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October, 1910 "TAE Marine REVIEW PLAN OF COUNTERWEIGHT CAR, ble, as the machine is liberally pro- vided with electric lights. An electrically-driven centrifugal pump is located in the machinery house, for pumping out the water- tight compartments, and_ stairways, with water-tight hatches, are fitted for convenient access to the hold. At one end of the machinery house is a neatly appointed office for the use of the officer in charge. The Automatic Counterweight. -- By far the most interesting and unique feature of this machine, how- ever, is the automatic counterweight, which consists of a series of heavy castings bolted together, two of which are so formed as to make truck castings to support the axle bearings.. This counterweight car (weighing about 600,000 pounds) travels on dou- ble tracks laid lengthwise through the center line of the floor of the hull. The line engravings show end and side elevations and plan of this device. This counterweight is necessary in or- der to prevent the machine from list- ing more than the specified limit of 3 per cent in either direction. On top of the car is mounted a 100-horse- Power Westinghouse mill-type series wound motor which drives, through a worm and worm wheel, a_ pinion which meshes with: a rack lying be- tween the rails on which the counter- weight runs. In order to stop the ~ weight immediately when desired a solenoid post brake is provided, which releases the brake when current is applied and sets it when the current is iffferrupted. The current for the motor is rey: ulated by a controller mounted right on the counterweight. This consists of a number of magnetically operated switches and an automatic device for limiting the starting current of the motor. To start the motor in a given direction it is only necessary to sup- ply a small magnetizing current to the solenoids which operate a group of magnetic switches "which then close in proper rotation until full voltage is applied to the motor. Current is collected from two~contact bars, by means of sliding shoes mounted upon the counterweight. The current for operating the con- troller switches is applied by a pendu- lum-operated switch which swings in a plane parallel to the bridge and counterweight track. This is the in- genious feature of the counterweight- ing apparatus. When the load has given the bridge a predetermined list, the pendulum closes a contact on that side which supplies current to the proper group of controller switches, which, in turn, set the motor armature in motion in the proper direction to counterbalance the load. When the position of the load is altered so that the machine is listed in the opposite 397 direction, the pendulum swings in the Opposite direction, closing another con- tact which supplies current to the other group of switches and brings the counterweight back until the pendu- lum again swings free. To provide against overtravel, a limit switch is . provided, to stop the motor automat- ically at each end of its runway. A manually operated controller is also fitted, so that the counterweight can be operated by hand when desired. This electric automatic counterweight system has proven very satisfactory, and has been patented by the Well- man-Seaver-Morgan Co. An interest- ing feature in connection with its op- eration is the unusual use which has been made of it. When it is desired to take a lift very slowly, the hitch is made and a strain taken /on the cables. Then the counterweight is moved gradually up the incline, in- creasing the strain on the cable and thus carefully lift the load. The nice- ty with which this can be done is very interesting to observe. : The crane was recently tested for acceptance by the government engin- eers and more than fulfilled the speci- fications. The test load for the main hoist consisted of pieces of armor plate weighing almost 243,000 pounds, which was handled very easily by the hoisting engines, although it is about 8 per cent in excess of the specified load. The test load for the auxiliary hoist was over 39,000 pounds, about- 16 per cent in excess of requirements.' 4 3 A Large Floating Shear Leg a Herewith will be found'an interesting example of another type of hoist of equal capacity, which is usually found - as an item of shore equipment. This has been installed by the Vulcan Co, in its new shipyard at Hamburg. The questions of stability involved are considerably greater in the case of the shear leg, because of the great height: of the legs, which are 143 feet 7 inches long from center of pivot bearing to' the head. The legs have a maximum' outfall of 47 feet 5 inches. The ar- rangement of pontoons is noteworthy. There are two pontoons, that in front upon which the legs are stepped being 92 feet 8 inches long, 36 feet wide and 9 feet deep, and the second, connected to the first by girders, as seen in the illustration, is 74 feet by 29 feet 6 inches by 8 feet 3 inches, the distance between centers being 32 feet 10 inches. The distance between the two pontoons may be varied by means of cable and cap- stan gear driven by the main engine and