Driving a real-life Tonka toy

Standing underneath 35 American tonnes of bloody great big dumper truck, I have the distinct feeling that my sex parts aren't big enough. This is the Bell B50D - one of the world's biggest dumper trucks. And it's really quite intimidating.

Largely because of the numbers. It's 10832mm long, 4067mm wide and weighs 34,520kg. It's an absolute colossus. Stand it on its end - you may need some friends for this - and it'll reach up nearly four floors. And it'll take 17.6 S-Classes to match its mass. Looking at it, you could probably park two of them in its tippy bit (which I'm reliably informed is called the body).

Then there's the engine. It uses a 16.0-litre Mercedes V8 that produces 1770 lb ft of torque. Or 25 VW Ups. With sufficient malice and a few tubes of KY, you could fit an average-sized cat into each of the cylinder bores. Top speed is a tad over 30mph, but despite its massive heft you'll reach terminal velocity in around 5 seconds.

To send drive to all six of its wheels, there's a clever six-speed Allison transmission (the founder of which also co-founded the Indy 500, fact fans). It's got a special torque converter that multiplies power. It's a variant of the very same unit used in fire trucks, the highest security prison vans and London buses.

From just under two metres up on the bridge - it'd be underselling the sense of gentle imperiousness to call it anything but - things are actually quite civilised. The visual grammar's remarkably familiar; there's a faintly retro radio/CD head unit, sporty three-spoke steering wheel, coolant temperature, RPM, fuel and transmission temperature gauge, LCD screen for the reversing camera, indicator stalk... Bit disappointing, really - I was hoping it'd be a bit less SEAT, a bit more S&M dungeon.

Wielding the B50D doesn't take a huge leap of imagination, the only difference to an ordinary car being that the transmission's automated via a little key pad, which also controls the three locking differentials, tipping body, lights and air-con (remember, these things work in the Middle East and Africa where temperatures regularly reach 40 degrees Celsius).

One profound difference is steering. It's deeply, utterly odd.  The wheels don't actually turn - instead, you have two steering cylinders between the body and engine. When you turn the steering wheel, one pushes and the other pulls, creating a sort of military-grade swivel chair.

With a few minutes practice, the linearity of input's actually quite intuitive. Give it ten and you're piloting your own yellow Tonka avalanche on slopes you literally couldn't walk down. Its off-road ability is utterly confounding, partially because the 6ft 1in of wheel/tyre shrinks obstacles, partially because it's got three locking differentials the size of beach balls, and partially because there's the equivalent to a Porsche 911 powering each wheel. What's the stopping distance, though? Does it need half a mile to put on the anchors?

Nope. Not a bit of it. Which is surprising, because it's got oil-bath brakes. Yep, the friction surfaces are literally bathed in oil, which hardly seems conducive to pulling up on a sixpence. The dual-circuit full hydraulic oil-immersed wet multidisc brakes are on all three axles and capable of creating 89,699lb ft of force, and there's an automatic exhaust brake, engine valve brake and variable adjustable hydraulic retarder in the transmission, just in case.

The latter automatically brakes for you when you're pointing downhill and let off the accelerator, just like a Range Rover's hill descent system. By Massive Great Big Stuff standards, it's as stoppable as a Caterham Superlight. And as quick off the mark.

OK, so it only produces 503hp@1800rpm, but the vertebrae-nudging 1770lb ft of torque comes in just 1200rpm, so full power feels like it's constantly on tap. Nissan Leaf owners will be familiar with the sensation.

I plot a circuitous course via a small pond, locked onto the horizon with what I hope is a deeply masculine stare. I have conquered the massive Tonka toy. I am Chuck Norris, I am Bear Grylls, I am that bloke off the Davidoff adverts. I am being politely asked to leave the bridge.