Lego Road Grader - Built in 2006, this was my favorite Lego Design. It was not an industrial Design project but involved quite a few new mechanical designs- such as a 3-axis joint to allow the blade to pivot in every direction. Most functions are pneumatic and powered by manually-compressed air. However the steering wheel turns the front wheels and a large hand from the air pushes the grader while the pistons in the engine move.
Lego Road Grader - Every part in this entire design is Lego. The Lego company (commonly called TLC by Lego Builders) started producing a line of sets and parts for technical designs in 1977. This was called the "Technic" theme.
Suspension - The suspension system is pendular- meaning that there are no shocks; only wheel systems swinging on turning axles.
Lego Road Grader - Lego does not make a ball joint that can take pulling force. The 3-axis joint was developed for that purpose. Ground clearance was a challenge. Real Grader blades may only lift 18" off the ground. This blade lifts about 1/2" off of the ground.
Lego Road Grader - While it wasn't designed to be ergonomic (this was 2 years before studying Industrial Design) it was designed so every switch could be controlled from the cab. The gigantic hand from above provides the air supply. The driver never complains about comfort.
Lego Road Grader - The front suspension basically is a top and bottom set of A-frames that pivot around the center axle. Minature pneumatic pistons are what tilt the fron suspension. In real life Grader wheels tilt to provide better traction during steering.
Lego Road Grader - Lego started making round pistons and cylinders in 1990. Their crankshafts only have lobes 180 degrees apart, but who cares? The lever holding the hood up has an elbow that can be locked and then unlocked.
Lego Road Grader - A good way to describe road graders is that they are a pencil with an eraser. The blade is the pencil that creates the road and the ripper in back is the eraser.
Since the rear suspension is pendular, there is one differential and two wheels are geared off of each output.
The blade has 4 axis of movement. The overall turning is only about 40 degrees while real Grader blades can turn/swing 120 or more degrees overall.
26" is the total length.
So far there is no large-scale road grader kit ever by the Lego company.