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Aviation History
1955
1955 - 0085.PDF
21 January 1955 85 9 1 2 IO „ The basic hydraulic pump/ motor unit of the variable- ratio drive is here shown sectioned. The key is as follows: 1, 2, motor plunger; 3, main rotor shaft; 4, variable-angle swash-plate; 5, over- and under-speed governor cylinder; 6, plunger cylinder body; 7, pump valve plate; 8, port plate; 9, motor valve plate; 10, motor body; 11, fixed-angle motor swash-plate; 12, output clutch and drive gear; 13, input gear; 14, fixed-dis- placement charge pump; IS, scavenge pump. 12 TEST FOR SUNDSTRAND SYSTEM (PARALLEL Case Parallel alternators with load on one only ... Load switching up to 80 kVA Full-load acceleration and deceleration Half-load acceleration and deceleration "One-up, one-down" Nominal load Total kW kVAr 16 — 16 — 16 + Pulse32 — 32 + 24 48 -I- 24 48+48 64+48 64 — 32 — 32 — OPERATION) Input Speeds (r.p No. 1 5,000 5,000 5.000 to Q tW\O,UUU 5,000to 8,000 8,000 m.) No. 2 5,000 5,000 5,000 5,000 4,000 Approx. acc'n and dec n(r.p.m. sec.) — _ 1,000 1,000 — 6,000 r.p.m. (400 c.p.s.) between input-speed limits of 3,000 and8,100 r.p.m.—values well suited to most of the larger modern aero engines. Under a rapidly accelerating input speed, the alter-nator frequency can be maintained within 5 c.p.s.; in steady conditions, better than unity is attainable. As for load-sharing ina paralleled system, 14 kW is the maximum out-of-balance during sudden changes in input r.p.m. or supply load, and this is re-duced to 4kW under steady conditons. The test set-up at Acton, which was demonstrated publiclyyesterday, January 20th, consists of a pair of English Electric/ Sundstrand drives, each coupled to a blast-cooled 40 kVA alter-nator. The two alternators are connected to a common bus-bar, which feeds a system of various resistive and reactive loads upon (concluded at foot of next page) This diagram shows, in schematic form, the basic components and circuit for the English Electric/Sund- strand drive. The key is as follows: A, charge pressure; B, working pressure; C, overdrive control pressure; D, underdrive control pres- sure; E, oil pressure; F, vented to atmosphere. 1, oil relief valve; 2, charge relief valve; 3, overspeed trip valve; 4, overspeed governor; 5, basic governor; 6, frequency-control motor; 7, underdrive control cylinder; 8, overdrive con- trol cylinder; 9, scavenge pump; 10, 11, output- and input-driven transmission charge pumps; 12, input spline (internal); 1 3, alternator drive.
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