Trailer surge brakes

[Lou C]

Interesting, I’ve never seen what modern aircraft brakes look like. I find it interesting that trucks still use drums in air brake applications at least here in the US although that seems to be gradually changing. I find disc vs drum debate kind of like the debate on radial vs bias tires for trailer tires. There are good arguments on both sides. That said I think the most important thing to do is get your trailer weighed fully loaded with the boat. I was surprised how much my 20’ boat actually weighed. A lot more than I would have thought based on what the manufacturer listed.

 

[jlh3rd]

For cars, and generally speaking...
disc brakes are less complicated, easier to service, easier to inspect, are more fade resistant, and more uniform, predictable , and more importantly reliable in braking pressure applied to each wheel simultaneously ....
Plenty of accidents back in the day from one front wheel grabbing too much while the other front wheel didn't......
mandatory inspections were not the norm back in the day which didn't help...

 

[dingbat]

I recall reading this on Champion Trailers tech articles but not sure if it is of any practical significance. The idea being that the surge coupler only develops hydraulic pressure in proportion to the weight of the trailer pushing against the trailer hitch.

What your saying is correct about "Force" available at the actuator, but it does not address the displacement of the master cylinder which plays a pivotal role in the conversion of Force to Pressure.

My actuator (foot print) is available in #6,600, #7,0000 and #7,500 rated units. Same fit, form and function but with master cylinders of different displacements.

It also doesn't factor in the Area over which the Pressure is applied.
#1,000 of Pressure acting on a 1" piston develops 785 pounds of Force
#1,000 of Pressure acting on a 2" piston develops 3,141 pounds of Force

I have no idea if the "servo effect" of drums has been quantified. Can't find any research data on it.

 

[Lou C]

There’s that and then there’s the difference in surface area between disc brake pads and drum brake shoes. So it’s likely that disc brake caliper pistons are larger than drum wheel cylinders but the drum shoes have larger surface area. While I have not seen it quantified anywhere I have have seen it said many times that drum brakes develop greater braking torque at the same hydraulic pressure or, require less hydraulic pressure to develop the same braking torque.
I owned a 1965 VW Beetle with 4 wheel manual drum brakes and a 1980 Honda Civic with power disc/drum brakes. The Honda weighed about 100 lbs more than the VW. They stopped about the same with the same pedal effort except the Honda warped the little 7.5” front discs regularly. The VW had 9” drum brakes.