Showing junction house, screening hopper, 13,000-volt catenary and

440-volt trolley

2

FIG. 6-MAN TROLLEY

[RYERSON AND CRANE]

Showing transformer house and method of distributing 440 volts to bridge

and carrying five tons of coal; the moving equipment, hoist, cab, air compressor, etc., weigh approximately fifty tons. Each hoist is equipped with two 150-h.p., three-phase, 440-volt, 25cycle wound-rotor motors. Both motors are geared together and used for opening and closing bucket and for hoisting. For raising and lowering the boom one 30-h.p. motor is used. For moving the bridge along the dock, one 75-h.p. motor in front, and two 40-h.p. motors in back, are placed at the bottom of each leg. These bridges are guaranteed to make 50 round trips per hour from the hold of the boat to the storage pile. When "breaking down" a boat one of these bridges has made eighty trips and unloaded 400 tons of coal in one hour.

The control system is direct-current magnetic, actuated by air. The direct current is furnished by small motor-generator sets, and the air by small air compressors in each cab.

Both pneumatic and dynamic braking are used. In dynamic braking, direct current from the motor-generator sets is connected to the armatures of the hoist motors, with the secondaries shortcircuited through resistance. This type of braking is satisfactory but requires the use of a considerable amount of additional energy.

The screening hoppers at the rear of the dock, shown in Fig. 4, empty the screenings on to the rear end of the storage pile, which is inconvenient, and some other method will probably be devised for disposing of the screenings.

The car pullers and box car loaders have been described before. The second type of man trolley equipment is shown in Fig. 5. This type is equipped with clam-shell buckets weighing 7 tons, while the total weight of moving equipment is 40 tons.

The energy is delivered to the transformer house, shown in Fig. 7, at 13,000 volts, three-phase, and is reduced to 440 volts by three 500-kw., single-phase transformers. The current is distributed to the bridges, as shown in Fig. 7, by three conductors running on the rear elevated stationary leg. Each hoist is equipped with one 225-h.p., three-phase, 25-cycle wound-rotor motor for closing and hoisting the bucket, and two 112-h.p. motors for racking.

The control is alternating-current magnetic, and has thus far operated with no trouble at all. The braking is friction, operated by foot levers.

The first type of man trolley equipment has been in use about two years, and while considerable trouble was experienced at first, the difficulties are being overcome and satisfactory results are now assured.