Advance 120C Heavy Duty Marine Gearbox 3.35:1 Reduction
Description
Cut gear train noise using the Advance 120C Marine Gearbox built with a deep 3.35:1 reduction gear ratio. This transmission rates for 120 horsepower at 1,800 RPM under demanding commercial duty cycles. Internal hydraulic clutch packs clamp tight under oil pressure, preventing driveline slip during heavy towing and continuous net hauling on commercial fishing trawlers.
Heavy gray cast iron forms the rigid outer casing to stop housing deflection under massive propeller shaft thrust. Carburized helical gears feature precision ground teeth conforming to AGMA Class 11 standards for quiet mesh under load. Sintered bronze friction plates alternate with steel reaction plates inside the hydraulic clutch pack. Mechanical utilities include an SAE 3 bell housing, 3/4-inch raw water cooler barbs, 7/16-20 JIC hydraulic test fittings, 485 lbs dry weight, and six quarts fluid capacity.
Key Features of Advance 120C
Commercial mariners buy Advance 120C marine gearbox packages to drive large-diameter propellers on displacement trawlers and push boats. The heavy-duty gear train isolates engine torsional pulses from the stern tube during long hours of continuous offshore towing.
- 3.35:1 reduction ratio generates maximum shaft torque to swing deep-pitch wheels on workboats
- 340 PSI hydraulic pump pressure locks multi-disc clutches tight without slippage during heavy towing
- Advance 120C reduction gear train teeth undergo heat treatment to deliver deep case wear resistance
- 26-spline input shaft connects straight to standard flexible rubber marine torsional damper drive plates
- 0.002-inch gear tooth tolerances eliminate driveline gear rattle during extended low idle trolling operations
- Seawater-cooled cupronickel heat exchanger maintains stable transmission fluid temperatures during non-stop barge towing
- External mechanical shift valve directs oil flow to forward, neutral, and reverse clutch packs
Torque Transfer Hydraulic Operating Limits
Hydraulic clutch line pressure holds between 290 and 340 PSI to lock the friction plates under continuous diesel engine loads. Operating sump fluid temperature remains between 150°F and 180°F through continuous raw seawater flow across the cooler bundle. This transmission accepts up to 350 lb-ft continuous input torque at engine speeds up to 2,500 RPM under commercial service. The 3.35:1 reduction ratio provides maximum propeller thrust for displacement hulls and tugs. Thermal heat rejection across the external cooler removes up to 18 kW under full engine load.
Output Companion Flange Thrust Alignment
The output companion flange features a 6.69-inch outside diameter with a 5.51-inch pitch circle diameter drilled for six mounting bolts. An integrated tapered roller thrust bearing absorbs up to 20 kN of propeller axial push. Coaxial shaft centers align straight to vessel stringers with dial indicator runout tolerances held within 0.003 inches.
Valve Actuation Maintenance Duty Protocol
A heavy manual directional control valve directs hydraulic fluid flow to forward, neutral, and reverse circuits via push-pull helm linkage cables. This marine transmission is not engineered for rigid direct-drive engine couplings without dampers, high-speed un-governed gasoline racing engines, or high-performance surface-piercing drive speedboats.
- Check transmission fluid level on the clean dipstick each shift prior to cold diesel engine start
- Clean the reusable wire-mesh oil suction strainer screen every 250 hours to remove wear debris
- Drain transmission fluid and inspect internal magnetic drain plugs every 12 months or 1,000 running hours
Commercial Warranty Factory Crate Manifest
Advance marine products provide a 1-Year limited commercial warranty covering casing castings, shafts, bearings, and internal gear sets. Each wooden shipping crate holds the bare transmission unit, input torsional flex plate, seawater oil cooler bundle with brackets, output companion flange, dipstick, and an illustrated factory workshop service manual.
