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slip joint to the crankcase front intermediate section diaphragm and drilled passages therein to the cam ring and valve tappets. (See Fig. 35.) Pressure oil is metered to all plain rocker bearings through passages in the tappets, push rods, and valve rockers.

Accessory drives are lubricated through drilled passages in the supercharger rear cover leading from the main oil annulus around the crankshaft extension bushing.

This source also supplies a two- position propeller control valve in the right side of the rear cover. Oil from this valve is led through drilled

passages housings

in and

the supercharger crankcase front

sections and through tubes in the crankcase main sections to a journal- type seal on the propeller shaft. This seal is mounted within the stationary reduction gear. A spun tube in this gear completes the two-position hydraulic propeller control system. A diaphragm in the propeller shaft separates propeller oil in the forward part from the engine oil in the after part.

Scavenging of the main portion of the engine is accomplished by drainage to an oil sump mounted at the bottom of the supercharger front housing. The main scavenge section of the oil pump draws oil from this sump and discharges it to the external system in the conventional manner. The third section of the oil pump takes rocker box scavenge oil from a small oil sump mounted on No. 1 front cylinder at the extreme bottom of the engine. Oil from the rocker boxes on Cylinders 1, 2, 3, 6, and 7 front and 3, 4, 5, and 6 rear drains from box to box into this sump. Upper cylinder boxes drain through push-rod housings and tappet guides directly into the valve

gear drive compartment. ACCESSORIES


MISCELLANEOUS — Information on accessories for this engine is very

meager. An electric




mounted on the conventional six-bolt starter pad and engages a three-jaw end of the crankshaft extension.

The magneto photographs, Figs. 36 and 37, presented herewith are believed to be from a magneto similar but not that used with this engine. The remainder of the ignition system is radio-shielded in a manner

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very similar to American engines, including spark-plug elbows and spring contactors in the spark-plug well. Illustrated with the complete magneto is an interesting quick- disconnect fitting which makes it possible to remove the radio shielding from the magneto without disturbing the blocks and wire





attachment. Seven through each of

however, as mentioned before, this equipment is not from the engine on which this report is based, but represents one system which is in use.

No carburetion data on this engine are available to the writer.

An accessory drive gear box, Fig. 38, is mounted on the right-hand side of the rear cover. This box forms the drive for a single tachometer and two accessories, the nature of which is not known. This drive involves a small spur gear (probably twelve teeth), which is not available, splined into the right- hand accessory drive-gear shaft. Fig. 39 shows drive parts. It meshes with a 30-tooth gear mounted in the accessory drive housing, and splined to a shaft mounting a bevel gear. Tachometer drive is through a splined coupling directly from this shaft. It is 0.5 crankshaft speed (if th missing gear mentioned above is twelve-tooth.) A square-pad drive similar to the air-pump drive on American engines and a triangular- pad drive are accomplished through two bevel gears each mating with the gear on the main shaft.

The nature of the drive used on the crankcase front section is not know, but it is believed that a combination gun synchronizing impulse generator and constant- speed propeller governor drive is made available at this point on later engines.

The oil pump is mounted at the left-rear of the engine, taking its drive through a spline in the oil pump and fuel-pump drive shaft mentioned previously. Parts are shown in Fig. 40. A magnesium- alloy housing is cored for oil passages and mounts the gears and shafts directly. The 1.12 in. wide nine-tooth scavenge gears splined to the engine shaft and drives the main oil pump shaft on which three eleven-tooth gears are mounted. The 0.88 in. wide oil pressure pump


consists of a gear keyed to this main shaft driving a nine-tooth idler. Both of these pumps are in the main pump housing. A thin plate separates the pressure pump from the valve gear scavenge pump which is a duplicate of the pressure pump except that the teeth are only 0.47 in. wide. The main oil pump shaft is also fitted with a floating member to provide a tongue drive for a square pad accessory on the rear of the valve gear scavenge pump housing. A quill drive for this accessory is formed by a 0.27-in. diameter by 3-in. long neck between the splines which fit into the forward end of the main shaft and the slotted journal. All oil- pump gears are carburized low-alloy steel.

The remains of a spark plug is sectioned and shown in Fig. 41. It is a mica-insulated plug of quite conventional construction.

Engine mounting is accomplished by means of seven longitudinal bolts in bosses cast at alternate intake pipe connections in the supercharger front housing. Breathing appears to be through a flange at the top of the magneto drive shaft housing in the supercharger rear cover.

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