ANOTHER CHASSIS FOR THE SUBSIDY.
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A Description of the Salient Features of the New Karrier W.D.-type Chassis for Gross Loads of 21 Tons.
mllERE Is uo doubt that the modi
lied subsidy specification brought out some months ago by the War Department and reviewed in The Commercial Motor has proved most successful and has provided a range of chassis of various makes which will satisfactorily meet both the requirements of the War Department and those of private users.
An interesting addition to the growing list of manufacturers is Karrier Motors, Ltd. A particular feature of the chassis which they have developed is that it is suitable for carrying a gross load of 2i tons, or a net load of 2 tons when carrying bodywork weighing not more than 10 cwt.; moreover, it is claimed that it is the only model of this capacity which has yet been built to be eligible for the subsidy of £120.
It will be noted from the illustrations which we publish that the vehicle has not lost what may be termed its Karrier personality. It certainly looks a machine capable of doing most useful work at low running cost.
The power unit has an R.A.C. rating of 25.6 h.p. It is a four-cylinder monobloc of the L-headed type with the tappets enclosed by dust-tight covers. The bore is 4 ins, and the stroke 5 ins., and it develops 26.5 b.h.p. at 1,000 r.p.m. The bottom half of the crankcase can be removed without disturbing the main bearings, and an oil filter of large capticity is provided in the sump.
The lubricant is forced to the main bearings and crankpins by means of a „ear pump driven by skew gears from the camshaft. The pressure is controlled by a relief valve, and test plugs in the crankcase give the high and low oil levels. The oil pressure is indicated by a plunger, the lead to which is fitted directly to the crankcase, and an extension to the dashboard allows the driver to feel if the oil system be working. To assist in the timing of the engine the flywheel is clearly marked to a fixed pointer. Incidentally, the ignition is by b.-t. magneto.
Running in cold weather is assisted by the provision of hot-water jacketing for the inlet connection.
A centrifugal pump is employed to circulate the cooling water, but this is so arranged that if by tiny chance it fails, circulation will continue on the thermo-siphonie principle. Suitable provision is made for the complete draining of all parts and for cleaning the cylinder water jackets and passages.
Coil springs are utilized on the bolts by which the radiator is supported on the chassis, these obviating the risk of damage by distortion on rough ground. The filler cap opening has a diameter of 24 ins. The cap is hinged so that it cannot be lost. A stout bumper bar carried by brackets bolted to the frame side members acts as a protector. Coolink is assisted by a fan of large diameter driven by a link belt.
Power from the engine is conveyed through a clutch of the internal-cone type faced with Ferodo and affording ample wearing area.
Gear changing is assisted by the employment of a clutch stop, and special attention has been paid to the satisfactory lubrication of the clutch spigot and withdrawal collar.
Engine and gearbox are separately mounted on a single sub-frame, which Is carried at three points to avoid distortion. This' is of pressed steel, as is the frame, which is of deep channel section tapered slightly to front and rear, but otherwise straight. Substantial towing ,hooks are provided at each end.
Reverting to the gearbox, this has right-hand control which is independent of the frame, so that jamming cannot occur. The gearbox casing is of aluminium, and the oil filler, which projects under the off side of the frame, also indicates the maximum height of the oil. A convenience for new drivers is a diagram on the dash which shows the arrangement of the slots for the gate change.
The gearbox provides four speeds and a. reverse, direct drive being en top gear. With the vehicle mounted on 34-in. by 7-in. pneumatic tyres or 853 mm. by 90 mm. solids, the respective ratios are: Top, 7.00 to 1; • third, 11.55 to 1; second, 18.83 to 1; first, 35.4 to 1; reverse, 46.3 to 1, these giving
speeds of 14.4, 8.75, 5.38, 2.85 and 2.18 m.p.h. respectively.
From the gearbox the drive is carried through a tubular propeller shaft, with universal joints of the laminated fabric-disc type, to an overhead worm-driven axle, in which the whole of the gearing is carried by the top cover and is removable as a unit from the pot-type casing, which is made from a pet stamping with the pot formed in one with the side tubes, this making an extremely strong construction, which also obviates any chance of oil seepage. t'he ratio of the final drive is 7 to 1, and the maximum road clearance 10i ins.
Steering is effected through a gear of the worm-and-wheel type, capable of easy control under all conditions, and with all the parts thoroughly well protected from the effects of water, mud, sand, etc. Stops are provided to prevent the front-wheel tyres from fouling the chassis.
Braking has received careful consideration. The hand-brake shoes have Ferodo linings, which are •held in position by three T-headed bolts, and both this and the foot brake are capable
of stopping and holding the vehicle when fully laden on a gradient of 1 in 5, whether in the forward or reverse direction. All the wearing parts are of large dimensions.
It is interesting to note that the chassis lubrication throughout is on the Tecalemit pressure system.
The petrol tank, with a capacity of 16 gallons, is made of sheet brass and mounted on the dash, the feed being by gravity, an adequate supply to the engine is ensured on all gradients up to 1 in 31. There is a two-way cock, which enables 2i gallons of fuel to be retained for emergency purposes, and the supply cock to the carburetter is operable from outside the frame. A petrol gauge and easily accessible filter are provided.
The dimensions of the chassis are : Wheelbase, 11 ft. 9 ins.; track, 4 ft. 8 ins.; platform space (from the back of the driver's seat to the end of the chassis frame), 10 ft, 6 ins.; turning circle, 44 ft.