Engine Operations

Steam Flow

Steam entered the engine at 265psi and flowed through three increasingly larger diameter piston cylinders (triple expansion); one 39inch high-pressure, one 63inch intermediate-pressure and two 83inch low-pressure. (Some ocean liners had quadruple expansion engines).  While the steam pressure decreased as it went through each cylinder, the lower energy was offset by the increased area of piston surface for the steam to expand on.  

• Engines are one-stroke (dual action):  Unlike a four-stroke car engine or a two-stroke motorcycle, BB35 engines were one stroke.   Each up and down movement of the pistons was a power stroke because steam entered on the top and bottom of the pistons.   During a power stroke, the steam on the opposite side of the cylinder was exhausted to the next cylinder (or the condensers if at the low-pressure cylinder).

When both low pressure pistons filled with steam, the volume of steam had expended to 10.6 times the original volume that entered the high pressure cylinder. 

When the steam was exhausted from the low pressure cylinders, the pressure was below atmospheric and had to be evacuated with a pump to the condenser which is outboard of each engine, against the outboard bulkhead. Cold saltwater circulated through the condenser to convert the warm steam to fresh water, which was then pumped into fresh water feed tanks for use by the boilers to make steam that goes back to the engines.

Cutting off steam: To perform maintenance on the engine, all steam is cut off.  To cool the engine at an even rate to prevent warping, the engine is mechanically rotated with the jacking gear.  On the crankshaft is a large brass toothed gear. A worm gear intersects with the brass teeth with the worm gear shaft being connected to a 15hp motor, through a series of reduction gears.  According to data on a BB35 drawing, one rotation of the crankshaft takes about 7.5 minutes

Starting a cold engine:  1.5 to 2 hours was needed to get a TEXAS engine ready to operate if starting cold, according to a 1941 US Navy pamphlet for operating large steam reciprocating.

Fuel efficiency: At low speeds the reciprocating engines were more fuel-efficient then most turbines. A July 1935 US Navy fuel consumption table  shows that of he 15 US battleships gallons of fuel oil consumed at 6 knots of speed, TEXAS was 6 out of 15. (4 other turbine ships and NEW YORK used less fuel then TEXAS). TEXAS engines used more fuel then NEW YORK at all speeds with the difference increasing speed increased. TEXAS engines were more fuel efficient then OKLAHOMA, up to 10 knots.

Other Engine Facts

Last US battleships with reciprocating engines: NEW YORK -BB34, TEXAS - BB35 and OKLAHOMA - BB37 

Largest US Battleship Engines TEXAS and NEW YORK

Unmodified since 1913: Some small items such as steam traps and valves were changed but the mechanics of the engine (crankshaft, bearings, pistons, cross-member heads etc) are as they were, in 1913.

Designed for turbines:  Original propulsion drawings 29 Sept 1910 for one turbine with four propeller shafts. The turbine was of the ARKANSAS design, shaft horsepower 32,000 (about 4,000 more then reciprocating engines) with rpm 330 vs 125.  By early December 1910, before the contract was issued, the USN changed propulsion specifications to reciprocating engine.  The change was due to the fuel efficiency of the turbine at lower speeds being much less efficient than the reciprocating engine.

1923 plans for turbine installation: In 1923, US Navy drawings were made for replacing the reciprocating engines with a turbine. The turbine location was to be in the boiler rooms, with the boilers being moved outboard. The plan was not implemented.

Not affected by 1925-1926 modernization