The Works Of Messrs. Schneider And Co.

ISO-TON ELECTRIC TRAVELLING CRANE 47 main countershaft. This friction clutch carries a bevel wheel of phosphor-bronze, gearing with a similar wheel keyed to a vertical shaft (see Fig. 108), at the other end of which is a second bevel wheel gearing with a couple of similar wheels running loose on a horizontal shaft. Either of these wheels, however, can be temporarily keyed to this shaft by a clutch, and the arrangement accordingly acts as a reversing gear. By means of this gear, light loads can be lifted at a high speed, as the horizontal shaft above mentioned, drives, by a worin, a wheel running loose on the intermediate shaft of the crab, but which can be keyed to it by another clutch engaging at will either with this wheel or with the wheel Controlling the main lifting gear. In order to lower a load, the clutches are set so that the wormwheel turns in the proper direction, and then this wheel is keyed to its shaft by its clutch, and the wheel driving the main gear is released. The worm shaft, we sliould add, is also provided with a band break and counterweight, which must be released before it can turn. 7. The Crâne Traversing Gear.—The traversing gear is also controlled by a friction clutch on the main counter- shaft. This clutch drives a vertical shaft by bevel gear- ing, and at the bottom of this shaft is a bevel reversing gear of the usual type, by means of which a long hori- zontal shaft extending from end to end of the crâne is driven. On this shaft are bevel wheels gearing with others mounted on vertical shafts, by means of which motion is finally communicated to the worm shaft which drives the wormwheels keyed to the wheels carrying the crâne, as shown in Fig. 107. The speed of traverse is 10.75 metres (35.26 ft.) per minute. 8. The Chain Car Traversing Gear.—For this also, a friction clutch on the main countershaft is used £or driving this gear, the arrangement for reversing being similar in principle to that on the main traversing gear. In this way motion in one direction or another is trans- mitted to a vertical shaft carrying a worm at its end. This worm gears with a wormwheel mounted on a hori- zontal shaft, to which also is keyed a pair of chain wheels over which pass the chains, the ends of which are attachée! to the chain truck, as shown in Fig. 105. Throughout their lengths these chains are supported by guides, those for the upper portion resting on the upper flange of the main girders, whilst special channel-iron guides are pro- vided for the lower ends. The speed of traverse in this case is 8 metres (25.84 ft.) per minute. 9. The Motors.—The two motors are of the Ganz continuons current type, and were built by Messrs. Schneider and Co., who are sole licensees for the system in France and its colonies. Each motor is designed to take 45,000 watts. Two uninsulated cables, supported on porcelain wheels, are used to convey the current to the crâne. Carbon brushes are used on the crâne for picking up the current from these cables. These brushes are hoHow, the cable passing through them, and they raise it from its supporting pulleys as the crâne passes over them. Belts are used to connect the motors with the clutch shaft. When the load to be lifted does not exceed 75 to 80 tons, only one of the motors is used. Ail the fittings required for the working of the motors are grouped together in the attendant’« cabin. Amongst these may be noted a sulphate of copper rhéostat, which enables the motors to be started without shock. To do this the main switch is closed, and the électrodes of the rhéostat brought gradually into contact. A second metallic rhéostat is also provided, which enables the strength of the magnetic ■fielcl and the speed of the motors to be varied, beside which the work done by the two motors can be equalised by its means. A special safety device is also provided in case of the attendant allowing the chain to drop too far. This consists of a switch on the armature circuit of the motors, which is opened when the chain passes a certain point. As the field magnets still remain excited, the load is brought up almost immediately by the résistance de- veloped to the motion of the armatures. The voltage at which the motors are designed to work is 220 volts. The dynamo providing the current has an output of 100,000 watts, and is a four-pole Ganz machine. Both. dynamos and motors are compound wound. 10. The Foot Bridges and Cabin for the Crâne Attendant.—Footways are provided on both sides of the crâne, and run from end to end, giving access to ail bearings and other parts requiring attention. They are supported by brackets fixed to the main girders. The attenclant’s cabin is built of iron plates and angles, but bas a wooden floor. It is fixed below the main girders of the crâne, and from it the attendant can easily follow ail motions of the hook. All the handwheels, foot levers, &c., are grouped together as close as possible, so as to be within easy reach of the attendant, thus enabling him to do his work most efficiently. The total weight of the crâne is 200 tons.