Operation

The marine gear is attached directly to the engine flywheel housing. Full power is transferred from the engine through the marine gear in either a forward or reverse rotation at a reduced speed to the propeller shaft.

Back to back, hydraulically actuated clutches operate the forward and reverse drives. A selector valve directs the flow of oil to either of the clutches for forward or reverse operation. The valve is operated by a lever which can be manually or remotely controlled.

A gear type oil pump, mounted on the rear of the marine gear, provides oil pressure to actuate the clutches, and also, the oil to lubricate the bearings in the marine gear.

The clutch front section engages the three gear drive section and rotates the propeller shaft in the same direction of rotation as the engine. The clutch rear section engages the two gear drive section and reverses the direction of propeller shaft rotation.

The direction of flywheel rotation for a standard engine is counterclockwise, when viewed from the flywheel end of the engine. With a right hand propeller, the clutch rear section is engaged to produce ahead motion.

COUNTERCLOCKWISE ROTATING FLYWHEEL WITH CLUTCH REAR SECTION ENGAGED
1-Clutch rear section. 2-Clutch front section.

CLOCKWISE ROTATING FLYWHEEL WITH CLUTCH REAR SECTION ENGAGED
1-Clutch rear section. 2-Clutch front section.

In twin engine installations a standard engine (counterclockwise flywheel rotation) and an engine option which provides clockwise flywheel rotation is desirable. The standard engine propeller should be a right hand propeller and the other engine propeller should be a left hand propeller. This type of engine installation allows the clutch rear section to engage the two gear drive, in each marine gear and produce ahead motion from both engines.

Hydraulic System

NOTE: In the following information the clutch rear section will be referred to as the "ahead clutch" and the clutch front section will be referred to as the "astern clutch".

HYDRAULIC OIL TO ENGAGE AHEAD CLUTCH
1-Manifold. 2-Selector valve. 3-Passage. 4-Clutch spider. 5-Passage. 6-Clutch cylinder. 7-Passage through driving ring. 8-Cavity. 9-Ahead clutch plates. 10-Ahead clutch piston. 11-Dump piston.

When selector valve (2) is moved to engage ahead drive clutch plates (9), high pressure oil flows from manifold (1) through passage (3) around the tube in the center of the oil pump drive shaft.

AHEAD CLUTCH DRIVE SCHEMATIC

Oil through passage (5) in clutch spider (4) is directed through passage (7) in the clutch driving ring and into clutch cylinder (6). High pressure oil moves dump valve piston (11) toward the center of the cylinder where the piston blocks the dump valve oil exit. High pressure oil enters clutch cylinder cavity (8) behind the ahead clutch piston (10), and moves the piston to engage the ahead clutch.

The two cutaway illustrations show oil flow through the dump valve. Clutch disengagement occurs when the actuating oil pressure is cut off from the dump valve piston by action of the selector valve. The dump valve piston moves outward by centrifugal force aligning dump passage (15) in the piston with the passage to clutch cavity (14). Oil which was behind the clutch piston is now ejected through dump port (13) by action of the clutch piston return springs.

HIGH PRESSURE OIL FLOW THROUGH DUMP VALVE (Dump Valve Cutaway)
11-Dump valve piston. 12-High pressure oil inlet. 13-Dump valve exhaust port. 14-Passage to clutch cavity.

DUMP OIL FLOW THROUGH DUMP VALVE (Dump Valve Cutaway)
11-Dump valve piston. 13-Dump valve exhaust port. 15-Dump passage through piston from clutch cavity.

HYDRAULIC OIL TO ENGAGE ASTERN CLUTCH
1-Manifold. 2-Selector valve. 4-Clutch spider. 16-Passage. 17-Passage. 18-Passage. 19- Astern clutch piston. 20-Astern clutch plates. 21-Passage. 22-Cylinder. 23-Dump valve piston. 24-Cavity.

When selector valve (2) is moved to engage astern clutch plates (20), high pressure oil flows from the manifold through passage (17) in the center of the tube, through the oil pump drive shaft and through passage (16) in the retainer cover and the hub of the clutch spider. Oil in the hub flows outward through passage (18), through passage (21) to move the astern clutch dump valve piston (23) inward which blocks the dump exhaust port. The astern clutch dump valve is located 180° from the ahead clutch dump valve. High pressure oil enters cavity (24) behind astern clutch piston (19) and the piston engages the astern clutch.

