Engineering Abstracts 1969
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Engineering Abstracts from 1969
Fuel Pump
Bryce Berger Ltd. have introduced the F-size fuel injection pump, which has a plunger stroke of 50 mm and which can be fitted with plunger barrels of from 36 to 50 mm bore giving a maximum output of 32 cm1 per stroke. It is designed
to operate at injection pressures in excess of 1100 kg/cm2 (15 500 lb/in2) and is suitable for engines with running speeds of 400 rev/min and over. The pump body is in two parts and these are tied, together with the heavy collar securing the delivery valve head, by four long through-studs which transfer the pumping stresses to the lower part of the housing. This construction has an additional benefit in that it is possible to provide a number of alternative configurations for the fuel inlet and control rod positions. Patented features in the plunger design are available to ensure complete control of the pumping rates at the end of injection. Forced lubrication is applied to the plunger and the tappet block, both of which are located by keys. The robust cam-follower tappet assembly is fitted with a roller which, although wide enough to remain conservatively stressed, can incorporate large edge radii for use on direct-reversing engines. This pump is suitable for the new generation of medium-speed engines now coming forward with outputs of 1000 bhp per cylinder and upwards.
—Marine Engineer and Naval Architect, May 1969, Vol. 92, p. 206.
U.S. Designed and Manufactured Diesel Engine
The purpose of this paper is to present an American designed and manufactured Diesel engine, suitable for marine propulsion. The engine described is the Model 38A20 opposed-piston engine, as produced by Fairbanks Morse Power Systems Division of Colt Industries. The 38A20 Diesel engine is a two-cycle, uniflow scavenged, opposed-piston engine with cylinders in line or a 45° vee. It has been designed with six and nine cylinders in line or 12 and 18 cylinders in vee, all rated at 1250 hp per cylinder. For marine propulsion, the engine may be direct reversing.
The cylinder block and lower base are mild steel weldments with low stress levels. A series of transverse bulkheads carry the stress between the upper and lower portions of the cylinder block. Power is transmitted to the shaft through a cast-iron cocktail shaker, oil-cooled piston, and a nodular-iron connecting rod. The large lower piston controls the air inlet parts while the small upper piston controls the exhaust parts. Since the valving action of the upper piston develops 15 per cent of the rated power, it is connected to the engine output by a rocker arm, rods, upper crankshaft, and vertical gear train.
The crankshafts are high-strength, nodular-iron castings with large corings in the mains and pins to reduce weight. Successful operations on heavy-oil fuel have been achieved on cast-iron liners with an untimed cylinder lubricating oil system. The success is attributed largely to the low metal temperatures in the engine. As marine Diesel engines must operate on the fuels available in the area in which the vessel is scheduled, the 38A20 engine has been operating on a heavy fuel which has a wide range of chemical and physical characteristics. For the purpose of this study, 3500 sec. Redwood 1 at 100°F has been used. Maintenance schedules for the engine were laid out on this premise. With proper design considerations, a 400 to 450 rev/min trunk-type, two-cycle engine without valves can operate on residual fuels successfully. As in other engines, the piston ring and ring groove wear will be slightly more rapid than on light oil. Increased maintenance on the fuel injectors may be required, depending on the fuel filtering and treatment system employed. Manoeuvrability on heavy fuel is not a problem if adequate heating of the fuel system is provided. The figure is proposed layout for twin-pinion, 18-cylinder 38A20 engines used to develop 45 000 bhp in a twin-screw ship.
—Schumacher, G. F., Maritime Reporter/Engineering News, February 15th 1969, Vol. 31, p. 14.