Twin Disc MG518 Marine Transmission Parts Catalog

Introduction: Power and Reliability for Marine Applications

The Twin Disc MG518 marine transmission is built for reliability and performance in a variety of demanding marine environments. Whether powering commercial fishing boats, tugboats, offshore vessels, or workboats, the MG518 delivers smooth power transfer, durability, and long-lasting service life.

At Diesel Pro Power, we offer a complete selection of MG518 parts, from rebuilt transmissions to essential components for maintenance and overhaul. With fast global shipping, competitive pricing, and expert support, we help keep your MG518 transmission in top condition.

Rebuilt Twin Disc MG518 Marine Transmissions for Sale

Our rebuilt MG518 transmissions are meticulously reconditioned to OEM standards, delivering exceptional performance, reliability, and longevity. Each unit is carefully disassembled, thoroughly inspected, and rebuilt using high-quality components, ensuring it meets the rigorous demands of marine environments. Following reassembly, every transmission undergoes comprehensive testing to verify performance, durability, and smooth operation under real-world conditions.

Each rebuilt MG518 transmission comes fully tested and equipped with:

• Mechanical selector valve assembly (control valve): Provides precise gear selection and smooth shifting for optimal power transfer.

• Pilot housing flange: Ensures a secure and seamless connection between the transmission and the engine.

• Oil pump: Maintains a continuous supply of lubrication, reducing friction and wear on critical internal components.

• Oil level gauge: Allows for easy monitoring of fluid levels, promoting regular maintenance and preventing operational issues.

• Output flange: Ensures a robust connection to the propeller shaft, transmitting power efficiently and reliably.

Note: Drive ring is sold separately. All rebuilt MG518 transmissions are sold with a refundable core deposit. See details for more information.

Our rebuilt MG518 transmissions are available in a range of gear ratios, each tailored to specific operational needs and vessel requirements. Selecting the right ratio ensures optimal performance, fuel efficiency, and reliability for your marine application.

Available Gear Ratios:

• Twin Disc MG518 Marine Transmission 1.5:1 for Sale – Ideal for high-speed vessels such as patrol boats and fast ferries that require a balance between speed and torque for efficient cruising and quick acceleration.

• Twin Disc MG518 Marine Transmission 2.0:1 for Sale – A versatile option for commercial fishing boats, workboats, and recreational vessels, providing a balance of power and efficiency for varying sea conditions.

• Twin Disc MG518 Marine Transmission 3.0:1 for Sale – Offers enhanced pulling power for utility vessels and operations requiring higher torque, ensuring reliable performance under heavier loads and rougher conditions.

• Twin Disc MG518 Marine Transmission 4.0:1 for Sale – Delivers strong performance and high thrust for vessels that demand control and power, including trawlers and support boats.

• Twin Disc MG518 Marine Transmission 4.5:1 for Sale – Provides excellent torque and precise control, making it an ideal choice for demanding commercial marine operations where reliability is paramount.

• Twin Disc MG518 Marine Transmission 5.0:1 for Sale – Ensures maximum torque and dependability for heavy-duty marine applications, including tugboats and large cargo vessels, offering superior propulsion and control.

• Twin Disc MG518 Marine Transmission 6.0:1 for Sale – The ultimate in torque and pulling power, designed for the most challenging conditions and demanding tasks, including operations that require exceptional thrust and maneuverability.

Every rebuilt MG518 transmission from Diesel Pro Power is ready to install and built for dependable operation, backed by our commitment to quality and performance. Our fast global shipping and expert support ensure you get the parts you need with minimal downtime.

Essential MG518 Parts for Maintenance and Overhaul

Overhaul Plate Kit – For Twin Disc MG518 Transmission

Our overhaul plate kit includes all the brass friction plates and steel plates necessary for a complete clutch rebuild. Engineered for precision fit and durability, these plates restore smooth clutch engagement and optimal transmission performance. Designed to withstand high-torque conditions and continuous use, the kit ensures long-lasting operation with reduced wear and tear. Ideal for routine overhauls or scheduled maintenance, this kit helps prevent slippage, inconsistent engagement, and premature component failure.

