LAUNCHING AND LAND ING A LIFEBOAT BY MOTOR.
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THE expeditious handling of a lifeboat is a matter of very great importance, and one which has given considerable trouble to the authorities of the Royal National Lifeboat Institution. The boats to be handled range up to 61 tons in weight and are of considerable length, so that the problem is by no means an easy one, especially considering the type of surface to be traversed, which may vary between loose shingle and soft sea-soaked sand. A very interesting demonstration of how these difficulties can be overcome by the tractor-trailer type of machine •iirith creeper tracks was recently given to the authorities of the Institution and to members of the Press by the Four Wheel Drive Lorry Co., Ltd., at Slough.
The tractor concerned is one which the F.W.D. Co. has developed for cross-country work, and which was fully described in the issue of The Commercial Motor for January 25th, 1927. Roadless-Traction tracks are employed at the rear, whilst the fact that, in addition, power is conveyed to the front wheels on the wellknown F.W.D. principle, ensures that the machine can surmount difficult obstacles which would be quite impassable to one driven by rear tracks only.
It will be recalled that the design of the F.W.D. chassis was very considerably modified in the production of this special tractor, one of the most important alterations being to shift the engine sideways so as to give a comparatively low seating position for the driver and his mate alongside it. However, another point of importance is the provision of a reducing gearbox containing two silent chains, giving alternative ratios between the engine and the gearbox proper.
These chains also serve to convey the drive from the offset engine to the central gearbox. It will be B38
recalled that the tractor, is fitted with a powerful winch at the rear, the drum of -which is mounted on a vertical spindle, whilst the cable is guided by pulleys traversed by means of an Archimedean-screw mechanism. A pull of over 5 tons can be obtained on the cable.
This machine has proved eminently suitable for handling a lifeboat carriage, with but few modifications. The carriage itself is the same as that normally used by the R.N.L.I., but instead of being mounted upon two large wheels of the cart-wheel type, a pair of RoadIess-Traction track units is employed. As will be seen from one of the photographs reproduced, the height of these track units is very much less than that of the wheels which they replace, and this is an important advantage because, when being launched in a rough sea, incoming waves are apt to lift the boat off its carriage and then allow it to drop back again. Consequently, with the old-pattern carriage the boat was very liable to foul the wheels. The provision of semi
elliptic springs constitutes another improvement. • Another point is that special plates had to be used to prevent the cart-wheels frOm sinking into the sand, and these become unnecessary when :tracks, are eirf= pioyed. The fore part of the carriage teas upOn a turn-table secured to the rear end of the tractor, and the manceuvrabflity of the complete unit is a very striking feature. Thus, it can be turned in a circle (measured to the off-side front wheel) of only 53 ft. 4 ins. in diameter, the total width from the innermost to the outermost of the tracks being then only 16 ft. The engine is of the type which was specially brought out for this tractor, and which has a bore and stroke of 5i ins. and 51. ins. respectively ; it is, of course, considerably larger than the engine ordinarily fitted to F.W.D. trucks.
For handling lifeboats the power unit has had to be specially modified in order to make it highly waterproof, because when the tractor is in use near to a rough sea it may well get partially smothered by incoming waves.
The exhaust is taken up through a species of tower, which is clearly visible in the photographs, and which also in
eludes the air-intake pipe for the carburetter. This carburetter, which is a Solex, is completely boxed in and draws Its air through a lengthy pipe fitted with a strangling device.
It was found that there was a tendency for a partial vacuum to be created in the box enclosing the carburetter which was causing the engine to be starved of petrol, but the difficulty has been simply overcome by means of a balance pipe connected to the float chamber: The magneto is also completely enclosed in a housing with a readily detachable cover, and, to provide ventilation, piping is connected up so that air is continually being sucked through the casing past the magneto. So effective is the weather-proofing scheme that in the course of the tests buckets of water were freely poured over the engine without affecting its running in any way.
The boat With which the demonstrations were carried out weighs 6 tons 16 cwt., the weight complete 'with carriage being nearly St tons ; this is the heaviest type of boat which the tractor would ever be called upon to handle.
For launching purposes the tractor, with the carriage carrying the boat attached, drives down the beach, turns in a half-circle and then backs the boat and carriage clown into the water, the bows of the boat facing the sea. A cable is taken from the winch on the tractor down to a pulley at the rear end of the carriage and back to a hook secured to the stern of the boat. When the trailer is in sufficiently deep water the driver of the lorry starts the winch, and the pull on the cable causes the boat to be drawn off the carriage.
When the boat comes in it is run on to the carriage, which is then man-handled into position and hitched on to the tractor ; the balance is so good that the boat and carriage can readily be pulled round by four men.
In the course of the tests at Slough the machine was driven over an artificial patch of shingle, through soft waste ground. It gave every satisfaction and was regarded very favourably by everyone present, including Viscount Curzon and Mr. Rowley, of the R.N.L.I.
In addition to the works at Slough, the Feur Wheel Drive Lorry Co., Ltd., has offices at 46, Charing Cross; London, S.W.1.