The shaft is equipped with a series of “collars.” These collars, which are enlargements of the shaft, are so placed that they fit between a series of surfaces attached firmly to a heavy fixed base, and when the propeller thrust tends to slide the shaft lengthwise, the “collars” press against these interposed plates which prevent the shaft from moving laterally without preventing its rotation. Naturally enough these thrust blocks must be lavishly oiled, for the friction between the turning collars and the fixed thrust blocks would otherwise soon wear both the collars and the blocks. When the propeller is reversed the thrust is against the other side of the collars, and so the engine is relieved of all duties save those of turning the shaft.
When the shafts have passed these thrust blocks they have entered the engine room, which on these great liners is a place far different from the engine rooms on the smaller ships that are to be found the world over.
Perhaps the first thing that would strike an inexperienced visitor in the engine rooms—for there are three—of the Majestic is their size and the absence of moving parts. Aside from the hum of turbines and generators and the vibrations that are a part of every power plant, there is little to tell a person unacquainted with such power installations that the engines are going. Great turbine cases are bolted strongly to their bases, but the rapidly moving vanes are entirely hidden from view. A few men wander here and there, some watching indicators, others testing bearings, still others polishing the already shining machinery, but there are no turning shafts, no moving wheels in view. As a matter of fact, most of the visible motion and most of the sounds as well come from a lot of little machines whose duties are important, of course, but are not directly connected with that one great task of spinning the propellers at 180 revolutions every minute day and night while the miles are being rapidly put behind the great ship as she speeds along her route across the Atlantic.
So complicated and so huge is this collection of machinery that it may, perhaps, be better to pass by the engine rooms for the moment and go to the stokehold, or boiler room, in order to get an adequate idea of how the machinery is operated.
THE BELGENLAND
Belonging to the Red Star Line.
In smaller ships all the boilers can often be placed so that there will be but one stokehold—that is, one compartment from which all the boilers are fed. Ships of the size of the Majestic and Leviathan, however, are equipped with so many boilers that they cannot all be grouped about one stokehold. The Majestic, for instance, has forty-eight separate boilers which, if they burned coal, would require 12 chief stokers, 197 firemen, and 168 coal passers in order to keep the fires burning properly. The most modern of these giant ships, however, do not burn coal. Oil is led to the boilers in pipes and, on the Majestic, but eighty-four men are required to get the results that it would take 377 men to get with coal. These 84 men are divided into three watches, so that the fires are kept burning and the steam is generated with but 16 fire-room attendants and 12 cleaners at any one time. They work for four hours, and are then off eight, coming to the fire room every twelve hours for their four-hour watch.
Each of these boilers has five burners, to which the oil is forced under pressure. Each fire-room attendant (they can hardly be called stokers) has three boilers, or fifteen burners, and the steam pressure in the boilers can be carried at 240 pounds pressure per square inch.
In ships burning coal the stokehold is a grimy place, with yawning openings in the sides leading to the black bunkers where the coal is stored. A few dust-covered electric lights glow dimly in the murky dusk, and when a furnace door is opened the glare of the fiercely burning fires lights up the begrimed and sweating stokers, who seem almost like unearthly creatures toiling in an over-heated Inferno.