Advance 120C Heavy Duty Marine Gearbox Product Overview
The NEW Advance 120C Heavy Duty Marine Gearbox 3.35:1 Reduction is a compact marine hydraulic gearbox engineered for commercial marine propulsion systems where correct ratio selection, dependable power transfer, and professional installation matching are required.
Built for commercial vessel applications, the Advance 120C supports installations where the gearbox must be accurately matched between the marine engine and propeller shaft system. This model is configured with a 3.35:1 reduction ratio, making it suitable for propulsion setups requiring controlled reduction within the 120C ratio range.
For customers searching for an Advance 120C marine gearbox, Advance 120C 3.35:1 gearbox, heavy duty marine hydraulic gearbox, or commercial marine gearbox with Live PTO option, this unit provides a fitment-focused solution for workboats, commercial vessels, shipyards, fleet operators, and marine propulsion specialists.
Built for Commercial Marine Applications
The Advance 120C Heavy Duty Marine Gearbox is designed for commercial propulsion environments where the drivetrain must support controlled engagement, correct engine matching, and properly selected reduction.
Commercial marine applications may include:
- Workboats
- Fishing vessels
- Passenger vessels
- Utility vessels
- Small commercial craft
- Service vessels
- Fleet repower projects
- New marine propulsion installations
Its hydraulic transmission design supports controlled engagement and dependable power transfer when matched with compatible engines, drive plates, adaptor plates, controls, cooling systems, mounting arrangements, shafting, propeller requirements, and optional PTO requirements.
3.35:1 Reduction Ratio Configuration
This product is specified with a 3.35:1 reduction ratio, one of the available Advance 120C ratio options.
A marine gearbox reduction ratio determines how engine speed is reduced before reaching the propeller shaft. In commercial marine propulsion, the correct ratio must be selected based on engine output, propeller size, vessel duty cycle, hull type, load profile, operating speed, and application requirements.
The 3.35:1 ratio is suitable for applications where the propulsion system requires controlled reduction while maintaining proper engine-to-propeller matching.
Available Advance 120C ratio options include:
| Ratio Option | Rating |
|---|---|
| 1.48:1 | 0.136 hp/RPM |
| 1.94:1 | 0.136 hp/RPM |
| 2.45:1 | 0.136 hp/RPM |
| 2.96:1 | 0.122 hp/RPM |
| 3.35:1 | 0.109 hp/RPM |
This page is specifically for the 3.35:1 reduction configuration with a 0.109 hp/RPM rating.
Heavy Duty Hydraulic Marine Transmission
The Advance 120C is a heavy duty marine hydraulic gearbox designed to transfer engine power through the marine drivetrain while supporting controlled clutch engagement and dependable transmission operation.
Hydraulic marine gearboxes are commonly used in commercial vessel applications because they are built for smooth engagement and practical drivetrain integration when selected and installed correctly. The Advance 120C is intended for commercial propulsion requirements where gearbox weight, drop centre, ratio selection, input speed, PTO configuration, and cooling requirements must be matched carefully.
Key drivetrain considerations include:
- Engine output compatibility
- Gear ratio selection
- Maximum input speed
- Adaptor plate size
- Drive plate size
- Control type
- Shafting and propeller requirements
- Cooling and lubrication setup
- Optional Live PTO requirement
- Vessel duty cycle and operating profile
The gearbox should always be matched to the engine, vessel, propeller, auxiliary equipment, and duty cycle by a qualified marine technician or propulsion specialist.
Maximum Input Speed of 2500 RPM
The Advance 120C marine gearbox is rated with a maximum input speed of 2500 RPM.
This specification is important when matching the gearbox to the engine. The selected engine must operate within the gearboxs approved input speed range, and the final drivetrain setup should be verified according to the vessels propulsion requirements.
For commercial applications, correct matching of input speed, reduction ratio, propeller load, PTO demand, and duty rating helps support dependable gearbox operation and proper propulsion system integration.
SAE Adaptor Plate Options
The NEW Advance 120C Heavy Duty Marine Gearbox 3.35:1 Reduction is available with SAE adaptor plate options to support different engine installation requirements.
