Motor graders require a little more care than other pieces of heavy iron to ensure they can maintain precise grades. ?Considering that finish grade is typically from 1/8 to 1/4 in., turntable and moldboard slide tolerances must be maintained as close as possible,? says Phil Newberry, market development engineer, motor grader marketing, Caterpillar. ?Once wear reaches or exceeds these tolerances, it makes it extremely difficult to achieve grade in a productive fashion.?
Regular maintenance helps prevent excessive wear on critical moving interfaces. ?Grease points are by far one of the most important maintenance items on a motor grader,? says Woody Ferrell, vice president of sales and marketing, Champion Motor Graders. ?Motor graders have more moving joints and implements than most any other type of construction equipment. ?
This requires vigilant record keeping of the service intervals. ?Stay within the recommended service intervals stated by the manufacturer for all serviceable items, not just engine oil changes,? says Ferrell. ?There are other wear items that get overlooked, because the service technicians get used to performing a standard type service or the customer cannot have any extended downtime. Therefore, the customer will only allow the minimal service so he can keep working the motor grader.?
Yet, there are areas that require more attention. ?The most common wear points are the blade slide guides, circle guide shoes on the turntable and blade lift cylinder connections,? says Keith Lee, research and development, LeeBoy. ?Any play in these areas allows the blade to move ? 1/16th in. in two, three or four places can add up quickly.? This is known as tolerance stack. You start adding play in all of the critical joints together and pretty soon the whole system is loose.
The tighter you can keep the components, the better. ?Tightness in the moldboard slides, circle supports, drawbar ball stud and even the operator?s seat are all important factors to consider when determining if the grader can produce a finish grade to the tolerance specified,? says Brian Lowe, product and communications manager - motor graders, Volvo Construction Equipment. ?As the accuracy of most machine control systems are checked at least daily, if not more frequently, so too should the critical areas of the circle and moldboard slide be inspected.?
Lowe adds, ?Where ever there is a sliding surface, there is the potential to have wear and subsequent loss of blading tolerance. By default, the circle support shoes and moldboard slides get the most attention. But the operator must also consider the connection between the lift and sideshift cylinders and the drawbar.?
Tight tolerances allow the machine to react quickly to operator input. ?Clamp and guide shoes in the circle turn system can restrict the circle?s rotation when worn or out of adjustment, therefore, not allowing quick and accurate adjustments while grading,? says Ferrell. ?The ball stud connected to the drawbar can affect this, but not as much, and it is quickly adjusted if there are shims that can be removed once wear has been detected.?
You also need to watch the trunnions. ?The trunnions hold the blade lift cylinders and receive the majority of the shock loads during grading,? says Ferrell. ?You can properly adjust your circle and slide, but if your grader has excessive wear in the trunnions, then you lose the ability to hold tighter tolerances.?
In addition, out-of-tolerance components can create excessive wear. ?By not keeping your circle and slide maintained to within 1/16 to 3/16 in., you subject yourself to premature wear,? says Ferrell. ?A lot of play in your components allows lubricants to get out and more dirt [to get] in.?
Monitor the cutting edge
The type of material you commonly work with has a major impact on how often you need to examine your cutting edges. ?The type of material greatly affects cutting edge life,? says Newberry. ?Very abrasive material can wear out a set of cutting edges in an eight-hour shift. And in softer, non-abrasive material, the cutting edge may last a month.?