Trailer Brake Adjustment

[blued]

I'm having some problems with the brakes on my trailer. They have never really worked so last year I serviced them:

- New cable and adjusters each end
- Greased the hand brake and hitch ram
- Pulled hitch out as far as it goes and adjusted the shoes so that they just catch the inside of the drum when you spin the wheel
- Adjusted the cable

The handbrake has 3 click positions, when pulled to the second click the wheels lock. However when I tow the trailer and brake at a junction I get a 'thunk' from the back, I assume because the ram has got all the way in without pulling the brakes on. I can adjust the cable so it is tighter but then I'll get to the point where the handbrake won't get to the first click on the ratchet. Is there something that I'm missing? Could the ram be faulty?

It is an ALKO system. It has never been a problem because I don't tow more than a few miles to the loch and normally leave the boat on a mooring but with the Garda trip this year they need to work!

[Gazjen]

Can you take some photo's of the hitch?

it sounds as if something is missing or incorrectly seated if the handbrake works but the operation of the bar doesn't pull the cable

Can you put some bricks behind the trailer wheels and get someone to reverse the car to see if the cables are being pulled?

I can't find any pictures on the web to let me see the operation clearly.

[Capn Jack]

Hi Guys

There are usually 2 adjustments for brakes and handbrake. You will probably have a handbrake power store, which is basically a tube with a big spring and a rod running through it (later models have energy springs), attached to a clevis type of thing attached to the cable somehow. This is for the auto reverse brakes in case you park on a slope, like a slip and want to put the brake on if you are sloping backwards. The auto reverse mechanism will kick in but the energy store will re-establish braking (supposedly).

The adjustment is very fine and should pull the brakes on in the very last few inches of the ram bottoming out, otherwise you will get kangarooing.

If you have the energy store type with a rod through the middle then that will adjust the handbrake pull for you, the other cable adjustment might be a turnbuckle type which does the cable.

[blued]

Here is a manual for the system I have, I used this last year but until now was unable to find it again - http://www.al-ko.co.uk/edit/files/handb ... ndbook.pdf

Capn, I think the spring that you talk about is missing from my set up so as Gazjen suspected a missing part could be the problem. On page 3, figure 10, item 2 (spring cylinder) I have no spring inside. From memory it basically has the bolt from the end of the brake cable at one end and the bolt attaching it to the ram at the other end. I'll check this evening.

I put blocks behind it yesterday and reversed back until the ram was right in. The brake cable was not tight, but then I realised that whatever happens when you reverse at the drum would have kicked in so my test was pointless! Like you say I'd need someone else to reverse it to see what was happening.

Thanks for the info guys, I think first off I will have to source a new spring cylinder.

[betty boop]

Here is a manual for the system I have, I used this last year but until now was unable to find it again - http://www.al-ko.co.uk/edit/files/handb ... ndbook.pdf

Capn, I think the spring that you talk about is missing from my set up so as Gazjen suspected a missing part could be the problem. On page 3, figure 10, item 2 (spring cylinder) I have no spring inside. From memory it basically has the bolt from the end of the brake cable at one end and the bolt attaching it to the ram at the other end. I'll check this evening.

I put blocks behind it yesterday and reversed back until the ram was right in. The brake cable was not tight, but then I realised that whatever happens when you reverse at the drum would have kicked in so my test was pointless! Like you say I'd need someone else to reverse it to see what was happening.

Thanks for the info guys, I think first off I will have to source a new spring cylinder.

I had this on my alko a few years back, sounds like the hydrolic dampner in the hitch unit has gone, (de gassed) no adjustmant possible but you go from smooth braking to thud up ur rear end overnight. its a easyish job to replace the dampner cartridge from what I remember, wont affect the braking but will affect your comfort of drive - at the same time watch out for greese n rust on the ramp itself, mine was left with no greese by the supplier and it rammed in but wouldnt retract.

[Capn Jack]

You want one of these, plus I suspect a few more bits to go with it if it is missing.

Handbrake spring cylinder

You should have a U shaped bar inderneath the coupling too, the spring sits inside it and is attached to a piece of the mechanism inside the coupling.

If you can post some pictures I can tell you whats missing.

