Brake Disengage System

[Jim&Ann]

Hi all - I'm new to this forum so apologies if I've missed this topic from previous discussions. We're also fairly new to caravanning - proud owners of a little 17 year old Freedom purchased nearly 2 years ago. ..!

 

Some advice please. .. I've noticed that when we drive off, within a few hundred yards, there is a (very) loud 'clunking' noise, but this is always a one-off & doesn't repeat during the journey. After discussions with a very helpful mechanic I understand this is to do with the brake disengage lever, & there is a 'knack' to what I do when we park the caravan at home relating to pulling the caravan forward or applying the handbrake. Unfortunately, I can't remember the sequence !

 

Basically, when we get home we unhitch & push the caravan backwards down our driveway, & then I don't (knowingly) pull the caravan forward & tend to leave the handbrake off - the storage area is level & I put the stays down. Am I getting this wrong ?!

 

Any advice gratefully received please. Thanks.

 

[gumdrop]

The one I remember, you manually move the lever on the caravan drawbar,

to allow you to reverse using your car this disables the caravan brakes.

When you have the caravan in position you pull forward to extend the drawbar

and the brake lever drops back into place so that the caravan brakes work.

[Brecon]

With the normal Al-KO braking system, when you reverse and apply the brake, the rear brake shoe drops downwards and becomes the leading shoe, the front shoe becomes the trailing shoe.

 

When you pull forward and apply the brake it drags the rear shoe back into its normal trailing shoe position, the front shoe assumes its normal leading shoe use, and you may hear a clunk depending on how fast you are going.

[Black Grouse]

It's not clear from the OP's post whether the "reversing" is all hand-pushed so the operation of the reversing mechanism isn't relevant - or whether the car reverses the caravan part way.

[Jim&Ann]

Many thanks for the advice so far ! - Things are starting to make sense to me now - although I'm still not sure how to prevent the loud clunking noise. ..

 

The reversing down the drive is all by hand, so no compression of the drawbar, & also no reversing just before we unhitch.

 

Found this on an earlier post -

 

'' most caravans now have auto-reverse brakes. That is to say that the "overrun" brakes disengage when the caravan is reversed. In response to a reverse rotation of the caravan wheels, the brake shoes are withdrawn from contact with the brake drum, as the operating mechanism "collapses" within the brake drum, such that compression of the drawbar does not operate the brakes, and prevent the caravan from moving. Normal operation is automatically restored as soon as the drawbar is extended, and the caravan moves forward again. This is also the reason why you should always fully apply the handbrake lever to the upright position. This action compresses a spring, and the energy stored is used to overcome the collapsed brake mechanism, and apply the brakes should the caravan try to run backwards when unhitched!''

 

Putting all together, presumably I should (maybe) pull the caravan slightly forward (although this is hand pushed back into storage place so no braking mechanism being pushed on ?) but definitely apply the handbrake to re-set the brakes to normal - thus avoiding the loud clunk noise ?

 

That said - I'm happy to be told I've got this wrong !

 

Thanks.

[Guest]

See post #18 in this thread.

Maintenance

The AL-KO parking brake system comprises a handbrake lever mechanism actuating a Bowden cable, which operates a brake unit assembly contained within the wheel hub. AL-KO provides two types of parking brake system on their trailers, with the Bowden cable and the wheel hub brake unit being common to both types.

The difference between the systems is the handbrake mechanism used to actuate the Bowden cable. AL-KO’s unique parking brake system requires a source of stored energy to lock the wheel brakes should the trailer start to move after it has been uncoupled from the towing unit. This energy source can be provided by either a spring cylinder charged by hand or by a gas filled cylinder acting as an energy store. Each system requires a slightly different method of operation when parking the trailer, though they both operate in the same manner when for ward or reverse braking is applied. Spring Cylinder Type A spring system is attached to the link between the handbrake lever and the central brake rod. Full application of the handbrake lever (such that the lever is vertical) to the last tooth of the ratchet compresses a steel spring inside the steel cylinder and energy is stored.

The action of the brake lever imparts motion to the brake rod, the Bowden cable and the expanding clutch. This mechanism forces both shoes into contact with the drum. At this stage, the brake unit is latent, the mechanism waiting to see in which direction the trailer will start to move. If the trailer starts to move backwards, the stored energy in the spring will be released. The trailing brake shoe and by reaction, the leading shoe together with the expanding clutch will tend to move in the direction of rotation (reverse) and abut against the stop. Thus the trailer is braked. However, if the handbrake is NOT fully applied to the last tooth (i. e. vertical) and is set to some lesser position than the full vertical, then problems will almost certainly arise after the trailer has been uncoupled from the towing unit.

