Technical paper reprint from the 'ENGINEERING' journal on the Hydro-Kinetic Power Transmitter, with performance tests and component comparisons.
| Identifier | ExFiles\Box 156\4\ scan0089 | |
| Date | 2nd September 1938 | |
| 10 COMPARISON OF HYDRAULIC COUPLING, PUMP AND SALERNI TRANSMITTER. | | Duct of Ordinary Hydraulic Coupling | Duct of Ordinary Centrifugal Pump. | Duct of Salerni Transmitter. |--- | --- | --- | --- | Diameter of wheel— | | | | At inlet | ... | 7 in. | 7 in. | At outlet | ... | ... | ... | Angular disposition | Convergent by an angle of 6 deg. | Convergent by an angle of 6 deg. | Convergent by an angle of 6 deg. | Depth of ducts | Convergent by an angle of 12 deg. | Divergent by an angle of 5 1/2 deg. | Convergent by an angle of 4 deg. | Width of ducts— | | | | At inlet | 0.209 in. | 0.309 in. | 0.489 in. | At outlet | 0.663 in. | 0.382 in. | 0.435 in. | Depth of core | 0.717 in. | 0.211 in. | 0.42 in. | Number of ducts forming wheel | 30 | 28 | 18 Volume of discharge—Cub. in. per sec. (Assuming driving at 1,000 r.p.m.) Velocities of Flow in ft. per sec. | | FIG. 21. | FIG. 22. | FIG. 23. | FIG. 24. |--- | --- | --- | --- | --- | Water at 20 deg. C — From one duct | 0.7 0.56 1.01 | 0.9 1.83 | 15.17 16.84 | 33.88 | From all ducts | 210 16.8 30.3 | 27 54.9 | 455 505 | 1,016 638.44 | Corresponding quantities of oil having a kinematic viscosity ten times that of water at 20 deg. C. | 21 16.8 | 182 209.4 | 209.4 3,609 | 3,589 6,584 7,178 | Water at 20 deg. C. | | | | | Equivalent velocity for the oil medium (assuming vis. = 10x for water) | 5.09 8.21 13.00 | 4.74 7.57 9.50 13.70 | 3.65 4.25 7.80 | 8.40 | Nature of flow | Sinous at outlet | Highly eddying throughout | Stream-Line | Stream-Line | Sinous at outlet | Highly eddying over major part | Highly eddying throughout | Stream-Line | Minute eddies at outlet | Minute eddies over major part | Minute eddies throughout | As illustrated in Figs. | 21 (2) 21 (3) 21 (4) | 22 (1) 22 (2) 22 (3) 22 (4) | 23 (1) 23 (2) 23 (3) | 23 (4) life of the machine should be almost indefinite. The only parts which are subjected to comparatively high stresses are the pawls of the reaction element and the small dog member with which they become engaged, but, due to the effect of the dashpot in which they function, these parts are never subjected to shock. The author has examined the pawls and dogging after they had been used in an automobile over 65,000 miles, and there was no perceptible sign of their having been in use. The vaned elements are made of plain die castings and of metal stampings, the machining operations consisting mainly of drilling and turning. The cost of manufacture of the transmitter on mass-production lines compares favourably with that of the standard flywheel, friction clutch and change-speed gearing of which it takes the place. Road Tests.—The author has had opportunities of observing and testing the performance of the transmitter in an automobile. The automobile tested was a standard 21.6-h.p. 1936 model, fitted with the standard size tyres and the standard back axle ratio of 4.4 to 1, the unladen weight of the vehicle being 29 cwt. The transmitter fitted to this vehicle was of the two-stage type. The tests included trials under all driving conditions, i.e., in traffic, in hilly country and on the open road. The hill-climbing capacity of the vehicle was remarkably good. The rate of its acceleration at "get-away" and under all other conditions, have proved to be appreciably greater than is stated by the makers to be achievable by the same model when driven with the 1 Reprinted from "ENGINEERING," September 2, 1938. HYDRO-KINETIC POWER TRANSMITTER BY PROFESSOR F. {Mr Friese} C. LEA, D.Sc., M.Inst.C.E., M.I.Mech.E. THE problem of devising an hydro-kinetic power transmitter capable of performing effectively the functions both of a clutch and of a change-speed gear has not infrequently been declared to be incapable of solution. Tests of the transmitter which is the subject of this paper indicate that the problem has now been satisfactorily solved. Within the range of variation of torque ratio requisite in an automobile or a heavy lorry, the transmitter in question performs the two functions effectively and has an advantage over the orthodox clutch and gear mechanism in efficiency, performance, simplicity, soundness of construction, and also cost. Furthermore, due to its inherent smoothness, it relieves the whole of the transmission system, from engine to road wheels, of shock loads, and thus reduces general maintenance. A variable-ratio hydro-kinetic transmitter consists essentially of three vaned elements, viz., a centrifugal pump or driving element, a turbine or driven element, and a reaction element. In the transmitter which is the subject of this paper the design of each of these elements involves important original conceptions, and of these conceptions that which relates to the centrifugal pump is of a fundamental nature and has important implications. In an hydro-kinetic power transmitter which has to function under conditions varying as widely and unpredictably as in an automobile or a locomotive, the major causes of loss of energy have heretofore been (1) unsteadiness of motion of the liquid medium within the ducts constituting the hydraulic circuit of the transmitter; (2) shock at the inlet of the driven element. Of these two causes of inefficiency, the first, although per se the lesser, is fundamental, since the second, though considerably graver, is a consequence of the first. Since the liquid medium has to pass from 6974 A FIG. 1. VIEW OF FACE OF DRIVING ELEMENT. * Paper read before Section G of the British Association at Cambridge on Monday, August 22, 1938. | ||
From the Rolls-Royce experimental archive: a quarter of a million communications from Rolls-Royce, 1906 to 1960's. Documents from the Sir Henry Royce Memorial Foundation (SHRMF).