What are surge brakes?
Surge brakes are common in boat trailers due to their simplicity and effectiveness in wet conditions. They work by using the natural momentum of the trailer. When the tow vehicle slows down, the trailer pushes forward against the hitch. This forward motion compresses a hydraulic actuator located in the trailer's coupler, which in turn increases hydraulic pressure in the brake lines, activating the brakes.
The actuator contains a master cylinder similar to those found in automotive braking systems. As the trailer "surges" forward, the actuator compresses, forcing brake fluid through the hydraulic lines to the brakes on the trailer wheels. This process slows the trailer in synchronization with the tow vehicle.
Backing Up: To back up a trailer with surge brakes, you may need to use a manual lockout pin or an electrical lockout solenoid. The manual pin prevents the actuator from compressing, while the solenoid automatically locks the brakes when the vehicle is put in reverse.
Delayed Response: Surge brakes have a slight delay compared to electric brakes because they activate only after the tow vehicle slows down and the trailer pushes against the hitch. This requires drivers to allow more stopping distance when towing a trailer with surge brakes
Fluid Levels: Regularly check the brake fluid levels in the master cylinder. If the fluid is low, top it up with the appropriate type of brake fluid (usually DOT 3, but always verify with the manufacturer’s specifications)
Brake Pads: Inspect the brake pads periodically for wear and replace them if necessary. Squealing or grinding noises are indicators that the pads may need replacement​
Bleeding the Brakes: If you notice a spongy feel when braking, it may be due to air in the brake lines. Bleeding the brakes can remove these air bubbles and restore proper braking performance​