Four-wheel-drive 3-tonner Proves Its Worth in the Field
Page 32
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Details of a Karrier Special-purpose Military Vehicle Equipped with Poweroperated Winch having a 44-ton Pull
AS the war progresses we are able, from time to time, to publish Atails of transport equipment specially built to meet the exacting needs of military requirements, and by such releases we are the more able to assess the splendid efforts which are being put forward by vehicle manufacturers in this country.
The accompanying illustrations show a special vehicle, supplied in large numbers to the War Department, for the transport of loads up to 3 tons, a loading which, with special equipment, comes out at nearer 31 tons.
Known as the Karrier K6, it is. the product of Karrier Motors, Ltd., Luton, the armoured car of which was dealt with in our issue dated July 16 last. The present machine is shown equipped with a power-driven vertically disposed winch, having a maximum pull of about 41 "tons, with a• specified breaking strain of about 14 tons.
As shown in one of the pictures, this winch is disposed just forward of the rear axle, the drive from the transfer case being by worm and worm wheel, with controls taken forward to the driver's. cab. Included in the power take-off unit is a Bendix non-servotype brake, and an automatic payingon device, together with a tooth lock controlled by a cam on the drum. With the engine turning over at 1,000 r.p.m., the speed Of the cable, when winching, is about 78 it. per min.
As to the general specification of the chassis, the engine is a six-cylindered side-valve unit, having a bore and stroke of 85 mm. and 120 mm. respectively; it develops 80 b.h.p. It gives a torque of 178 lb. ft., and its governed spied is 3,200 r.p.m.
From the engine the drive is taken by a 12-in.-diameter, single, dry-plate clutch to a four-speed gearbox having dog-operated top and third gears, with first, second and reverse gears. of the sliding-pinion type. A Layrub-jointed "shaft takes the drive to the two-speed transfer case,. from -which the fully floating front and rea'r axles are driven through Hardy Spicer shafts provided With needle-roller universal joints. Tracta constant-velocity universal joints are used on the front axle and, through them, both the driving torque and the steering are carried out. Provision is made for declutching the front axle from the drive on such occasions as when the vehicle is being driven on normal roads.
Brake drums of 16-in, diameter on all wheels accommodate 3o4n.-wide shoes, a pedal controlling hydraulically operated brakes on all four wheels, and a leverthe mechanical brakes on 'only the rear wheels. Trunnion-ended semi-elliptic springs, having rebound
plates and rubber snubbers, form the suspen4en system, and the divided type steel wheels are equipped with 10.50-M. by 20-in. cross-country, lowpressure tyres.
Equipment on this interesting vehicle includes a spring drawbar, tow ing loop at the front end, and a spare wheel accommodated ori a special carrier arranged immediately behind the driver's cab. Three-point, flexibly mounted, the latter is of all-metal construction, and gives a forward-control position.
With a fuel-tank capacity of 30 gallons, the radius of operation over reasonable roads is about 270 miles.
Fitted with the shorter of the two bodies and with tubular hoops and can vas sheet the approximate laden weight of the Karrier K6 is 7 tons, and in low first gear it has a. tractive effort
equal to 60 per cent, of its. gross weight. It will climb an earth grade of about .1 in 21, and has a maximum speed of 43 m.p.h.
Its powers of acceleration are such that, in top gear, it takes but 27 secs.
to reach 30 m.p.h. from 10 m.p.h.
Braking efficiency ma'y be judged from the fact that the foot brake, which operates on all wheels, will stop the vehicle from 20 m.p.h. in 19 ft., and the hand brake, which takes effect on only the 'rear wheels, gives a figure of 36 ft, from the same road speed.
Numbers of these vehicles have acquitted themselves well in the operations now concluded in North Africa, which campaign, as is well known, proved an exacting testing ground for all forms of meclaanized transport.