Even in the flesh it looks like a compact machine with its short, steeply sloping “snout”, while inside the cab the view of the blade is unrivalled for a machine of this size. The stack is neatly hidden by a cab pillar, so other than the two cab pillars only the air intake (low down) intrudes into the view of the blade.It’s only when you look at how much dirt the machine moves that its size becomes apparent. At the end of the day, that’s what counts with a bulldozer.Komatsu has achieved two recent landmarks in bulldozer evolution: this dozer and the earlier D155AX-6 dozer with the Sigma blade. This revolutionary blade efficiently rolls the material from the blade’s unique centre edge. The Sigma blade has since moved up the line and is now offered on the larger D275 as an option.But back to the D51, where emphasis has been added to other areas as well. The D51 is Komatsu’s first truly international dozer. It commenced development in 2002 at Komatsu’s Chatanooga facility in the US and involved significant input from Brazil, Europe and Japan in arriving at the product that has entered the market as the D51EX-22. Ease of use is one of the main attributes of the dozer, as illustrated by the set forward position of the cab, which provides the operator with a clear view of the sides and top of the blade.The biggest obstacle to forward vision is the space taken up by a front-mounted radiator, so Komatsu moved the radiator behind the cab, where the air is cleaner and the radiator is readily accessible (the fan swings up with the grille to give access to the cooling cores). Mind you, there shouldn’t be a lot of need to access the cores because the hydraulic drive fan reverses to clear them.The front grille swings away to give access to the respective service points, and there is standing room inside the massive cast push frame so that the fitter doesn’t have to be a contortionist.Getting into the dozer itself is equally easy: there’s a step on the side of the push frame and grab rails on the top of the bonnet, and with the cab forward it’s a short walk with three-point contact all the way from ground level to the step under the cab door.But a lot of what a dozer is about comes down to the blade and the transmission. The hydrostatic transmission control allows smooth delivery of power to the tracks and full power turns, including counter-rotation for tight environments. Speed control has two modes: variable speed and quick shift (three gears), with both using up/down buttons on the steering joystick. The hydrostatic transmission also adjusts travel speed automatically according to load or ground conditions. The power angle tilt blade has a large centre ball joint design that facilitates a wide range of blade movement via Komatsu’s proportional pressure control joystick.Two undercarriages are offered so that the buyer can choose the most appropriate for the ground conditions that will be encountered. The EX has narrowed shoes and suits hard ground applications, while the PX has wide shoes for soft conditions.A look over the D51 suggests that the dozer is designed to be as bullet-proof as possible: solid hull chassis, massive push bar, well-protected hydraulic hoses, plate steel nose, good air and fuel filtration, and so on.Some of the standard Komatsu niceties, such as being set up to take a Topcon machine control system, having onboard diagnostics and offering the KOMTRAX remote machine monitoring system, form part of a very complete dozer package.If the real test is market acceptance, then comments from local representatives – that the market for the dozer is larger than they anticipated and market share in this class of machine has improved – would seem to answer that question. The D51EX-22 is the first in a range of four dozers that will follow the same design philosophy and line up roughly against the D3, D4 and D5.This new range is a genuine leap forward in dozer design, and it sounds like the market agrees.