Gasket and Seal Kit – For Twin Disc MG518 Transmission

The gasket and seal kit contains main housing gaskets, O-rings, seal rings, and auxiliary gaskets to maintain a leak-free seal and consistent system pressure. Manufactured with marine-grade materials resistant to oil, saltwater, and temperature fluctuations, these components ensure reliable sealing and reduced risk of contamination. Regular replacement of gaskets and seals helps prevent fluid loss, maintain lubrication integrity, and protect internal components, extending the service life of your transmission.

Clutch Plates – For Twin Disc MG518 Transmission

Our individual brass and steel clutch plates allow for targeted repairs, ensuring consistent performance and clutch engagement without the need for a full overhaul kit. These plates are crafted to OEM specifications, providing long-lasting durability and smooth operation under varying load conditions. Ideal for addressing specific wear or damage, they are a cost-effective solution to restore functionality and maintain optimal performance.

Rubber Block (Coupling) – For Twin Disc MG518 Transmission

The rubber block, also known as a torsional isolator, connects the transmission output flange to the propeller shaft. It absorbs torsional vibrations, reduces mechanical stress, and compensates for minor misalignments caused by hull flexing or engine movement. Manufactured from high-quality marine-grade materials, the coupling ensures quiet, smooth operation and protects critical drivetrain components from damage. Regular inspection and replacement of worn rubber blocks can help maintain transmission longevity and reduce vibration-related wear.

Seal – For Twin Disc MG518 Transmission

Our high-quality input and output shaft seals, along with dynamic sealing solutions, play a critical role in maintaining fluid integrity and internal pressure. Designed to withstand high-pressure and temperature conditions typical in marine environments, these seals protect your transmission from fluid leaks, contamination, and component wear. Regular inspection and replacement of seals during maintenance ensure long-term reliability and consistent performance.

Oil Strainer – For Twin Disc MG518 Transmission

The oil strainer filters out contaminants, debris, and impurities from the transmission fluid, ensuring clean lubrication and protecting internal components from damage. Essential for maintaining optimal oil flow and system cleanliness, the oil strainer helps extend the life of bearings, gears, and other internal components. Routine inspection and replacement of the oil strainer prevent clogging, reduced lubrication, and potential system failures, keeping your MG518 transmission running smoothly.

Marine Transmission Specifications & Applications of the Twin Disc MG518

Overview of the Twin Disc MG518 Marine Transmission

The Twin Disc MG518 is a powerful and durable marine transmission built for continuous-duty operation in heavy commercial and industrial vessels. It is specifically engineered to accommodate high-horsepower marine diesel engines in applications where reliability, torque capacity, and smooth clutch engagement are critical. The MG518 is commonly found in offshore service vessels, tugboats, dredges, and ocean-going trawlers.

With a cast-iron housing, hydraulic multi-disc clutch, and multiple gear ratio options, the MG518 delivers long-term performance in environments where high load cycles and extended operation are the norm. Its availability in both straight and down-angle configurations, along with optional PTO and trolling valve setups, makes it a versatile choice for high-demand marine propulsion systems.

Key Specifications of the Twin Disc MG518

• Type: Heavy-duty marine transmission with hydraulic clutch

• Horsepower Rating (Approximate):

• Continuous Duty: Up to 900 HP @ 1800 RPM

• Intermittent Duty: Up to 1,050 HP @ 2300 RPM

• Maximum Input Speed: 2500 RPM

• Reduction Ratios Available:

• 2.00:1

• 2.47:1

• 2.95:1

• 3.47:1

• 4.00:1

• Input Housing: SAE No. 0 or SAE No. 1

• Flywheel Compatibility: 18", 14"

• Clutch Type: Oil-cooled, hydraulically actuated multi-disc clutch

• Cooling System: Standard oil-to-water heat exchanger; oil-to-air optional

• Lubrication System: Internal oil pump with pressure-fed lubrication

• Oil Capacity: Approximately 18–22 quarts depending on configuration

• Dry Weight: Approximately 1,200–1,400 lbs

• Mounting Options: Straight or down-angle output; rigid or flexible mount options

• Rotation Compatibility: Bi-directional input; supports left- and right-hand engine rotation

• Optional Features:

• Mechanical or hydraulic PTO

• Trolling valve for low-speed thrust control

• Companion flange or custom shaft outputs

Common Marine Applications for the MG518

The MG518 is ideal for mid- to large-scale marine vessels requiring continuous-duty operation, consistent propulsion, and high torque capacity. Typical applications include:

• Tugboats and Pushboats: Reliable performance under heavy load in harbor, river, and offshore towing operations.

