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New Chassis and Engines from Thornycroft
Page 122
Page 123
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ACOMPLETELY new heavy-duty tipper chassis and two new power units will be featured by Transport Vehicles (Thornycroft), Ltd., at the Commercial Motor Show. Other exhibits will include two examples from the Trusty range, two Mastiff vehicles and an Antar-Sandmaster left-hand-drive oilfields chassis.
The new tipper chassis is a 4 x 4 design rated for a maximum gross weight of 20 tons. The wheelbase is only 10 ft., giving a turning circle of 49 ft., and the power unit is one 'of the new Thornycroft engines—
the Q6 150 b.h.p. engine.
Welding is employed extensively in the construction of the chassis frame and the side members are 15-in. by 4-in, rolled-steel channels. The 1-section cross-members are horizontally gusseted to the side members, with the leading cross-member bolted in position to facilitate engine removal.
The Q6 engine has a Borg and Beck 16-in.-diameter single-dry-plate clutch with mechanical actuation, and the gearbox is mounted separately from the power unit. Offering five forward speeds with constant-mesh engagement, the gearbox has a disengagement drive to the front axle, avoiding the need for a separate transfer box as found on large chassis with a driven front axle. Ratios are 7.759, 5.122, 3.047, 1.746 and 1 to 1, whilst the reverse gear is 7.66 to I.
Despite the incorporation of the frontwheel-drive engagement and main gearing in one unit, the new gearbox is not bulky and is a notable design achievement. Engagement of front-wheel drive is by air pressure, and a warning light in the cab indicates to the driver when the front axle is being driven,
29 m.p.h. on Standard Tyres
Hardy-Spicer propeller shafts are interposed between the engine and the gearbox, and the gearbox and the two axles. The rear axle is a heavy-duty doublereduction unit with an overall reduction ratio of 11.49 to 1, giving a maximum speed of 29 m.p.h. on standard tyre equipment. The primary reduction gearing in the axle is by spiral-bevel gears with a ratio of 3.9 to 1, whilst the secondary epicyclie reduction gears are in the hubs and have a ratio of 2.9471 to 1.
The driven front axle is also A doublereduction unit with a similar gear layout. The steering hubs are carried on taperroller bearings and the drive shafts have double universal joints to give constantvelocity characteristics. As an alternative to the driven front axle, a nondriven unit with an I-section beam can he supplied.
Semi elliptic springs are used on both axles, with helper springs at the ;ear axle and telescopic dampers at the front. The spring . hanger brackets are robust fabrications bolted directly to the side-members. eh romi umplated spring Pins arc employed in all cases.
The Mules cam and double roller steering is hydraulically assisted and the power cylinder incorporates the regulation valves so that the complete assembly forms a single unit in the drag-link layout.
Air-pressure operation of the brakes is standard, and a separate hand control valve on the steering column permits all four brakes to be locked on. The 17-in.diameter front brakes have 4-in.-wide linings, whilst the 19-in.-diameter rear brakes have 7-in-wide linings. The multi-pull hand brake actuates the rearaxle brakes only.
Twin rear wheels are specified as standard equipment and all six wheels are 8.37-24-in, equipment with four-piece rims. On these may he fitted 12.00-24-in. (16-ply) or 13.00-24-in. (18-ply) tyres, whilst, as an alternative, 18.00-25-in. equipment on single rear wheels can be supplied.
The new chassis has forward control and is laid out for use with a one-man half cab. This gives good engine accessibility and permits the paper-element air cleaner and vertical exhaust system to be mounted on top of the engine cowling alongside the cab. • Equipment supplied with the chassis includes robust guards for the radiator and sump, front and rear towing jaws and a 50-gallon fuel tank carried transversely on the top of the chassis frame behind the cab and engine.
The new dumper is nominally rated as a 10-13-ton unit, the exact payload which may be carried varying according to the specification and tyre equipment chosen. The bare chassis weight is approximately tons, and the vehicle has an overall length of 16 ft. 81 in., with an overall width over the rear tyres of 9 ft. N in. The ground clearance under the rear differential pot is 1 ft. 2 in.
Optional equipment which can be supplied with the tipper includes a power take-off on the side of the gearbox, solid mountings for the rear axle, and a cyclone-type air-filter pre-filter. A direct power take-off capable of transmitting full engine power is a standard fitting on the top of the gearbox casing.
