30 November 2020
Coming up with lists of extremes is not difficult for this Test Book. Not even if it concerns the biggest climb that driver Jan Jacob Bles has to make to reach a cabin. The Doosan DL420-7 is the undisputed winner of this 'climbing competition'. A favorable omen for the test of the latest edition of the 23-tonne wheel loader?
The fact that the Doosan DL420-7 meets the Stage V requirements and offers a lower fuel consumption is not the only good news from the Korean manufacturer. We should not underestimate the importance of the new, more rounded design and a whole host of other improvements. The metamorphosis that the (almost) 24-ton truck has undergone has been a long time coming. After the takeover by Daewoo in 2005, the excavators were first overhauled at Doosan. Now that they can fully compete with the competition, it is the turn of the shovels; the Doosan DL420-7 will be launched in December. The Doosan DL550-7 and Doosan DL580-7 are also on the way, although Covid-19 has caused some delay.
The new design not only pleases the eye, but also has practical advantages. A larger glass surface gives the operator a better view. A reversing camera, which is part of the standard equipment, also literally completes the picture. The cabin has a safety cage that offers extra safety in the event of a rollover, protection against falling objects has also been thought of.
For a manufacturer of high-end model machines, the new Doosan must be a dream example: side-hinged fenders for easier maintenance, all kinds of flaps that open, a railing that makes climbing the stern easier, that's something you can indulge in if you want to perfection strives in miniature. In one on one, however, it is also a beautiful sight, all those opened parts, whereby Jan Jacob quickly comes to the conclusion that you can reach everything very well. He doesn't stop there: 'You can see that everything has been thought through thoroughly, many check points are accessible from the ground, without having to climb on the machine. I also notice that cooling air does not flow over the engine, but enters the radiators through the side, which air is much cooler. The gas oil tank is on the back, you can easily fill it. You also top up Adblue from the ground, just like draining oil, you can easily reach the drain plugs.'
This brings us to the 12,700 cm³ Scania six-cylinder. 'There is absolutely nothing wrong with a good four-cylinder,' according to those present, 'but such a six-cylinder runs beautifully!' The Swedish powerhouse is equipped with the latest edition of the SAT2 (Situation Awareness Technology) energy management system. This permanently analyzes the use of the machine in all facets, with the pleasant 'by-catch' a 7 percent lower fuel consumption. The power is 257 kW/345 hp at 1,800 rpm and the maximum torque is also impressive with 2,196 Nm at 1,100 rpm. The more favorable emission values are partly achieved by selective catalytic converter reduction, a diesel oxidation catalytic converter and a diesel particulate filter. With that DPF, the cleaning cycle has been extended to more than 6,000 hours. The on-board computer keeps track of this, just like all other maintenance periods. DoosanCONNECT is very useful for digitally keeping an overview of the performance of the machines. It is also ideal for planning preventive maintenance and additional theft protection.
The powerplant is paired with the familiar five-speed powershift transmission, which gives the operator a choice between fully automatic or manual shifting and semi-automatic, with the option to use the kickdown if extra pulling power is required. If you disconnect the transmission briefly by pressing the brake pedal, the full engine power is sent to the hydraulic system.
The lifting system has been developed for heavy-duty use and has Z-kinematics, which means that the bucket remains at the same angle during lifting and returns to its original position after unloading. Speaking of buckets: ex works there is a choice between 4.3 and 4.5 cubic meters of 'Ecobuckets' to 4.4, 4.5, 4.7 and 4.9 cubic meters of gobbling 'Performance' versions.
You can see that everything has been thoroughly thought through, many parts are accessible from the ground
Jan Jacob climbs on the machine and is not economical when it comes to compliments for the 'command post'. 'I get up very easily, there are plenty of handles and prongs to hold on to. I'll keep it here for a day, the chair has plenty of adjustment options and there is nothing wrong with the seat. The brochure talks about business-class comfort and that's no exaggeration, including side suspension, adjustable lumbar support and built-in heating. A fridge is standard, it's nice to have a few cans of cool fresh in stock in the summer. For an additional charge you can even order a compressor with an air jet, which is handy if you want to blow clean the cabin.'
According to Jan Jacob, the operation is logical and clear: 'You quickly feel familiar here, everything is, ehhh… how do I say… completely driver-oriented. The normal steering wheel takes precedence over everything, but that is not illogical with a machine like this, with which you can drive on the road at 40 km/h. You activate the Comfort Drive Control steering via a button in the left armrest.'
According to our driver, the touch screen has a nice size at 8 inches. 'You can control all kinds of settings with it, but that goes without saying. Furthermore, the images of the reversing camera are displayed on it and you use the screen to operate the radio and climate control. A weighing system is an option; on the screen you can see how much you have in the bin', says Jan Jacob. 'With the electronic key in your pocket, you start the engine at the push of a button. You use the same button to switch it off, handy if you have to briefly interrupt work. Opening and closing the cabin door is done remotely, this is called “keyless entry” in the car world. That is extra handy with a machine of this height. Imagine standing on top of the stairs with a bag in one hand, while fiddling with a key in the lock with the other. Then this is a solution, isn't it? By the way, electrically adjustable mirrors are an option, I'm not surprised about anything anymore. But if I can get to work now, we'll talk later!'
Excellent noise reduction
Jan Jacob starts the six-cylinder to tackle a huge sand mountain. Steering and digging seems to be extremely easy for him, with graceful movements the Doosan moves back and forth through the sand. If this was a video recording, a waltz by André Rieu's orchestra would fit in perfectly.
We don't ask Jan Jacob whether he also heard that music when he returns to earth an hour later, but his look betrays that he had a good time. 'I soon realized that you can work well with such a DL420-7. You are very relaxed in it. You can barely hear the engine, the sound dampening has been taken care of, although I think you'll still hear it if something isn't right and it should be. Regarding the view, there is nothing to complain about, that glass to the floor is very nice.
You can set the CDC control to three different modes. I quickly put it on the fastest setting. It may sound a bit contradictory, but even then the machine does work very quietly and remains well manageable, while you can still get a lot of work done. Don't forget that we're talking about a 24-ton machine here, it's amazing how smoothly it moves! That flexibility can be felt under all circumstances; I rammed on over the road plates at full throttle, but nothing wrong, he behaved nicely.'
I've been pushing a lot in the sand mountain with a thick four cubic meters on it, but no trace of protest
Up to twelve LED work lights
According to our operator, the tire pressure of the Doosan is actually too high for the soil conditions in the sand pit. “Actually I would like to have less pressure on the tires for better traction, but that really only increased my respect for the machine. I've been pushing hard in the sand mountain with a thick four cubic meter box on it, but no sign of protest. And that with a tire pressure that is actually too high! The machine plays with the box. You lift it up at a sand car, empty the bin and put it back on the ground without a jolt. It is handy that you can preset both the height and the baking angle.
We walk around the machine one more time, which looks like a walk with this giant that is more than nine meters long and almost three meters wide. On the left and right, never-before-seen details stand out, such as the LED work lighting, with four lamps at the front and four at the rear as standard, which can be optionally extended to a total of twelve. And then there are all those beautifully constructed steps, handles and 'railings', which make climbing considerably easier.
As an expert and practical man, Jan Jacob gets the last word: 'I think it's a great machine, almost beyond my expectations. You can call it a big friendly giant, very flexible in operation and operation, but in the meantime also very strong!'