The diagram at left illustrates the basic concept of the triple expansion marine engine, which introduced a new level of reliability into steam engineering in the late 1880s, being universally adopted by all the world's navies within a few years. High-pressure steam (red) is admitted to the smallest, high-pressure (HP) cylinder, exhausted into the steam chest for the intermediate pressure (IP) cylinder (orange), which in turn exhausts it to the low-pressure (LP) cylinder (yellow/blue), whose enormous piston allows the depleted steam to do a last bit of work pushing a large area before being recycled back to the condenser, to be boiled again and recirculated. The driving rods and valve rods, all attached to the same crankshaft, keep the valves opening in synchrony and the whole complicated assemblage spinning away with considerable noise and vibration. Engines for heavy battleships and vast ocean liners were among the largest built. The very largest, in fact, were constructed at Harland & Wolff's Belfast works for the White Star liners Olympic, Titanic and Britannic. These gigantic machines were more than 30 ft (9m) tall and weighed over 1,000 tons each. They developed 15,000 IHP at 75 rpm, driving the ships at 22.5 kts. Footage of the mighty engines turning is generously featured in the movie Titanic; in that disaster, as in many maritime and naval sinkings, the entire engineering staff perished, hewing courageously to their posts until the last. Engine rooms in battleships were seldom the spacious affair seen on screen in the movie, however; such space was only available on these record-breaking 45,000-ton floating palaces. More good views of the triple-expansion engine in action and repose may be found in the Steve McQueen classic "The Sand Pebbles" (1966) in which McQueen plays Jake Holman, the loner chief engineer on an ancient gunboat cruising the Yangtze and its tributaries in the 1920s. The engine used was the heartbeat of a WWII Liberty ship, and may be viewed by the public on board SS Lane Victory in San Pedro (Port of L.A.). Of course, the father of all engine room footage is Sergei Eisenstein's "Battleship Potemkin," a Lenin-era silent propaganda film about the 1905 mutiny, featuring dramatic B&W footage shot aboard the subject ship in the early 1920s.
The hot, piping-packed spaces of the engine rooms in this era drummed with the ear-splitting chunka-chunka of the pistons and the deep rumble of the crankshaft turning in its bearings. The numerous shafts and rods threw off a fine spatter of oil which got over and into everything. When running at speed, the increase in noise and vibration was terrific, while the bearings had to be constantly splashed with water to cool them. As a result the engine room became a wet, steamy, noisy, rather chaotic space. Voice tubes to the bridge could become unusable because of background noise, making the engine room telegraph (above right) with its loud annunciator bells the only reliable means of 2-way communication with command. Retired Scots engineers were stereotyped -- not without reason -- as all being hard of hearing.
Engines for HMS Triumph at Armstrong's Elswick works, 1901. Twin 6250-HP engines propelled the 475-foot battleship at a reliable speed of 19 kts from her commissioning in 1902 until her fiery demise off Turkey in May 1915. The rusted, but still monumental, remains of the twin engines may be glimpsed to this day on dives to the wreck off the coast of Turkey. The engines of HMS Majestic, also sunk off Gallipoli in 1915, are not so accessible since the vessel turned turtle while sinking, landing on her masts and eventually settling weather-deck down on the bottom as the masts snapped under the weight. Engines of HMS Hood of 1893 were visible through holes in the hull plating at her grave outside Portland Harbour, where she was scuttled in 1914; but divers report the wreck has been collapsing inward and losing the integrity of its original structure in the past 15 years.
Above is a model of a 4-cylinder triple expansion engine (click here to enlarge). In this variation, there were two LP cylinders each feeding off the IP cylinder. This reduced the bore of each to a manageable size for such a large engine. Although after 1905 all the most important navies switched to the Parsons steam turbine for their ships which needed the best speed and power, triple expansion engines continued to be used for most everything else. In reality, triple expansion engines had reached their limits for high-speed, high-performance manuevers and needed a lot of adjustment and maintenance when performing near peak. This was particularly evident with torpedo boats, which competed for speed records on their trials, but often proved unable to perform reliably at speed for long. By contrast, turbine engines, with far fewer moving parts and little friction, performed like a champion at continued high-power demand, but were much less efficient at lower revs. Turbines had been adopted with great success in Royal Navy destroyers after 1899, so the way was smoothed for a massive and daring (because heretofore untried) application in battleships. The first battleship to rely on turbine engines was HMS Dreadnought of 1906. Few engineering officers lamented the shift to turbines, for it marked a radical improvement in their working conditions. Gone were the pools of standing water, the perpetual grease in the air and the pounding of the machinery, replaced by a less colorful but calmer station, with only the whine of the turbines whirling in their massive pressure casings to remind one of the business of the station. But in many foreign navies, including the USN, the familiar clicking of the rods and thunder of the pistons remained common right through WWII on battleships such as the USS Texas and USS Arkansas, built before WWI when U.S. engineering and manufacturing was still unequal to the task of supplying turbines for all our capital ships. It should be noted that the 4-cylinder triple-expansion engines of these vessels performed up to expectations over their long careers. With adequate maintenance, these engines were quite dependable, though they could not deliver the sustained high speeds that were commonplace for turbine engines. On the other hand, there were many problems with producing turbines proficient at low enough rpm's to be efficient with the propellers of the day. The screws were all directly shafted to the engine on these ships, after all. The solution was found just before WWI, by gearing the turbines to the propeller shafts instead of direct-drive. Industry was not up to producing the numbers of precision gear sets needed, however, and the geared turbine option did not come into general acceptance until the 1920s.
