Larger Capacity: Same Weight
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Changes in Design of Daimler Lightweight Double-decker Chassis Enable Larger Body to be Fitted Without Increasing Total Unladen Weight of the Vehicle
THE Daimler lightweight doubledecker chassis, displayed at the 1952 Commercial Motor Show, was a good example of weight-saving
• toi., attention to frame design and the use ci suitable auxiliary equipment. With an M.C.W. 58-seat body its unladen weight was 6-} tons and it has been operated by the Potteries Motor Traction Co., Ltd.,. for 70,000 miles -at an average fuel-consumption rate of 12.5 m.p.g.
Although the latest version of the chassis is basically similar to the original model and has a comparable weight, it is designed to carry a 27-ft. 6-in. by 8-ft. bodyand is fitted with heavier brake equipment, an automatic chassis-lubrication system and larger tyres at the front. It represents a further notable saving in weight, and the chassis is also of interest on account ot other changes in the equipment.
Powered by a Gardner 61-W engine, v.hich is inter-changeable with a 5LW unit, the bare chassis weighs 4i tons, The hydraulic brake equipment fitted to the prototype has been replaced by the triple-vacuum-servo type produced by the Clayton Dewandre Co., Ltd., and a 24-point pedal-operated chassis lubricator, supplied by the same company, is included in the standard specification. The 9.00-in. by 20-in. tyres, which were originally fitted at both front and rear, have been replaced at the front by 12-ply covers of 11.00 in. by 20 in. to accommodate the extra loading with a larger body flendix Westinghouse air pressure braking equipment of Clayton Dewandre manufacture will later be available. This is of the diaphragm type and has a weight equal to that of the triple-servo equipment.
It is fitted to a demonstration chassis on which is mounted a 61-seat body by the Northern Counties Motor and Engineering Co., Ltd., who are also ploducing a 65-seater for Walsall Transport Department. This will be equipped with the standard triple-servo brakes, a Twiflex centrifugal clutch (an optional extra) and a Gardner 5LW engine.
Frame Design Changed
The main modifications to the frame include fitting flitch plates to the side members between the inner spring hangers, instead of " boxing " the channel sections, and of local boxing in line with the front cross-members and the bump pads of the front springs.
Reinforcing brackets are now mounted on the off side and include pedal supports which enable the original cast-steel brackets to be dispensed with, This form of modification is reversed in stiffening the rear of the chassis, where the side members are boxed locally at the tops of the wheel arches, instead of having flitch plates of more than double the length. The total saving on frame weight is 153 lb.
Other weight-saving measures include the use of a modified radiator core, a reduction in the diameter of the brake drums from 16/ in. to 16 in., the use ' of Dunlop lightweight wheels at the rear and the replacement of the 35-gallon fuel tank by one of 30 gallons, having a plain filler neck and hinged flap of Daimler design.
The radiator core is of the Coventry Radiator iator three row
gilled-tube type, with which air-flow experiments were performed -on the Motor industry Research Association's test track. As a result it was found that a number of tubes in the rear row on the outer sides could be removed without reducing cooling efficiency, and this saved 30 lb.
The smaller brake drums are more rigid than the former type and facilitate cooling The arc length of the facing has been increased to provide the same total area and adjustable stops are fitted to the forward camshaft levers to ensure a correct setting.
A cold-air intake in the body canopy was an interesting feature of the original lightweight vehicle, but it complicated the work of the bodybuilder. The intake of the latest chassis has been located under rearward-facing louvres on the upper surface of the bonnet and is connected to the inlet manifold by a flexible pipe.
An AC-Delco oil-bath filter can be fitted (to be supplied from the cold-air intake). An interesting feature is a head with one manifold and three inlet ports developed by the engine manufacturers. Hose connections can be made to any one of the three ports (the remaining two inlets are blanked off) and this allows valuable latitude in placing the cleaner and intake extension.
The Twiflex clutch was developed by Compression Ignition, Ltd., Twickenham, in conjunction with the Daimler company and can be supplied to users requiring a positive drive. Judged by tests over a distance of 20,000 miles. the friction material should not need to be renewed for 80,000-100,000 miles.
Six shoes with friction facings arc linked to a hub member by arms with Metalastik pre-loaded rubber bushes. which retain the shoes in the inner position until an increase in speed above idling causes them to move outwards under centrifugal force and contact an inner drum of the flywheel. A guide projection on each shoe ensures true radial movement and a smooth take-up. The clutch can be fitted, if required, with a locking device in the hub which enables the vehicle to be towed for starting.