The new Q6 engine is specified for the 10-13-ton tipper and it is a derivation of the QR6, which has been the standard power unit in Trusty maximum-capacity four-, sixand eight-wheelers for several years.
Like the QR6, the Q6 has a capacity of 9.83 litres and is similar to the original unit, except in output figures. Whereas the QR6 has a traction rating of 130 b.h.p. at 2,000 r.p.m., the Q6 can develop 170 b.h.p. at 2,200 r.p.m., with a recommended traction rating of 150 b.h.p. Similarly, the net torque output of 450 lb.-ft.„ at 1,200 r.p.m.; is 20 lb.-ft. 'higher than that of the Q13.6 at the same speed.
This additional power has been obtained by employing new cylinder heads with improved air-intake flow, different'exhaust-valve materials and modified fuV injectors, , The exhaustvalves, haveEN.54 heads and EN.18 stenis, which are welded together, whilst the QR6 has EN.52 one-piece valves. Stellited valve seats are used.
The Q6 engine is to be shown as a separate exhibit and it will also be the power unit of the Trusty 18-ft 4-in.wheelbase eight-wheeled chassis, to be displayed on the Thornycroft stand.
Same Power Output
The third new power unit is a derivation of the KRN6/S and is known as the K6/S. These two engines have the same power output, the common traction rating being 200 b.h.p. at 1,900 r.p.m. with a peak torque output of 625 lb.-ft. at 1,000 r.p.m.
The most important difference between the two designs is that chain drives have been replaced by a helical timing-gear train. This in turn has necessitated the use of a new cylinder block and crankshaft, the former being more rigid than that of the earlier KRN6/S unit. At the same time, the vibration damper is mounted at the front of the crankshaft external to the timing case, whereas before it was inside the timing case. A full-output power take-off can be fitted at the front end of the crankshaft The K6S is a turbocharged unit, like the KRN6/S, and will be the subject of a separate display at the Show.
A new version of the KRN6 naturally aspirated engine has been developed. This K6 engine produces 162 b.h.p. and 520 lb.-ft. torque, compared with 155 b.h.p. and 508 lb.-ft. torque.
The largest exhibit on the Thornycroft stand will be the Antar-Sandmaster 6 x 4 oilfields tractor. This vehicle is powered by a Rolls-Royce C6.TFL turbocharged six-cylindered oil engine with a gross power output of 300 b.h.p. and a maximum torque rating of 850 lb.-ft.
The transmission consists of a 20-in, diameter Fluid-Friction coupling with an R.V.30 eight-speed air-actuated semiautomatic epicyclic gearbox. Both units are made by Self-Changing Gears, Ltd. This particular exhibit has a wide-base rear bogie to permit the use of single 21.00-25 in. (914-ply) tyres, the tubeless equipment being of Atlas manufacture.
The Antar-Sandmaster is suitable for a gross train weight of 78 tons in conjunction with a semi-trailer, and the exhibit has been built for operation by the Esso Petroleum Co., Ltd., in Libya. Because of the distances likely to be covered between refuelling facilities, a 900-gallon fuel tank is fitted, whilst the front bumper incorporates a 16-gallon water
speed.
tank. Power-assisted steering is employed, Of the two Mastiff exhibits. one is a 17-ft. 101-in.-wheelbase six-wheeler on which is mounted a 24-ft. light-alloy body. This chassis has a QR6 engine, as has the Mastiff four-wheeled tractive unit, which is to be shown with a Task ers lifth-wheel coupling.
One of the Trusty exhibits is an eightwheeler with the new Q6 engine, whilst the other is a left-hand-drive normalcontrol six-wheeler, built for export. It has a gross solo weight of 22 tons. This exhibit has a QR6 engine and is equipped with an eight-speed transmission and 16.00.-20-in. sand tyres.
The remaining exhibit on frit Thornycroft stand is a three-speed transfer gearbox, as fitted to Big Ben 6 x 6 heavyduty chassis. This unit provides ratios of 2.52, 1.33 and 0.84 to 1, with an independent control for engagement of frontwheel drive. It will be shown with a full-output power take-off, rated for 134 b.h.p. at 2,300 r.p.m. input speed.