The abandonment of the triple-expansion recriprocating engine by the top flight of the world's navies, however, did not put the engine out of use. It had already had nearly as salubrious an effect on the world's commercial fleets as it had had on the navies in the Nineties. Triple-expansion power plants continued to power all manner of craft from steam launches to 450-foot freighters, Coast Guard cutters, tramp freighters, screw ferries, river craft around the world. Before the advent of diesel, they exclusively powered naval supply ships and auxiliaries. The thousands of Liberty ships that rolled down the ways of American shipyards in WWII were all powered by triple-expansion machinery shafted to single screw. For the ships' companies, more revolutionary still was the shift away from coal to oil fuel in the 1920s, once again improving their quality of life. It relieved a fortnightly torment known as coaling ship. In this periodic agony, the ships tied up next to coal barges or other coaling facilities and the men stripped half-naked loaded coal into baskets and burlap sacks and manually brought it aboard and dumped it down hatches and chutes to the bunkers, where trimmers loaded it into wheelbarrows and raked it even to balance the trim of the ship as the fuel was loaded. At the conclusion of each refueling episode, coal dust would have found its way into every corner and crack of the vessel, and about two days of intensive cleaning would be required to restore naval spit and polish.
For the coal-burning navies of the world, the management of the fuel below decks and the generating of steam would now revert to the "Black Gang," the coal-dust streaked stokers and trimmers who would handle the coal and, with well-aimed shovel strokes, spread the fuel over the glowing aggregate in the ship's furnaces. In the lofty firerooms the great boilers loomed over the infernally lit rows of furnace doors, an effect completely lost in these early flash photos. Little honored in histories of the time, the stokers were the modern equivalent of the rowing slaves who powered the Roman galleys, made an indispensable part of modern steam navies until after WWI. They led a life of unremitting, brutal, dirty labor, shoveling the coal into the fire, periodically tending the fires in each of a number of furnaces to ensure efficient combustion, and (worst of all) breaking up the clinker with "slice bars" (small steel girders). Clinker was a red-hot, stone-hard residue of impurities left over when the combustible parts of the coal had burnt off. After the clinker was broken into workable pieces, the stoker had to rake it out of the furnaces, extinguish combustion with firehoses, shovel out the ashes, load and despatch the mixture over the side in bucket hoists provided for the purpose. Then (in addition to tending all his other fires) the stoker had to reignite the newly-cleaned furnace with a fresh load of fuel. Depending on the need for steam, the stokers were cued by annunciator bells set in the engine room; they were slaves to those signals as surely as ancient galley slaves had been to the timekeeper's drumbeat. It was hellish, back-breaking work and the stokers, shunned by 'society' on shipboard and ashore, formed their own hard-bitten in-group. With the impressive physiques built up by their profession, they were renowned pugilists, known for their earthy approach.
Yet without the strong backs and burly muscles of the stokers, none of the fleets of the day could have sailed. There is noted in the statistics for many of the later pre-dreadnought ships a small allowance of oil fuel. Starting around 1902, oil was used to assist the speedy raising of steam. To accomplish this, oil droplets were sprayed over the top of freshly heaped coal to assist in speedy combustion, much as we use lighter fuel to fire up charcoal today. This technique was only used when restarting a grate newly raked out and refueled, or in meeting emergency demand for full steam. However, so successful was the technique that it soon led to the replacement of coal by oil fuel. The spray nozzle was refined to an adjustable jet which could efficiently burn oil alone, making all the steam one could wish without the eternal mess and hard labor entailed by coal. Winston Churchill and Lord Fisher, recognizing the major bottleneck caused by continuing reliance on coal fuel, championed the adoption of oil instead, an innovation realized with the advanced Queen Elizabeth class battleships of 1915. One sympathizes with Churchill and Fisher. Refueling the British fleet during WWI was a huge logistical problem. It demanded thousands of trainloads of coal sent weekly to northernmost Scotland. From there it was transshipped to the Orkneys, where it once again it had to be laboriously bagged, shoveled, and lifted by cargo booms and cranes into the vessels of the Grand Fleet in its anchorage at Scapa Flow. During the lengthy periods of enforced inactivity at the base, coaling fleet perversely became one of the breaks in the monotony. Unfortunately, the source of Britain's oil was Persia (present-day Iran). Britain's ever-increasing thirst for the artificially cheap fuel led it into an ever more predatory relationship with the land of its origin.
