The Dow Steam Turbine is shown in Figs. 13, 14, 15. In Fig. 13 each alternate disk be ginning with the second one, is stationary, the others being portions of a revolving plate, the manner of their coniblina thin being evident from Fig. 14. In its external appearance the motor is a short cylinder about J in. in diameter and 5 in. in length, with two covers haying., hubs forming bearings for the shaft. The body or shell is a casting, a u u o. The covers b b b b are through-bolted to the shell. Two disks cccc screw permanently into the wall of the body. On the outward face of each disk are formed six series of stationary guide-plates, as shown in Fig. 13, analogous to those of water turbines, separated by annular spaces concentric with the shaft. The interior of the motor is thus divided into three chambers, of which the central one, e e, receives the steam direct from the steam-pipe, and the two outer ones, f f receive the exhaust steam which passes out of the motor Ihrough the exhaust-pipe g. The main shaft h h is jonrnaled to the bear ing formed in the covers. A sleeve i i cov ers the central part of the shaft, at a sliding fit, being splined to receive two correspond ing feathers on the shaft. Two wheels //// arc secured to the sleeve, and it is these wheels which are revolved by the action of the steam, transmitting rotation to the shaft. Upon the inward face of each wheel are formed series of turbines, as shown in Fig. 13, concentric with the shaft and corresponding with and fitting into the annular spaces of the station :OW disks ; thus the faces of the moving wheels seat (nearly) upon the bottom of the annular spaces of the stationary disks, and the faces of the stationary disks seat (nearly) upon the bottom of the annular spaces of the wheels. In the central chamber, midway between the partitions, is a disk I', mounted upon the sleeve ; on each side of the disk, distant from it of an in., is the inner face of the partition, or rather the inner face of an annular face-plate d, whose hub screws into the partition. The disk part of each face-plate stands clear from its partition. and is per
forated by three concentric rows of boles, and the inner face of each face-plate is channeled in concentric grooves between the holes, and cross-channeled by radial grooves, starting near the periphery of the face plate, and running between the perforations. Steam from the boiler enters the central chamber e e, passes through the disk-like ports or spaces between the central disk or face-plate on each side of it, as well as through the perfor at ions in the face-plates ; flows along the channels in the face plates to the annular spaces in ut surrounding the wheel hub: then right and left to ward each wheel ; then ex pands radially outward, through the zigzag of alternate guide-plates and turbines, until it finally exhausts from the circumference of the steam-wheels into the outer chamber, the ex haust-pipe, and the at Ill isphere.
The first practical application of the motor has been on the launching-tubes for the Howell automobile torpedo for the iTnited States Navy (see TommoEs). It is used to spin up the fly-wheel of the torpedo, which is one in which the power used for self-propulsion is stored in a rapidly revolving tly-wheel. The dimensions of the wheel are: 13'S in. in diameter. 6-5 in. in width, and otherwise such that the radius of gyration is 5.57. The energy stored when running at 10,000 revolutions per min. is over 500.000 foot-pounds. and in order to spin it up to the required velocity of 10.000 revolutions per min. in 1 minute's time it requires an expenditure of over 15 horse-power. This expenditure of power commences at zero on starting the wheel, and to average 15 horse-power for the minute the motor must develop power at the final instant at the rate of 30 horse-power. Another application of this motor is to driving a dynamo at the United States Torpedo Station, at Newport R. I, The machine has a capacity of about. 150 lights, and is intended for a normal speed of 9.000 to 10,000 revolutions per inin.—a figure easily reached.