ASTERN CLUTCH DRIVE SCHEMATIC

Selector Valve in Neutral

The selector control valve assembly is mounted on the rear of the marine gear. This valve directs and regulates the flow of oil delivered to the marine gear. The pressure regulating section of the valve furnishes automatic regulation of the pressure, with a slight delay effect to afford smooth transmission of power when shifting from NEUTRAL to either FORWARD or REVERSE.

With the engine running and the directional valve (2) in the NEUTRAL position, the oil flow through the selector valve is as follows:

OIL FLOW IN THE NEUTRAL POSITION
1-Selector valve body. 2-Directional spool valve. 3-Pressure regulating springs. 4-Port to oil cooler. 5-Oil inlet port. 6-Bypass valve. 7-Damping valve.

Oil flows from the filter to inlet port (5), around the stem of bypass valve (6) and through a cored passage to the NEUTRAL chamber of directional spool (2) where it is blocked. As the oil cannot flow on from the NEUTRAL chamber, the oil pressure rises. Pressure oil opens damping valve (7) and fills the bottom portion of the bypass valve. When the pressure behind bypass valve (6) is great enough to overcome springs (3), the bypass valve is forced open (up) and oil passes out of the control valve through port (4) to the oil cooler.

Selector Valve in Ahead Position

With the engine running and the directional valve (6) in the AHEAD position, the oil flow through the selector valve body (1) is as follows:

Oil from the filter flows around the stem of bypass valve (16), through a passage in the directional spool valve to the ahead clutch port (13). At the same time, oil forces ball check valve (11) against its upper seat and the oil flows on to main check valve (5). The oil forces check valve 5) against stop (3), flows through small holes in the four plugs in the bore of the check valve and flows through orifice (4) of check valve (5). The oil from the orifice flows to the end of load piston (2) and compresses pressure regulating springs (10) until the force of the load piston and the bypass valve force balance. Bypass valve (16) regulates the maximum clutch engagement pressure while check valve orifice (4) provides a gradual pressure build up to assure smooth clutch engagement. As oil enters the engaging clutch cavity, oil pressure also increases behind load piston (2) forcing it down. When clutch engagement pressure is reached, the bypass valve moves upward and oil not needed to maintain clutch engagement flows through port (12) to the oil cooler.

OIL FLOW IN THE AHEAD POSITION
1-Selector valve body. 2-Load piston. 3-Stop. 4- Orifice. 5-Check valve. 6-Directional spool valve. 7-Port to sump. 8-Port to sump. 9-Port to astern clutch. 10-Pressure regulating springs. 11-Ball check valve. 12-Port to oil cooler. 13-Port to ahead clutch. 14-Oil inlet port. 15-Port to sump. 16-Bypass valve.

Any oil which may leak by the directional spool (6) returns to the sump through return ports (7) and (15).

When the directional spool valve is again moved to NEUTRAL, oil in the ahead clutch drains through the dump valve to the sump. The decrease in pressure allows the ball check valve to move from its seat and the oil behind check valve (5) flows out to the sump through port (7). Since the pressure on the bottom side of check valve (5) is now less than the pressure on top of the check valve, the pressure oil on top of the load piston pushes the check valve open and allows the oil to flow out port (7) to the sump.

Selector Valve in Astern Position

With the engine running and directional valve (6) in the astern position, the oil flow through selector valve body (1) is as follows:

Pressure oil from the filter flows around the stem of bypass valve (16), through a passage in the directional spool valve and to astern clutch port (9). Oil which may leak by the spool valve is returned to the sump in the same manner as the AHEAD position.

OIL FLOW IN THE ASTERN POSITION
1-Selector valve body. 2-Load piston. 3-Stop. 4- Orifice. 5-Check valve. 6-Directional spool valve. 7-Port to sump. 8-Port to sump. 9-Port to astern clutch. 10-Pressure regulating springs. 11-Ball check valve. 12-Port to oil cooler. 13-Port to ahead clutch. 14-Oil inlet port. 15-Port to sump. 16-Bypass valve.

The regulation of oil pressure for clutch engagement is the same as in the AHEAD position, except that the ball check valve (11) is held on the seat at the opposite end.

