Ro-Ro Platform

Ro-ro Platform Latch Cylinder
Mechanical Self-Locking

When a ro-ro ramp is stowed for sea transit, a latch bolt locks it in place. This cylinder drives the bolt — and a built-in mechanical spring lock holds it engaged even if all hydraulic pressure is lost. No power, no pumps, no problem — the ramp stays locked.

80/45·60/32Specs

25 MPaPressure

SS RodStainless Steel

DNVGLType Approval

Technical Specifications

Parameter	Specification
Product Name	Ro-ro Platform Latch Cylinder (Mechanical Self-Locking)
Features	Lock the bolt after ramp is stowed; mechanical spring lock
Specifications	80/45S, 60/32S — front and rear locking
Working Pressure	25 MPa
Piston Rod	Stainless steel
Classification	DNVGL type approval
Application	Ro-Ro Platform

How Mechanical Self-Locking Works

Ro-ro Platform Latch Cylinder (Mechanical Self-Locking)

The mechanical self-locking latch cylinder uses a spring-engaged locking mechanism built into the cylinder body. When hydraulic pressure drives the bolt into the locked position, the spring mechanism engages automatically — holding the bolt in place mechanically, independent of hydraulic pressure. To unlock, hydraulic pressure must actively compress the spring before the bolt can retract.

This means the ramp latch remains locked even if the hydraulic system loses pressure due to pump failure, hose burst, or power loss — a critical safety requirement for ro-ro vessels during ocean transit where storm waves can generate 100+ tonnes of force on the stowed ramp.

The stainless steel piston rod resists the corrosion from salt spray and condensation that accumulates on the ramp mechanism during sea passages. Browse the offshore hydraulic cylinder range for all ro-ro products.

Mechanical vs Hydraulic Self-Locking — When to Choose Which

Mechanical Self-Locking ← this product

✓ Holds without any power source
✓ Simplest fail-safe — spring is always engaged
✓ Fewer hydraulic connections
✗ Spring adds to cylinder length
✗ Spring force limits maximum bolt retraction force

Hydraulic Self-Locking

✓ More compact cylinder body
✓ More size options (80/50, 63/40, 40/28)
✓ Higher bolt retraction force available
✗ Requires trapped hydraulic pressure to hold
✗ Pilot-operated check valves add complexity

Safety Features and Compliance

DNVGL type approval — the latch cylinder is type-approved under DNVGL rules for classification of ships, meeting the requirements for ro-ro loading equipment safety devices.
️ Front and rear locking — the bolt can lock in both the extended and retracted positions, providing positive locking in both the ramp-stowed and ramp-deployed configurations.
Visual position indicator — an external indicator shows whether the lock is engaged or released, allowing crew to verify latch status without accessing the hydraulic system.

Latch Cylinder OEM & ODM

Korea Ever-Power supplies mechanical self-locking latch cylinders for new-build and existing ro-ro vessels. Provide the ramp model, bolt diameter, locking force requirement, and classification requirement. Complete DNVGL documentation package included. Contact the Korea Ever-Power hydraulic cylinder team for ro-ro ramp system quotations.

Hydraulic cylinder types for marine applications

Frequently Asked Questions

What does 80/45*S mean?

80 mm bore, 45 mm rod, S = stainless steel rod. The 60/32*S is the smaller variant: 60 mm bore, 32 mm rod, stainless steel. Both are available with front and rear locking.

How many latch cylinders does a ramp need?

Typically 2–4 latch cylinders per ramp, depending on the ramp weight, stowage geometry, and classification requirements. Each latch point requires one cylinder.

Should I choose mechanical or hydraulic self-locking?

Mechanical is preferred when fail-safe holding without any power source is the primary requirement (e.g., ocean-going vessels with long sea passages). Hydraulic is preferred when space is constrained or higher bolt forces are needed. Both have DNVGL type approval.

What maintenance does the spring mechanism require?

The spring is a disc-spring (Belleville washer) stack — high fatigue life, no maintenance interval for the spring itself. The seal set should be inspected and replaced at the same interval as the main operating cylinder (typically every 3–5 years or at each drydocking).

Can the latch cylinder be ordered with the main operating cylinder?

Yes — Korea Ever-Power supplies the complete ro-ro ramp cylinder set (main operating + latch + jacking) as a single package with coordinated DNVGL documentation. Browse the offshore hydraulic cylinder range.

What Our Customers Say

★★★★★May 2026

"The mechanical self-locking latch cylinders give our crew peace of mind during North Atlantic crossings. Even during the worst storms, we know the stern ramp is positively locked — no hydraulic system required to maintain the lock."

Capt. O. Magnusson — Master, Icelandic cargo ferry

★★★★★Jan 2026

"DNVGL documentation was complete and accepted without revision. The type approval certificate covers both the 80/45 and 60/32 specifications."

H. Petersen — Classification Coordinator, Danish shipyard

★★★★☆Sep 2025

"Good latch cylinders. The stainless rod is the right choice for our Mediterranean routes — salt spray corrosion was destroying our previous chrome-plated rods within 2 years. Only minor note: the mechanical lock adds about 80 mm to the overall cylinder length compared to hydraulic."

A. Ferrante — Technical Manager, Italian ferry operator

★★★★★Jun 2025

"The visual position indicators are a practical addition — our deck crew can verify latch status at a glance during pre-departure checks. Saves time and eliminates the need to check hydraulic pressures manually."

K. Papadopoulos — Deck Officer, Greek island ferry

★★★★★Feb 2025

"Replacement latch cylinders for a 15-year-old ferry. Korea Ever-Power matched the bolt engagement dimensions from our original MacGregor equipment. The mechanical spring mechanism is a direct equivalent — same lock force, same engagement depth."

R. Gonzalez — Fleet Maintenance, Spanish ferry line