THE RECORD-BREAKING LANCHESTER. Details of a Remarkable Chassis.
OF the many startling records established during last year, those set up by the Lanchester car, described in the following notes, are among the most remarkable, principally on account of the few modifications made to the standard chassis used for this famous racing car. Many standard touring models, altered to suit racing conditions, are known to followers of the sport of motor
racing ; but in majority of cases no secret has been made of the fact that many radical departures from the original design are included, whereby great extra speed has been attainable ; so that when a practically standard chassis is fitted with a racing body and put to work on the track, the general public, not unnaturally, assumes that a considerable amount of ” faking ” has been done.
manship is still as excellent as in the days when hours and hours were spent in scraping all the joints of the engine by the exacting hand process.
The Frame Construction.
While being normal as far as appearance is concerned, the Lanchester chassis possesses many features of interest. The side members themselves are partially tubular in construction and have a maximum depth of 6 in., and a width of 4 in. At the upswept portion near the rear of the frame, the side members are braced transversely by a tubular cross member 8 in. in diameter. A smaller tubular cross member is used in front of the engine, the middle cross member being a steel pressing of channel section with exceptional width.
The writer recently had the opportunity of making a close examination of the racing Lanchester and, furthermore, was given every facility for comparing the actual details of construction with those of the standard 40 h.p. chassis. The Lanchester ” Forty ” differs very materially from the earlier types of Lanchester vehicles, and in many respects follows what is now accepted as orthodox practice. In looking back some twenty odd years or so, when the writer was one of the fortunate youths privileged to undergo a course of workshop training at the Birmingham factory, it is difficult to recognise the Lanchester principles of to-day with those in vogue so long ago. But, nevertheless, many of the constructional features are the same in principle and the work
Front Axle and Suspension.
The front axle calls for no special comment, and has underslung semi-elliptic springs of generous dimensions, but for track work it is fitted with wind resisting shielding.
The rear suspension is of the Lanchester cantilever design in which the full cantilever springs are pivotted at their centre on bearings with a floating phosphor bronze bush. In the place of the usual shackles, the ends of the springs are carried in bronze trunnions, which are provided with a rectangular aperture for the reception of the spring extremities. Rollers are provided in these apertures and the spring passes between them to serve as a guide for the leaves. To this system of suspension, aided by Hartford shock absorbers for the front and rear axles, the THE RECORD-BREAKING
Lanchester racer owes its extreme steadiness on the track at high speeds, a factor which has materially contributed to its successes.
The standard mechanism of the steering column needed no modification, but for the streamline effect of the single seater, the column has been moved and mounted on the gear box, the column being shortened to give the correct position for racing. An ingenious system of combined worm, nut and trunnion gear is adopted for actuating the steering drop arm and the car is extremely light to handle in all conditions.
The Lanchester Power Unit.
One of the remarkable points concerning the Lanchester racing car is that the only alteration from standard consists in a modified form of induction pipe to carry two Zenith carburettors, the ordinary design
construction, the strength of which is further increased by wide flanged oil joints and the large number of bolts securing the two portions together.
The power unit, together with the housing for the change speed gear, is mounted in the frame by means of two arms extending from the forward portion of the crankcase and at the rear by a pair of brackets carrying the weight at the rear of the unit. Although unit construction has been adopted, attention has been paid to the matter of accessibility and all the external components are arranged so as to avoid difficulties should dismantling be necessary at any time. This point, of course, becomes important to the racing man, who may need to dismantle his engine from time to time for various reasons. Seven bearings are used for the support of the crankshaft, which is of exceptionally robust construction, and balanced to the finest possible limit of accuracy. The crankshaft is of hollow construction, the shaft and
and production methods permitting the rapid acceleration and high engine speed for record breaking. The six cylinder engine is cast with two blocks of three cylinders each, of which the combustion heads and valve chambers are integral parts of the castings, thus ensuring an unrestricted circulation of the cooling water and eliminating the possibility of water and cylinder pressure leakages, to which some heavily stressed engines with detachable heads are susceptible.
