Changing a motor grader blade

Proper maintenance is vital for keeping a motor grader performing optimally – and of all maintenance tasks, the most important is ensuring that the grader has a good cutting edge.

The blade that's bolted to the moldboard has a cutting edge along its bottom. Depending on the grader, there may also be cutting edges attached on each side of the blade.

It's the cutting edges that do the real work, cutting into the material to be graded. The time it takes for the edges to get worn down will depend on how abrasive the material is and on factors like the angle at which edges make contact with the material.

When to change a motor grader blade

Generally a motor grader performs effectively with about 3.5 centimetres of useable space exposed on the cutting edge. If the edge gets worn down too far, the grader won't perform as it should. There's also a risk of wearing right into the moldboard, which may then have to be replaced.

Depending on the type of material a grader is cutting, manufacturers recommend that you visually inspect cutting edges after every 25 to 50 hours.

Checklist for changing a motor grader blade

When changing a motor grader blade, it's best to wear gloves, a hard hat and close-fitting clothing that can't easily become snagged on equipment.

The recommended procedure for changing the blade is as follows:

  1. Block tandem wheels at the front and back of the grader.
  2. Ensure the parking brake is set and start the grader.
  3. Lower the moldboard until it just touches the ground, without exerting downward pressure on it, and then shut down the grader. Dismount safely.
  4. Remove the bolts from one section of the cutting edge at a time. Typically up to a dozen bolts hold a cutting edge in place. You should check the bolts and replace any that are worn.
  5. Dislodge the blade, standing alongside it so it falls away from you, off the moldboard onto the ground.
  6. Use a wire brush to clean the surfaces where the cutting edge will be secured and then set the new section of cutting edge in place. Insert bolds, secure them with nuts and tighten the bolts.
  7. Remove the blocks from the grader wheels, start the grader, and lower the moldboard until its full weight is on the ground.
  8. Move all controls to the neutral position and shut down the grader.

To replace separate cutting edges on either side of the moldboard, you can follow an alternative procedure. First raise the blade evenly about 20 centimetres above the ground and place a block at each end of the moldboard. Raise one end of the moldboard until the opposite end rests on ground. Change one of the cutting sections. Then reverse the procedure and change the other section.

Once you've successfully fitted a new cutting edge, remember to store the worn cutting edge for safe disposal.

At KH Plant, we specialise in importing and rebuilding Caterpillar 140G, 140H and 140K motor graders. For more information, contact us online or call one of our representatives on +27 83 274 4882.