CLASS 02 · MARINE GEARMarine GearGear parts, pre-start inspection, startup and testing
01 / Available lesson
Gear parts and terminology
Learn the names on the gear before following the startup checks. Select each part in the interactive CAD reference, watch the zoom, then drag to see how it connects to the surrounding assembly.
Why the vessel needs a marine gear
The engine makes power at its crankshaft, but the propeller needs a suitable shaft speed, torque and direction to move the vessel. The marine gear is the controlled connection between them. It lets the engine run while the propulsion clutch is in Neutral, reduces engine speed through its gear train for the propeller, and selects which clutch carries power to change the output rotation.
Follow the power: engine crankshaft → coupling → gear input → selected clutch and reduction gear train → output flange → propulsion shaft → propeller. In Neutral, the engine and input can turn without engine torque being applied to the propulsion shaft. A moving vessel or propeller can still backdrive the output, so Neutral does not mean every shaft is stationary.
On this MGX-61000SC: main oil pressure applies the primary or secondary clutch. The selected path determines output direction relative to the input; the vessel’s ahead and astern mapping must be confirmed from its approved drawings and during commissioning. Oil also lubricates and cools the internal parts.
Service manual 1026987 Rev. C, pp. 9–11; confirm the unit ratio and vessel direction mapping from the approved configuration.
Words you will use at startup
Input / output
The engine-side torque entry and propeller-shaft-side torque exit.
EC600 and FEMAS valves
The EC600 top housing and the two cylindrical FEMAS valves beneath it; identify them separately in the CAD view.
Oil pump / filter / screens
Oil supply, filtration and debris protection before pressure and engagement checks.
Trailing pump
A gear-driven auxiliary pump to identify with its external screen housing when tracing the oil supply arrangement.
Breather, oil fill and dipstick
The fill/vent area and the oil-level check point.
Manual override
The manual direction control valve; recognize it without operating it in this lesson.
Explore the power path
Choose a clutch state and predict what the transmission drives. The vessel’s ahead and astern mapping comes from the approved propulsion configuration.
Rotation arrows compare output with the engine/input reference; they do not specify the vessel’s absolute clockwise direction.Conceptual training schematic. Direction and clutch assignment must match the approved unit and vessel drawings.MGX-61000SC service manual pp. 10, 31–33.
Interactive CAD reference
Explore the MGX-61000SC
Orbit to inspect the housing, mounting areas and visible connections. Switch to section view and move the cut plane to see which surfaces are present in the export.
Parts
Locate: Engine-side flange and coupling at the power-entry end of the transmission.Function: Carries engine torque into the gear; the input and gear shafts can turn while the clutch remains in Neutral.At startup: Match the flange and coupling to the installation drawing. Review the builder’s coupling and alignment record before the first run.
Locate: Shaft-side flange connected to the vessel’s propulsion shaft.Function: Delivers torque from the selected clutch through the reduction gear train to the shaft. Primary and secondary engagement give opposite output directions relative to the input.At startup: Confirm shaft clearance and alignment evidence. During the authorized test, record the commanded clutch, observed shaft response and direction.
Locate: Auxiliary pump on the trailing-pump side of the gear, with its own inlet screen circuit.Function: Supplies lubrication when the propeller backdrives the output with the engine shut down; it is distinct from the main oil pump.At startup: Trace the fitted suction, filter and discharge path against the unit drawing. Record its configuration before commissioning; do not assume it is active during an engine-driven startup.
Locate: Service access for the trailing pump’s suction strainer, separate from the main sump screen.Function: Stops debris from entering the trailing pump during backdriving lubrication.At startup: Identify the access plug/housing and verify any inspection or cleaning record under the approved procedure.
Locate: Electronic interface on top of the GP hydraulic control valve.Function: Commands the proportional cartridges and controls clutch-pressure rise during engagement.At startup: Identify the fitted connectors and harness routing. During the test, correlate the command, clutch response and any control fault; keep this module distinct from the two hydraulic valve blocks below.