• Offshore Supply Vessels (OSVs): Common in vessels delivering crew, cargo, and equipment to offshore oil and gas platforms.

• Ocean-Going Fishing Trawlers: Withstands large propeller loads and demanding operating hours in offshore fisheries.

• Dredging and Research Vessels: Supports powerful hydraulic equipment and onboard systems through PTO integration.

• Vehicle and Passenger Ferries: Smooth, consistent operation during repetitive, multi-stop service schedules.

Most Common Engine Models Paired with the Twin Disc MG518

The MG518 is typically paired with high-output marine diesel engines ranging from 700 to 1,050 horsepower. Its ability to work with SAE No. 0 and No. 1 housings allows it to interface with some of the industry’s most powerful commercial-grade marine engines.

Cummins Marine Engines

• Cummins KTA19-M3 / M4

• Cummins KTA38-M

• Cummins QSK19 (light commercial duty)
  These engines are commonly used in OSVs, tugs, and high-torque workboats requiring reliable transmission support under continuous load.

Caterpillar Marine Engines

• Caterpillar 3412C / 3412E

• Caterpillar C18 / C32 (light commercial ratings)
  High-power Caterpillar platforms are well-matched with the MG518 for dredging, supply vessels, and offshore transport craft.

Detroit Diesel Marine Engines

• Detroit Diesel 16V92TI

• Detroit Diesel 12V71 (high-performance commercial ratings)
  These engines remain in service in legacy fleets and heavy-duty pushboats. The MG518 provides dependable clutch and gear support.

MTU Marine Engines

• MTU Series 183, 396, and 2000 (select ratings)
  Often used in high-end or fast-response workboats. MG518 is selected for applications requiring a rugged, serviceable transmission.

John Deere and MAN (High HP Commercial Models)

Large-displacement diesel engines from John Deere and MAN are occasionally paired with the MG518 in commercial builds or refit projects, particularly when compact yet powerful drivetrain solutions are required.

Advantages of the Twin Disc MG518

• Built for Continuous Load: Rated for demanding 24/7 operation in industrial workboats and offshore supply environments.

• Smooth Hydraulic Clutch Engagement: Oil-cooled design ensures long clutch life under repetitive shifting.

• High Torque Capacity: Withstands extreme propeller loads and vessel thrust cycles without gear damage or overheating.

• Gear Ratio Flexibility: Wide selection of ratios supports customization for vessel speed and thrust requirements.

• Robust Aftermarket Support: Easily serviced using parts and kits available through Diesel Pro Power.

Ideal Use Cases for the MG518

Additional Resources

Practical Guide to Servicing the Twin Disc MG518 Marine Gear

Introduction for Twin Disc MG518 Marine Gear

• Overview of the Twin Disc MG518 Marine Gear

• Purpose and Scope of the Service Manual

• Importance of Regular Maintenance

• Safety Precautions and Guidelines
  

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Specifications for Twin Disc MG518 Marine Gear

• Technical Specifications (Weight, Dimensions, Capacity)

• Lubrication Requirements

• Torque Specifications

• Compatible Fluids and Materials
  

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Component Identification for Twin Disc MG518 Marine Gear

• External Component Overview

• Internal Component Breakdown

• Identification of Major Assemblies

• Parts Labeling
  

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Installation Procedures for Twin Disc MG518 Marine Gear

• Pre-Installation Checklist

• Mounting Guidelines

• Alignment Procedures

• Connection to Power Source and Controls

• Initial Inspection Before Operation
  

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Operating Instructions for Twin Disc MG518 Marine Gear

