A30-CWT. VEHICLE TO HAUL 8 TONS.
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Details of a Powerful New Crossley-Kegresse Track-laying Machine which can Climb Gradients up to 1 in 2.
A FEW weeks ago we were able to give our readers a description of the 15 h.p. Crossley-Kegresse vehicle. During a visit which we paid a few days ago to the works of •the company at Gorton, Manchester, we were able to obtain details of a larger and much more powerful vehicle of the same type. This is a 30-cwt. model and has a fourcylinder engine of 4-in, bore and 51-in. stroke, which develops 30 b.h.p. at 1,000 r.p.m. Apart from this, it embodies a number of very interesting features, including Perrot-Bendii three-shoe servo brakes for the front wheels, these being made by the Crossley Co.. under licence. Both the front and the rear-wheel brakes have cast-aluminium shoes, which are not only light, but assist in radiating the heat.
The maximum load which can be carried is two tons, despite its classification as a 30-cwt. model. With the vehicle loaded it will, in 'addition to the weight carried, haul a load of from six tons to eight tons in normal eireunaStances. Thus it is eminently suitable for hauling guns and for other work where a powerful drawbar pull is required. Some of our illustrations show the machine during its recent tests by
the War Department at Farnborough. In this case it took guns up and down gradients of 1 in 4, stopping and restarting on the slope.
One feature which makes it particularly valuable for such heavy work is that, when required, a powerful winch may be fitted. This winch is mounted on the axle of the Kegresse tracks. It is driven from the front end of the layshaft of the gearbox via a Renold chain and long shaft to a pair of worm gears, fabric universal joints being employed for the drive shaft. At the other side of the winch drum is a worm gear operating the laying-on gear for the cable. Hauling can be conducted from the front or rear. In one illustration it is shown functioning in the 'latter way.
To facilitate manceuvring, the hand brake gear—which operates brakes on the tracks—is so arranged that either brake can be locked and steering then performed by the -other. ' This is effected in a simple manner by the employment of a single rocking lever in place of the ordinary brake lever. Normally, this lever is kept centred by springs and it is merely necessary to pull it straight back to annlv the brakes to both tracks. If, however, it be moved to one side and then pulled back it puts on only the brake for that particular side. There is also a transmission broke behind the gearbox and this is applied, together with the front-wheel brakes, by foot.
The usual type of auxiliary two-speed gear is employed in the track drive and embodied with this gear is a lock for the differential, the speeds and this lock being controlled by a single lever. The arrangement, in conjunction with the gearbox proper, gives eight speeds forward and two in reverse.
As this vehicle may be called upon to climb gradients of up to 1 in 2, the engine lubrication is on the dry sump principle, as this avoids heaping of the oil to one end when the vehicle ie at a steep angle, as, if this were permitted, the big-ends would dip deeply and throw an excessive amount of lubricant into the cylinders. Incidentally, the whole of the working parts are lubricated by oil, even including the steering joints and the spring pins.
Two all pumps are used in the engine, one to keep the sump empty, whilst the other lifts oil from the reservoir (which is below the crankcase and forms part of the sump, but is connected to it only through the pumps) and sends it through the drilled crankshaft. The pump which empties the sump has an output 50 per cent, greater than that
ensuring the feed : a neat feature is that the filter can be taken out from above without draining the oil.
Flang:. mounting is employed for the dynamo, which is driven by an enclosed Renold chain from the front end of the cranksqaft. The last named has five main bearings. The cylinders are Lheaded with the valves enclosed and at the near side, the heads being detachable. Pistons and connecting rods can, if necessary, be withdrawn from below.
i Carburation s attended to by an instrument of the Zenith vertical type supplied from a 15-gallon tank fixed on the dash. Apart front the petrol tank just mentioned there is an auxiliary tank under the driver's seat, and the dash tank is replenished from this by a hand pump when necessary.
The engine and gearbox are mounted separately on a sub-frame which is so secured that it forms two three-pointsuspended sections, this being achieved by pivoting the sub-frame at the centre of each side and at the centre of each end. To avoid the possibility of binding, the change-speed .tontrol is mounted direct on the box. For a similar reason all track cross-shafts are carried in ball trunnion brackets.
The drive between engine and gearbox is taken through a fabric-faced cone clutch of the internal type, with a spring-loaded clutch stop to facilitate gear changing. Hardy joints are also employed for the propeller shaft.
In the steering gear a complete worm wheel is employed, adjustment is provided by an eccentric bush, also by moving the worm Wheel to'a fresh position when worn. An unusual feature is the provision of a link motion between the steering arm proper and the steering box. Although difficult to understand why, it has been proved in practice that this greatly diminishes the transmission cf road shocks to the steering wheel, and, incidentally, the weight of the steering column can very easily be adjusted, whilst the ratio of the gear can conveniently be varied by altering the lengths of the link levers.
The track-laying equipment is of the latest type, in which the wheels carrying and driving the track are lifted clear of the ground and the weight of the rear part of the vehicle is carried at each side by eight small wheels running on the inside of the track. At the back of the chassis and mounted upon a laminated spring the full width of the frame, is an exceptionally strong towing hook. The frame itself is made of high tensile steel, the side members being of channel section with five cross-members additionally strengthened at the rear by channelsteel ties which bridge the corners between the last and penultimate crossmembers.
The frame is very wide and the road springs are carried beneath the sidemembers to prevent torsional stresses. An exceptionally large radiator is used. This is mounted on two ball-and-socket joints held in place by spiral springs, which, allow a small amount of movement and thus assist in the prevention of shocks.
There are some further details in the engine and general design which may prove of interest.
Separate header and bottom tanks connected by f,-in. internal-diameter gilled tubes are employed for the radiator, which is supported on large balland-socket joints. Water is circulated through this and the jackets by a centrifugal pump.
To permit access to the engine bigends without removing, the whole unit the sump is made. detachable. Apart from the h.-t. magneto, provision is made for the addition of distributor ignition if required. A Renold chain with a means of adjustment is provided for the timing gear.
The main gearbox affords four speeds and a reverse, the respective ratios being: top, direct ; third, 1.884.1; second, 3.291i.; first, 5.4471; reverse, 4.339.1. The Kegresse-track rear axle replaceo the usual standard wormdriven axle, and its special gearbox, which affords two speeds, gives on high gear a total reduction of 727 to 1 and on the low gear 34.43 to 1. The totals of each with the first gear of the main box in use are 39.50 to 1 and 157.54 to 1.