The abandonment of the triple-expansion recriprocating engine by the top flight of the world's navies, however, did not put the engine out of use. It had already had nearly as salubrious an effect on the world's commercial fleets as it had had on the navies in the Nineties. Triple-expansion power plants continued to power all manner of craft from steam launches to 450-foot freighters, Coast Guard cutters, tramp freighters, screw ferries, river craft around the world. Before the advent of diesel, they exclusively powered naval supply ships and auxiliaries. The thousands of Liberty ships that rolled down the ways of American shipyards in WWII were all powered by triple-expansion machinery shafted to single screw. For the ships' companies, more revolutionary still was the shift away from coal to oil fuel in the 1920s, once again improving their quality of life. It relieved a fortnightly torment known as coaling ship. In this periodic agony, the ships tied up next to coal barges or other coaling facilities and the men stripped half-naked loaded coal into baskets and burlap sacks and manually brought it aboard and dumped it down hatches and chutes to the bunkers, where trimmers loaded it into wheelbarrows and raked it even to balance the trim of the ship as the fuel was loaded. At the conclusion of each refueling episode, coal dust would have found its way into every corner and crack of the vessel, and about two days of intensive cleaning would be required to restore naval spit and polish.
For the coal-burning navies of the world, the management of the fuel below decks and the generating of steam would now revert to the "Black Gang," the coal-dust streaked stokers and trimmers who would handle the coal and, with well-aimed shovel strokes, spread the fuel over the glowing aggregate in the ship's furnaces. In the lofty firerooms the great boilers loomed over the infernally lit rows of furnace doors, an effect completely lost in these early flash photos. Little honored in histories of the time, the stokers were the modern equivalent of the rowing slaves who powered the Roman galleys, made an indispensable part of modern steam navies until after WWI. They led a life of unremitting, brutal, dirty labor, shoveling the coal into the fire, periodically tending the fires in each of a number of furnaces to ensure efficient combustion, and (worst of all) breaking up the clinker with "slice bars" (small steel girders). Clinker was a red-hot, stone-hard residue of impurities left over when the combustible parts of the coal had burnt off. After the clinker was broken into workable pieces, the stoker had to rake it out of the furnaces, extinguish combustion with firehoses, shovel out the ashes, load and despatch the mixture over the side in bucket hoists provided for the purpose. Then (in addition to tending all his other fires) the stoker had to reignite the newly-cleaned furnace with a fresh load of fuel. Depending on the need for steam, the stokers were cued by annunciator bells set in the engine room; they were slaves to those signals as surely as ancient galley slaves had been to the timekeeper's drumbeat. It was hellish, back-breaking work and the stokers, shunned by 'society' on shipboard and ashore, formed their own hard-bitten in-group. With the impressive physiques built up by their profession, they were renowned pugilists, known for their earthy approach.
Yet without the strong backs and burly muscles of the stokers, none of the fleets of the day could have sailed. There is noted in the statistics for many of the later pre-dreadnought ships a small allowance of oil fuel. Starting around 1902, oil was used to assist the speedy raising of steam. To accomplish this, oil droplets were sprayed over the top of freshly heaped coal to assist in speedy combustion, much as we use lighter fuel to fire up charcoal today. This technique was only used when restarting a grate newly raked out and refueled, or in meeting emergency demand for full steam. However, so successful was the technique that it soon led to the replacement of coal by oil fuel. The spray nozzle was refined to an adjustable jet which could efficiently burn oil alone, making all the steam one could wish without the eternal mess and hard labor entailed by coal. Winston Churchill and Lord Fisher, recognizing the major bottleneck caused by continuing reliance on coal fuel, championed the adoption of oil instead, an innovation realized with the advanced Queen Elizabeth class battleships of 1915. One sympathizes with Churchill and Fisher. Refueling the British fleet during WWI was a huge logistical problem. It demanded thousands of trainloads of coal sent weekly to northernmost Scotland. From there it was transshipped to the Orkneys, where it once again it had to be laboriously bagged, shoveled, and lifted by cargo booms and cranes into the vessels of the Grand Fleet in its anchorage at Scapa Flow. During the lengthy periods of enforced inactivity at the base, coaling fleet perversely became one of the breaks in the monotony. Unfortunately, the source of Britain's oil was Persia (present-day Iran). Britain's ever-increasing thirst for the artificially cheap fuel led it into an ever more predatory relationship with the land of its origin.
Instrument panel, USS Olympia (c. 1895)
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