66 units with one exception. The

66 units with one exception. The

Allis-Chalmers cooling units on the older main motors are made in three sections which cover approximately 90 percent of the outer surface of the motor

power ranging from 20 hp to 2,700 hp per propeller shaft at speeds ranging from approximately 67 rpm to 282 rpm.

For submerged operation, using various

frame. The remaining surface is covered with a dummy section to secure the necessary clearance for the motor arrangement in the motor room.

This arrangement is such that each motor has its cooler sections placed on different portions of its outer surface.

6C7. Description of the double armature propulsion motor. On the latest type submarines, main motors and reduction gears have been replaced by two 2,700-hp double armature motors, directly connected to the propeller shafts, one to the

starboard, the other to the part shaft.

The motors are of the two-wire, direct-current, compounded, compensated type with shunt and series field windings and commutating poles.

Separate excitation for shunt fields is provided by the excitation bus which receives power directly from the battery in the control cubicle. The motors are totally enclosed with a water tube air cooler mounted crosswise over the motor frame.

Mechanical air filters are located in the air ducts between the coolers and vent blower. When the motors are operating in the SLOW position, neither cooling air nor circulating water is required.

The motor frame is split at an angle of approximately 11 degrees from the horizontal center line to permit easy removal of the armature. The motor is watertight below this joint and

waterproof above.

The armature is mounted on a hollow forged steel shaft which is flanged at the after end for coupling to the propeller shaft. Each end of the shaft has a bearing journal for a

force-combinations of armatures and taking power from the batteries, the motors will develop power ranging from 30 hp to 1,719 hp per propeller shaft, and will give a speed range from 42 to 219 rpm.

6C8. Main control equipment.

Fundamentally, the construction of main propulsion control equipment produced by General Electric (See Figure 6-2), Westinghouse, and Cutler-Hammer is similar. Individual components may vary somewhat in design; their locations and method of installation in the

assembly may differ; cables and conduits will be found routed differently; but, each assembly as a whole performs the same function and is operated in a similar manner.

6C9. Split type main propulsion control equipment. (See Figure 6-3.) The split type control equipment is installed on some of the later type submarines on which double armature, slow speed, directly connected

propulsion motors are used. This equipment performs the same functions as the standard control cubicle, and with minor exceptions is operated in the same manner.

The two halves of the control panel are essentially the same. Each half is

mounted in a steel frame that is joined to form a single unit and shock mounted to the hull. The starboard control panel consists of the generator levers for the No. 1 and No. 3 generators, starting with reversing levers for the starboard motor, a bus selector, and a forward battery lever. The port control panel consists of the generator levers for the No. 2 and No. 4 generators, starting and reversing levers for the port motor, a bus selector,

lubricated, split sleeve bearing, mounted in a pedestal, separate from the frame. In addition to the radial bearing, the forward end of the shaft is fitted with a collar for a Kingsbury thrust bearing which takes the propeller and motor thrust load.

For surface operation, using the

various combinations of armatures and taking power from the main

generators, the motors develop

and after battery lever.

6C10. Functions. The control equipment performs the following functions:

1. Start, stop, reverse, and regulate the speed of the main motors for both surface and submerged operation.

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Figure 6-2. General Electric main propulsion control cubicle.

2. Provide for series, parallel, or series-parallel connection of the motor armatures.

3. Provide for uniform speed control of the main motors throughout the entire range of propeller speed from about 42 to 219 rpm submerged to about 280 rpm on the surface.

independent of each other except for a common excitation bus.

7. Provide for operation ahead on one propeller shaft and astern on the other at any speed within the designed operating range.

8. Provide, by means of shore connections, for charging the main

4. Provide for operating the main motors from one or both main storage batteries and from any combination of the main generators.

5. Provide for charging one or both storage batteries with main generators individually or in combination. Main generators not being used for battery charging may be used for propulsion power.

6. Provide for driving the starboard motors from the starboard generators and the port motors from the port generators entirely

battery from shore or tender.

6C11. Simplified circuit description.

The main control cubicle circuit consists essentially of two buses, the motor bus and the battery bus, to which the main power units are connected by means of their associated contactors in order to provide the various operating

combinations. The motor bus is the one to which the main motors are connected for any of the running conditions by means

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Figure 6-3. Split type of main propulsion control cubicle.

of their starting contactors.

The motor bus can be split for operation of the motors on each side independently of the other sides (BUS TIE OPEN), closed for parallel

operation of both motor groups (BUS TIE CLOSED), connected to the battery bus for battery operating of the main motors (BATTERY BUS), and lastly, for series operation of all motors the positive side of one motor

a. Port and starboard motor reversing switches.

b. Port and starboard motor starting contactors.

c. Bus selector switches.

3. One forward contactor group comprising:

a. Port and starboard main generator contactors.

b. Forward and aft battery contactors.

bus can be cross-connected to the negative side of the other motor bus, so that by proper closing of the motor contactors, all four motors can be placed in series for slow-speed

operation on the battery bus (SLOW).

Either or both batteries are connected to the battery bus by closing their respective contactors which, in turn, are controlled by one operating lever.

6C12. Principal parts. The principal parts of the equipment are as follows:

1. One main propulsion control panel and operating bench with necessary instruments, rheostats, and operating levers.

2. One aft contactor group comprising:

c. Motor bus tie contactors.

All parts are mounted in a number of steel frames which in turn are joined to form a single unit. The assembly is supported on rubber shock mounts that are welded to the hull.

6C13. Operating levers. There are 10 levers for manual operation of the contactors in the various switch groups.

These levers are provided with lock latches and are connected mechanically to the contactor camshafts through a series of bell cranks and rods. The purpose of the levers is as follows:

a. Two reverse levers. These levers are

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