LH or RH DRUM UNIT ?
Actuating Arm is towards driving direction. When the brake magnet is pushed in either direction on the brake assembly (forward or backward), the brake shoes are forced apart which activates the trailer brakes. When pushed backwards the brakes won’t apply quite as hard as when going forward, but they still do work.
PARKING BRAKE
Parking brake is engaged by pulling the lever. (In the picture the green wires are pushed through the lever hole, that’s not where they go. I guess it makes the picture look more tidy). I’ll update the picture eventually.
ELECTRIC BRAKE CONTROLLER
You need one, could be one of the very costly, and marginally functional, Australian trailer mounted units. OR you could get one of the advanced electronics units common in USA.
The USA units are all designed for cab mount, with informational display, and manual override. Most cars and trucks in USA have the electric control circuits built right in. A lot of trucks come with the controller factory standard. Installation is dead simple, find the plug on the harness and plug the aftermarket controller in.
In NZ we rarely see the pre-installed wiring harness. A cab mounted controller is therefore only a convenient option if the trailer is exclusively used with one tow vehicle.
A couple simple solutions: Wire the cab mounted controller with a long lead. Roll up the lead when not in use, stays with the trailer. This preserves the ability to access all the info and manual control while driving, but chances are, someone forgets the cable after disconnecting the trailer. Our preferred option is to mount the USA units on the trailer. Must be mounted in a water proof electric box. You can not see the info panel, or use manual override. So the interface is exactly what you would get from the Aussi units. The USA electronics inside are still far superior, and the price is much lower.
IMPORTANT WIRING NOTE: Hard to believe how much of a difference it makes, the BLUE leads to the individual brakes must be identical; lengths, grade of wire, solder connections, not crimp only. Same for connections from the wheel to ground. (wheel units come with 2 green wires, it does not matter which way these are connected).