French Military Motor Searchlights.
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In view of the important services -winch automobile searchlights are capable of rendering to an army on active service or for coast defence work, the latest type of machine secured by the French army will be examined with interest. The motor searchlights, which have teen built throughout in the factory of Messrs. Haile and Co., of Paris, are the result of many ex
periments. So carefully has the question of weight-saving been considered that the complete vehicle, fully equipped for active service, weighs only 3.1 tons, of which amount the searchlight alone is responsible for about 13i cwt.
The chassis has a four-cylinder 18 h.p. motor placed forward under a bonnet, and, as it has to run under full load for long periods while the vehicle is at rest, the 'cooling arrangements have been well considered, the water circulation being by pump, and the cooling assisted by a powerful fan placed at the rear of the gilled tube radiator. Lubrication is assured by pump circulation and splash. High-tension ignition only is employed. The clutch is of the multiple disc type, and the gearbox provides for four speeds and reverse, and the final drive is by side chains. The gear ratios have been selected with a view to mountain service, the vehicles having been tested on grades of 15 to 18 per cent., with full load and full equipment of men, before being accepted by the army authorities. The fuel consumption averages one gallon for 13 miles and the tank has a capacity for running the motor eight hours at full power with the searchlight in operation, which is about equal to 12 or 14 hours ordinary travelling on the road. The road wheels, which are of unequal size, are shod with solid-rubber band tires in front and staggered block-section tires on the rear.
The machine is designed to carry five men, two being on the broad seat by the side of the driver, and one on each of the spacious tool chests to left and right of the chassis, just behind the driver's seat. The occupants of these seats face rearwards. Immediately behind the main seat is a reel carrying about 330 ft. of insulated cable, which is required when the search light is operated away from the vehicle. The searchlight is carried at the rear of the truck on rails which are practically level with the lower portion of the frame members, thus securing a low centre of gravity. It is mounted on a light bogey with small rubber-tired wheels, and may be turned on its base in all directions. The mounting has been so designed that the searchlight can be employed without dismounting it from the truck ; it is thus ready to be nut into action instantaneously, or may even be used at full power while the truck is under way on its low gear. The comparatively low weight of the entire vehicle and the ability to climb any grade make dismounting of the searchlight a comparatively rare occurrence. When, however, it is desired to place the searchlight in a position inaccessible to the vehicle, it can be brought to the ground by means of a pair of folding rails carried under the base, and the use of a rope and pulley. Under military direction three men are employed for lowering the searchlight, but the operation can be accomplished without fatigue by one man.
In addition to removing the searchlight a distance of about 300 yards from the truck, provision is made for operating the lamp—raising, lowering, turning to left and right, closing the shutter, or opening full—by means of a long distance control. The electric controlling system, which comprises a small metal case carried by a strap over the shoulder, allows the officer in charge to withdraw to a distance of almost, 1,000 ft, from the searchlight and there to operate with as much precision as if he were mounted on the rear platform.
The.dynamo, which furnishes 120 amperes at 80 volts, forms the flywheel of the motor, and the projector, which has a metallic reflector, is 35 in. in diameter.