My interest in motor graders was sparked at the age of 11 when I first saw one of these strange machines in a French mountain village. I watched it, fascinated, as it spread tarmacadum over the narrow main street, covering drains and blocking doorways in the process.

Like many of the British of my generation, I was a Meccano boy, and as soon as I got home I built a model of the grader. Meccano was the English counterpart to Erector Sets, and even today has some 3,000 adult enthusiasts worldwide. Working only from memory, the model probably bore as much resemblance to a grader as those medieval drawings, conjectured from a pile of fossil bones, did to a dinosaur.

When I returned to the hobby in later life I decided to build another grader, and this time properly. First, research was needed. Road graders are not as common a sight in the UK as in the USA or continental Europe. More than once, rubbernecking while passing one, I nearly crashed into a ditch. When I could stop, I would jump out of the car and run over, camera in hand, getting strange looks from anyone around.

Of the many types seen, the Caterpillars, with their articulating frames and ingenious circle offset geometry, were far the most interesting, and the 14G was perfect to reproduce at 1:10 scale. The product literature is a modeller's dream, and even Caterpillar yellow an exact match to the contemporary Meccano colour.

In other respects Meccano had not kept pace with modern engineering. Now in its 100th year, the system is rooted in the technology of yesterday. Modern graders, I noticed, were all-hydraulic, and there are no hydraulics in Meccano.

At first, home-made real hydraulics were tried, using small pneumatic actuators as rams, fed by TQF at 10 bar pressure by two windscreen-washer motors. The only available control valves were from a plastic toy kit. Too bulky to fit inside the model, and designed for only 2 bar, they quickly failed in spectacular fashion, coating the ceiling with hydraulic fluid.

Success came by simulating the hydraulics electrically, fitting small electric motors with reduction gearing inside the rams turning lead screws inside internally-threaded pistons. The rams work at prototypical speed and produce over 5 lbs of thrust each. That is strong enough to articulate the 60 lb. model whilst stationary. Two other miniature motors turn the circle and the steering wheel.

The ten simulated hydraulic circuits are:

Steering * Front wheel lean * Moldboard sideshift * Circle centershift * Circle rotation * Blade angle * Blade lift (right) * Frame articulation * Blade lift (left) * Ripper lift

All are operated by reversible micro switches and a battery concealed in the engine housing.  A larger 12V motor inside the dummy engine block drives the four rear wheels via a locking differential.

A lever to the right of the driver's seat sets and releases the differential lock, and another retracts the locking pin of the circle sideshift radius arm.