Systems Operation

Usage:

Operation

MARINE TRANSMISSION CUTAWAY

1. Oil pump.

2. Input shaft.

3. Ahead clutch (discs and plates.)

4. Drive pinion.

5. Flexible connector (to engine flywheel).

6. Ahead clutch gear.

7. Output shaft.

8. Driven gear.

9. Astern clutch gear.

The marine transmission has a flexible connector (5) on input shaft (2). Drive pinion (4) and driven gear (8) make a reduction in speed (rpm) so output shaft (7), from the transmission, turns slower than the speed (rpm) of the engine.

The flexible connector (5) has a spider with gear teeth on the diameter of the spider. The spider is on the input shaft of the transmission. Another part of the coupling is a ring with gear teeth in the bore of the ring. The ring is on the engine flywheel. The flexible parts are the rubber blocks between the teeth on the spider and the teeth in the ring. The engine turns the flywheel and ring, the teeth in the ring push on the rubber blocks. The rubber blocks push the teeth on the spider which turns the spider and the input shaft of the transmission.

MARINE TRANSMISSION
1. Oil pump. 10. Rubber block. 11. Spider

The oil pump (1) is connected to the end of input shaft (2) and turns at the same speed (rpm) as the engine. The oil for the pump is in the sump of the transmission. The oil from the pump is both for lubrication and is the supply of pressure oil that can activate either the ahead or the astern clutch.

NOTE: The reference to the clutches, is the astern clutch (reverse motion) and the ahead clutch (forward motion of the vessel when the propeller has a right hand pitch).

The ahead clutch gear (6) is the drive gear for astern clutch gear (9) and both gears turn when the engine is running. With the control valve lever in the NEUTRAL position, the ahead clutch and the astern clutch are not engaged and drive pinion (4) on input shaft (2) and the drive pinion on the astern clutch shaft do not turn.

NOTE: The positions for the control valve lever will be NEUTRAL, AHEAD (forward) and ASTERN (reverse). In some vessels the installation of the engine and marine transmission (or the direction of the pitch of the propeller) changes the lever position locations for ahead and astern motion of the vessel.

SCHEMATIC OF MARINE TRANSMISSION (GEARS) (Control Lever in NEUTRAL Position)
2. Input shaft. 4. Drive pinion. 6. Ahead clutch gear. 7. Output shaft. 8. Driven gear. 9. Astern clutch gear.

Move the control lever to the AHEAD position and the pump oil from the control valve engages the clutch in ahead clutch gear (6) on input shaft (2). When the clutch in gear (6) is engaged, drive pinion (4) turns with gear (6). Drive pinion (4) turns driven gear (8) on output shaft (7) but in a different direction. The output shaft (7) turns clockwise with the ahead clutch engaged (when seen from the stern towards the bow of the vessel and when the engine flywheel turns counterclockwise).

SCHEMATIC OF MARINE TRANSMISSION (GEARS) (Ahead Clutch Engaged)
2. Input shaft. 4. Drive pinion. 6. Ahead clutch gear. 7. Output shaft. 8. Driven gear. 9. Astern clutch gear.

Move the control lever to the ASTERN position and the pump oil from the control valve engages the clutch in astern clutch gear (9). Ahead clutch gear (6) turns astern clutch gear (9) in a different direction. When the astern clutch gear (9) is engaged, the drive pinion from the astern clutch turns the same direction as gear (9). The astern clutch drive pinion turns driven gear (8) on output shaft (7) in a different direction. The output shaft (7) turns counterclockwise with the astern clutch engaged (when seen from the stern towards the bow of the vessel and where the engine flywheel turns counterclockwise).

Pinion (4) is a driven pinion when gear (8) turns pinion (4). The pinion now turns in a different direction as ahead clutch gear (6) and input shaft (2).

When the engine runs, oil pump (1), ahead clutch gear (6) and astern clutch gear (9) turn. Engage either the ahead or the astern clutch and all of the gears in the marine transmission turn.

SCHEMATIC OF MARINE TRANSMISSION (Astern Clutch Engaged)
2. Input shaft. 4. Drive pinion. 6. Ahead clutch gear. 7. Output shaft. 8. Driven gear. 9. Astern clutch gear.

Hydraulic System

The gear-type pump (2), for both lubrication and hydraulic oil, is at the back of the transmission and on the end of the input shaft. The pump turns the same speed (rpm) as the engine crankshaft. The pump gets oil from the oil sump through an oil strainer (1) in the transmission.

