I’m curious about this: is the suppposed self energizing quality of drum brakes actually an advantage vs discs in a surge system?
That's a good question. I suspect the "self-energization" has a relatively small effect on overall performance given all the things at play in these surge systems. For instance:
- Larger surge actuator piston diameter would create lower brake pressure (bad), but less actuator stroke or movement (good).
- Larger brake piston diameter (drum or disc) results in higher brake torque and force (good), but more actuator stroke or movement. (bad)
- Unique to surge brake systems is that actuator pressure is a function of trailer weight MINUS braking force, which is a function of actuator pressure. That's why it's critical these systems have dampers and orifices so you don't get into a brake on-off oscillation situation.
There are a lot of dynamics and differences between drum and disc systems in how much brake force is generated for a given trailer deceleration load. Given the above, I'm not surprised you didn't notice any difference when going to larger wheels.
I believe disc brakes, in general, produce more brake torque than drum brakes for a given pressure and fluid volume. At least that's what I felt when I switched to discs, but I'm not an expert on drum brakes. Airplane brakes are all multi-rotor designs.
![777 brake.jpeg 777 brake.jpeg](https://forums.iboats.com/data/attachments/375/375804-a0b54d3bde0a54f020eb2da85fa30e8e.jpg)