U. S. NAVAL INSTITUTE, ANNAPOLIS, MD.

SPEED CONTROL IN MODERN STEAMERS.

BY LIEUTENANT M. L. WOOD, U. S. Navy.

When steam was applied to the propulsion of vessels, the control of the speed was effected by means of verbal orders passed along the deck to the engine-room. The boys employed on board the early passenger steamers in the Thames seem to be conspicuous in the accounts of travellers in those days.

In ocean steamers a system of communication was gradually developed which was in general use up to within a few years. This consisted of signals transmitted by ordinary bells, of which two were used, one a single stroke gong and the other a "jingle bell." The signals in common use were as follows with the single stroke bell: I bell (when stopped), "ahead slow." I bell (when going ahead full speed), "slow." I bell (when going ahead slow or backing), "stop." 2 bells, "back." The jingle bell indicated full speed on engine whether backing or going ahead. It was also used to indicate "stand by the engine" or "through with the engine." This system has stood the test of extensive practical use in all sorts of vessels, giving satisfaction until the introduction of more modern means. It will be noticed that the meaning of the signal depends upon preceding signals and the action of the engine at the time. A slight lapse of memory or of attention at critical moments might result in misunderstanding the signals for working the engine, with possible damage to the vessel itself or to others in close quarters.

The extent to which a system of sound bells can be developed is shown in some of the western river steamers of the United States. The old Mississippi River steamers, where the strong

99 66

ping, in case of a hail, at almost every plantation-landing with the bow up-stream, have a very efficient system which serves admirably for handling vessels under exceptionally difficult conditions, and, incidentally, as an example of extreme complexity. The larger river steamers were side-wheel, with each wheel actuated by a separate engine controlled by a complete set of signal bells. For each engine there were “go ahead," stop," "back," and "slow" jingle bells; there was also a "shifting" (single stroke) bell to indicate reversing the "hooking-in" valve gear when the next signal would require a change in valve motion. This would seem complex enough, but, in addition, each bell had double pulls in the pilot-house, so all the bells could be worked from either side of the wheel. Besides these there were also bells to the firemen to "open doors" and to "fire up," and to the gangplank engines, with voice-tubes to engines and other parts of the boat. The whistle was worked usually by a treadle or foot lever. All this was manipulated by one man-the pilot-who, in addition, handled the steering-wheel alone, unless he had an apprentice-called a "steersman "-temporarily under his instruction.

To enable one man to steer the large steamers along their devious track, the steering-wheel was made large, ten to thirteen feet in diameter, with the axle below the floor of the pilot-house.

This was the system in use on the Mississippi river in the palmy days of the trade, and is still in use, with few changes, at the present day.

One peculiarity of this system is that every signal to the engine signified "full speed" unless accompanied by a "slow" bell. The signals are nearly all "positive" in their meaning, as they do not depend upon preceding signals.

In spite of its apparent complexity, this system of engine control certainly served its purpose, as the engines were worked with a promptness and certainty that resulted in the delicate and efficient handling of the vessels necessitated by the conditions of the trade.

In the older steam vessels of the U. S. Navy, including those yet in use at the present day, a system is in use differing from both those described, as it makes use of but one single stroke gong. With this system, I bell, "ahead slow"; 2 bells, "stop"; 3 bells, "back"; 4 bells, "ahead full speed." The advantages

the second bell and the wiring, and also that the signals are positive, having but one meaning, irrespective of preceding signals.

The principal disadvantages are: that it is noisy, hard upon the bell connections, that it is liable to fail at critical moments if signals are given under excitement or by an unpractised hand; that it is slow, as time must be lost waiting to see if there be a following stroke, which may change the signal completely; if obeyed too quickly and therefore improperly, hesitation or doubt is produced by the attempt to go ahead and back at the same time; that the first two strokes of "4 bells" is often mistaken for 2 bells, with the result that the engine is partially slowed, or even stopped, when "ahead full speed" is required to avoid accident; last but not least, there is no provision for backing full speed, which may be the only means of averting danger.

In fact, the "4-bell" system is about the worst in use anywhere. Its disadvantages come out strongly in the case of smaller vessels making frequent landings, and in these it is usually avoided by the adoption of the merchant code whenever practicable without attracting official attention.

