Electric over hydraulic brake actuators are devices used in automotive and trailer brake systems to control the application of hydraulic brakes using an electric signal. They are typically used in towing applications, such as trailers and recreational vehicles (RVs), where the towed vehicle needs to synchronize its brakes with the towing vehicle's.

Here's how electric over hydraulic brake actuators work:

1. Electric Control: The system starts with an electric brake controller installed in the towing vehicle. This controller allows the driver to activate the trailer brakes when needed. It can be adjusted to control the braking force applied to the trailer.
2. EOH Actuator: The electric signal from the controller is sent to the electric over hydraulic brake actuator. This actuator is essentially an electrically powered hydraulic pump. It converts the electric signal into hydraulic pressure.
3. Brakes: The actuator's hydraulic pressure is applied to apply the brakes on the trailer. This can be done through a hydraulic brake system similar to what you find in many vehicles. Still, the key difference is that it's actuated by an electric pump instead of the traditional mechanical linkage or vacuum boost.
4. Proportional Control: Many electric brake controllers allow for proportional control of the trailer brakes. This means that as you apply the brakes in the towing vehicle, the controller sends an appropriate amount of electric signal to the actuator, which in turn applies the trailer brakes with a force proportional to the towing vehicle's deceleration. This provides smoother and more effective braking, especially when you need to slow down or stop quickly.

Advantages of electric over hydraulic brake actuators include:

1. Enhanced Control: They provide better control over the trailer's braking force, allowing for smoother and more responsive braking.
2. Compatibility: They can be used with various trailer types, including utility, boat, livestock, horse, and 5th Wheel RVs. Any trailer equipped with an electric over hydraulic brake setup.
3. Safety: They improve overall towing safety by reducing the risk of trailer sway and enabling more effective braking.
4. Adjustability: Many electric brake controllers allow adjustments to suit different towing conditions and preferences.
5. Towing Capacity: They are suitable for larger trailers and heavy loads, where effective braking is crucial.

Electric over hydraulic brake actuators are essential in modern trailer brake systems, offering improved performance and safety compared to traditional mechanical systems. However, ensuring the system is installed correctly, bled, and maintained for safe towing is important.