dar512 has it sussed. There has been a longstanding argument between big truck makers, as to whether to have Diesel Electric or Mechanical drive.
Caterpillar came out in favor of Mechanical drive for all their trucks, stating the Mechanical drive they build, was cheaper to build, and easier to maintain .. whilst many other manufacturers such as Liebherr chose Diesel Electric.

Caterpillar have lost out now, because of the weight penalty with Mechanical drive. A Diesel electric truck, when it gets to the large sizes, has a 30% weight saving over Mechanical drive. This weight saving is not available in the smaller size trucks .. in fact, with a small truck, Diesel electric has a weight penalty over Mechanical drive.

The change that has made all the difference, is the change to AC motors from DC motors.
DC motors were used in the dump trucks for a long time, because AC motors are more difficult to control .. and it was only the advent of modern electronics, that made using AC motors, viable.

Re the "fuel waste'' ... these trucks are highly efficient, in comparison to the amount of dirt shifted in relation to fuel cost .. the cost of earthmoving with these trucks runs to merely cents per tonne over many kilometres.
The cost of moving dirt has been coming down steadily over the decades, as technology increases .. this means cheaper end products for all.

Re the questions on how do you manage to drive a monster like this? They are, in fact, quite easy to drive .. to the extent that many women are operating them.
The controls are only a little different to an automatic car .. the major thing is getting used to the size of what you are driving .. which is no different to readjusting your thinking when you drive a bus instead of a car.

They do have very limited vision though, and the operators must exercise great care, as running over small vehicles presents a real hazard. Accordingly, it is against mine regulations to park with 20 metres (66') of any truck, unless the truck is shut down and maintenance or fueling is being carried out.

The operators are taught to drive them on simulators, much like jet simulators. These simulators are amazingly realistic, with the ability to programme in the minesite layout, on a panoramic wide screen.
The cabin is replicated exactly, the engine sounds are included, as are other smaller vehicles moving across your path, road signs, waste and ore stockpiles, the mine ramp, other equipment .. all the potential hazards of a standard minesite.
Safety in mining is given extremly high priority, and the safety levels on a minesite are 10 times higher than your average street .. and the low level of accidents reflect that.
However, occasionally things do go wrong, and accidents happen.

The biggest hazard is waste or ore stockpiles. Even though a low wall, or bund is kept in place around the edge of stockpiles, sometimes the soil slips without warning, when the truck is dumping, and the truck can roll off the dump.
The cabins are heavily reinforced and can withstand great impact. Seat belts are worn at all times, and if the truck rolls, you stand a very high chance of survival without major injury. The only fatalities that have happened in recent years are those where an operator did not wear their seatbelt.

Fire is another hazard that is taken care of with an on-board fire suppression system. At the first sign of fire, the extinguishers are activated automatically or by the operator, limiting any chance of a fire taking hold.

Low bridges
 

Well, Watch out for low bridges!

Oh lawd that's funny! :lol: Barring taking the thing apart, how on earth would they right it?

With great difficulty, much planning, and a couple of heavy cranes. Maybe even dismantling some of the overhead framework.

That wreck is the result of some dopey operator forgetting to lower his hoist.
They usually string a heavy cable with big empty drums attached, 100yds in front of any overhead obstructions, so the half-asleep operator gets woken up with a helluva lot of banging noises .. which immediately means the brakes very promptly get applied before damage can be caused.

Of course .. there are just plain bad days .. when the wheels and other bits just fall right off ... :dead:

[IMG][IMG]

Speaking of lurkers coming out of the woodwork... :-)

This image made me remember a great article in Car and Driver some years ago, where they reviewed a 797 dump truck. I assume the one in the picture her is bigger, but it's still fun reading.
http://www.caranddriver.com/article....&page_number=1

Fun stats:
Zero to 30 mph. . . . . . . . . . . . . . . . . . . . . . . . . .27.1 sec
At 40% load factor. . . . . . . . . . . . . . . . .65 gallons/hr, 0.3 mpg

Tim

My favorite spec is

Tires. . . . . . . . . . . . . . . . . . . . . . . . . Michelin 55/80R-63

Could be a great prank call. I doubt Valley Forge Tire and Auto carries it, but it'd be fun making them check.

(R-63 indicates a radial with 5 foot 3" inner diameter. The 55 specifies tread width, and the 80 is sidewall height as a percentage of the tread width). For normal tires the tread width is in millimeters, but I suspect it's in inches here. So the tire is just over 5 feet inner diameter, just under 5 feet wide, and with a sidewall height of 4 feet. Apparently the current best tire for this truck is a 59/80R63, which is a bit bigger)

I Cannot believe that you ladies let this get past you.

Spin it. :)

I've been reading C&D since Oct '62. There specialty files are always super. The USS JFK was a favorite. :thumpsup:

i think one of these was used for Jackie Chan's 'Mr nice guy', i remember thinking "i MUST get one of those!!"

Found this one from another post. I think there is one bigger than this one. Could of sworn I saw one that the ground clearance was so high, it could actually driver OVER a standard pick-up truck!

Not so big
 

World's Smallest Car

If you munch on Alice's mushroom you might be able to drive this one.

Another pic I found..