Adaptor plate options include:
- SAE3
- SAE2
- SAE1
The correct adaptor plate should be selected based on the engine flywheel housing, mounting configuration, and marine installation requirements. Choosing the correct adaptor plate is essential for accurate engine-to-gearbox alignment and secure mechanical integration.
Mechanical and Electronic Control Options
The Advance 120C 3.35:1 marine gearbox can be configured with different control options depending on the vessels control system.
Available control options include:
- Mechanical control
- Electronic control
Mechanical control setups are commonly used in traditional marine installations with cable or linkage-based control systems. Electronic control options may be suitable for vessels using electronic throttle and shift architecture.
Buyers should confirm the required control configuration before purchase to ensure compatibility with the vessels helm controls, control cables, electronic interface, and overall propulsion setup.
Drive Plate Options
The Advance 120C is available with multiple drive plate options to support different engine and gearbox connection requirements.
Available drive plate sizes include:
- 11.5 drive plate
- 14 drive plate
Drive plate selection should be confirmed based on engine specification, flywheel configuration, torsional requirements, torque rating, and gearbox compatibility. Correct drive plate matching helps support smooth torque transfer between the engine and gearbox.
Live PTO Option
The Advance 120C Heavy Duty Marine Gearbox is available with an option for Live PTO.
A Live PTO option can support auxiliary power requirements in compatible commercial marine applications, depending on the vessels setup and equipment needs. This may be important for operators requiring power take-off capability for approved auxiliary systems.
The Live PTO requirement should be confirmed before ordering, as PTO configuration can affect gearbox specification, installation planning, auxiliary equipment compatibility, and final system layout.
Gearbox Oil Cooler Option
The Advance 120C Heavy Duty Marine Gearbox also offers an option for a gearbox oil cooler.
A gearbox oil cooler may be required in commercial marine installations where operating conditions, duty cycle, engine output, PTO load, and transmission demand require additional temperature management. Cooling requirements should be confirmed based on the vessels propulsion system and manufacturer recommendations.
Correct gearbox cooling helps support stable operating conditions when the transmission is working under commercial marine load.
Commercial Repower and Replacement Applications
The NEW Advance 120C Heavy Duty Marine Gearbox 3.35:1 Reduction is suitable for commercial repower projects, gearbox replacement, and new vessel installations requiring a compact hydraulic transmission with optional PTO capability.
During a repower or replacement project, the gearbox must be matched carefully to the vessels engine, propeller, shafting, mounting arrangement, cooling system, control type, PTO requirements, and duty cycle.
Buyers should confirm:
- Advance 120C gearbox requirement
- 3.35:1 reduction ratio
- 0.109 hp/RPM rating requirement
- SAE3, SAE2, or SAE1 adaptor plate
- Mechanical or electronic control
- 11.5 or 14 drive plate
- Live PTO requirement
- Oil cooler requirement
- Engine output and input speed
- Shafting and propeller compatibility
- Vessel duty cycle and commercial application
Correct configuration helps support dependable marine propulsion system integration.
Installation and Compatibility Considerations
The Advance 120C marine gearbox should be installed according to manufacturer specifications and matched carefully with the vessels propulsion system.
Important installation considerations include engine model, adaptor plate type, drive plate size, gearbox ratio, control configuration, mounting arrangement, shaft alignment, oil cooler requirements, Live PTO configuration, lubrication, foundation support, coupling setup, and service access.
This gearbox should be installed by qualified marine technicians familiar with commercial marine propulsion systems. Proper installation helps reduce the risk of alignment issues, control mismatch, overheating, drivetrain vibration, PTO mismatch, premature wear, or incorrect gearbox selection.
Worldwide Marine Equipment Supply
The NEW Advance 120C Heavy Duty Marine Gearbox 3.35:1 Reduction is suitable for customers requiring professional commercial marine gearbox supply.