The oil from the pump goes through an oil line into filter (3). The filter housing has an oil bypass valve. When the bypass valve is closed, all of the oil from the pump goes through the filter element and then into the control valve for the marine transmission. When the difference between the inlet and the outlet oil through the filter is too much, the higher pressure of the inlet oil opens the filter bypass valve. When the bypass valve is open, the oil from the pump does not go through the filter element as the oil goes to the control valve. A filter that is full of dirt or cold oil are causes for the increase in inlet oil pressure that opens the filter bypass valve.

MARINE TRANSMISSION (REAR) (Earlier Transmission)
1. Strainer. 2. Pump. 3. Filter.

MARINE TRANSMISSION (REAR) (Later Transmission)
1. Strainer. 2. Pump. 3. Filter. 4. Inspection covers.

MARINE TRANSMISSION (FRONT)
3. Filter. 5. Control valve.

Control Valve

NEUTRAL Position

The control valve is on the right side of the marine transmission. All of the oil from the pump, when the engine is running, goes into the control valve. The lever on the control valve has three positions which are: AHEAD (forward, ASTERN (reverse) and NEUTRAL.

CONTROL VALVE IN NEUTRAL POSITION (Engine Running)
1. Control valve body. 2. Selector spool. 3. Springs (relief valve). 4. Outlet passage (to oil cooler). 5. Inlet passage (from filter and pump). 6. Relief valve. 7. Poppet.

The NEUTRAL position of the control lever keeps selector spool (2) in a position where the pump oil through inlet passage (5), and a passage in valve body (1), goes to a chamber with no outlet to the clutches. The pump oil also goes through a passage in relief valve (6) thru orifice in dampening poppet (7). With no outlet for the pump oil in the control valve the pressure of the pump oil increases. Pump oil pressure of 35 ± 5 psi (240 ± 35 kPa) opens relief valve (6) since the force in the dampening poppet (7) chamber of this valve (6) is greater than force of springs (3). As relief valve (6) opens pump oil goes thru outlet passage (4) thru the oil cooler and thru the lubricant passages in the transmission.

AHEAD Position

The AHEAD (forward) position of the control lever keeps selector spool (2), in a position where the pump oil through inlet passage (5), and a passage in valve body (1), goes through passage (16) to the ahead clutch. The pressure of the pump oil must increase to engage the clutch. The pump oil in passage (16) also moves ball (15), goes into check valve (11) and moves the check valve against stop (9). The pump oil is metered gradually thru the check valve orifice and into load piston (8) cavity. Pump oil flow thru passage (16) to ahead clutch fills the clutch piston and pressure increases to 35 ± 5 psi (240 ± 35 kPa). Relief valve (6) opens allowing oil to flow thru passage (4) to oil cooler and transmission lubrication. Pump oil continues to flow thru orifices (10) into flange end of load piston (8). Pressure increases on load piston (8) and forces the load piston (8) to move against springs (3) which increases force on relief valve (6). The gradual flow of oil metered thru check valve (11) gradually moves load piston (8) which gradually increases the pressure setting of relief valve (6) thus modulating the engagement of the ahead clutch. When movement of load piston (8) is stopped against bottom of counterbore in body (1), relief valve pressure is at 272 ± 8 psi (1870 ± 55 kPa) and ahead clutch is now fully engaged.

CONTROL VALVE IN AHEAD POSITION
1. Control valve body. 2. Selector spool. 3. Springs (relief valve). 4. Outlet passage (to oil cooler). 5. Inlet passage (from filter and pump). 6. Relief valve. 8. Load piston. 9. Stop. 10. Orifices (three). 11. Check valve. 12. Drain outlet (for oil to transmission housing). 13. Drain outlet (for oil to transmission housing). 14. Passage (for astern clutch). 15. Ball. 16. Passage (for ahead clutch). 17. Drain outlet (for oil to transmission housing).

ASTERN Position

The control valve operates the same in astern position as previously described for ahead position except:

1. Pump oil flow goes thru passage (14) to astern clutch instead of passage (16) to ahead clutch.

2. Ball (15) is seated in the opposite direction as shown for ahead position to direct oil from the astern clutch to check valve (11).