Believe it or not you should be able to push the coupling in sufficiently to see if any slack is taken up, it's hard but it will move. This will also tell you if BB's theory is right as it will move easily if the damper is kaputt!!

[blued]

Now that I've seen what the spring cylinder looks like I can confirm that it is there, but rusty. I had it confused with the part that comes after it, it makes more sense now. I will take some photos tonight just to be sure I have everything!

I'm unable to push the damper in by hand so it sounds like I may have the same problem as BB had. I'll need to remove it and see what sort of state it is in.

Thanks again guys, hate to think what the local trailer place would have charged if I'd put it in there. When I went in for cabling and parts he had nothing to suit a boat trailer!

[Capn Jack]

Mine's a little rusted now and could do with a new one, but the principle of the operation is simple. The handbrake works by pulling on the U shaped bracket in which the store is held, which has a studding running through it. The back of the U section pushes against the energy store, the nut at the front captures the handbrake power and pulls the cable taught.

When the brake overun operates (because the energy from the forward motion pushes the damper and the coupling) the the energy store is by passed because of the studding running through it and it pulls the cable taught.

Handbrake adjustment is via the nut in front of the store...........brake adjustment is via the turnbuckle on the cable.

Hope this helps a little more.

[blued]

Thanks for the pictures and info Capn and here is a shot of mine. As you can see it is quite rusty! Just in case anyone is wondering the nut on the threaded rod is something I had fabricated when I was unable to find a replacement for the rod that was originally there! There is one at the other end as well.

I think the next step will be to get the damper off and see if it has failed. With the damper off should I be able to check the brake operation by pushing the ram in freely?

I'm also going to replace the spring cylinder seeing as it is relatively inexpensive.

[Capn Jack]

No problem blued, glad to help.

Your set up is very similar, except you have a single bracket which pulls the rear of the energy store. The nut on the front is the handbrake adjustment. Although there should be an adjustment on the cable somewhere. Later trailers tend to have studding rather than cable because cable tends to stretch, however as long as the cable is adjusted correctly I think it's fine, the extra stretch in my opinion, helps with a softer braking.

I'm not sure your damper may be faulty, it's always worth a look though, just in case. You see as soon as you disconnect the brake cable it will thump you in the back when you brake. The fact that you cannot push in the coupling also indicates it may be ok. Having said that, with even pressure, it's quite strong you should be able to push the coupling in a little.

I would put money on the enrgy store being completely rusted and stuck, which is another reason you cannot adjust the handbrake. When you pull it on you should be able to feel the spring as it tightens.

You should pump in loads of grease into the nipples and then squirt some WD up into the underneath of the coupling to free off the mechanism.

Correctly adjusted brakes should come on just before the damper bottoms out, not halfway, not a quarter way, not 3 quartes of the way but almost at the end so as there is just enough braking not to get the thump in the back. A little tip is to support the cable with cable ties along it's length, this will help with its weight hanging on the brake springs. you'll get a finer adjustment.

[Gazjen]

Well mine was nothing like that

[blued]

I'll see if I can pick up a spring cylinder locally from a caravan place because Trailer Tek want £7 for delivery

The handbrake just pulls straight on to the cable, no spring can be heard, so I think you're right about it being stuck.

[betty boop]

my Alko is slightly differenet from that with the cylinder being inside the head unit all I see is a cable but Im guessing the theroy is the same?

[blued]

I would have thought so, where the spring cylinder sits probably depends on your trailer manufacturer?

[Capn Jack]

Well mine was nothing like that

Later trailers have the energy store with the handbrake as Betty describes, si yours may have been like that too...it's a better system and away from any water.

The handbrake just pulls straight on to the cable, no spring can be heard, so I think you're right about it being stuck.

Blued, looking at your picture again, are you sure the handbrake mechanism pulls straight onto the cable. The bracket which looks like its's from the handbrake also looks like it goes around the back of the spring cylinder, the principle should be (and I say should be because I think it's rusted solid as we discussed) that when the handbrake is applied the spring gets pushed against the front nut, thus creating an energy store and pulling the brakes on. It's the coupling mechanism which is directly attached to the cable, am I not correct?