>>1608729>illegal in EuropeI'm currently in Germany and not only are they legal here, they're the ONLY option on new trailers. The only way to get the old surge brake is to buy used now.
>>1609149>how do they work?A brake controller is wired into the vehicle's electrical system and senses when you brake the vehicle. There's 2 types: Time delay (deprecated) and proportional (current best). When you press the brake, the first waits a user-programmed set amount of time then brakes the trailer. The latter instantly brakes the trailer to the same degree you're braking the tow vehicle. You also have your choice of straight electric or electric-over-hydraulic (the latter usually only found in triple-axle or bigger trailers where the extra braking power at the cost of potential brake fade really matters).
>like air brakes? No.
>how do they adjust to different loads and pedal pressures?Time delay doesn't, which is why it's largely falling out of use (currently its only benefit is it's slightly cheaper). Proportional auto-adjusts.
>installing in old vehiclesYou need to wire in a brake controller, which can be done on any vehicle including 24/36/48v vehicles. Likewise, the time-delay brakes can be retrofitted to just about any trailer.
>benefitsMore braking power than surge brakes, especially on larger, multi-axle trailers (each wheel gets its own brake)
Can back up the trailer without having to disable the surge brake
Better mileage on hilly roads due to no "slinky effect"--potentially up to 15% better on really heavy trailers
No/reduced brake fade depending on whether electric or electric-over-hydraulic
Higher tongue load due to 1-piece trailer neck
Gradual braking=greatly reduced risk of fishtailing, less brake and tire wear on both tow vehicle and trailer
Proportional brakes usually feature ABS
Significantly less maintenance and calibration (one and done)
