Doosan Moxy MT31-lll ADT

By: Tim Dittmer

doosan moxy mt31 picking up speed The moxy picking up speed. gear changes were smoother with a load. doosan moxy mt31 picking up speed
doosan moxy mt31 tipping Tipping time is 11 seconds. doosan moxy mt31 tipping
doosan moxy mt31 The quiet and comfortable cab. doosan moxy mt31
the doosan moxy mt31 taking the steep ascent Taking the steep way. the doosan moxy mt31 taking the steep ascent
doosan moxy mt31 getting loaded Getting loaded. doosan moxy mt31 getting loaded
doosan moxy mt31 free swinging bogies. doosan moxy mt31
doosan moxy mt31 colour reversing camera is very handy. doosan moxy mt31

The Doosan Moxy MT 31 is a top-quality ADT that would happily carry any load asked of it.

Doosan Moxy MT31-lll ADT
The Moxy MT31-lll is an ADT with a five-cylinder turbo-diesel Scania DC 9 engine.

At the heart of the new Doosan Moxy MT31 is a five-cylinder Scania DC 9 turbocharged engine. The nine-litre powerplant is capable of delivering up to 347hp (259kW) while complying with Tier 3 emission regulations.

A ZF 6 WG 260-4 automatic/tiptronic transmission takes care of the gear shifts, while still offering the operator full control of the transmission when in tiptronic mode. The ZF box also has torque converter lock-up in all six gears. A dropbox is next in line and delivers the power to the front and rear diffs.

Up front the Moxy is fitted with independent front suspension while free-swinging tandem bogie housings allow a large range of wheel movement at the rear. Only one rear diff is required due to the use of the bogie design, helping to reduce the overall tare weight.

Each wheel is also fitted with wet disc brakes to ensure equal braking force in any conditions. Two variable displacement piston pumps, offering a combined flow of 230 litres per minute, provide the hydraulic pressure; one for steering and tipping while the other takes care of the cooling fan, brakes and auxiliaries.


Servicing the MT 31 is fairly easily. The front hood lifts up to give access to the engine bay and air and oil filters. A large underbelly plate hinges down to allow more access should you need it. With a couple of bolts removed the whole cab can be tilted back via a hand pump to allow access to the transmission and hydraulic pumps.

An auto greasing system is fitted as standard spec, which should help prevent wear.

Weight is distributed evenly to the rear wheels by the free-swinging bogies, up front the osculating steering joint shares the load between the tyres, reducing tyre wear and giving a tight turning circle with minimal sledging. The dump body is constructed of abrasion-resistant Hardox 400 plate.

Operator station

The air-suspended seat gives good support and should help soak up the bumps, while a smaller, harder passenger seat is fitted in the back left corner of the cab. Both are fitted with non-retractable lap belts.

To the right of the steering wheel is a panel consisting mainly of switches for the lights, hazards and retarder. Behind them are two levers, the left controls the transmission. From neutral the button on top needs to be pushed to allow forward or reverse to be selected. With the lever forward the transmission is in auto mode and shifting the same lever sideways puts it in manual tiptronic mode. The second lever lifts and lowers the dump body.

The diff lock and parking brake are both on switches alongside. Visibility is excellent to the sides and rear, aided by a reversing camera and large mirrors. Looking forward, the curved bonnet dives away out of sight, giving great vision and no blind spots.


Doosan's demo model Moxy MT 31 was hauling rock from the bottom of Infracon Aggregates' quarry at Linton, near Palmerston North, to the stockpile.

It's a fairly steep haul road down into the bottom of Infracon's quarry but the retarder easily holds the empty 21.3-tonne ADT - in fact it pulled it up so well that I had to give it a bit of throttle to keep it moving. I chose manual mode on the transmission for the descent as I didn't want any unexpected up changes.

Once at the bottom a Doosan DL400 wheel loader heaped the dumper with rock.
With the bin full I turned and started the climb out, putting the transmission back to auto to see how it coped with the decision making. It got to second gear as I hit the hill climb. Even with full throttle the cab remained very quiet.

As the gradient increased the ground speed began to decrease, and the revs started to drop with my foot still hard down. As they fell below 1500rpm I expected the Moxy to down change but it didn't; surprisingly the five-cylinder Scania managed to hang on to the end. As the haul road flattened out a bit the ZF box grabbed a higher gear. Its changes were smoother when loaded than empty.

On the flat I grabbed fifth gear. With a bit of speed on there was no wallowing or instability - the Moxy remained smooth. After arriving at the top of the stockpile there is a short track that needs to be reversed up before tipping the body.

I was using the large mirrors to find my way up the track but when I turned fully to negotiate a tight corner the rear of the body disappeared out of view. This is where the reversing camera is fully appreciated, as it allowed full vision out the back. 

With the fully laden MT 31 in position I pulled the tip lever to raise the body and was greeted by an ear-piercing alarm to alert me that the bin was lifting. The tipping lever would benefit from having a detent on the body lowering side so you could drive away easier while lowering the bin.

Besides that, the dump body has a healthy speed of 11 seconds up and 10 seconds down. Once empty the Doosan Moxy felt nimble at speed; though it got a bit of bounce in its stride as to be expected. 

  • Huge amount of wheel travel thanks to free-swinging bogies
  • Excellent retardation
  • Smooth changing transmission
  • Good access for servicing
  • Quiet and comfortable cab with great visibility

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