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74 it is desirable to incorporate in the design of the electric equipment for anchor windlasses, due to the nature of the loads handled, and, which may at times reach an overload value suffi- cient to stall the motor. Electrically, this is provided for by an automatic current limiting device (step-back), which enables the motor to stall and hold tension on the lines or anchor chains. Although this point of current limitation is an arbitrary point and may be set for any given overload desired, it is usual practice to allow for 125 per cent full load torque with the motor armature at standstill. As the momentary overload is_ relieved, MAGNETIC CONTROL PANEL FOR UNDER DECK AUXILIARIES the motor again automatically starts up and continues to haul in. The nature of the work performed by capstans, gypsies and warping winches, such as warping a ship into dock, the handling of heavy lines or miscellaneous hositing duty, calls for a relatively slow speed, generally not over 50 feet per minute at full load. The tendency in de- sign is to provide rheostatic control with step-back arrangement to take care of overloads, smiliar to that used for anchor windlasses. For rapid economical cargo handling, the electric cargo winch is supreme. Equipment has been designed to take care of the most extreme conditions as to load, rope speed and tonnage capacity. From an operating stand- point, such equipment has been made fool-proof. As the largest part of the cost of loading and unloading vessels is the labor cost, the tendency is to de- sigan the equipment for such rope speeds and capacity as to keep the stevedores busy under all conditions. MARINE REVIEW. The special features included in the most up-to-date equipment, provide for automatic acceleration, automatic retardation and dynamic braking. An electric holding brake of the auto- matic solenoid type is also provided so that at all times when the con- troller is in the “off” position, the brake is set, also at any time when the current fails. Overload circuit breakers are also provided which automatically reset when the controller is brought back to the “off” position. From an operator’s point of view, the operations are extremely simple and the stevedore familiarizes him- self with the equipment much more rapidly than with steam equipment. As electric machinery requires no warming-up or expenditure of power, except when actually working a load, and no time is lost in getting the equipment into working order after the ship is docked, it is rapidly com- ing into favor. Even on types of ships in which a calculated analysis might show steam and electric equip- ment to be about on an economic par, there are many intangible fea- tures which favor the electric drive and which are only brought out by direct comparison or observation over long periods of service. Electric Winches, Reliable (Continued from Page 60) the load is light or heavy and use a manual brake for lowering. These did not prove very successful and helped to establish 280-volt direct current as being best suited for cargo winch control. Immediately following, came the successful installation of electric winches on the motor ship WILLIAM PENN. The mechanical portions of November, 1926 these winches were built by the American Engineering Co. and the electric parts by the Westinghouse company. While there were a num- ber of other electric winch installa- tions by this time, including some reported reasonably successful, most of them represented an attempt to adapt to land service equipment by adding marine fittings, water tight gaskets, etc. The WILLIAM PENN winches illustrated the advisability of furnishing equipment built for marine service from the ground up. These. winches are heavily built with a 30-horsepower, 75-degree centigrade mill type motor driving the drum through a two-speed double-reduction of spur tooth gearing. This design followed the “safety first” plan of a very heavy winch with change speed gearing because it was not definitely known how flex- ible the electric motor driven winch would prove to be or what load and speed ranges it would have to meet. The success of the lighter single speed reduction winches as_ installed on the motor ships SuPHENCO and CHALLENGER, has been so marked that practically all the recently designed ships use that type rather than the heavy two speed type as. on the WILLIAM PENN. The lighter winches are all of the positive drive single keyed drum type with rheostatic con- trol for hoisting and dynamic brak- ing control for lowering. There are a number of winches of special design including one with mechanical load lowering brake, the hydraulic speed gear drive winch, and the friction drum winch. But none of these have as yet been installed on American ships in sufficiently large numbers to (Continued on Page 86) oto 20 so] ao) St 7X loverain ere ak | |260| 70 20| 160| 40] I [lol sll ral ol af aol of | Load on Single Whip- Thousand Pounds FIG. 8—CHARACTERISTIC CURVES FROM BRAKE TEST OF CARGO WINCH ILLUS- TRATED IN FIG. 2