CONTROL VALVE IN ASTERN POSITION
1. Control valve body. 2. Selector spool. 3. Springs (relief valve). 4. Outlet passage (to oil cooler). 5. Inlet passage (from filter and pump). 6. Relief valve. 8. Load piston. 9. Stop. 10. Orifices (three). 11. Check valve. 12. Drain outlet (for oil to transmission housing). 13. Drain outlet (for oil to transmission housing). 14. Passage (for astern clutch). 15. Ball. 16. Passage (for ahead clutch). 17. Drain outlet (for oil to transmission housing).

Clutches

ONE HALF OF CLUTCH (CROSS SECTION)

1. End plate.

2. Drive ring.

3. Clutch gear.

4. Piston.

5. Drive plates and lined discs.

6. Spring (eight).

7. Pinion shaft.

8. Bolt (ten).

9. Oil passage.

10. Hub (on pinion shaft).

11. Shaft.

Gear (3), for the ahead clutch, has left hand gear teeth and the gear like it for the astern clutch has the same amount of gear teeth, but the astern clutch gear has right hand teeth. Clutch shaft (11), for the ahead clutch, is the marine transmission input shaft. This shaft also drives the oil pump. The clutch shaft for the astern clutch does not extend from the transmission housing. All of the other parts in the two clutches use parts with the same part numbers.

Eight studs in end plate (1) go through drive ring (2) and clutch gear (3). Drive plates and lined discs (5) are friction parts in the clutch. Two of the three drive plates are between the three lined discs. The plates have teeth that go between the teeth in the bore of drive ring (2). Each lined disc has teeth in the bore that go between the teeth on hub (10). Pinion shaft (7), the taper roller bearing and hub (10) are installed together and make a unit. Eight bolts and springs (6) keep piston (4) against gear (3) where the clutch is disengaged. Ten bolts (8) through clutch gear (3) connect the clutch gear to shaft (11).

When the engine is running, with the clutch disengaged, all of the clutch parts except the three lined discs and the pinion shaft hub unit (7 and 11) turn with the engine (same rpm). Move the control lever for the marine transmission to the AHEAD position and the pump oil from the control goes through oil passage (9) into the chamber between piston (4) and gear (3). The pressure of the pump oil increases and moves piston (4) and a drive plate against a stationary lined disc. As the piston moves farther, the drive plates, that have the same speed (rpm) as the engine, go against the other lined discs and there is more friction until the drive plates turn the lined discs and pinion shaft hub unit at the same speed as the plates and gear (3).

CLUTCH ENGAGED
3. Gear. 4. Piston. 7. Pinion shaft. 9. Oil passage. 11. Shaft.

Move the control lever to NEUTRAL position and the pressure of the oil in passage (9) and in the chamber between piston (4) and gear (3) decreases. With no oil pressure in the chamber, springs (6) pull the bolts that move piston (4) against gear (3) and the drive plates are not against the lined discs.

Lubrication

The oil pump (8) is connected to the end of ahead clutch shaft (12) which is also the input shaft for the marine transmission. The input shaft is connected to the engine flywheel and turns the same speed (rpm) as the engine crankshaft. The pump gets oil from sump (11) through strainer (9) in the transmission housing. The oil from the pump goes through filter (4) and into control valve (2).

When the lever of control valve (2) is in the NEUTRAL position, there is no pump oil in either line (3) or line (5) and all of the pump oil is for lubrication. The pump oil with a pressure of approximately 15 psi (105 kPa) goes from control valve (2) through the marine transmission oil cooler on the engine. The oil from the oil cooler goes into manifold (7) in the transmission housing. The oil goes through passages from the manifold to the bearings and clutches on both astern clutch shaft (1) and ahead clutch shaft (12). The oil from the manifold also goes through other passages to the bearing on both the pinion shaft on astern clutch shaft (1) and the pinion shaft on ahead clutch shaft (12). The oil goes through all of the bearings and goes into sump (11) in the bottom of the transmission housing.

When the lever of control valve (2) is in either the ASTERN position or the AHEAD position, as shown, some pump oil goes through either line (3) or line (5) to engage the clutch (and keep it engaged). When a clutch is engaged, a pinion shaft turns the gear on the output shaft. The large gear on the output shaft turns in the oil in sump (11) and the oil runs off the gear onto bearings (10) for the output shaft.

OIL SYSTEM WITH AHEAD CLUTCH ENGAGED