Locate: Two stacked GP hydraulic valve blocks beneath the EC600: upper valve body and lower main regulator block.Function: Regulates oil pressure and directs high-pressure oil through internal passages to the selected clutch.At startup: Inspect the block joints and external connections for leaks. Compare pressure and engagement response with the approved test plan; the FEMAS cartridges and manual override are separate side-mounted parts.
Locate: The sensor and electrical connector protrude from the GP control valve. Use the unit drawing to identify the fitted main-pressure sensor and its port.Function: Converts hydraulic pressure at the valve into an electrical signal so the control system can monitor main oil pressure. The manual identifies the PM11394 pressure sensor as a 24 VDC, 4–20 mA device with a 0–3000 kPa range.At startup: Check that the connector is seated and its wiring is protected. Inspect the sensor fitting for leaks, then compare the displayed pressure with a calibrated gauge at the approved main-pressure test port under the specified test conditions. Record the readings and investigate a mismatch before proceeding.MGX-61000SC manual 1026987 Rev. C, control assembly drawing and sensor note C; confirm the installed part number.
Locate: Temperature-sensor fitting at the GP control valve's oil point before the heat exchanger. Confirm this gear's fitted port on the installation drawing.Function: Reports oil temperature at that point when fitted. The GP control drawing identifies PM11395 as a three-wire PT1000 sensor; the manual says this sensor is not required on every MGX configuration.At startup: Confirm the sensor and connector against the serial-number drawing. Inspect the fitting for leaks, then observe and record the indicated temperature as the oil warms under the approved procedure.MGX-61000SC manual 1026987 Rev. C, GP control drawing note B and item 27. Confirm the fitted part and expected readings before field use.
Locate: The potted module and slender harness crossing the bolted cover near the control assembly.Function: A programmed electronic assembly supplied in a housing with a cable. The drawing identifies PX1035384 and requires programming before shipment; confirm its exact function in this EC600 configuration.At startup: Match the installed part to the unit drawing. Check the housing, retention, harness routing and connector for damage or loose connections before applying control power. Record any associated EC600 fault during the approved test.MGX-61000SC manual 1026987 Rev. C, PX1035384 Smart Chip drawing. Programmed contents and controller interface require verification.
Locate: Pair of cylindrical proportional cartridges on one side of the GP control valve, with electrical connector ends.Function: Meter oil for primary and secondary clutch application as commanded by the electronic interface.At startup: Identify both connectors and mounting areas. Observe the selected clutch response and look for leaks during the authorized engagement test; never apply an uncontrolled power source to a cartridge.
Locate: Domed vent and oil-fill area on the gear housing.Function: Lets the housing breathe and provides a clean route for adding the specified lubricant; it does not indicate oil level.At startup: Keep the opening free of debris. Confirm the approved lubricant, fill quantity and final level using the unit’s oil-level procedure.
Locate: Stem, knob and locking pin on the side opposite the FEMAS cartridges.Function: Provides manual direction selection when used under the approved procedure; its Neutral-position switch is part of the start interlock.At startup: Confirm it is secured in Neutral as found. Do not move it as a training exercise or during commissioning without the authorized procedure.
Locate: Main oil pump mounted at the suction-tube end of the gear.Function: Driven by the secondary clutch shaft, it draws oil through the sump suction screen and feeds the hydraulic circuit.At startup: Trace its inlet and outlet, inspect connections for leaks, and record pressure at the approved port and operating condition after startup.
Locate: External canister-style filter between the main pump outlet and the selector valve.Function: Removes particles before oil reaches the control valve and clutch hydraulic passages.At startup: Confirm the installed element and seal against the unit package. Watch the canister and fittings for leaks during the first run.
Locate: Loop-handled oil-level gauge inside a fixed guide tube; the tube remains in the housing.Function: Shows sump oil level under the specified operating and temperature conditions.At startup: Confirm oil is present before starting. Recheck at low idle in Neutral and finalize the level at normal oil temperature as directed by the manual. The animated blade is illustrative.
Locate: Cone-shaped serviceable strainer inside the suction tube below the main oil pump.Function: Catches debris between the sump and the pump inlet; its wide end faces the housing and its narrow end points toward the pump.At startup: Identify the four pump-side bolts, tube and O-ring sealing area. The withdrawal animation illustrates access only; use the approved removal and inspection procedure before opening the circuit.
