For instance, Volvo uses a high-density polymer material called Duramide to completely isolate the circle from the drawbar. "There is no metal to metal contact," says Gary Atkinson, product manager of road machinery, Volvo Construction. It is self-lubricating with no external lubrication required. It contributes to circle turn power since it has a very low coefficient of friction. "The expected life on the Duramide circle support would typically exceed 5,000 hours before those bearings have to be replaced. "They are shim adjustable and can be run up to where there is virtually no clearance at all. I usually recommend to people when they get close to 1/8 in. horizontal and vertical then they should be tightened up." Volvo also uses this Duramide material for the moldboard slide bearings.
Deere & Company simplified maintenance procedures when it introduced its latest generation of motor graders."The new John Deere G-Series motor graders have an exclusive moldboard adjustment system that allows the moldboard to be adjusted to factory specifications within minutes," says Nathan Horstman engineer, Deere & Company. "An exclusive circle wear insert design allows for quick replacement of the circle inserts with a 9/16-in. wrench. "The lift cylinder ball and socket joints can be easily tightened by removing shims."
Likewise, Caterpillar made major strides to reduce maintenance time. "The new Caterpillar M Series motor graders provide a shimless moldboard retention system, which provides horizontal and vertical adjustment capability," says Wade Porter, motor grader product & application specialist, Caterpillar Inc.. The elimination of the shim pack from the predecessor H Series has dramatically reduced the maintenance/repair time associated with the moldboard slide rail inserts. For routine maintenance, Caterpillar provides a bi-directional wear strip adjustment system that uses two jam screws and locking nuts on the top and one jam screw and locking nut on the rear of each adjustment point."
A patented top adjust design is used for accessing and replacing the drawbar wear inserts. "Now maintaining and replacing these inserts is simple and easy and done completely from the top of the drawbar." In addition, bronze allow wear inserts on the lift cylinders and centershift cylinder allows the owner/operator to replace the wear insert rather than replacing the ball stud.