If the trailer is parked on a reverse slope or if it is pushed backwards, then the brake mechanism will act as though the trailer is being reversed by the towing unit. The shoes and expanding clutch will tend to move with the direction of rotation (reverse), which imparts pressure to the spring-loaded reverse lever, causing it to collapse. Thus, friction between the shoes and the drum is almost eliminated and the trailer will run away.

Operating the Handbrake Some people may find it difficult to set the handbrake lever to its full vertical position without a great deal of physical effort. However, AL-KO have designed their system so that the average user need not do so. For successful parking on a reverse slope or steep hill, the operator need only apply the handbrake with one hand while gently but purposefully inching the caravan trailer a small distance backwards with the other.

The user must supply this small but essential backward movement to ensure that the fulcrum of the transmission lever moves past the point of reverse, thus preventing the lever from collapsing, as it would normally do when reversing. Most users will find it easier to stand facing the towing unit while applying the hand brake and at the same time gently push the caravan an inch or two backwards with their posterior

[beejay]

Many thanks for the advice so far ! - Things are starting to make sense to me now - although I'm still not sure how to prevent the loud clunking noise. ..

 

The reversing down the drive is all by hand, so no compression of the drawbar, & also no reversing just before we unhitch.

 

Found this on an earlier post -

 

'' most caravans now have auto-reverse brakes. That is to say that the "overrun" brakes disengage when the caravan is reversed. In response to a reverse rotation of the caravan wheels, the brake shoes are withdrawn from contact with the brake drum, as the operating mechanism "collapses" within the brake drum, such that compression of the drawbar does not operate the brakes, and prevent the caravan from moving. Normal operation is automatically restored as soon as the drawbar is extended, and the caravan moves forward again. This is also the reason why you should always fully apply the handbrake lever to the upright position. This action compresses a spring, and the energy stored is used to overcome the collapsed brake mechanism, and apply the brakes should the caravan try to run backwards when unhitched!''

 

Putting all together, presumably I should (maybe) pull the caravan slightly forward (although this is hand pushed back into storage place so no braking mechanism being pushed on ?) but definitely apply the handbrake to re-set the brakes to normal - thus avoiding the loud clunk noise ?

 

That said - I'm happy to be told I've got this wrong !

 

Thanks.

 

The Freedom website shows disc brakes so does your caravan have these?

 

Assuming it has drum brakes and auto-reverse. ..

 

If you do not reverse immediately before unhitching and then man-handle caravan backwards on the drive it is most unlikely that the auto-reverse will be engaged as it requires some force to operate the mechanism and a clunk would be heard as it engages. .

 

However, if auto-reverse was engaged it would release the first time the brakes were applied after moving off when the shoes contact the brake drum and is probably the source of the noise. .

 

The problem on a 17 year old caravan may be the hitch if the drawbar is corroded and seizing. When stopping the drawbar may seize closed until the next time you hitch up and on moving off sufficient pull overcomes the sticking shaft with a clunk.

Check if the drawbar is fully extended before you hitch up. Can the drawshaft be compressed by hand?

[Jim&Ann]

My apologies for not coming back to the above responses sooner - busy with work & now we have today finally got away for 3 days in the caravan !

 

I need to fully re-read & digest the above - first thoughts - the drawbar is ok, as this can be compressed by hand & has been greased. .. but - this did stick once or twice before greasing & was freed with a gentle tap with the hammer.

 

When we left this morning, (I had applied the handbrake a few days ago) I noticed that we got a quieter clunking noise as we pulled off the driveway when I tried applying the brakes, & nothing more later. So - hopefully I'm more than half way there to solving the issue !

 

Does the auto-reverse engage with just the reverse wheel movement, or does it need the brake to be applied as well - eg. when reversing when hitched up ? If it applies just with reversing (& no braking - as when man-handling back along driveway unhitched) then presumably this would still go through the process of re-engaging the normal brakes & hence the 'clunk' when I first brake on next hitch-up. If it only applies with both reversing & applying the brake then I'm still confused !

 

That said - I do need to understand & digest the above 2 posts so apologies if I'm not coming back with the correct queries. I will look through again over next few days now I hopefully have some time !

 

Thank you again for helping on this.

 

Jim