AEROMARINE SIX-CYLINDER VERTICAL MOTOR
These motors are four-stroke cycle, six-cylinder vertical type, with cylinder 45⁄16′′ bore by 51⁄8′′ stroke. The general appearance of this motor is shown in illustration at [Fig. 236]. This engine is rated at 85-90 horse-power. All reciprocating and revolving parts of this motor are made of the highest grades of steel obtainable as are the studs, nuts and bolts. The upper and lower parts of crank-case are made of composition aluminum casting. Lower crank-case is made of high grade aluminum composition casting and is bolted directly to the upper half. The oil reservoir in this lower half casting provides sufficient oil capacity for five hours’ continuous running at full power. Increased capacity can be provided if needed to meet greater endurance requirements. Oil is forced under pressure to all bearings by means of high-pressured duplex-geared pumps. One side of this pump delivers oil under pressure to all the bearings, while the other side draws the oil from the splash case and delivers it to the main sump. The oil reservoir is entirely separate from the crank-case chamber. Under no circumstances will oil flood the cylinder, and the oiling system is not affected in any way by any angle of flight or position of motor. An oil pressure gauge is placed on instrument board of machine, which gives at all times the pressure in oil system, and a sight glass at lower half of case indicates the amount of oil contained. The oil pump is external on magneto end of motor, and is very accessible. An external oil strainer is provided, which is removable in a few minutes’ time without the loss of any oil. All oil from reservoir to the motor passes through this strainer. Pressure gauge feed is also attached and can be piped to any part of machine desired.
Fig. 236.—The Six-Cylinder Aeromarine Engine.
The cylinders are made of high-grade castings and are machined and ground accurately to size. Cylinders are bolted to crank-case with chrome nickel steel studs and nuts which securely lock cylinder to upper half of crank-case. The main retaining cylinder studs go through crank-case and support crank-shaft bearings so that crank-shaft and cylinders are tied together as one unit. Water jackets are of copper, 1⁄16′′ thick, electrically deposited. This makes a non-corrosive metal. Cooling is furnished by a centrifugal pump, which delivers 25 gallons per minute at 1,400 R. P. M. Pistons are made cast iron, accurately machined and ground to exact dimensions, which are carefully balanced. Piston rings are semi-steel rings of Aeromarine special design.
Connecting rods are of chrome nickel steel, H-section. Crank-shaft is made of chrome nickel steel, machined all over, and cut from solid billet, and is accurately balanced through the medium of balance weights being forged integral with crank. It is drilled for lightness and plugged for force feed lubrication. There are seven main bearings to crank-shaft. All bearings are of high-grade babbitt, die cast, and are interchangeable and easily replaced. The main bearings of the crank-shaft are provided with a single groove to take oil under pressure from pressure tube which is cast integral with case. Connecting rod bearings are of the same type. The gudgeon pin is hardened, ground and secured in connecting rod, and is allowed to work in piston. Cam-shaft is of steel, with cams forged integral, drilled for lightness and forced-feed lubrication, and is case-hardened. The bearings of cam-shaft are of bronze. Magneto, two high-tension Bosch D. U. 6. The intake manifold for carburetors are aluminum castings and are so designed that each carburetor feeds three cylinders, thereby insuring easy flow of vapor at all speeds. Weight, 420 pounds.
WISCONSIN AVIATION ENGINES
The new six-cylinder Wisconsin aviation engines, one of which is shown at [Fig. 237], are of the vertical type, with cylinders in pairs and valves in the head. Dimensioned drawings of the six-cylinder vertical type are given at [Figs. 238] and [239]. The cylinders are made of aluminum alloy castings, are bored and machined and then fitted with hardened steel sleeves about 1⁄16 inch in thickness. After these sleeves have been shrunk into the cylinders, they are finished by grinding in place. Gray iron valve seats are cast into the cylinders. The valve seats and cylinders, as well as the valve ports, are entirely surrounded by water jackets. The valves set in the heads at an angle of 25° from the vertical, are made of tungsten steel and are provided with double springs, the outer or main spring and the inner or auxiliary spring, which is used as a precautionary measure to prevent a valve falling into the cylinder in remote case of a main spring breaking. The cam-shaft is made of one solid forging, case-hardened. It is carried in an aluminum housing bolted to the top of the cylinders. This housing is split horizontally, the upper half carrying the chrome vanadium steel rocker levers. The lower half has an oil return trough cast integral, into which the excess oil overflows and then drains back to the crank-case. Small inspection plates are fitted over the cams and inner ends of the cam rocker levers. The cam-shaft runs in bronze bearings and the drive is through vertical shaft and bevel gears.