A New Mechanical Horse of Well-known Parentage
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Many Ingenious Features in Attractive 3o-40,cwt. Outfit, Developed by Personnel who were lately Members of the London Latil Company
ANEWCOMER to the British commercial-vehicle market, that has just made its appearance, is a mechanical-horse outfit, introduced by L. C. Rawlence and Co., Ltd., of 39, Sackville Street, London, W.1, 5, Lower Marsh, London, S.E.1, and Eclipse Works, Salisbury. The vehicle incorporates a Crane semi-trailer" and is rated at 30-40 cwt. capacity. For the development of the design of the mechanical horse itself, coupling gear, turntable, etc., Mr. Rawlence and Mr. Le Voi, respectively late chairman and managing director of Latil Industrial Vehicles, Ltd., are responsible.
One of these machines, we are informed, has now been in the service of Thomas )3antock and Co., G.W.R. agent, Greatbridge, Wolverhampton, for eight months, and has been giving entire satisfaction.
Having a platform measuring 12 ft. by 6 ft. and a loading height of 3 ft. 4 ins., the complete outfit weighs 30 cwt. unladen, The tractive unit is of the type which has two front wheels spaced apart fairly widely and two driving wheels close together. Actually their respective tracks are 4 ft. 2 ins. and 2 ft. 4 ins. For the trailing wheels the track dimension is 5 ft. 3 ins, Approximate wheelbase figures are : tractive unit 6 ft., and semi-trailer 7 ft. All wheels are shod with 25 by 6 tyres.
Power is provided by a Ford 10 h.p. engine-gearbox unit, which is mounted in a sub-frame as an assembly with the rear axle—a sturdy underslung-worm component—to which the sub-frame rear ends are rigidly attached. Transmission between gearbox and axle is
afforded by a Hardy-Spicer shaft incorporating two needle-roller universal joints.
The main-frame is a substantial
structure having a welded-on crossmember at the front, a similarly attached fitment for the coupling gear, etc., at the rear and a riveted-on channel at about the centre. On this middle cross-member is abracket carrying a Silentbloc attachment to the front of the sub-frame. At the rear the driving assembly is secured by slippers to the ends of two quarter-elliptic springs clamped to the main frame within its box-section ends.
Thus, by undoing the one-bolt front fixing and disconnecting the controls the whole driving assembly, including radiator, axle and wheels, can be with drawn bodily. This is a valuable point from the maintenance angle.
Movement of the sub-frame relative to the main frame is permitted by the hinged joint at the front, and beerthis incorporates a Silentbloc bush a limited amount of lateral rocking is allowed to relieve the rigid parts of undue stress when varying road cambers and the like throw the axles out of alignment, Most of this, however, will be taken up by the front or rear springs, which are semi-elliptics in both cases.
Considerable ingenuity is represented by the coupling gear. Under the front of the trailer is a turntable, the lower part of which carries a tubular crossmember, to the extremities of which the jockey-wheel legs are fixed. These are not of the retractable type. Free to rotate under the cross-member is a flanged roller described as the " diabolo " wheel.
Integral with the rear of the tractor frame is an inclined girder-section beam forming a ramp with which the diabolo wheel engages when the two units are being coupled. On the sides ot the forward end of this ramp are Ushaped horizontal jaws which receive extensions of the shaft of the diabolo wheel when this has been lifted by running up the ramp, as the tractor is backed under the trailer.
At the sides of the jaws are hooks, having their backs shaped in such a manner that, on striking them, the cross-shaft lifts them out of its way. On reaching the end of its travel, the shaft encounters a spring buffer, which permits it to advance, just far enough for the hooks to drop down on to the shaft, which cannot be released again without manual assistance. For security the jaws of the • hooks are undercut, so that a rearward force tends to push them down, and they are retained in the engaging position by spring pressure as follows.
Each hook is fixed, at its front end, to a cross-shaft, having a drop-arm at the near side. The lower end of this slides on a longitudinal rod, running forwards to the control lever, which works in a quadrant, and running rearwards for a matter of about 18 ins., to terminate in a stop. Threaded on this rod between the drop-arm and the stop are two compression springs, one of heavy square-section wire, the other less powerful. A further stop is fixed in front of the drop-arm.
The three positions of the hand lever (for which there are slots in the quadrant) are " release," "engage," and "lock." To release the hooks the rod is moved backwards and the forward stop pushes the drop-arm in the same direction, lifting the hooks. For engaging the trailer the rod is in the mid position, whilst the hooks, in being raised by the diabolo crossshaft, swing the drop-arm back, compressing the lighter spring. When the lever is in the "locked " position, the rod is pulled forwards and the droparm is loaded by the pressure of the compressed spring, and partly by that of the heavy spring. Another function of the last-named, however, is to permit coupling of the two units to be accomplished even if the lever has been inadvertently left at "locked."
The spring buffer, in addition to the function referred to earlier, presses the shaft back into the radius of the hooks and prevents chatter and consequent wear when the vehicle is travelling.
Some interest attaches to the remote control of the gearbox. The gear lever is mounted on the steering column and has two motions—one in a horizontal plane, the other in a plane radial to the column. Two Arens encased flexible cables transmit these motions to the gearbox lever. The former is converted to longitudinal motion to shift the gear wheels and the latter to transverse motion to engage the appropriate selector. The arrangement struck us as being both neat and' ingenious—typical, indeed, of all mechanical details of the outfit.
Another detail worthy of mention is the means for imparting braking action from tractive to trailing units. Incorporated in the turntable gear is a small pulley, around which the trailer-brake main cable runs. It is itself pulled forwards by the trailer parking-brake lever.
One end of this cable conveys the pull to the brakes, whilst the other is fixed to a stop. The last-named is a part of a push rod, the forward extremity of which abuts, when the units are coupled, against a corresponding rod on the tractor connected to the brake pedal. All brakes are of Girling make and operate in 10-in. by 11-in. drums on all wheels.
Here are some further chassis spedfication particulars. Of 1.172 litres capacity, the engine has four cylinders, measuring 63.5 mm. by 92.56 mm. It develops 32 b.h.p. at 4,000 r.p.m. and torquc. of 52.5 lb.-ft. at 2,350 r.p.in. The carburetter is a Solex downdraught instrument, fed with petrol by a fuel-lift pump from an 8-gallon tank under the driver's seat.
Holding 21 gallons of water, the radiator is mounted on the sub-frame in front of the power unit, and cooling is assisted by a belt-driven fan working in a cow!., Behind the engine is a single-dryplate clutch. The gearbox is of the synchromesh type and affords ratios of 1, 1.76 and 3.07 to 1 forwards and 4,01 to 1 in reverse. The axle ratio is 11.66 to 1. All wheels run on taperedroller bearings.