Moldboard maintenance

Your motor grader’s moldboard, the moveable blade ring-mounted beneath the grader’s frame, can be swivelled vertically to adjust the angle of the blade itself. Moldboards come in various sizes, depending on motor grader model and function.

Because the moldboard does the hard cutting work, keeping it in tip-top shape is crucial for ensuring a motor grader’s productivity and longevity.

Checking the blade

Above all, keep an eye on the cutting edge at the bottom of the moldboard. Ideally, blades should be checked after every 25 to 50 hours of operation. There should be an available cutting edge of around 3.8 centimetres (1.5 inches) on the blade for the moldboard to work properly. Anything less than 2.5 centimetres may cause unnecessary damage to the moldboard.

Do regular inspections on site to answer these questions:

  • Does asphalt or debris need to be cleaned off the blade slides and bolts?
  • Are any blade bolts loose or missing?
  • Is the blade linkage loose, or showing signs of excessive use and damage?

Changing the blade

Depending on the material you're working with and the machine operator’s skill in manoeuvring the blade, the blade and bolts that keep it in place may need to be replaced fairly regularly.

Guidelines for changing the blade are as follows:

  • For safety, wear a hard hat, gloves and overalls (or close-fitting clothes).
  • Block the front and rear tandem wheels and sit in the operator’s seat in the cab. Start the grader, with the park brake on. Then lower the moldboard so it just touches ground, but with no down pressure. Turn the machine off and dismount the grader.
  • Work on one section of the cutting blade at a time, standing so the blade is turned away from you, removing the bolts to dislodge the blade. Use a wire brush to clean the matching surfaces, then put the new blade in place, inserting and securing the bolts with nuts. If the bolts you removed earlier were worn, it’s best to replace them as well.
  • Remove the blocks from the machine’s wheels, and get into the operator’s seat to start the grader. Now lower the moldboard to the ground with the full weight. Put all controls in neutral, then shut the machine down as per operation procedure.
  • Dismount and place all the items used, and replaced, in storage. Keep a log of the maintenance procedure.

For information about the range of refurbished Caterpillar 140G, 140H and 140K motor graders available from KH Plant, contact us online or call one of our representatives on +27 83 274 4882.