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What Are Hydraulic Trailer Brakes?
Hydraulic brakes use pressurised brake fluid to apply braking force to the wheels. When the towing vehicle slows, hydraulic pressure travels through lines to the calipers, clamping pads onto the brake discs. The result is strong, consistent braking suited to New Zealand trailers and conditions.
How Hydraulic Brakes Work on a Trailer
A trailer system combines a coupling or actuator, rigid lines and flexible hoses, brake calipers and pads, and the disc and hub assembly. Actuation can be surge override or electric over hydraulic. Both create hydraulic pressure, but the control method differs, which affects response and performance at higher weights.
Surge Override Hydraulic Brakes (Up to 2500kg)
In a surge system, deceleration compresses the master cylinder in the coupling, generating fluid pressure to the brakes. This self-contained setup is simple, reliable and ideal for lighter trailers. See our ready-to-fit 2500kg hydraulic brake kits designed for fast installation and dependable stopping.
Electric Over Hydraulic (EOH) Brakes (Up to 3500kg)
EOH uses an electric brake controller signal from the tow vehicle to drive a hydraulic actuator. This delivers stronger, more repeatable braking for heavier loads up to 3500kg GVM. Trailers over 2500kg in New Zealand require an electric control with a compliant breakaway system. Explore our 3500kg EOH brake kits for complete solutions.
Hydraulic Calipers – Cast Iron vs Stainless Steel
Calipers convert hydraulic pressure into clamping force. Cast iron calipers offer robust performance and value, while stainless steel calipers provide superior corrosion resistance for boat trailers and coastal use. Browse our full range of hydraulic calipers to match your environment and duty cycle.
Hydraulic Brake Kits – Why Bundled Is Better
Bundled kits include the matched components you need: calipers, discs and hubs, hoses and lines, and either a surge coupling or an EOH actuator. A complete kit saves time, reduces compatibility risks and simplifies compliance. Compare our hydraulic brake kits to find the right fit for your trailer.
Maintenance Tips for Hydraulic Brakes
Maintain performance by bleeding the system to remove air, inspecting hoses for leaks or abrasion, and checking caliper slide action and pad thickness. Keep fluid fresh to protect seals and ensure consistent braking performance from season to season.
Why Choose Treadway Hydraulic Brakes?
Our components are interchangeable with competitor systems, making upgrades and replacements straightforward. With local stock, technical support and NZ-ready kits, we help manufacturers, repairers and owners build reliable braking systems that suit real-world conditions.
Where to Buy Hydraulic Brakes in NZ
Shop our hydraulic brake kits, hydraulic calipers, EOH actuators, surge couplings and hoses and accessories. For help matching components to your trailer and tow vehicle, contact the Treadway team.
Hydraulic Trailer Brakes – FAQs
What is the difference between surge override and electric over hydraulic brakes?
Surge systems generate pressure mechanically in the coupling as the trailer compresses during deceleration, making them simple and self-contained for lighter trailers. Electric over hydraulic uses a tow-vehicle brake controller to drive a hydraulic actuator, delivering stronger, more consistent braking preferred for heavier trailers up to 3500kg GVM.
Do trailers over 2500kg need electric over hydraulic brakes in New Zealand?
Trailers over 2500kg GVM require an electric control system with a compliant breakaway function. Electric over hydraulic systems pair an electronic controller with a hydraulic actuator to meet performance and safety expectations at higher weights.
Which caliper material should I choose for a boat trailer?
Stainless steel calipers offer superior corrosion resistance and are recommended for marine and coastal environments. Cast iron calipers provide excellent value for general use where corrosion exposure is lower.
What comes in a hydraulic trailer brake kit?
A kit typically includes calipers, discs and hubs, lines and hoses, and either a surge coupling or an electric over hydraulic actuator. Bundled kits ensure component compatibility and streamline installation and compliance.
How often should hydraulic trailer brakes be serviced?
Inspect the system at least annually, or more frequently for heavy or marine use. Check fluid condition, bleed the system if spongy, examine hoses and fittings for leaks, and verify caliper function and pad thickness.