Sperry Gyroscope Company

T

HE equipment which applies the principle set forth in a practical way consists of:

• 1.The Master, True North Compass.
• 2.Comp­ass Con­trol-Pan­el—for con­trol­ling the elec­tric cur­rent.
• 3.Re­peat­ers—op­er­ated from the Mas­ter Com­pass, and in­di­ca­ting its exact read­ing at any ins­tant.
• 4.Mo­tor-gen­er­a­tor—for con­vert­ing the ship’s cur­rent into cur­rent of proper char­ac­ter­is­tics for spin­ning the gyro wheels and op­er­a­ting the re­peat­ers.
• 5.Stor­age Bat­tery—for emerg­en­cy op­er­a­tion of the equip­ment in case of fail­ure of the ship’s sup­ply.

The function of each piece of equipment and its relation to other parts is shown on pages 22 and 23.

The Master Compass

The Master Gyro-Compass is contained within a binnacle stand, with glass dome top.

Using Bearing Repeater at Sea.

As shown in the pho­to­graphs and sec­tion­al view, the twin gyro-wheels are sup­port­ed from a frame-work which is in turn set in gim­bal rings. The out­er gim­bal ring is at­tached to the bin­nacle stand by means of a num­ber of sup­port­ing springs. The springs are pro­vid­ed for pro­tect­ing the com­pass against sud­den jars and vi­bra­tions. Fig­ure 18 shows a pho­to­graph of the top view, while the wheels are shown from be­low in Figure 16.

A diagrammatic representation of the Sperry Gyro-Compass is shown in plan view in Figure 17. The elevation, or side view, is shown in Figure 15. These drawings show the working parts of the Gyro-Compass. Each of the twin gyro-wheels is enclosed in a case, which is in turn suspended from the main frame and spider.

The wheels are spun at a high speed in unison by means of electricity. The force of the earth’s rotation combines with the force resulting from the rotating wheels. The resultant action of these two forces is that both wheels turn their axes directly into, or parallel with, the earth’s north and south meridian. The compass card, of course, also turns and indicates direction by comparing the stationary “lubber line,” representing the ship’s head, with the compass card.

A single gyro-wheel would cons­ti­tute a sat­is­fact­ory sta­tion­ary, or “land com­pass.” On ship­board the roll, yaw and pitch of the ship would impose ad­di­tion­al duty on a single wheel. It would have to point not only True North, but also offset the effect of the sea. One of the two wheels is ar­ranged to always point True North, while its twin wheel op­poses and neutralizes all in­fluences other than the force of the earth’s rotation. The force of both wheels is utilized in seeking the mer­i­dian.

The Master Gyro-Compass is a marvel of mech­an­ical per­fec­tion and rug­ged­ness. Every ro­tat­ing or re­volv­ing part moves upon special bearings to reduce friction. It should be noted also that the gyro-wheels do not directly operate the compass card. The compass card is turned by a small electric motor (Azimuth Motor), Figure 17. The slightest change in position between the wheels and card operates the “trolley” or electrical contact, which controls the Azimuth Motor. The card is made to “shadow” the wheels. The follow-up is so close that the card frame has been called the “phantom.”

An electrical transmitter, Figure 17, is operated by the movement of the card. This transmitter is the means by which the repeaters are kept in unison with the movements of the Master Gyro-Compass, and made to show the exact reading at any instant. Again the Azimuth Motor furnishes the very slight amount of power required to operate this device.

Figure 13.

The Master Compass is placed near the center of the ship at the water line. At this point the effect of rolling is at a minimum. It is, however, not necessary to place it exactly at this position. Figure 13 shows the approximate location of the various pieces of equipment aboard ship.

A familiar application of the repeater principle is that used in hotels and public buildings, where a number of repeater clocks are operated from one master instrument. Likewise, the repeater used upon the bridge, the bearing repeater, and the one at the after steering station, are all operated by electricity in perfect unison with the Master Gyro-Compass and show the exact reading of the Master at any instant. Repeaters are operated by a small electric motor within each case, controlled by the transmitter at the Master Gyro. In designing the repeaters particular attention has been given to the electrical circuits so as to make all connections water, spray and condensation proof. Stuffing tubes of improved design are used at all outlets and entrances.

A miniature electric lamp within the repeater supplies the necessary illumination of the dial. The illumination can be brightened or dimmed by turning the switch handle on the face of the terminal box.

The repeaters are supplied in three styles:

• 1. Repeater mounted on steering stand—for use on bridge.
• 2. Bearing repeater mounted within pelorus stand.
• 3. Repeater mounted on bulkhead in Master’s room, or at the after steering station.

