Originally Posted by Robert L
The hydraulic brakes are ineffective when towing?
Originally Posted by halla
Nothing wrong with hydraulic brakes, just felt the air brakes is a big upgrade, personal opinion
I know this thread has been silent for a few months, but I wanted to point something out--air brakes are in no way superior to hydraulic. In fact it is the other way around.
First of all, both systems use the same types of components to create the stopping friction: calipers and rotors or drums. The potential for stopping force is mainly controlled by these items. The diameter of the rotor or drum, the surface area of the brake pad or shoe, the piston diameter, and outside air flow determine the amount of stopping force and the thermal resistance of the system. Thus, stopping power is not a function of air or hydraulic fluid.
The hydraulic fluid or the air pressure is used to actuate the components mentioned above. This is where hydraulic is really better: hydraulic fluid has very little compressability. This means the brakes react instantly. Air brakes have a delay. Hydraulics also have few parts in the system and are unaffected by outside air temperature. Additionally, hydraulics lend themselves to better to technologies like ABS and stability control.
So why are air brakes so prevalent in big commercial trucks? Because you can easily couple air brakes between the tractor and the trailer. This creates a very uniformed braking system that is far superior to hydraulics on the cab and electric on the trailer.
Most of us that are towing with Super C's won't be towing a trailer with air brakes. If you have a trailer with air brakes, then you will definitely want a Super C with air brakes. If you are towing a trailer with electric or surge brakes, then you are much better off with hydraulic brakes.
Now earlier the question was raised about hydraulic brakes in the F550 vs. the air brakes of the Freightliner. If you want to know which will stop better, get the specifications for the braking hardware for each. The vehicle that generates the most brake torque retaliative to the weight of the coach and trailer will always have more stopping power. (There are calculators available online to compute brake torque.)
I do know the the Ford has a descent ABS system and the ABS system ties into the builtin electric brake controller to help prevent trailer lockup, too.
One thing I should mention is the F550 lacks an exhaust brake. This isn't a traditional brake at all. It uses exhaust system backpressure to make the engine aid in slowing the truck down. Exhaust brakes are extremely useful when coming down steep grades. Many times the need to use the air or hydraulic brakes is minimized or eliminated. This keeps heat out of the primary brake system and gives you increased braking performance.
The lack of the exhaust brake on the F550 is only true for models using the F550 Cab Chassis, though I'm not sure if anyone builds a F550 based motorhome on the truck chassis. The truck chassis version of the 6.7L uses a variable vein turbo that can be used as an exhaust brake. The Cab Chassis, such as Thor uses, doesn't have this type of turbo and thus doesn't get the exhaust brake.