Thread: trailer breaks/kits

Originally Posted by No.3

While @Moa Hunter is correct in what he says with mechanical rods, against that no one in NZ is manufacturing them to my knowledge and supply lines if (or to be fair, when) you damage something could be problematic. My own experience of mechanical brakes is they do get out of balance and they are also a lot more expensive, bulky, more prone to damage and also heavier than the equivalent hydraulic. Apart from some sort of specialist reason that I can't currently think up hydraulic override is the most simple to configure and also easiest to source parts for in NZ.

I've converted two electric drum brake setups and one mechanical to the hydraulic override for that reason (the electric drums while effective need to be used otherwise they seize up quickly) and the mechanical setup was good but we couldn't get parts locally (all indent from Aussie as the nearest agent).

I've converted one hydraulic override to electric over hydraulic (TB-class 3500Kg) as that was set up with one 3/4 master cylinder driving two axle sets of calipers and one 3/4" master cylinder doesn't produce enough oil volume to drive two sets of calipers. Thats why a 2500Kg trailer will only have one axle braked - the brake master cylinder can't drive any more. Interestingly enough, the Trojan style calipers are rated to a max of 2000Kg per axle (on 275mm discs - the usual size you encounter is 225mm@1400Kg) so theoretically aren't rated to stop a 2500Kg trailer. I don't have the Al-Ko or Trigg specs off the top of my head, but they probably aren't rated much more.

The hydraulic systems are the least prone to damage as the bundy tube and hoses do not project out from the chassis of the trailer, and apart from a mechanical kink in bundy tubing the worst you can expect is overheating through operator error or some sort of foreign crud jamming the works up (sticks and stones haha are bad for that if you go off road a lot). The benefit of the override hydraulic systems which to my experience no other system has is that on a downhill the trailer will lightly apply the brakes on itself independant of the towing vehicle as the trailer weight tries to override (or overrun which is the other name for the system) the towing vehicle. This helps keep everything in a straight line and also minimises wear and tear on the towing vehicle.

Looking at the drums on the mechanical brakes they look for all the world like the rear drums on a VX Cruiser with the cable handbrake actuator that works over the hydraulic drums - the drums have have hydraulic and mech actuators on the one set of brake shoes.