Special stands or fixtures can be supplied if necessary.

A metal “non-reflection” cover is supplied which can be fitted to either the bridge or the after steering repeaters. The cover has adjustable doors and a hood. Its object is to exclude all light from the top glass of the repeater except at the lubber’s line. No light will be reflected into the eyes of the helmsman. The doors can be closed until a very small sector of the repeater dial appears at the lubber’s line. Experience has proved that it is easier to watch and concentrate when only a small portion of the dial is visible. A magnifying glass can be used in conjunction with the cover so that the repeater indication can be read at a distance.

An improved design of azimuth circle is furnished which fits directly over the top of the repeater. Figures 24 and 26, on page 30, show the azimuth circle and bearing repeater in use, taking a bearing on a distant object, and on the sun respectively. This azimuth circle is so constructed as to bring the object, the spirit level and dial within the field of vision concurrently. The bearing can be taken with great accuracy. There is no possibility of the Master Compass changing its position while the pelorus is in use. Such an occurrence is not uncommon when using the ordinary pelorus or “dummy” compass.

An additional graduated ring, Figure 25, is supplied for placing under the azimuth circle so that in case the Gyro-Compass is not operating such, for instance, as when the ship is at anchor, the pelorus can still be used as a “dumb” compass. The main compass setting is made upon the ring, and the azimuth circle used in the usual manner.

The bearing repeater can be furnished with any one of three kinds of azimuth circles. The Ritchie circle is usually supplied. The purchaser also has the option of choosing either the Sperry circle or the Kelvin Azimuth Mirror.

Compass Control-Panel

The compass control-panel provides a means for controlling the various electrical parts of the Gyro-Compass, the storage battery, motor-generator and ship’s supply current. It is very compact, neat, and of good appearance. It receives electrical power from the ship’s mains and distributes it to the motor-generator set, Master Compass and repeater.

The switch panel is made up of black ebony asbestos, mounted upon angle iron. The panel is usually mounted with its back near the bulkheads, but so hinged as to admit of access to its rear.

Motor-Generator

An outstanding feature of the Gyro-Compass is that it makes possible the recording of the actual courses steered by a vessel. The recording compass is connected to the electrical circuits like a repeater and follows the movements of the Master Compass. It not only indicates the heading at any instant, but also makes a graphic record on a chart. Radial lines on the chart represent the various courses. Concentric circles represent time—each small division five minutes—each large division one hour.

The dial on which the chart is mounted turns with the movements of the master compass bringing the correct course under the marking point. As the time advances a line is marked on the chart showing the exact course steered at a definite time. On starting, the marking arm is at the inner edge, clockwork moves it toward the outer edge with uniform motion.

The chart shown in Figure 32 forms a valuable record. It was taken on a ship at a time a radio call was received from a burning oil tanker. Being within the distance defined by law, the ship was legally, as well as morally bound to proceed to the distressed ship. The chart shows that the course was altered to go to the tanker’s aid. It also showed the exact time, thereby establishing proof as to the fulfillment of the obligation. A few minutes later another radio call advised that the fire aboard the tanker was extinguished. The chart shows that the course was again altered to bring the vessel back on her original given course.

The chart further shows the actual courses steered in holding the ship on its given course. It shows just how efficiently each helmsman handles the ship. It provides an excellent method of training helmsmen to use less helm, effecting a saving by less frequent use of the steering engine.

The recording compass is a great aid to the Captain and Navigator in improving the navigating efficiency of the ship.

The recording compass can be supplied as a part of the Gyro-Compass equipment—its additional cost is small when compared to the saving and benefits derived from its use.

Operation

The operation of the Sperry Gyro-Compass is made easy by making all parts as simple as possible.

In starting the equipment it is necessary to turn but one switch. The twin wheels immediately start spinning and will in a short time come up to the normal speed.

After the speed has been attained, a short time is allowed for the wheels to cause their axes to “settle,” or, in other words, to seek and hold the meridian.

In case of failure of the ship’s supply, or other trouble, an audible signal immediately gives indication that something is wrong. This is a decided improvement over the ordinary compass, as no indication is afforded of the presence of factors which cause errors in its reading.

Care

All of the greatest commercial aids require some care, such, for instance, as the telephone, typewriter, adding machine, duplicating machine and so on.

Fig. 33. Repeater at After Steering Station. Fig. 35. Repeater on Wing of Upper Bridge. Fig. 34. Bearing Repeater on top of Wheel-house.

Fig. 38. Master Compasses on Long Run Floor Test. Fig. 39. Master Compasses under Test on Special Machine constructed to simulate the motion of a Ship in a Heavy Sea.