Cooling System

OIL COOLING COMPONENTS
1-Coolant connections. 2-Oil cooler. 3-Oil inlet to cooler. 4-Oil outlet from cooler. 5-Oil temperature control bypass valve. 6-Oil temperature gauge. 7-Oil line (to front end of lower gear shaft). 8-Oil temperature sensing switch. 9-Oil cooler bypass line. 10-Oil line from filter. 11-Oil line to manifold.

The oil cooler is mounted on the left side of the marine gear housing. The cooler maintains the oil temperature at 150° - 160° F (65° - 71° C). When the temperature of the oil is below 150° F (65° C), bypass valve (5) is open and the oil flowing to the oil manifold and marine gear does not pass through the cooler. When the temperature of the operating oil increases to approximately 150° F (65° C) the bypass valve begins to close and some of the oil flows through the oil cooler. The bypass valve is fully closed when the temperature of the oil is 160° F (71° C). Now all of the oil passes through the cooler and on to the oil manifold and marine gear.

Oil temperature sensing switch (8) is an electric switch that can be connected to some type of an alarm which can be located at any distance from the marine gear and engine. High temperature oil will close oil temperature sensing switch (8) and actuate the alarm.

Lubrication System

LUBRICATING OIL FLOW
1-Oil pump. 2-Manifold. 3-Selector valve. 4-Passage. 5-Ahead clutch shaft rear support bearing. 6-Passage. 7-Cavity. 8-Ahead clutch. 9-Passage. 10-Astern clutch. 11-Passage. 12-Front spider hub bearing. 13-Astern clutch shaft rear support bearing. 14-Rear spider hub bearing. 15-Oil tube. 16-Astern clutch shaft front support bearing. 17-Ahead clutch shaft support bearing. 18-Passage. 19-Output bearing assembly. 20-Planet gear bearing. 21-Lower shaft rear support bearing. 22-Lower shaft front support bearing.

The gear-type oil pump (1), located at the rear of the marine gear, is splined to a shaft which is pinned to a cover and bolted to the drive spider. The volume of oil delivered by the pump depends on engine speed. Oil is drawn from the sump through a metallic stainer by the pump and then pumped through the filter to the selector valve, oil cooler, and marine gear. These components are connected by a series of flexible hoses and steel tubing.

EXTERNAL LUBRICATION COMPONENTS
1-Oil pump. 2-Manifold. 3-Selector valve. 23-Oil cooler. 24-Line to front of lower shaft. 25-Oil cooler bypass valve. 26-Temperature sensor.

Oil to lubricate and cool the clutch plates is pumped directly through manifold (2), through passage (4) between the oil pump drive shaft and the astern clutch shaft. This passage permits the oil to reach passage (9) leading to the ahead clutch plates and passage (11) leading to the astern clutch plates. Grooves in the sintered bronze driven clutch plates, channel the oil outward between the driving and driven plates. Centrifugal force throws the oil off the clutch circumference and the oil returns to the sump. Bearings (12, 13, and 16) are lubricated by the oil to the clutches.

Bearings (5 and 22) are pressure lubricated through oil tubes connected to a common tee at the rear of the lower housing. Oil to this tee flows through a passage leading from the area between the outer races of bearing assembly (13).

Drilled passages in the planetary housing carries oil from another passage at the rear of bearing (13) to the center of output bearing assembly (19). A passage (18) through the planetary shaft and carrier provides oil to lubricate the planet bearings (20).

Oil from the cooler enters the left side of the lower housing and travels through a tube and slip coupling to the front of the sun gear shaft. A passage through the center of the sun gear shaft directs the lubricating oil to the meshing sun and planet gear teeth.

NOTE: Regardless of the position of the selector valve lever (when the engine is operating), an ample supply of oil is supplied to lubricate and cool all bearings and clutch plates.

Oil Filter Bypass Valve

The normal oil flow is from the pump to the oil filter, through the oil cooler and then to the oil manifold and marine gear. An oil filter bypass valve allows lubrication and cooling oil to flow to components if the oil filter becomes clogged or restricted. If the filter is restricted, oil flows directly to the oil cooler, manifold, selector valve and marine gear.

Oil Cooler Bypass Valve

A thermostatically controlled bypass valve maintains normal lubricating oil temperature by controlling the oil flow through the cooler.