Nikola Tesla U.S. Patent 1,061,142 - Fluid Propulsion Patent Wrapper Page 13

T [ E 1 E 1 J 1 E T 8147 tively to the runner and to the effective area of the disks and. inversely, to the distance separating them. The machine will, generally, perform its maximum work when the effective speed of the runner is one half of that of the fluid. But to attain the highest economy the relative speed or slip for any given performance, should be as small as possible. This condition may to any desired degree approximated by increasing the active area and reducing the space between the disks. When apparatus of the kind described is employed for the transmission of power certain departures from similarity between transmitter and receiver may be necessary for securing the best result. It is evident that, when transmitting power from one shaft to another by such machines, any desired ratio between the speeds of otation may be obtained by proper selection of the diameters of the disks, or by suitably staging the transmitter, the receiver, or both. But it may be pointed out that in one respect, at least, the two machines are essentially different. In the pump, the ràdial or static pressure, due to centrifugal force, is added to the tangential or dynamic, thus increasing the effective head and assisting in the expulsion of the fluid. In the motor, on the contrary, the first named pressure, being opposed to that of supply, reduces the effective head and the velocity of radial flow towards the center. Again, in the propelled machine a great torque is always desirable, this calling for an increased number of disks and smaller distance of separation, while in the propeliing machine, for numerous economic reasons, the rotary effort should be the smallest and the speed the greatest practicable. Many other considerations, which will naturally suggest themselves, may affect the design and construction, but the preced-7813