My worst concern about surge brakes is that if hydraulic fluid leaks off, there are no trailer brakes. This month marks 50 years ago that I bought my first semi with air brakes and bumper pull trailers scare me. But sometimes using a semi just isn't economically feasible. Last week I hauled a load of truck parts to an auction in Dallas. The stuff weighed right around 10,000 lbs. My GMC 2500HD and trailer with 2 7K axles and E rated tires handled it fine. The pickup has diagnostics and it flashes a warning on the speedo if there is a fault in the trailer wiring and I occasionally used the trailer brakes only right before a red light just to make sure they were still working. Everything went ok, but It would have been a whole lot more enjoyable ride in one of my semis.
