B-4 After Engine Room

Destroyers built just prior to WW2 and after were designed in a alternating machinery space configuration. This means from forward to aft, there was a Fireroom, Engineroom, Fireroom No 2, and Engineroom No 2. This alternating arrangement which provided for the cross-connecting and flow of steam/electricity between the different spaces allowed the ship to operate in case of damage to any one or two areas. The after engineering spaces very much duplicated those in the forward section of the ship. While the forward engine room's geared reduction gear and turbine controlled the starboard shaft, the after engine room turned the port shaft.

Gearing class Destroyers operated a 650lb superheated steam plant operating at 850 degrees F. Steam would enter into the engineroom and into a General Electric (GE) high pressure turbine, a GE low pressure turbine, a cruising turbine if applicable, and then into a condenser and Dearating Feedwater tank before going back to the Fireroom for resuse in the boilers. The force of the steam turning the blade in a turbine creates rotational force that is applied to a Westinghouse reduction gear that turn the ship's port propeller shaft. The ship was rated to produce 60,000 shaft horsepower (30,000/shaft) and reach speeds of over 35 knots.

Steam entering the turbine would be controlled at a Throttle board where a sailor called a throttleman would turn large valve wheels. The four main wheels on the throttleboard were for forward, astern, auxiliary, and a crossover valve. This board had indicators according to speed, revolution of the shaft per minute, and direction that the personnel in the Bridge of the ship requested. The sailor at the throttle's would "answer the bells" and turn the valve wheel until matching the request from the Bridge. Wearing a sound powered phone headset and next to a communication station in the engineroom, the sailors could monitor the engineer's circuit on the phone system and ensure that the associated fireroom is enabled to provide enough steam to match the turning of the valves in the engineroom.

Other equipment on the upper level of the Aft engine room includes an evaporator to create fresh water for the boiler and crew from seawater, the ship's service turbogenerator for making electricity, Worthington Low Pressure air compressors to create air for needle guns and air powered systems, and electrical switchboards that controlled the lighting and power distribution to the after part of the vessel.

Conditions were somewhat harsh working in the engineering spaces of a destroyer. The area was noisy, temperatures were sometimes 135 degrees F, and could be dirty. A steam leak at the operating pressure could immediately kill a sailor. Historically, these sailors were called Snipes or the "Black Gang" referring to when their predecessors worked with coal and were typically covered in coal dust.


Throttleboard on USS Harold J. Ellison DD864 (Photo by Ed Zajkowski)


Reduction gear on USS Harold J. Ellison DD864 (Photo by Ed Zajkowski)

Before Restoration



JPK's Throttleboard


B-4 Reduction gear with HP and LP turbines


Reduction gear to the left and both Worthington LP Air compressors in front with LP flask above