I've realised that the problem of binding brakes can to a large extent be ameliorated by being extremely careful how you park the trailer.

It's all too easy to reverse the trailer to where you want it, and leave it. It's also tempting to leave the hand-brake on. However, either of these actions leave the brake shoes pressing against the hubs. This may not be too bad if you've just finished towing for some miles, but if you've just recovered from the water then the brake shoes are wet which seems to make them prone to stick, and the mechanism is in greatest danger of seizing - especially so if it's salt water.

Earlier this year I had to completely strip and de-rust the brakes on all four wheels, and I took some time to understand exactly how the braking mechanism works - it's quite interesting! Mine are Al-ko hubs, but I think the other makes work essentially the same way.

What I do now when parking is first make sure I exercise the whole brake mechanism. This helps stop things getting seized up through lack of use. Then I ensure that I leave it parked with the brakes completely released, and the hand-brake off (I chock the wheels to prevent any rolling).

To exercise the brakes, you first need to reverse the trailer a short distance (a foot or so is enough). This action applies the brakes, then invokes the mechanism that releases the brakes as the wheels turn backwards. The next thing is to put the hand-brake on - it should spring up to about half-way. Then try to reverse a bit further - the trailer should move a few inches while the handbrake springs up to vertical. This action invokes the mechanism that fully brakes the wheels in reverse. Each of these actions moves different parts inside the brake hub, encouraging them not to stick, and also confirming that they work.

Then, to park the trailer with the brakes released, take the hand-brake off and pull the trailer gently forwards into position. Be careful not to stop suddenly, or you'll apply the overrun brake again! The piston behind the tow hitch should be fully extended. Finally chock the wheels. If you have trouble stopping with the piston extended you can pull forward a tiny bit after you've chocked wheels.

If you don't have a spring-up hand-brake then your mechanism is a bit different, but I would still recommend using this process except for the reverse-with-hand-brake-on part which probably wouldn't do anything.

I was forever having problems with binding brakes when I came to move the trailer, but so far everything's been fine since using this process. I'd be interested to know if it works for anyone else!

Hi Mike

You've just described the puzzle that intrigued me, and was the reason I took the time to work out how the bits of the brake mechanism move inside the hub. It's an interesting engineering challenge: how do you allow backward rotation of the wheel to release the brakes when reversing, yet still allow the handbrake to lock the wheels against backward rotation when parked?

It's all to do with how far the brake linkage moves. When you reverse, the movement of the linkage, and hence the mechanism inside the hubs, is limited by the travel of the piston at the tow hitch. The brakes must be adjusted so that this movement is sufficient to apply the brakes when moving forwards, which means that when you reverse, the brakes are also applied initially.

However, one end of one brake shoe sits on a spring-loaded support, and when the wheels turn backward it gives, and allows the pressure on the shoes to release. As this end of the shoe releases, the cable continues to tighten the other end because it's still trying to apply the brakes, but stops when the piston reaches the limit. The wheels can therefore rotate backwards continuously in this state.

If you apply the hand-brake at this point, it will only move halfway up. The hand-brake lever is sprung upwards, which is very important. When the wheels continue to turn backwards, the spring-loaded shoe-end reaches its limit, while the sprung handbrake lever continues to tighten the cable. There's no more "give", and the brakes are now securely applied, preventing rotation either forwards or backwards.

When this fully-locked position has been reached, all the brake parts in the hub have moved, even the adjuster! It was discovering this that made me realise that deliberately exercising the mechanism should help prevent things from seizing up.

So the secret is that the hand-brake can pull the cables further than the piston, this is what enables it to prevent rolling backwards. The upward-sprung design of the brake lever is an essential feature, and the breakaway cable simply applies the hand-brake.

Hopefully the technically curious will find it all interesting!

I also fitted a flushing kit about 3 yrs ago. I don't think my kit made any recommendations about where to fit to the backplate, and it seemed logical to fit at the top. But I realised that the pipes would foul the chassis on full suspension travel which would bend, and eventually break, the hoses. Mike: does yours not give that problem?

There were no pre-drilled holes in mine anyway, so I had to drill and tap 1/4 BSP, and I put them fairly low down so the hoses don't foul.

I'm still not entirely convinced whether washing the hubs really makes any difference, but I do it anyway, and with the water flowing I very slowly pull the trailer forward for at least a full turn of the wheels. I reckon that will at least wash the whole braking surface of the drums, if not a lot more!

brake adjuster holes? what are these??

Hole in backplate that you poke a screwdriver through and rotate the adjuster by levering the notches.

Brake diagram:

Or with more details, see this page

The hole is behind where the brown parts sit. Note this diagram is rotated approx. 90deg from the orientation of our trailer hubs.

The adjuster is a big problem, because the piston sits in a socket that's part of the backplate. It's steel-on-steel, can't dry out easily, and so rusts and seizes. It not only has to turn to adjust the brakes, it has to slide in and out when the handbrake is applied in order to get reverse braking. A good dollop of waterproof grease when assembling it helps.

"No grease" is always the received wisdom for purely road-going brakes, and the previous time I fully serviced the brakes I took that approach. In fact I put a thin smear of copper anti-corrosion grease on everything hoping that would stave off rust.

A year later, after several salt water launches, the brakes were so seized I needed a hammer and a blow-lamp to separate the parts! And this despite flushing the drums every time. I left the trailer with all the brake parts removed over 2011 because I knew I wasn't going to tow anywhere, and it just functioned as a storage and launch trailer.

When I re-assembled everything last spring, I used waterproof grease (from Western Towing) on all the moving parts in the drum. It's sticky stuff, not unlike vaseline, so it should stay put and not go runny. Since then I've towed up to Oxfordshire and back, and launched several times here, and the brakes are still working efficiently, including reverse handbrake. I know the brakes work because I can easily mac-bump it - I discovered last year that with no brakes it's impossible, the car brakes alone cannot provide the deceleration needed.

My conclusion is that no-grease is not an option with salt water, but the right grease is fine - in fact essential!

Don't forget the adjuster piston!

This is the most infernal bit of the whole mechanism, and seems as though it could have been designed to rust up. The piston must be free to move in the socket both in rotation and in & out. And of course the screw must be free to turn in the thread. The only way to properly lubricate and protect it is to take it apart and coat all the piston and thread surfaces with grease. To do this you have to remove the brake shoes, so it's almost a complete strip-down just to get to that part. :x

About 3 years ago I used copper grease, smearing it on all the moving surfaces when servicing the brakes. By the end of the season all the parts in the drum were seized solid! It doesn't seem up to the job, especially when hubs are regularly dunked in salt water (as mine are).

I've subsequently used waterproof grease, as sold by Western Towing, and so far it seems to work pretty well. I can't be entirely conclusive though until I check out the hubs in the spring in readiness for next season.