A NEW TWO-LITRE AMBULANCE CHASSIS.
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Details of the Latest Vulcan Product, Which Has a Six-cylindered Engine and Other Noteworthy Features.
TRE exacting nature of ambulance service is such that special features are demanded in those motor vehicles which are built for work of this kind. Most of these features are concerned with the design of the chassis itself, which, to be really suitable as the basis of an ambulance, must possess good powers of acceleration, have a powerful and efficient system of braking, be well suspended and Quiet in running. In fact, it must, in many respects, closely resemble the design of the high-class touring car chassis and must possess a degree of refinement in detail as well as general construction which is visually only to be found on such vehicles. These features are essentials of all motor am' bulances, but are vital on vehicles operating in busy traffic areas where short bursts of speed at high rates have to be made in order to ensure as little delay as possible in the conveyance of patients.
It would certainly appear that the Vulcan Motor and Engineering Co. (1906), Ltd., Crossens, Southport, has paid Particular heed to these factors in the design of a new two-litre six cylinder chassis which it has just placed on the market expressly for ambulance duties.
In the main the chassis is conceived on orthodox lines, and a glance at the illustrations which appear on this page will serve to indicate that it is of sturdy and workmanlike build. In view of the advantages which the six-cylindered engine Offers, particularly in the matter of flexibility, it is not surprising to find that the power unit is
of this type, its bore is 65 ram. and its stroke 100 mm., and it has a cubic capacity of 1,990. The cylinders are raonobloc castings and have detachable east-iron head on which are mounted the camshafts, these being disposed at an angle of 90 degrees.The combustion chambers are hemispherical and the sparking plugs are centrally placed in them. In order to ensure that
c28 the unit is properly cooled, liberal water jacketing has been arranged around them, as well as around the valve pockets and combustion chambers. It is possible to effect easy adjustment of the valves by an eccentric device which is accessibly placed.
The crankshaft runs in seven bearings and is fitted with a vibration damper of simple design at the forward end. The main bearings are die-cast white metal, the big-end bearings having bronze shells
with cast-in white-metal liners. The crankcase is an aluminium casting of substantial proportions and it is supported at three points in the chassis frame. The sump has a capacity of three gallons and the gear-type pump, which is mounted on the timing cover, draws oil from it through a large suction filter. It is a simple matter to withdraw this filter for cleaning purposes
without the need for draining the sump. The oil is force-fed to the main bearings and the big-ends, whilst the overhead camshafts are lubricated through a valve which reduces the supply of oil at low speeds, thus avoiding the possibility of overolling.
The engine is cooled thermo-siphonirally, and the radiator has a large cooling area. For ignition purposes the Duplex high-tension magneto and coil system is relied upon, this being driven in tandem with the dynamo and connected by a coupling which is fitted with an automatic ignition control.
The clutch and gearbox form a unit with the engine, the clutch being of the single dry-plate type and having a clutch stop; and the gearbox providing four forward speeds and a reverse. Right-hand control is providkl to effect the changes of gear, and it is interesting to note that . the selector mechanism is so arranged that distortion cannot normally take place, The gear ratios are as follow : Top, 5.75 to 1 ; third, 8.9 to 1; second, 14.7
to 1; first, 21.1 to 1; reverse, 27.5 to I.
From the gearbox a twopiece open propeller shaft conveys the drive to a semifloating, be'veld r.i v e n rear axle. The propeller shaft has metal universal joints of the ring type, these being totally enclosed and filled with soft grease.
• The rear axle consists of a banjo-type steel pressing containing the spiral-bevel gear and differential gear in a separate housing. The cover is a light pressing which can be easily removed when it is necessary to inspect the gears. The driving shafts are of high-tensile steel and, together with the bevel pinions and differential gearing, are mounted on taper-roller bearings. The front axle is a high-tensile steel stamping of I section.
Special attention has been given to the . subject of 'braking. The foot pedal Operates shoes of the expanding type in dims of 14 ins, diameter on the front and rear axles, the braking effect being assisted by a servo motor, thus rendering the physical effort requiredon the part of the driver extremely light. The hand brake, operates fabric-lined shoes of the expanding type in the rear-axle drums only. The drums are ribbed.
The suspension system of the chassis has also received much consideration, and in addition to-offset semi-elliptics at the front and the rear, shock absorbers are fitted The front springs are 34 ins. long, and those at the rear 51 ins, long, and the leaves are protected by leather gaiters.
The frame is a channel steel pressing. The side-members are 54 ins, deep and, apart from being tapered at the front, are upswept to clear the rear axle and tapered at the rear. Adequate bracing is given to the frame by straight crossmembers, in addition to a substantial X-member built in halves, which are bolted together.
Wire wheels of the screwed-on type are employed and these are fitted with British Goodrich reinforced low-pressurs tyres of 30-in. by 5.77-in. dimensions.
The petrel tank is of 10 gallons capacity and is fitted between the framemembers at the rear of the chassis. It has a large accessible filler having a filter gauze and is provided with an indicator which shows the level of the fuel in the tank.
The chief dimensions of the new ambulance chassis are as follow :---Wheelbase, 11 ft. 2 ins.; track, 4 ft. 8 ins. overall length, 15 ft. 8 ins.; road clear
ance, 9i ins. The height from tin ground to the top of the frame when the vehicle is loaded is .1 ft. 8i. ins.
The new chassis sells at q500, which, considering that it has been specially designed for ambulance Service and is built on sound, modern lines, is a most 'moderate figure. •