• Starting Procedures

• Engagement and Disengagement of Gear

• Operating Temperature and Load Conditions

• Monitoring Systems During Operation

• Emergency Procedures and Shutdown Instructions
  

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Routine Maintenance for Twin Disc MG518 Marine Gear

• Daily, Weekly, and Monthly Inspection Checklists

• Fluid Level Checks and Replenishment

• Filter Replacement Procedures

• Lubrication Points and Intervals

• Inspection of Moving Parts for Wear and Tear
  

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Troubleshooting Guide for Twin Disc MG518 Marine Gear

• Common Operational Issues and Causes

• Step-by-Step Diagnostic Procedures

• Solutions for Common Mechanical Failures

• Electrical and Hydraulic Troubleshooting

• Guidelines for Identifying and Fixing Leaks
  

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Disassembly and Reassembly Procedures for Twin Disc MG518 Marine Gear

• Tools Required for Disassembly

• Safe Disassembly Techniques

• Identification and Handling of Critical Components

• Cleaning and Inspection During Reassembly

• Torque Specifications for Reassembly
  

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Repair and Replacement Guidelines for Twin Disc MG518 Marine Gear

• Determining When to Repair or Replace Components

• Commonly Replaced Components (e.g., Seals, Gears, Bearings)

• Installation of Replacement Parts

• Testing After Repairs
  

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Storage and Preservation for Twin Disc MG518 Marine Gear

• Proper Long-Term Storage Procedures

• Protective Coatings and Covers

• Periodic Checks During Storage
  

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Health and Safety Considerations for Twin Disc MG518 Marine Gear

• Personal Protective Equipment (PPE)

• Handling Hazardous Materials

• Emergency Procedures in Case of Accidents

• Safe Handling of Heavy Components
  

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50 FAQs About The Twin Disc MG518 Marine Gear

Appendices

• Recommended Tools List

• Maintenance Schedule Templates

• Troubleshooting Checklists
  

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Disclaimer

If you have any questions, contact our staff at Diesel Pro Power or consult the OEM service manual.

Why Choose Diesel Pro Power for MG518 Parts?

• Extensive inventory of Twin Disc MG518 parts, including rebuilt transmissions, overhaul kits, plates, rubber blocks, seals, and more.

• Fast global shipping, with most orders processed within 24 hours.

• Competitive pricing on high-quality aftermarket and OEM-quality parts.

• Expert support for part selection and technical guidance.

Frequently Asked Questions (FAQs) about the Twin Disc MG518

1. What types of vessels use the MG518 transmission?

The MG518 is suitable for commercial fishing boats, tugboats, offshore vessels, workboats, and recreational vessels, offering reliability and performance across a wide range of applications.

2. What key parts are essential for MG518 maintenance?

Essential parts include the overhaul plate kit, gasket and seal kit, clutch plates, rubber blocks, seals, and oil strainers.

3. What is included in the overhaul plate kit?

It includes all brass friction plates and steel plates needed for a complete clutch rebuild, ensuring smooth engagement and long-lasting performance.

4. How often should I replace the oil and filter?

Change the oil and filter every 500 hours of operation or annually, whichever comes first, to maintain optimal performance.

5. How do I know when to replace the coupling?

Replace the coupling if you notice increased vibrations, unusual noises, or visible wear and cracks during inspections.

6. Are Diesel Pro’s aftermarket parts reliable?

Yes! Our aftermarket parts are engineered to meet or exceed OEM standards, ensuring long-lasting performance.

7. How quickly can I get MG518 parts from Diesel Pro Power?

Orders are typically processed within 24 hours, with fast global shipping to minimize downtime.

8. What signs indicate the MG518 may need maintenance or overhaul?

Watch for slipping gears, fluid leaks, overheating, unusual noises, or reduced performance.

9. Can Diesel Pro Power help me select the right parts for my MG518?

Absolutely! Our experienced team offers expert support and guidance to ensure you choose the correct parts and maintain your transmission properly.

10. Do you offer warranties on rebuilt transmissions and parts?

Yes, we provide a comprehensive warranty on rebuilt transmissions and parts. Contact us for specific details.