There is a system of signals to the engine-room suitable for use on board vessels where it has not been deemed expedient to fit modern engine-room telegraphs, which has been developed probably by accident, but which has stood the test of practical working wherever tried. In this, two bells are used, a singlestroke bell and a jingle bell. The signals are as follows: I bell, "ahead slow"; 2 bells, "stop"; 3 bells, "back"; jingle bell, open throttle," i. e. "full speed" on the engine whether going ahead or backing.

The advantages of this are numerous enough to warrant its adoption on board all vessels of the Navy not fitted with engine telegraphs. The signals are all "positive," since they do not depend upon preceding signals. The reliability of the bell is improved, as it does away with "4 bells," with its chance of breaking down or of confusing signals. It also furnishes the important signal "astern, full speed," which is an important one. The only change required to introduce this system would be the placing of a second bell on board vessels. This expense will be very slight compared with the lessened risk of damage

In all these systems using sound codes the only information given to the pilot-house as an indication of the proper transmission of the signal is the sound, assisted by tubes, of the bell itself, which for this purpose is much louder than would otherwise be necessary.

In modern steamers the necessity for quicker and more reliable signals to the engine-room has developed the use of engine telegraphs, using visual signals in place of sound signals. As at present in use on board all, or nearly all, modern steam vessels, the engine-room telegraph, whatever may be the special design, consists essentially of a small lever moving over a dial on the bridge connected by various mechanical means with a pointer in the engine-room, whose motions are made to correspond exactly over a similar dial. Each position of the lever with the corresponding motion of the pointer indicates a signal and rings a bell to call attention. The signals transmitted are as follows: "Ahead, full speed," "three-quarters speed," "half speed," "slow," "stop," "back slow," "half speed," "three-quarters "speed," "full speed astern." Sometimes other intermediate signals are used. The indication that the signal has been received is a return signal made by a lever in the engine-room which moves a pointer over the telegraph dial on the bridge repeating the signal and acknowledging the receipt of the signal to be carried into effect. The motions of the propeller shafts are shown by indicators in the pilot-house which indicate the motion and the direction of motion of the engines.

There are several designs which work efficiently upon the principles stated generally above. Their working is shown by thorough tests in service which demonstrate their utility. It will be noticed that the signals are greater in number than with the bell codes using sound signals, thus giving greater delicacy in handling vessels than was before thought possible or deemed essential.

The management of the helm has also been developed. Vessels were steered by a tiller on the rudder-head by hand-power directly applied, until the increase in size of ships led to the adoption of a steering-wheel to give increased mechanical power over the movements of the rudder. The shifting of the steering

handling, necessitated longer wheel connections with increased friction, which in turn led to the use of engines for controlling the rudder. After many attempts, lasting through many years, the present systems of steam steering gear have been developed. The difficulties of the problem were great. A heavy rudder, in large vessels, weighing thousands of pounds, exposed to violent shocks from waves, was to be moved either by slight changes, starting from any position, or rapidly, from one side to the other. This motion had to be under perfect control, since the rudder was, by the conditions accompanying its use, required to follow exactly the motions of the steering-wheel on deck. Too much motion of the rudder was as bad as too little, since its duty is to steer a large, fast steamer to degrees of arc on her course, or, on the other hand, to change direction suddenly to avoid danger. These mechanical difficulties have been completely overcome, there being several designs of steam steering gear which can now be relied upon in every respect.

The general design of all the patterns is about the same, the principal differences being in the means used to attain the end. Steam steering gear in general is as follows: A small steeringwheel in the pilot-house, or on the bridge, in the forward part of the vessel, is connected by shafting and gearing, wire ropes, or combinations of both, to mechanism moving the valve of the steam steering engine in a compartment near the stern; this valve admits steam to the cylinders revolving the drum in the direction decided by the motion of the valve. A small motion of the valve produces a small motion of the drum connected with the tiller by chains or gearing.

This limitation of the effect is produced by a "stop motion," differing in different systems, in which a lug or projection attached to a cut-off valve follows the valve by the revolution of the drum until it catches up with the valve, when it stops the engine and, therefore, the tiller, by shutting off steam. It will be readily seen that the devices to produce this effect are necessarily too complicated for description here. They, however, have been found to do their work properly and are thoroughly reliable. When the small wheel in the pilot-house is moved slightly, the rudder makes a correspondingly slight movement, stopping in the new position, held firmly by the steering engine