Tracklayers Move the Earth
Page 49
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iE capabilities of the David Brown Crackmasier four-cylindered oilned industrial crawler tractor were lively demonstrated last week when, s site near Leeds, examples of these hines were shown working in contion with Blaw Knox earth-moving. potent.
most of its dimensions this new vler tractor is similar to the foursdered vaporizing-oil or petrolned Trackmaster which has been in for some time in agriculture. It a drawbar pull ranging from 0 lb. in high third gear to 7,500 lb. sw first gear.
rawbar horse-power at 1,600 r.p.m. 1.6, and belt horse-power at the e speed is 25. A three-speed gear. with ausiliary two-speed box gives six forward ratios and two in reverse, the speed range at an engine speed of 1,600 r.p.m. being from 1.06 m.p.h. in low first to 5.72, m.p.h. in high third; in low reverse and high reverse the respective speeds are 1.27 m.p.h. and 2.62 m.p.h. The power take-off, which is integral with the rear axle, gives four speeds ranging from 468 r.p.m. to 1,800 r.p.m. with the engine running at 1,600 r.p.m.
This machine is the most recent track-laying mcidel to be manufactured by David Brown Tractors, Ltd., and incorporates the David Brown fourcylindered direct-injection oil unit, with 12-volt electric starting. The company's Duotrack steering, by geared differential, is incorporated, giving a positive power drive to both tracks.
the power being distributed according to the direction of turn.
Although the Trackmaster is a postwar development, in earlier days the company produced a prototype which evolved into the wartime DB2 industrial tracklayer, many of which were built under contract for the Government, At the same time the works were producing Churchill Tank transmission units embodying a similar principle of epicyclic gears to that employed in the Trackmaster to-day.
A New " Six "
A second David Brown machine made its debut last week in the form of a prototype six-cylindered crawler, which also gave a convincing exhibition of ability to operate under difficult conditions. The four-cylindered machines were seen working with various Blaw Knox equipment, being shown backfilling excavations, side-filling excavations, grading and trench dozing.
The six-cylindered prototype worked with a Blaw Knox scraper and demonstrated loading and dumping; its marked degree of manceuvrability at high digging and travelling speeds was particularly noted.
The Trackmaster four-cylindered oilengined tractor has a shipping weight of 7,400 lb., is 9 ft. 5 ins, long overall,
4 ft. 7 ins., wide and 4 ft. 8 ins. high (excluding exhaust and air-cleaner intake). Standard-track shoe width is 10 ins, and track-base measurement is
5 ft. with a ground contact area of 8.35 sq. ft. Ground clearance is 11 ins, and the drawbar is 1 ft. 1 in. above ground level. The engine unit has a 31-in, bore and 4-in. stroke, 'giving a piston displacement of 165 cubic ins.