With experience shipping marine engines, transmissions, gearboxes, propulsion components, PTO components, and spare parts worldwide, this gearbox can support vessel owners, shipyards, marine technicians, fleet operators, and repower specialists requiring dependable commercial marine drivetrain solutions.
Technical Specifications
| Specification | Details |
| Product Name | NEW Advance 120C Heavy Duty Marine Gearbox 3.35:1 Reduction |
| Manufacturer | Advance |
| Model | 120C |
| Product Type | Heavy Duty Marine Hydraulic Gearbox |
| Primary Application | Commercial Marine Propulsion |
| Selected Ratio | 3.35:1 |
| Selected Ratio Rating | 0.109 hp/RPM |
| Available Ratio Options | 1.48:1, 1.94:1, 2.45:1, 2.96:1, 3.35:1 |
| Rating Options | 0.136 hp/RPM, 0.122 hp/RPM, 0.109 hp/RPM depending on ratio |
| Maximum Input Speed | 2500 RPM |
| Adaptor Plate Options | SAE3, SAE2, SAE1 |
| Control Options | Mechanical, Electronic |
| Drive Plate Options | 11.5, 14 |
| Live PTO | Optional |
| Gearbox Oil Cooler | Optional |
| Weight | 225 kg |
| Drop Centre | 180 mm |
| Dimensions | 352 694 650 mm |
| Suitable Use | Commercial vessels, workboats, fleet repower projects, new marine installations |
| Component Type | Heavy-duty commercial marine transmission |
Key Product Details
The NEW Advance 120C Heavy Duty Marine Gearbox 3.35:1 Reduction is a configurable commercial marine hydraulic gearbox designed for dependable drivetrain applications.
Key details include:
- Advance 120C heavy-duty marine gearbox
- 3.35:1 reduction ratio
- 0.109 hp/RPM rating for the 3.35:1 option
- 2500 RPM maximum input speed
- SAE3, SAE2, and SAE1 adaptor plate options
- Mechanical or electronic control options
- 11.5 and 14 drive plate options
- Optional Live PTO
- Optional gearbox oil cooler
- 225 kg gearbox weight
- 180 mm drop centre
- 352 694 650 mm dimensions
- Designed for commercial marine applications
This gearbox should be selected only when the engine, vessel, control system, PTO requirement, ratio, mounting arrangement, and drivetrain requirements match the Advance 120C specification.
Frequently Asked Questions
What is the Advance 120C marine gearbox used for
The Advance 120C marine gearbox is used in commercial marine propulsion systems to transfer engine power through a hydraulic transmission to the propeller shaft system.
What reduction ratio is this gearbox configured with
This product is specified with a 3.35:1 reduction ratio.
What is the rating for the 3.35:1 ratio
The 3.35:1 ratio option is listed with a 0.109 hp/RPM rating.
What ratio options are available for the Advance 120C
Available ratio options include 1.48:1, 1.94:1, 2.45:1, 2.96:1, and 3.35:1.
What is the maximum input speed
The maximum input speed is 2500 RPM.
What adaptor plate options are available
Adaptor plate options include SAE3, SAE2, and SAE1.
What control options are available
The gearbox can be configured with mechanical or electronic control options.
What drive plate sizes are available
Drive plate options include 11.5 and 14.
Is Live PTO available
Yes. The Advance 120C has an option for Live PTO.
Is a gearbox oil cooler available
Yes. A gearbox oil cooler is available as an option.
What is the weight of the gearbox
The gearbox weighs 225 kg.
What is the drop centre
The drop centre is 180 mm.
What are the dimensions
The dimensions are 352 694 650 mm.
Should compatibility be verified before purchase
Yes. Buyers should verify engine compatibility, ratio requirement, adaptor plate type, drive plate size, control option, Live PTO requirement, oil cooler requirement, shaft alignment, mounting arrangement, and vessel duty cycle before purchase.
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