Marol MR40-RV50BR Hydraulic Valve

Marol MR40-RV50BR Hydraulic Valve – New Surplus Marine Steering Gear Component

The Marol MR40-RV50BR is a precision marine-grade hydraulic control and pressure relief valve engineered by Marol Co., Ltd. (Tokyo, Japan) for rigorous marine propulsion, deck machinery, and power steering applications. Built specifically to protect hydraulic circuits from thermal expansion spikes and high rudder-stock backpressure, this valve ensures linear, chatter-free relief characteristics under continuous ocean duty.

Constructed from a corrosion-resistant ductile alloy block with micro-honed internal spools and seat assemblies, the MR40-RV50BR provides leak-tight isolation and immediate bypass actuation when line pressure exceeds set parameters. This unit is offered in New Unused Surplus (Open Box) condition, dry-stored with factory protective plugs intact to ensure contaminant-free deployment into mission-critical hydraulic power units (HPUs) and steering servo loops.

Key Features

1. Hydro-Balanced Spool Architecture: Employs precision-machined internal porting to deliver rapid crack-to-reseat response times without cyclical pressure oscillation or hydraulic hammering.
2. Marine Corrosion Protection: Body surface treated with marine-grade anti-corrosive passivation to resist continuous salt-fog, bilge moisture, and atmospheric oxidation.
3. Direct Subplate / Manifold Interface: Conforms to standard industrial interface tolerances, allowing direct sandwich or line mounting into Marol power steering consoles and remote manifolds.
4. Tamper-Resistant Pressure Adjustment: Features a locknut-secured external hexagonal screw allowing calibration between nominal system pressure and peak load thresholds.
5. High-Integrity Nitrile/FKM Sealing: Fitted with marine-rated elastomeric dynamic O-rings and backup rings compatible with mineral-based hydraulic oils and synthetic fluids.

Compatibility & Equipment Models

• Marol Steering Systems: Compatible with Marol H-600 series helms, power-assist C-Steer units, and MRS continuous-duty hydraulic steering consoles.
• Marine Actuators & Power Packs: Matches Marol MSB, D-Series, and linear dual-acting steering cylinders operating up to 210 bar.
• Deck Machinery: Secondary safety loops on mooring winches, capstans, small cranes, and davit hoisting arms requiring local relief settings.
• Cross-Brand Hydraulic Loops: Readily adaptable as a safety relief bypass on HPUs built by Kawasaki Marine, Daikin Marine, Yuken, and Tokyo Keiki matching CETOP/BSPP port configurations.

Part Number Cross-References

• Marol OEM: MR40-RV50BR, MR-40-RV-50-BR
• Alternative/Interchangeable Codes: MR30-PV Series, RV-50 Series Marine Relief Manifolds

Industrial Applications

• Primary Commercial Vessel Steering: Main and auxiliary rudder angle power-assist systems.
• Workboats & Tugs: Towing winch line tension backpressure control and maneuvering thruster hydraulics.
• Commercial Fishing Vessels: High-pressure net haulers, longline reels, and power-block hydraulic bypass protection.
• Offshore Support Craft: Hydraulic gangway deployment rigs, anchor windlasses, and stern ramp actuation.

Frequently Asked Questions

What is the functional difference between the MR40 and standard relief cartridges?

The MR40-RV50BR is purpose-built for maritime duty, featuring specialized corrosion coatings, marine-grade sealing compounds, and a dampened poppet specifically configured to handle the rapid shock loads generated by rudder wave impact.

Can this valve be adjusted beyond 175 bar?

While the structural valve block is rated up to 210 bar (3,045 PSI), the installed internal spring rate in the RV50BR configuration is optimized for standard commercial marine steering systems operating between 35 and 175 bar. Exceeding this band requires replacing the internal spring pack.

Is this valve suitable for synthetic hydraulic fluids or bio-oils?

The default sealing is high-grade Nitrile (NBR), which works with petroleum-based oils and synthetic diester lubricants. If your vessel uses biodegradable polyol ester (HEES) or phosphate ester fluids, the dynamic seals must be upgraded to FKM/Viton prior to commissioning.

How do I detect internal seat bypass without removing the valve?

Perform a thermal inspection using an infrared thermometer. Run the steering gear continuously in a neutral state; if the body of the MR40-RV50BR shows a temperature rise significantly higher than the surrounding manifold block, oil is leaking past the internal poppet seat to the tank line.