RIPPING EXTREME

David Wylie reports on the first 9000 hours put on Europe’s largest dozer

Last month we covered the undercarriage overhaul of a 115-tonne dozer working for Fife Silica Sands, marking its 9000-hour anniversary in this extremely arduous application. This month, we review how this up-armoured Komatsu D475A-5, currently the largest dozer working in Europe, has fared since it was commissioned at the Burrowine Moor Quarry at the end of 2017.

Background

Over the years, the management team of this silica sand quarry has tried different extraction methods for the highly abrasive material. None has performed as well as a large dozer, as its sheer weight, ripper action and deep grouser tracks also act to primary crush the material. A Komatsu D375A was successfully used for six years. Fitted with an over-sized ripper from its bigger brother, it weighed close to 80 tonnes.

In the May 2016 issue of Earthmovers, we reported on its replacement, a new 70-tonne class Cat D10T2 dozer. Unfortunately, within six months of the Cat’s arrival, the team hit an extremely hard band of material, which no normal dozer could be expected to cope with. A 100-tonne Cat D11R, one of only two examples in the UK, was hired in for a year to keep production going, while the team searched for a suitable machine of their own.

With experience of these unique site conditions gained while supporting the

Below and inset: The 900hp Komatsu D475A-5 dozer is 4.65m tall and 11.5m long, and this up-armoured version weighs 115 tonnes.

D375A, UK dealer Marubeni-Komatsu recommended a somewhat extreme solution, the 900hp D475A-5 model, up-armoured to cope with the abrasive material. It was available with a comprehensive 12,000-hour/five-year warranty and service support package. Up front there is a 3m-high semi-U blade offering a capacity of 27.4cu.m. This attachment now weighs 20 tonnes, thanks to the armour package designed and fitted by Marubeni-Komatsu. Together with other bespoke wear protection, this ultra-class dozer tips the scales at 115 tonnes.

Ripping Performance

Key to this application is the big dozer’s ability to generate 853kN of pry-out ripping forces, applied to the tough silica sandstone through its rear single-shank ripper attachment, which provides a maximum working depth of 1774mm.

At the time of our visit the D475A-5 was working in a section known as A-bed, which contains a low iron content material. The Komatsu was providing consistent and good ripping performance. The expectation was that its ripper tip may last as long as a week in this material.

However, there are other areas of the quarry where there are much harder materials and where a ripper tip lasts only a day or so. Ripper shank shrouds play a vital part in the attachment’s performance. This dozer uses the Apex shark-fin shroud, which helps it cut into the rock and extend the life of the shank face of the ripper.

Quarry manager Martin Lyle said, “The machine started out with a small number of teething troubles, as it settled into the