Hydraulic Steering Systems in Modular Semi Trailers: How They Work & Why They Matter

A deep technical guide to hydraulic steering systems used in modular and multi-axle semi trailers — including steering cylinders, control modules, pressure circuits, valve blocks and maneuvering advantages for heavy transport.

Hydraulics Heavy Transport
📅 Published on 2025-11-17 | ✍️ Semi Trailer News Engineering Desk

Image: Hydraulic steering cylinders and valve block on a multi-axle modular trailer

🔧 What Is a Hydraulic Steering System in Modular Trailers?

Hydraulic steering is used in modular and multi-axle heavy transport trailers to allow precise movement of axles during tight maneuvers. Unlike mechanical or self-steering axles, hydraulic steering provides **full synchronized control** over steering angles using:

• Hydraulic cylinders (steering rams)
• Valve blocks and pressure circuits
• Electronic or manual steering modules
• Hydraulic power pack (pump + tank)

This system enables trailers with 6, 8, 12, even 24+ axles to move heavy loads through extremely narrow industrial zones, city roads, or construction sites.

🛠 How the Steering System Works

The tractor unit or operator’s control module sends steering commands. These commands adjust hydraulic pressure to each axle’s steering cylinder, creating synchronized movement.

Key components:

• Steering Cylinders: Apply force to steer axle arms.
• Hydraulic Lines: Deliver pressurized oil to each axle.
• Valve Block: Controls direction (left/right) and pressure.
• Power Pack: Provides required hydraulic flow.
• Electronic Steering Unit (optional): Angle sensors + CAN-bus control.

🔄 Types of Hydraulic Steering Systems

1. Manual/Remote Steering

Operator controls steering via joystick or wired remote. Used for modular systems like Goldhofer, Faymonville, Scheuerle.

2. Tractor-Coupled Steering

Steering follows the tractor’s movement. As the truck turns, steering angle is automatically synchronized.

3. Electronic Multi-Axle Steering (EMAS)

Advanced system using:

• Angle sensors
• Steering computers
• Hydraulic proportional valves

Provides high precision at low speeds and automatic centering.

🎯 Advantages of Hydraulic Steering in Modular Trailers

• Tight Turning Radius: Essential for industrial plants & ports.
• Improved Load Distribution: Axles steer according to load path.
• Better Tire Lifespan: Reduced side-scrub.
• Higher Safety: Stable control at low and moderate speeds.
• Flexible Configurations: 2-line, 3-line, 4-line modules.

⚠ Common Problems & Failure Symptoms

• Hydraulic oil leakage from steering cylinders
• Valve block overheating or clogging
• Uneven steering angles (desynchronization)
• Slow response due to low pump pressure
• Misalignment after heavy-load operation

🧰 Maintenance Recommendations

• Check hoses for leaks or cracks
• Monitor hydraulic oil temperature and contamination
• Calibrate steering angles regularly
• Test remote/manual control before operation
• Keep valve block clean to prevent debris damage

🏁 Final Thoughts

Hydraulic steering systems are the backbone of modern modular heavy transport. These systems allow precise maneuvering, improve safety, reduce tire wear, and enable the transport of extremely heavy and oversized cargo through challenging routes.

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