My name is Len Legros, I am an RV service technician wih over 25 years of experience. I have installed hundreds of brake controls of all different shapes, sizes and manufacturers, in almost every tow vehicle available. Below I comment briefly on the different generations of brake controls, in terminology that even the "greenhorn" RVer can understand.
The first generation of brake controls are a combination of electric and hydraulic operation. A "T" is installed at the brake cylinder of a towMvehicle and a hydraulic brake line 1/4 inch in diameter is connected betweenMthe "T" and the brake control. When you push on the brake pedal to stop, brake fluid being forced thru the line activates a cylinder in the brake control to make electrical contact which in turn sends electricity to the magnets on the trailer and applies the brakes. You can also push a handle on the control and manualy apply the trailer brakes. Not a bad system and works fairly consistantly, but not well liked as an RV technician. The brake system of the tow vehicle requires the installation of the brake "T" therefore exposing myself and the RV dealership to a liability risk. Not available any more.
The second generation of brake controls are inertia/electric operated. A leveling sensor or pendulum inside the brake control will move forward as braking of the tow vehicle is applied, thus sending electric current to the brake magnets to apply the trailer brakes. This pendulum must be properly adjusted to give it's best performance for braking. Most concerns I have had of this style from my customers is the sometimes complex procedure for setup and adjustment of the control, to get the best braking available. These controls are sensitive to installation applications. A "touch pad" on the control will apply the brakes manualy if required.
The third generation of brake controls is 100% solid state technology. A dial or slide activated adjustment switch determines the amount of electricity required to apply the trailer brakes. An adjustable synchronization switch shortens or widens the time for brake activation after your foot hits the brake pedal. These can be installed at any angle or even up-side down. They have a slide handle to activate the brakes manualy. I personally find these controls far superior, installation and set-up are definitley user friendly.
For more detailed information, please feel free to contact me thru RVer's Online (Advisors section).
Len