Motor graders carry their working load through a long, slender front frame and a drawbar-circle-moldboard assembly that is constantly side-loaded. Frame cracking near the articulation and the drawbar ball, circle wear and tooth damage, and blade lift cylinder mount failures are the recurring findings. On haul roads, brake performance and visibility matter as much as on the trucks they share the road with.
A grader inspection covers the drawbar, circle and moldboard, the front and rear frames and articulation, the tandem drives and final drives, braking and steering, and the cab and protective structures.
Inspection checklist areas
- Drawbar, circle and moldboard
- Drawbar ball and socket wear, circle teeth and drive pinion condition, circle wear strips and clearance, moldboard slide rails and cutting edge, blade lift and side-shift cylinder mounts.
- Front frame and articulation
- MT of front frame welds at the drawbar ball mount and lift arm saddle, articulation pin and bearing clearance, articulation frame welds and lock.
- Rear frame and tandems
- Rear frame and engine mount welds, tandem case welds and pivot bearing wear, tandem chain tension and wear, final drive leakage.
- Front axle and steering
- Front axle pivot and leaning-wheel mechanism wear, kingpins, steering cylinders and tie rods, wheel lean lock.
- Braking
- Service, secondary and park brake performance to AS 2958.1, accumulator condition and low-pressure warnings.
- Cab, ROPS and visibility
- ROPS/FOPS identification and condition, cab mounts, seat belt, mirrors and cameras, lighting, ripper and scarifier condition where fitted.
Known failure modes
Front frame cracking
Fatigue at the drawbar ball mount and lift arm saddle welds under blade side-load.
Articulation joint wear
Excess pin and bearing clearance producing steering instability and frame cracking.
Circle and drawbar wear
Worn circle teeth, pinion and wear strips causing blade movement under load and loss of grade control.
Tandem case and pivot failure
Cracked tandem cases or worn pivot bearings causing misalignment and chain failure.
Brake performance loss
Worn brakes or accumulator faults on a machine that shares haul roads with loaded trucks.
Applicable standards and regulations
| Reference | Title | Relevance |
|---|---|---|
| AS 2958.1 | Earth-moving machinery — Safety — Wheeled machines — Brakes | Performance basis for brake assessment. |
| AS 2294.1 / ISO 3471 and ISO 3449 | Earth-moving machinery — Protective structures | ROPS/FOPS identification and condition. |
| AS/NZS 1554.5 | Welding of steel structures subject to high levels of fatigue loading | Acceptance criteria for frame and drawbar repair welds. |
| AS/NZS 4024 series | Safety of machinery | Guarding of circle drive and tandem areas. |
| NSW MDG 15 | Mobile and transportable plant for use at mines | Design and maintenance expectations for graders on mine sites. |
When to inspect
- Introduction to site and pre-hire inspection
- Measured circle, drawbar or articulation clearance approaching OEM limits
- After front frame, drawbar or articulation repair
- Brake or steering concerns on haul road duty
- Before sale or purchase
Frequently asked questions
What is specific to a grader compared with other mobile plant?
The drawbar, circle and moldboard assembly, the leaning front wheels and the long front frame. Wear in the circle and drawbar ball affects grade control; cracking in the front frame near the drawbar ball mount and articulation is the main structural risk.
Is the grader ripper inspected?
Yes, where fitted. Ripper and scarifier frames, shank pockets, pins and cylinder mounts are inspected in the same way as on a dozer.
How is brake performance assessed on a grader?
Against the criteria of AS 2958.1 for wheeled earthmoving machines, covering service, secondary and park brakes, with accumulator and warning system checks.