Show the suction screen section drawing
Source: 1024771L.step. Section view clips the supplied surfaces. The separate power-flow exercise illustrates clutch operation. Verify connection identities and installation details against the approved drawing for the unit.
COOLER · FLOW ROUTING
See the water and oil pass in opposite directions
The gear oil releases heat to the cooler. Raw water carries that heat away. Follow each circuit from its inlet to its outlet before startup; the water must flow against the oil for the intended counterflow arrangement.
Drag the cooler to rotate
Gear oilIllustrated left → right, entering hot and leaving cooler.
Raw waterIllustrated right → left, entering cool and leaving warmer.
Why counterflow matters: fresh cooling water meets the oil near its outlet, maintaining a useful temperature difference along the exchanger. The arrows show the routing principle, not measured temperatures or internal construction.
Trace the ports
If the oil moves toward the right in this view, which way should the cooling water move?
Choose an answer to check the flow path.
Shipyard before Sewart arrives: Identify and label the actual raw-water inlet and outlet on the supplied 1024771A installation drawing; trace both installed water lines and the gear oil lines, confirm the approved connections and available flow, and record the result. Sewart commissioning: verify the routed circuits, observe flow and leaks during the authorized run, and record oil temperature before and after the exchanger under the approved test conditions.
Source: 1024771A, MGX-61000SC installation drawing, M1959AQ raw-water heat exchanger. The drawing labels the raw-water ports; the transparent internal paths here are conceptual. Confirm oil inlet/outlet, exact connections, flow requirement and temperature limits from the serial-number cooler package before field use.
02 / Working exercise
Inspect before startup
Training checklist. Resolve all holds and verify the current approved procedure and limits before startup. The checklist records evidence for the handoff. Startup authorization comes from the responsible personnel under the vessel procedure.
Shipyard prepares
Finish the mechanical installation and connected circuits. Record the alignment, endplay and supporting documents before Sewart arrives.
Sewart verifies
Review shipyard records and verify the gear-side test setup and commissioning prerequisites. During the authorized run, verify engagement and record gear test results.
Manual p. 163, Fig. 139. Compare the illustration to the installed arrangement and approved alignment method.
03 / Available lesson
Startup and commissioning
Work through an authorized gear test from neutral baseline to engagement and closeout. Agree on the test sequence, expected direction, limits and stop criteria before starting.
01 · Set up the test record
Record hull, gear position and serial, test-point locations, instrument units, approved reference revisions, and who commands and observes the test. Agree on the stop and communications procedure.
02 · Confirm neutral and observe the baseline
Use the approved neutral verification method. Under authorized test conditions, capture RPM, main pressure and applicable lube pressure, oil temperature, leaks and faults. The service manual describes the running oil-level check at low idle in Neutral (p. 36). Check oil presence before starting and use the procedure applicable to the fitted unit.
03 · Verify ahead engagement
During the authorized test, record commanded range, expected and observed propulsion response, RPM, relevant clutch pressure and any delay or fault. An unexpected response is a hold and follows the approved stop procedure.
04 · Verify astern separately
Return to neutral as directed by the test plan and confirm the authorized condition before the next command. Log astern as a separate observation. Relate command, clutch, and output response using the vessel’s approved mapping.
05 · Document temperatures and finish
Record gear oil temperature and applicable cooler inlet/outlet oil and water temperatures with timestamps and units. Check for leaks and faults. Record deviations, corrective action and any authorized retest. MR001 provides a recording pattern.
Interactive startup simulator
Run a commissioning scenario
Training scenarios use qualitative observations. Use the applicable approved limits for actual acceptance decisions.
04 / Available lesson
Troubleshooting field reference
Start with the symptom you observed. Capture the conditions while they are known and follow the vessel’s approved stop and isolation procedure before inspection.
Symptom-driven decision tree
MGX-61000SC manual pp. 39–42 for troubleshooting context. Use the approved configuration, limits and procedures for the installed unit.
05 / Available lesson
Final assessment
Submit each answer to see feedback. Use the lesson navigation to review a topic and return here.
