DEMONSTRATING ANOTHER KEGRESSE VEHICLE.
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Interesting Tests Carried Out Near Farnborough on the
were ascending an indescribably rough car track, V V with a gradient of 1 in 3, when the driver said casually: "Coming along here yesterday the track was completely blocked by some large tree-trunks." After glancing at the rough country to each side of the " roml," our representative not unnaturally asked : "What did you do then?" " Oh!" said the driver, quite as a matter of course: "we took to the country and went round them."
It is just this ability to go anywhere which marks the great advantage of the track-laying type of vehicle, and the Burford-Kegresse 2-tonner, which was the chassis in question, is certainly an admirable example of this class. Incidentally, it is capable of carrying a higher load than most chassis fitted with the Kegresse track.
Considerable interest is being evinced in this type of transport by companies exploiting estates in the Colonies, one of the principal reasons being that suitable ground for development can often be obtained very cheaply owing to its considerable distance from the nearest railhead, whilst a fleet of track-laying vehicles can then be used to transport the products to the railway without going to the expense of making a road. Indeed, it is a feature of any Kegresse vehicle that, in course of time, it actually improves the surface over which it runs, instead of churning it into ruts, which would be the effeet of the ordinary lorry running upon wheels.
Reverting to the demonstration of the capabilities of the Burford-Kegresse chassis, this was carried out over part of a 40-mile route which has been chosen for testing purposes in the country near to Farnborough and Bagshot. The chassis in question has been covering the 40 miles every clay for the past few weeks in the course of tests which are
being rim by the Empire Cotton Growing Corporation. The ten miles which we covered embraced many hilt with gradients ranging between 1 in 6 and 1 in 3, the route followed was the merest cart track abounding in ruts and with a surface consisting of loose stones, whilsthere and there in the bottoms of the valleys there was sand to a depth of 10 ins. or 12 ins. Not once in the course' of the run was the vehicle anywhere near to being baulked by any of these obstacles.
On the level it proved capable of 25 mph;, whilst up the steepest hill—a slope of 1. in 3—the climb vv-aS con:tinned slowly but surely without resorting to the lower back-axle ratio. The load carried, incidentally, was slightly more than 2 tons and the tare weight is nearly 3 tons.
The gear ratios require a word of explanation. There is the usual four-forward-speed box behind the engine, but, in addition, there are two alternative sets of gears in the back axle. It is not advisable to change the back-axle gear ratio when the vehicle is in motion, so that in the ordinary way it is driven using the four speeds only. When exceptionally difficult ground is encountered, however, the vehicle can be stopped and the lower axle ratio engaged by moving a lever placed to the left of the driver.' This lower ratio was never called for in the course. of the demonstration which we witnessed.
When descending steep slopes it proved usually S'ufficient to keep the second or third speed engaged and to allow the engine to do the braking ; • hut, should occasiont arise, there is a powerful transmission brake and, in addition, a pair of large internabeXnanding brakes on the rear driving wheela. of the Kegresse attachment. It proved quite easy to held the vehicle on 1 in 3 with the hand brake only.
Another test consisted of stopping the chassis when resting on very loose sand and then getting away again uphill. This was successfully done with the second gear engaged, and it was notable that the driving bands did not sink into the sand to any appreciable extent.
As regards steering we did not have an opportunity of testing the effort required, but the driver appeared to have no difficulty in manceuvring an soft ground. Steering is, of course, accomplished by the use of normal mechanism operating the front wheels, the latter being shod with pneumatic tyres. The front axle actually carries about 30 pUr cent, of the total weight. We understand, however, that to improve steering control when running on exceptionally loose sand it is the intention to provide a method of differentiating the braking effort on the driving bands so that one or other can be retarded when a sharp turn is desired.
The test in question did not exhaust the possibilities of the chassis by any raeans. PAT example, we are told that, using the emergency geats, a gradient of A in 2 can be climbed, and also that, in addition to the normal load, trailers earrying, 8 tons Can be hauled quite easily.
The chassis does not call for a very detailed description, as in general lines it is the well-known Burford 2-tanner. The only differences are found td the rem% of the gearbox. Thus, the power -unit is the normal four-cylindered job with a bore and stroke of 100 mm. and 140 mm. respectively, which develops 28 h.p. at 1,000 r.p.m. It is constructed in unit form, with a multiple-plate clutch and a four-forward-speed gearbox, the former, incidentally, working admirably and with great smoothness under the trying conditions of the test. The power unit is so compact that the driver can easily be mounted above and to the right of it, giving a forward dash and ample body space.
The back axle, in the ordinary sense of the term, Is discarded, the Keg,resse driving gear being pivot-mounted upon two substantial brackets secured to the side-members of the frame, reinforcement being provided at this point by two pressed-steel cross-members. The propeller shaft terminates in a universal joint just in front of the transmission casing, which contains a two-speed sliding gear, the bevel gear, differential and cross-shafts. The differential can be locked by the driver should one of the driving bands run on extremely soft ground. The cross-shafts drive the back wheels of the track unit through spur pinions and internal-toothed rings. A feature of these wheels is that they are arranged automatically to grip the 17 section of the belt more and more tightly as the tractive effort required increases. Each belt of the driving band runs • round its driving wheel, and also round an idler wheel.
The whole weight of the rear part of the vehicle is transmitted to the portion of the driving bands in contact with the road by means of four pairs of aluminium pulleys at each gide. These are sprung in such a way that the driving band can always conform to road or ground irregularities. The area of the bands in contact with the ground is so great that pressure is reduced to about 8 lb. per sq. in., and yet the grip is such that the bands do not commence to skid until the tractive effort amounts to 78 per cent, of the weight of the vehicle. The driving band is made up of rubber and canvas in somewhat similar manner to a tyre, and can be readily replaced on the road, should breakage occur, in a matter of about 20 mine. Replacement involves jacking up one side, unscrewing the tensioning adjustment which locates the forward idler wheel and then removing the belt. The driving bands have given very goad service so far, but, of course, are subjected to extremely rough treatment when passing over bard, flinty tracks. We understand that the cost of a replacement would be about 00 per band, but this, of course, would probably not be called for until several thousand miles had been covered.
TO sum up, the Burford-Kegresse is a thoroughly good commercial proposition for haulage in undeveloped countries, being capable of transporting considerable loads where roads are entirely absent. The address of, the manufacturers is II. G. Burford and Co., Ltd., 24, Haymarket, London, &W.1.
During the latter part of the test run the BurfordKegresse was followed by a 1-ton Morris-Roadless-Traction lorry which happenei to be on the route at the time. This appeared to consist of a standard Morris 1-ton chassis with the back axle and rear wheels replaced by one of the " Roadless-Traction " Co.'s all-metal creeper-tracks. We could not ascertain whether the Morris was loaded, but it appeared to be tackling the test route in an excellent fashion.