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18 FIG. 3—WHEEL AND ARMATURE OF GYRO ployed in this ship, showed, however, that the estimate of roll from the ship’s clinometer may have exaggerated this arc to some extent. After installation it was found that when the gyro was thrown “off,’ a free roll of from 24 degrees to 40 degrees of total arc was quickly developed while running in the trough of the sea, and when the gyro was thrown “on,” this was quickly re- duced and held at 2 degrees or 3 de- grees. From the characteristics of WHuIDGEON, the position selected and the fact that a little gasoline-electric generator installed for the purpose was available for driv- ing the gyro, a wheel of 3 feet diame- ter by 10-inch face was adopted as the size best suited to the conditions. This wheel is run at very low fibre stress, giving a very large factor of safety, the maximum stress being about 12,000 pounds. The current supply being direct current, a direct current motor was constructed practically as a part of the rotor shaft, as shown in Fig. 3. It is interesting to note how small a motor is really required to maintain such a wheel as this at a speed of about 2,750 revolutions per minute, this motor having run the wheel repeatedly to 3,500 for over-stressing and test pur- poses. The motor is in excess of the actual spinning requirements by fully 300 per cent for quickly energizing the THE MARINE REVIEW rotor mass in getting it up to speed. At the ends of the shaft are located the main _ bearings, which, though specially made, are of the ordinary annu- lar ball type, ample provision being made for taking care of the end thrust. In each end of the casing are oil wells and a little slowly rotating oil pump which circulates the oil upwardly through the coolers, a strainer seen in Fig. 2, and back over the top of the bearings, thus insuring both ample lubri- cation and cooling of the bearings. The temperature’ difference between the in- coming and outgoing oil is just notice- able when the gyro is doing full duty in heavy weather, this temperature practically equalizing when the gyro is not precessing. It is also extremely interesting to note that while the radial load on these bearings varies between practically zero and about six tons, the power varies only slightly, one observation showing a change of from only 35 to 40 amperes between these two conditions. This indicates that the power consumption is due only in small degree to the bear- ings, be they loaded or otherwise, but largely to windage, which is constant for the constant speed maintained in these tests. Use Auxiliary Gyroscope The system of control is practically identical with that which was finally adopted in the last experiments on Worven. A. small auxiliary gyro, shown in Fig. 5, is employed to feel out the incipient rolling of the ship by closing small electrical contacts plainly to be seen, as soon as the ship rolls very slightly one way or the other. These contacts are required to handle only a very few watts, in fact about one-quarter of the energy of an ordinary incandescent lamp, and through a relay switch serve to actuate a small reversing motor which constitutes the precession motor shown in Fig. 6. This motor precesses the gyro upon its main supporting gudgeons at the ends of the frame; it is here that the gyro lays hold’ upon the ship to. control its move- January, 1916 |; : = ape = 4 - F}- for Gudgeon Bearin aN FIG. 4—-ELEVATION OF GYRO PLANT ments. The motion of the precession motor is transmitted through a centrally lo- cated flexible coupling, on the periphery of which is seen the solenoid-controlled brake, which always goes “on” when the motor is off,” and vice vetsa. The coupling drives a worm engaging a worm gear within the oil-tight housing, shown at the left in Fig. 6. The steel pinion seen in the foreground at the endof theworm gear shaft engages the circular rack upon the precession frame, shown in Fig. 7, so that whenever the motor turns in either direction the pre- cession frame slowly oscillates to and fro upon its main gudgeons. The re- sponse to slight angles in the ship’s motion is found to be very complete— one person walking from rail to rail actuates it—and practically without time lag. With each of these tilts of the gyro very heavy gyroscopic moments are developed and delivered to the ship simultaneously with and in opposition to each wave increment from the sea; these opposite forces cancel each other. While this contest of forces goes for- ward, the ship, with its ponderous mass, which always requires time to take on motion, stands aloof and does not move one way or the other until one of these forces conquers. The gyro is always victorious, and the ship is thus actually given an incipient roll in the opposite direction, the contact of the little con- trolling gyro which initiated all of these FIG. 5—AUXILIARY GYRO FIG. 6—REVERSING PRECESSION MOTOR FIG. 7—GYRO SHOWING CIRCULAR RACK ON PRECESSION FRAME