A NEW SIX-CYLINDER WHITE CHASSIS.
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Produced by a Prominent American Manufacturer for Luxury Coach Work, the New Chassis has a Six-cylindered Engine of Advanced Design.
INFORMATION has " now reached us from the Director of Engineering of the White Co., of Cleveland, Ohio, concerning the White six-cylinder motor coach equipped with the . new 1A1 engine, the illustrations available covering the engine, clutch, and the mounting of the front and rear wheels on their axles.
In the design of the engine, particular attention has been paid to the development of a high-powered unitwith freedom from detonation or ignition hammer, together with reliability and economy in the consumption of fuel.
The engine is monobIoc in construction, consisting of head, cylinder block, upper half of the crankcase and sump, the bore of the cylinders being 0 ins, and the piston stroke 51 ins., so that the total piston displacement is 519 cubic ins.
The crankshaft is carried in seven bearings, and is of large diameter with heavy crank webs, whilst every bearing point in the upper half of the crankcase is thoroughly well ribbed to ensure the maximum rigidity. The detachable cylinder head carries the intake and exhaust valves in single line, the valves being operated through the medium of push rods and overhead rockers, with a special form of pivoted cam follower which reduces wear to a minimum. Surrounding each valve stem is an inverted plunger cup operating in a small cast-iron cylinder. This construction allows all working parts of the valve gear to be well lubricated and prevents any side thrust from the rocker being transmitted to the valve stems, so that valve-stem Wear and leakage are reduced to a minimum.
Particular interest again attaches to the exhaust valves, which are specially cooled by a salt mixture. This occupies approximately half of the hollow space in the valve stem and becomes molten at low tem
peratures. The molten salt is reciprocated within the hole of the valve stem by the motion of the valve itself, and acts as a mechanical conveyor to take heat from the valve head and to distribute it through the watercooled portion of the valve-stem guide..
Equal compression pressure in all the cylinders is obtained by machining the cylinders all over. The pistons are of aluminium and are made with Invar struts, which permit extremely close piston and cylinder clearances. The _gudgeon pins are fully floating and are held in place by a snap ring. The connecting rods are drop 'forgings of chrome nickel-steel, the big-ends being white-metalled direct ; this form of babbiting assists in cooling the bearings. The rods are drilled from end to end to permit forced lubrication to the gudgeon pins.
Lubrication is under pressure, wherever possible, to all wearing parts. The geared oil pump is bolted to the lower surface of the upper half of the crankcase, being driven from the Camshaft by spiral gears and a vertical shaft.. The customary practice of oil circulation is directly reversed, all the oil being withdrawn through a fine-meshed screen from the bottom to the top. of the oil sump. As a result, the screen is almost self-cleaning, as any dirt or carbon caught by the undersurface is free to fall off and drop into a trap in the bottom of the sump. The pump draws its oil from a compartment above the screen and delivers it to the camshaft rear bearing through a hole which is drilled vertically in the crankcase. The camshaft is drilled throughout its length and acts as a manifold for oil distribution. Radial holes are drilled through the camshaft at each of the seven bearings, and oil is led direct from these holes to each of the crankshaft main bearings; thus, all crankshaft and camshaft main
bearings, and the big-end bearings which receive their oil through holes drilled in the crankshaft, are at all times lubricated under full-oil pressure. Oil is thrown off on to each cylinder wall during 46 degrees of the revolution of the crankshaft, oil only being discharged when
it can serve this useful purpose. Provision is, of course, made for oiling the bearings of the shaft for the auxiliary drives and for the chain-adjusting idler for the front-end timing. During a portion of the revolution of the camshaft oil passes through one of the holding-down studs of the hollow-:camshaft follower shaft, which is at all times filled with oil, and oil is led to the valve-rocker shaft through a specially drilled stud and bracket which holds this shaft, And, as the top of the stud is higher than any part of the overheadvalve gear requiring lubrication, the valve mechanism is lubricated only from a gravity head of oil. Every detail of the valve mechanism is carefully provided for in the matter of lubrication.
Air to the carburetter is supplied through a cleaner of the wire-gauze type dipped in oil, and the mixture passes through an induction system of the six-port type with a down-grade manifold, the riser between the carburetter and the manifold being heated.
The ejector system is adopted in the exhaust, the manifold having two outlets at the centre and a double connection through a cross-over passage through the. cylinder head to the heated riser above the carburetter, a valve being fitted which controls the amount of exhaust gases allowed to pass through the riser, so that the temperature of the mixture is under perfect control.
The auxiliary driving shaft is located on the right-hand side of the B28
engine, and drives the auxiliaries in the following order :—(1) water pump ; (2) generator ; (3) .ignition unit. Battery ignition is employed, with two sparks per cylinder, the sparking advance being a combination of manual control and automatic. Failure of one plug, by the way, does not put -the other plug in the same cylinder out of action..
The water cooling • is adequate, the water being distributed through drilled holes on each side of the sparking plugs. Great care has been taken in the design to ensure that the water shall be automatically distributed in equal quantities throughout the entire length of the cylinder block and head. A thermostat installed at the water outlet at the front of the cylinder head maintains a minimum temperature of 160 degrees E. in the water jacket.
The drive is taken through a two-plate clutch, forcedair circulation cooling the friction Surfaces. The three Pressure plates are of east-iron, and the friction material on the two steel clutch discs is of the moulded type. The clutch-release mechanism embraces three levers with a grapho-carbon throw-out bearing working against a cast-iron sleeve ; nine springs ensure progressive engagement between flywheel and front pressure plate, whilst 12 main pressure springs are held in recesses in the clutch cover.
The gearbox is mounted as a unit with the engine and gives four forward speeds, direct on top, and with the following ratios for the lower gears :-1.64 to L 2.68 to 1 and 5.05 to 1.
A semi-floating rear axle with single-reduction spiralbevel driving gears is employed, the axle housing being a one-piece casting, taper-roller bearings being used throughout, the two bearings on each side being placed back to back for carrying wheel loads.
The rear-wheel hubs are attached to their shafts in an unusual manner, the inner end of the hub bore fitting on a taper on the axle shaft and the outer end of the bore being Wined to fit splines on the shaft. The outer end of the hub is tapered on the outside and slotted along the centre line, and over it is fitted a taper sleeve which is drawn up tightly on to the hub taper by four-studs on the hub flange. This construction ensures a positive fit of the hub on the axle shaft, and at the same time the wheel can be easily removed when necessary. No liners are used for the brakes, as the shoes are of what is known as the " throw-away " type. The emergency brake consists of a single drum mounted on a flange at the rear end of the front universal-joint shaft. The frame has a normal channel cross-section of 10 ins. depth.
The standard wheelbase of this White chassis, which is known as Model 54, is 18 ft. 11 ins., and the weight of the chassis (without fuel or water) is 8,000 lb. Two other wheelbases will be offered—viz., 17 ft, 2 ins. and 20 ft.