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Why Hydraulic Brakes Matter for Safe Towing
Hydraulic brakes provide the stopping power required for confident towing on New Zealand roads and work sites. A properly matched system improves stability under load, shortens stopping distances and helps ensure compliance for heavier trailers.
The Two Main Types of Hydraulic Trailer Brakes
Both systems rely on fluid pressure but differ in how that pressure is generated. Surge override systems create pressure inside the coupling during deceleration, making them simple and self-contained. Electric over hydraulic systems use a tow-vehicle brake controller to activate a hydraulic actuator, giving consistent, adjustable braking for heavier loads.
Surge Override Hydraulic Brakes (Up to 2500 kg)
The surge coupling compresses a master cylinder as the vehicle slows, sending fluid to the calipers. This makes them reliable for lighter trailers under 2500 kg GVM. Surge brakes are valued for straightforward installation, minimal components and dependable everyday use.
See our complete 2500 kg hydraulic brake kits for matched components.
Electric Over Hydraulic Brakes (Up to 3500 kg)
Electric over hydraulic systems use a brake controller signal to drive a hydraulic actuator that applies fluid pressure to the calipers. This design provides stronger, more responsive braking and is required in New Zealand for trailers over 2500 kg GVM when fitted with a compliant breakaway system.
Explore our 3500 kg electric over hydraulic kits for heavy-duty applications.
Surge vs Electric Over Hydraulic: Quick Comparison
| Criteria | Surge Override | Electric Over Hydraulic |
|---|---|---|
| Typical GVM Range | Up to 2500 kg | Up to 3500 kg |
| Control | Mechanical, automatic | Electronic controller, adjustable |
| Installation | Simple, self-contained | Controller + actuator integration |
| Best For | Light trailers, consistent loads | Heavy trailers, varied terrain |
| NZ Compliance | Legal below 2500 kg GVM | Required above 2500 kg GVM with breakaway |
Key Factors When Choosing a Hydraulic Brake System
Always begin with the trailer’s certified GVM. Match calipers to disc size and axle rating, and select materials suited to your environment. Stainless calipers are ideal for marine conditions, while cast iron provides robust performance inland. Consider terrain and towing habits; the controller adjustability of electric over hydraulic systems gives added security on steep or uneven routes. Treadway components are engineered for compatibility, making upgrades and replacements straightforward.
Hydraulic Brake Kits – Simplifying Your Choice
Bundled kits bring together matched calipers, discs, hubs, lines, hoses and the appropriate actuator. Choosing a kit reduces risk, speeds installation and ensures the braking system meets both performance and compliance requirements. Explore our full range of hydraulic brake kits, or select individual hydraulic calipers, surge couplings, EOH actuators and hoses and spares for hydraulic brakes.
Hydraulic Trailer Brakes – FAQs
Do I need electric over hydraulic brakes for a 3000 kg trailer in NZ?
Yes. Trailers above 2500 kg GVM in New Zealand must have electric control with a compliant breakaway system. Electric over hydraulic delivers the required stopping power and control.
Can I start with surge brakes and upgrade to EOH later?
Yes. Many components are interchangeable, allowing you to retrofit an electric actuator and controller as your trailer requirements change.
What is included in a hydraulic trailer brake kit?
A kit usually includes calipers, discs and hubs, rigid and flexible lines, and either a surge coupling or an electric over hydraulic actuator. Bundles reduce compatibility issues and save time.
How do I choose calipers for a boat trailer?
Stainless steel calipers are recommended for marine trailers thanks to their corrosion resistance. Match the caliper to your disc and axle size, and rinse and service the system after saltwater use.
Where to Buy Hydraulic Brake Systems in NZ
Treadway supplies hydraulic brake trailer kits, calipers, surge couplings, EOH actuators and hoses and spares for hydraulic brakes. Contact our team for advice on the right setup for your trailer and towing needs.