Next, cycle the hydraulics. “If the hydraulic pump has a lot of whining in it or it makes a lot of noise every time you engage the hydraulics, chances are you have an internal problem. Also look for blade drift.”
Finally, check the most critical part: the ground-engaging components. “The most common wear points are obviously around the blade and work equipment involved with the blade — which is, more than anything, the blade circle,” says Hendrix.
In order to fine grade, a motor grader needs to maintain tight tolerances. “It is very important to check wear strips, shims and everything used to tighten up a motor grader,” says Hendrix. “In the blade circle, there might be a dozen different ball joint couplers. Every one of those couplers will have some type of shims when they come from the factory. As the ball joint wears, these shims can be removed to maintain tight clearance.”
Look for the presence or absence of shims. If the shims are gone, then you will have to replace the ball itself. It gets a lot more involved and costly at that point.
Also observe how the blade was maintained. “Since the moldboard is where all of the grader action takes place... it is a good indicator of how the overall machine has been maintained,” says Olive. “If the cutting edge has been worn so much there are signs of wear into the moldboard, that is a big sign of neglect or misuse of the machine.”
When determining whether the moldboard might need to be replaced, first check how worn it is and if the cutting edges have been replaced prior to wear. “Other indicators the moldboard might need to be replaced are evidence of fishplating, or if the side shift pin is not straight,” Olive says. When inspecting the moldboard slide, watch for a bent rod and hydraulic oil leaks.
“You also want to make sure the moldboard has not been warped — that it hasn’t hit something in the middle or end that bent it one way or the other,” says Hendrix. “The only way to do that is to bend down and really look down the moldboard to make sure it is straight.”
Controls also need to be tight. “It is extremely critical to a finish grader operator to have ‘tight’ control linkages, just like the drawbar, circle and moldboard linkages,” says Porter. “A little bit of slop or play will remove the ‘feel’ of the cutting edge and negatively affect the ‘modulated’ performance capability of the operator. The linkage hardware in a conventional control motor grader is somewhat complex and has several moving parts, including the knob, control handle, rod, rocker arm, springs, bushings, etc.”
Finally, understand the specs of the machine you are purchasing, and don’t make any assumptions. This is especially true with the moldboard.
Check the moldboard length and make sure it is the correct length for the model. For example, a Caterpillar 140 grader should have a 14-ft. moldboard, and the 12G and 12H are ordered with 14-ft. moldboards in most markets, Hendrix points out. If any of these models are being sold with a 12-ft. moldboard, it can result in a significant reduction in value in some cases, especially on the 140.
Motor Wheel Scraper inspection
“The most common wear items on tractor wheel scrapers are the bolt-on edges and tires,” says Olive. “The most critical items to inspect on a used motor wheel scraper are the bowl, gooseneck and draft arms. Again, a complete walk-around inspection of the unit with a knowledgeable mechanic is well advised.”
“Really, the most important wear item to look at on a motor wheel scraper is the neck,” says Hendrix. Many motor scrapers are pushed with a dozer. “There is a lot of horsepower being applied to that middle and a lot of stress. The neck has a lot of wear points. A suspension system and the steering cylinders are there. There is a pivot for the front part of the tractor scraper.
“If those pins and those bushings are not changed out when they are starting to wear, then they will bang against each other,” he continues. “If you have to take the tractor scraper neck apart and line bore all of those points, you could be looking at a tremendous amount of expense and downtime to get that repair done. You need to look very carefully at the neck area and all around the bowl for any kind of structural problems.”