it’s a straightforward job.
Our Caterpillar approved tips and a dependable grader will ensure your regular grading sessions are manageable and effective.
Ensure the correct conditions for grading
If you want to dress the road and shape the crown make sure the road has sufficient moisture. Recent rains can achieve this or the road can be sprayed with water using a water tank.
Ensure good drainage so you don’t oversaturate the road surface and leave standing water.
If you want to drag the surface, only do so when it’s hard and dry, with the cutting edge 90 degrees to the surface.
Cut to the depth of major potholes. Don’t fill potholes with loose material, this doesn’t improve the road surface over time.
Check wear on the cutting edge frequently
You need to ensure a good cutting edge throughout grading to keep an even surface.
Cutting edges wear down quickly, especially in the centre, so check for edge wear frequently. Letting the cutting edge degrade too far can also lead to moldboard damage.
Maintain straight cutting edges by trimming them with a torch or dragging the cutting edges on a smooth concrete surface. Replace edges before the wear reaches the bottom of the moldboard.
Use centre position for general maintenance
The centre-shift mechanism allows the moldboard to be positioned on either side of the machine. It is secured by the centre-shift lock pin. For normal maintenance, the centre-shift lock pin should be in the centre position.
The drawbar, which supports the moldboard, and the circle, which angles and positions the moldboard, should both be centred under the grader’s frame. The grader’s frame itself should be straight or articulated only slightly.
To get the right angle, start with the top of the moldboard about 5 centimetres ahead of the cutting edge. Adjust downward pressure as needed to get a sufficiently deep grade but make sure not to overdo it.
Drive at the highest speed possible for maximum productivity but low enough to prevent machine bounce – 6 to 11 km/h.
Protect your cutting edge
Using a fixed tip angle will ensure that a consistent amount of the cutting edge is in contact with the surface while grading. A consistent angle will mean a longer edge lifespan.
Constantly changing the tip angle will result in more rapid wear on the cutting edge.
Use caution when back dragging material or reversing with the moldboard close to the ground. This could break or damage the cutting edge.
For the best durability, use the thickest edge that is suitable for the job at hand.
Use the widest cutting width
The cutting width of a pass will depend on the length of the moldboard and moldboard angle.
User the widest possible pass width by keeping the moldboard angle as square to the frame as possible. This will allow the moldboard to cover as much of the road width as possible.
If material starts to flow around the leading end of the moldboard, you may need to increase the blade angle to compensate.
On wider roads, use blade extensions on one or both ends of the moldboard. Extensions on both ends should only be used for light maintenance work.
Use crab mode to avoid bounce
As mentioned, the grader’s mainframe should be kept straight with the drawbar and circle centred under the frame. An exception to this is if the machine tends to bounce.
To address this, articulate the rear frame towards the toe of the moldboard 2 to 5 degrees. This crab mode is particularly effective when cutting washboards with the moldboard.
In the crab mode, one front tyre is slightly ahead of the other, allowing one tyre to be on top of a corrugation while the other is at the bottom. As the tyres roll up and down through the washboard, the front axle will pivot up and down helping to keep the mainframe stable.
Do not use the crab mode when scarifying washboard areas. It could bend the scarifier shanks and/or linkage.
Do road maintenance regularly
Gravel roads can deteriorate quickly, especially following heavy rains or lots of traffic. Grading the surface at regular intervals will keep the road safe and drivable.
Neglecting regular grading can also lead to damage that can’t be fixed with general maintenance. In extreme cases of neglect, roads may have to be rebuilt to restore a drivable surface.
How often you grade a road will depend on a few factors. Read this article for a guide to how often a gravel road should be graded.
Haul roads in particular take a beating from the heavy mining vehicles that use them. This article offers some tips that are specific to haul road maintenance.
This best management practice guide is written for UK roads but might be useful.
Other resources for building and maintaining gravel roads
Explore our other resources with tips and information for building and maintaining gravel roads in South Africa.
- 10 Basic Principles of Building a Great Gravel Road
- How to Build and Maintain a Farm Road
- How Often Should a Gravel Road be Graded
- Road Maintenance Tips for Farms, Lodges and Nature Reserves
- 8 Tips for Haul Road Maintenance in South Africa
How KH Plant can help
A reliable motor grader is the key to good grading. To help you implement these tips, you should invest in a proven motor grader brand like Caterpillar. Graders can be quite pricey but you don’t have to fork out for a brand new one.
At KH Plant, we specialise in restoring Caterpillar 140G, 140H and 140K motor graders (and individual components) to as-new condition – so you can get the benefits of a new motor grader at a fraction of the cost of a new machine. Contact us for more information or to discuss your needs.
