Erie Railroad - Erie Railroad Lake Line - Engine Performance, "George F. Brownell"
Excerpted from the March, 1914 issue of Erie Railroad Magazine
TELEGRAPH SIGNAL RECORD ENGINE SPEED/DIRECTION RECORD
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Signal Recording Apparatus Chart Reproductions of Graphic Signal and Engine Movement Recording Apparatus on Steamer "George F. Brownell" (From the Marine Review.)
The "Review" herewith presents reproductions of a section of each chart from the graphic signal and engine movement recording apparatus on the steamer "George F. Brownell," of the Erie Railroad Lake Line.
The charts show graphically the movement of the ship from the Erie dock at Washington Street to the Santa Fe dock at 27th and Robey Streets, in the south branch of the Chicago River and were selected because of the constant maneuvering required in the swift current of the south branch. It will be noticed at once that the engines were being worked principally on backing signals and the time intervals are very short. The chart speed is 6 in. per hour, the ordinate spacing representing 7 1/2 minute intervals. Some of the signals are less than fifteen seconds apart, yet the engine response is clearly indicated not only as to direction, but also as to speed. The latter is readily determined by the abscissae spacing, each space representing five revolutions. Not a response is missing. It will be at once apparent that, first, the signal actually given is recorded, and, second the action actually taken in the engine room is similarly recorded, the graphs moving side by side at the same speed and operated by the same clock mechanism.
Devices exist which indicate visually to the officer on the bridge what the engines are doing but so far nothing has been done to establish what was done on the bridge or to make a synchronous graphic record of either the signals given or the action which followed. Hence frequent disputes as to "mistakes in signals."
The numerals in the margin have been added merely for convenience in comparison and do not appear on the charts. The time spacing is not shown, since, as previously intimated, the apparatus has been under observation only, though continuously, and the speed and consequently time spacing, had not been finally determined when the charts were laid out.
The overrunning of the pen at the shift of signals is due to the momentum of the pen itself, the shift being instantaneous, but does not affect the clarity of the record. Similarly the wavy appearance of the engine record is due to the extreme sensitiveness of the pen which is affected by any vibration of the ship. In the case shown the ship was light and the tremor usually observable under such conditions is quite apparent. The record, however, is not in any way affected thereby.
Several interesting features will be discovered upon an examination of the charts.
Beginning with 1, the first signal is "ahead slow," then "stop," then "astern half," "stop," "astern slow/' "stop," "astern slow," "ahead slow," "stop," "astern slow," "stop," and in 5, "astern slow," followed almost at once by "astern half" then back to "astern slow," and within a few seconds to "ahead slow." The action of the engines is perfectly clear both as to direction and speed. Similarly in 11 is shown "astern slow" followed shortly by "astern half," and then "ahead slow" increased to "ahead half," swinging clear across to "astern half," the last working signal being "stop," followed by "finished with engines." The total time covered by this section is 93 minutes and records 51 signals given and answered, an average of one every 1.8 minutes. The longest interval between signals is 6 minutes, the shortest about 10 seconds.
The length of interval, however, or even the exact instant at which a signal is given, are relatively unimportant compared with direction and speed, and since ahead and astern working and signals are shown on widely separated portions of the cliart, agreement or disagreement is apparent instantly and on the most casual inspection.
The apparatus is not considered to be a preventive of, but a means of fixing responsibility for, disaster, though it furnishes also a pen picture of the handling of the ship and a continuous graphic record of performance under way, showing not only the interpretation of signals in the engine room as to speeds, but the promptness with which they are answered and even momentary variations in speed under way.
For instance, one chart showed a stoppage of engines in midlake without any shift of telegraph, bringing out the fact that the engines were stopped to secure an oil pipe which had worked loose, although not noted in the log, and started ahead again without notice to or from the bridge. It also brings out variations in steam pressure and the consequent change in engine speeds, not apparent in the regular log without comparison of hourly counter reading and checking of averages.
The "Brownell" passed through the terrible gale of Nov. 10 on Lake Huron and the engine record chart of that date brings out engine room conditions more clearly than any description. Although a high-powered ship, on two occasions it was found impossible to keep her head to sea at the permissible engine speeds. The chart shows the beginning of influence of sea on engine speeds at about Point Aux Barques, and from then on gradual increase in racing and the enormous range in the efforts to bring her back head to sea at which times the speeds varied almost instantaneously from 15 to 95 revolutions per minute. As these engines are 54-in. stroke, the piston speed varied from 135 to 855 ft. per minute.
There is no mechanical connection whatever between the different parts of the apparatus, even the operating current for the two recording pens being derived from different source.
A visual speed and direction indicator operated by current from the same source as the engine recording pen is fitted under the eye of the master merely to show him what is going on below but is not considered an essential, or even valuable, feature.
The "Review" believes it to be a subject for regret that its inventor announces that there is no present intention to offer the apparatus for general use. It was developed as a matter of interest only and to demonstrate a belief arising out of several instances of extensive damage attributed to mistakes in signals, in some of which the signal actually given and the responsibility for the damage incurred was open to serious doubt.
Its description, for which we are indebted to H. Penton, of Babcock & Penton, engineers and naval architects, New York and Cleveland, is offered as he says "merely to illustrate the results obtained in an effort to work out an interesting and always present problem." That it has been solved we think will be agreed.
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