Can someone please help me understand how my cooks army trailer brake system works

[alittlebitconcerned]

Didn’t quite know where to post this. Please move it mods if I’m not in the right place.




Hello wise forum.


When I first bought my beloved Cooks army trailer I swapped out the hydraulic override pintle hook hitch it came with for a “standard” hitch that doesn’t in any way interact with the braking system. I did this because as far as I could tell the brakes never engaged and the pintle hook system was so loud and frightened my poor dog every time it went bang!


Its been out of rego so long that I now need that I now need a blue slip and to get the blue slip the mechanic wants to see the brake system working.


Beside the master cylinder on the trailer is an electric doohickey thingo. What is this thing? If wired up (to what?) will it activate the hydraulic brakes somehow?


Any mechanic I’ve shown it to say they’ve never seen this setup and scratch their heads.


What day you wise forum?

[p38arover]

Moved to Military Trailers.

[AK83]

I know absolutely nothing about these trailers, but found a PDF describing how to service and repair stuff on them.


The brake master cylinder has a solenoid fitted to lock out the trailer brakes unless the towing vehicle brake
lights are activated. An electrical wiring diagram is shown in Figure 13.

See PDF here (https://afmsafety.com.au/wp-content/uploads/2015/02/H123_Trailer_1250kg_Light_Repair.pdf):

In the PDF scroll down to pages 14-15 ish ... and describes that energising and de-energising it allows the fluid to flow or not.

The description in the quote is from page 29 of the PDF, and has a wiring diagram.

Hope that helps.

[alittlebitconcerned]

Thanks AK83. That’s exactly what I’m after 👍

[BradC]

Unless I'm very much mistaken, looking at that manual and your photos you have no brakes.

The hitch is supposed to push upon the master cylinder to activate the hydraulic brakes (standard hydraulic overrider setup). The solenoid is there to prevent the brakes applying unless the brake light is on.

You changed the hitch and your current hitch isn't connected to the master cylinder, so the brakes won't work.

[Gippslander]

This is the manufacturer’s site and explanation.

How do Cebco Brakes work? : Ex-Military Trailer Spare Brake Parts (https://www.cebcobrakes.com.au/cebco-brakes-work/)

[alittlebitconcerned]

Thanks for the help everyone, all sorted now.

Had an interesting chat with one of the guys that work at cebco who make the brake.
Didn’t realise what a gem I had and that I considered going to the expense of pulling it off and installing electric brakes. Would have kicked myself had I realised after the event.

[BradC]

The brakes on our Caravan work the same way, but we don't have the solenoid, so I have to flip the reverse lever over before backing up. On the other hand, using engine braking down a steep hill without using the brakes on the car, the van brakes itself to stop it pushing the car. Simple, elegant and low maintenance.