The combustion spaces are partly spherical and machined all over, a very important point in arranging for the free passages of the gases. This feature also contributes towards efficiency in other directions, such as evading defects in combustion, which frequently occur in engines with untreated combustion chambers, where slight irregularities in the surface of the metal impede the gases and produce local “hot-spots.” Aluminium castings are employed for the crankcase and base chamber, the former taking a stiff girder-like
crank pins being bored to effect a saving in weight and suitable ducts are drilled for the distribution of oil, which is pressure fed.
Aluminium Alloy Pistons.
In view of the controversy among racing motorists concerning aluminium pistons, it may be of interest to remark that this type was adopted in 1919 as standard practice on the Lanchester car after successful tests extending over a period of six years. The pistons are of the design allowing the dissipation of the heat. The tubular connecting rods used on the earlier Lanchesters have now given place to high tensile drop forgings of the ” H ” pattern, these being machined all over to reduce weight and for balance equalising purposes. A specially selected specification is employed for the white metal used for the die-cast big-end bearings and the oil channels are cut so as to prevent the formation of any ridges on the crankshaft journals, which so
often happens if this detail of design is overlooked. To ensure proper lubrication for the floating gudgeon pins, which work in phosphor bronze bushes, an oil pipe is fitted to each connecting rod, allowing for the passage of the oil under pressure from the crankshaft journal to the gudgeon pins.
The Overhead Valve Gear.
Were it not for the fact of the Lanchester being designed as a high-class touring car, one might almost imagine it to be the product of a racing enthusiast, as far as the lay-out of the overhead valve gear is concerned, for even in such details as the valve spring, the ordinary form of valve washer and cottar, long discarded for high speed engines, is replaced by a neat and effective form of cone attachment fitting into the spring collars.
The overhead camshaft is actuated by worm gearing and operates the inclined valves by means of compact valve tappet levers. The exhaust valves are seated direct into the cylinder heads to ensure effective cooling, removable cages being adopted for the inlet valves. By the formation of the hollow valve spindles, the engine is very sensitive and the use of light valves assists very considerably in quick acceleration.
Though two separate systems are employed, i.e., magneto and Delco battery ignition, it is interesting to remark that for many of its record runs, the racing Lanchester employed the magneto alone.
Two plugs are fitted to each cylinder, the exact position having been selected with due consideration in the matter of flame propagation in relation to power output.
Water Cooling Arrangements.
This part of the engine is perfectly standard, except for the removal of the fan and the addition of a cowling extending some eighteen inches beyond the radiator and reducing the apparent ventage to about one-third the area of the radiator.
The Epicyclic Gear Change.
Since the first introduction of motor cars, inventors have spent much time and money in endeavouring to perfect the epicyclic form of gearing, but the Lanchester change speed mechanism provides the only practical solution to the problem, and it is even more remarkable that this type of gearing should stand up satisfactorily under the abnormal stresses imposed by racing conditions. Contained in the gear box, which externally is of normal appearance, are three epicyclic trains of gear, the epicyclic clutches and the main, or direct drive clutch. A peculiarity of the latter is that normally the frictional members are disengaged, the engagement being effected by means of two alternative cams mounted on the gear
change lever. The epicyclic system is the same in principle as that used on the very early Lanchester cars, but is now operated by means of selector mechanism with the change lever working in the ordinary form of gate.
An internal expanding brake, with cooling ribs on the drum, is mounted at the rear end of the gear box.
Final Drive Mechanism.
The drive from the gear box is taken by a universally jointed cardan shaft, enclosed in a tubular torque member, of which the forward end is secured to a spherical housing carried on the central transverse member of the chassis. No special comments are called for in connection with the rear axle, which is of the well-known Lanchester high-efficiency worm type, though in this particular case a special high gear ratio has been incorporated.
Body Work and Details.
As will be seen from the accompanying photograph, the form of body used for racing is built on somewhat unique lines, and while not conforming with the beauty of many racing cars, careful attention has been paid to