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Aviation History
1917
1917 - 1311.PDF
DECEMBER 13, 1917. <Fig. 17), and in the photograph of the parts (Figs. 18 and 19). The oil pump works diagonally in ihe sump, and is driven by a long shaft -and gear wheel which meshes obliquely with the distribution pinion on the rear end of the crankshaft. The functions of the triple oil pumps-are as follows :— Oil is drawn by the main pressure pump A (Fig. 17) from the reservoir in the sump through the holes in the end •cover of the pump, lubricating the main bearings through the main oil pipe and the small branch pipes and hollow crankshaft, thence to the gud- geon pin bearings through the small pipes inside the tubular connecting- Tods. The surplus oil is thrown out from the hollow cranks on to the •camshafts, &c, and returns by gravity to the sump, flowing over the air- cooling pipes in the base. The fresh oil is fed into the sump reservoir by the small suction pump B from the oil tank, whilst the correct "working oil level is maintained in the reservoir by the gear pump C, the oil being drawn off through the bent pipe E, and returned to the oil tank. The iresh oil from the oil tank passes through a cylindrical gauze filter, which is attached to the under side of the crank chamber. The complete oil pump with its filter is easily detachable from the sump by the studs through the flange. A small spring loaded ball is used as an oil pressure release valve in the main oil supply pipe. The gears of the oil pump and also the pump body -are of cast iron, and the weight of the complete pump -equals 2.89 lbs. Oil consumption during R.A.F. test is stated to be 4.5 pints per hour, equalling 0.02 pint perb.h.p. hour. Oil pressure equals 50 lbs. maximum, 28 lbs. normal. Ignition.—Two Z.H.6 magnetos are mounted on brackets at the rear end of the crank case, and are driven directly off the camshaft gear wheels. The •design of this magneto drive is very neatly carried out and is clearly shown in the rear end view of the •engine (Fig. 3). The contact breakers of the magnetos are advanced or retarded by small toothed quadrants "which mesh with teeth cut in the underside of the •cam box, and the interconnected levers of the timing advance quadrants are coupled by a rod which passes through the end of the crank case casting. . Two sparking plugs are fitted to each cylinder, •one on each side, and the H.T. wires are carried in a sheet aluminium casing attached to the cylinders. The ignition is timed as 300 E fully advanced, equalling 18 mm. on stroke. Power throttle and consumption curves are shown in Fig. 28. The engine was run up to 1,700 i.p.m., the peak of the power curve occurring at 1,650 r.p.m., at which 250 h.p. was developed. The maximum brake m.e.p. reached 119 lbs. per square inch at 1,100 r.p.m. The results of a one-hour test run were as follows :—R.P.M., 1,400 ; B.H.P., 229 ; petrol consumption, 150 pints ; oil consumption, 4.5 pints ; water inlet temperature (average), 620 C. ; water outlet temperature (average), 710 C. ; oil temperature (max.), 500 C. steady ; oil pressure (min.), 28 lbs. sq. in. steady. The curve (Fig. 29) shows inlet and exhaust valve 1311 Fig. 19.—Parts of oil pump. lifts at various angles of rotation. The engine was erected on a test bed and coupled to a Heenan and Froude water dynamometer. After preliminary running, during which the exhaust manifold broke and was replaced by one from a similar engine, the attached power, throttle, and consumption curves were obtained. 230 H.P. BENZ. List of comparative weights of parts and total weight of engine. Description of Part. •, Cylinders, complete, including supports for rocker levers (six at 44.25 lbs. each) Pistons, complete, with rings and gudgeon pins (six at 7 .62 lbs. each) Connecting rods, complete (six at 7.13 lbs. each) Valves and springs complete (twenty- four at 1 .14 lbs. each) .. .. Tappets, push rods and rocker levers (twelve sets at 3.2 lbs. each) .. Induction pipes, complete (two at 2.625 lbs. each) .. .. .. Carburettors, complete .(two at 6.54 lbs. each) .. .. .. .. Crank chamber, top half .. .. Crank chamber, bottom half (including cylinder studs and oil pump shaft).. Crankshaft, complete .. .. .. Propeller boss, complete .. .. Cam-shafts, complete, with bearings less gear-wheels (two at 8.25 lbs. each) .. .. .. .. .. Magnetos, complete (two at 10.75 lbs. each) .. .. .. .. .. Ignition wiring, complete (two at 2.12 lbs. each) .. Water pump, complete Oil pump, complete .. Petrol pump, complete. . Exhaust manifold Miscellaneous parts .. their Percentage oj Lbs. 265. 45' 42. 27- 38. 5- i3-103. no. 109. 19. 5 .72 78 36 4 25 08 25 25 25 32- Per cent.Total Weight. 3O.753 5.296 4-955 3.169 4-447 0.608 »:& 12.77 12.66 2.236 16.5 21.5 1.912 2.490 4 8 2 6 15 7 .24 •75 .89 •75 •53 0.4911-013 O-3350.782 1-737 0.872 100Total weight of complete engine 863 .32 230 h.p. Benz Engine Data. • "• ' Number and arrangement of cylinders ,v 6 vertical; bore, 145 mm. (5.71 ins.) ; stroke, 190 mm. (7.48 ins.) ; stroke/ bore ratio, 1 .31-1. Stroke volume of one cylinder, 3,137.476 cu. cms. (191.386 cu. ins.) ; total stroke volume of engine, 18,824.856 cu. cms. (1,148.316 cu. ins.) Area of one piston, 165.13 sq. cms. (25.59 sq- ins-) ; tota piston area of engine, 990.78 sq. cm. (153.57 sq. i&s,).
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