DVSA safe towing campaign

[Daniël Bos]

I am not an expert but on my trailers (ifor 3017, Gh94 and lm126) If you put the handbrake on and try and shove it backwards (I use a forklift with towbar on the forks) the wheels will not turn at all. This is with a 5t of forklift pushing. With the handbrake off you push it for a 25cm or so and then the wheels free up.

It depends mainly on the hitch.

The more modern ones with a big gas strut in them apply many times more force than the overrun mechanism. Tis extra force is to try and maintain brake effectiveness in reverse.

With enough force applied (loaded trailer, broken away backwards down a slope for instance) the auto reverse mechanism will still release the brakes.

 

Sent from my D5803 using Arbtalk mobile app

[Stubby]

Our chipper came off once when we went over a bump ( Jensen A 540 ) . Luckily it was stopped almost immediately by the 30 mph sign it hit . If that was a person or or a mum with a pram we would have been locked up . ( and rightly so . ) We now grease the ball hitch on a regular basis to make sure it is properly located .

[Justme]

I really dont get that everyone thinks that trailer makers would sell a trailer with a parking brake that only works in one direction.

 

They would get their ass in a sling if anyone got injured.

 

If you HB does not work both ways get it fixed (or stop parking on 1 in 2 hills).

 

Yes it can roll 12" or so whilst the lever is pushed further back by the spring or gas strut.

 

The amount the lever can move should always be more than the auto revers can release them by.

[gensetsteve]

I really dont get that everyone thinks that trailer makers would sell a trailer with a parking brake that only works in one direction.

 

They would get their ass in a sling if anyone got injured.

 

If you HB does not work both ways get it fixed (or stop parking on 1 in 2 hills).

 

Yes it can roll 12" or so whilst the lever is pushed further back by the spring or gas strut.

 

The amount the lever can move should always be more than the auto revers can release them by.

 

Your probably right I will check a few of ours out over the next few days. I am guessing it does not take much wear in thevbrake shoes before the travel on the handbrake becomes to much to be effective in reverse. Either way there has been many reports of modern caravans running away over the last few years.

[Justme]

This is what a few makers say:-

 

Knott Avonride

http://www.knottuk.com/fileadmin/Knott-UK/usr/pics/Products/The_Complete_Package___Instructions/KF085_-_Spreadlever_Brakes.pdf

PARKING

The handbrake, in conjunction with the energy store, is used to apply the brakes when the trailer is parked.

As the handbrake lever is raised, its lower end makes contact with the lower end of the overrun lever and begins to apply

tension to the brake linkage.

As the handbrake is raised further the energy store mechanism moves overcentre and pulls the brakes on fully. The spring

energy store is pre-tensioned with a force corresponding to at least the actuating force applied during normal trailer braking.

If the trailer is rolling rearwards as the handbrake is applied, or if it is pushed backwards with the handbrake on, the autoreverse

mechanism will be brought into action.

To overcome this, a greater actuating movement is introduced from the spring energy store, expanding the brake shoes further

so that full brake effectiveness is maintained.

 

 

AlKo

http://www.al-ko.co.uk/edit/files/handbooks/overrun-braking-system-handbook.pdf

 

Parking.

On the spring cylinder version, engage the handbrake lever right up to the last tooth (90°). On the gas strut handbrake

version, pull the handbrake lever over centre. The brake shoes (1 and 2) are pressed against the brake drum by the brake

linkage etc. and this applies the trailer brakes.

When the caravan/trailer has been reversed, the brake drum will also rotate backwards. The trailing brake shoe (1) is taken

with it and moves the transmission lever (4) back. This lever then pushes the adjuster assembly (5) which in turn pushes

the leading brake shoe (2) against the stop (6). The caravan/trailer is then braked.

 

It must be noted that when the handbrake is

applied, the vehicle may roll approximately

25 cm (10 inches) backwards before the

parking brake force is used to it’s fullest

extent.

 

[Justme]

Our chipper came off once when we went over a bump ( Jensen A 540 ) . Luckily it was stopped almost immediately by the 30 mph sign it hit . If that was a person or or a mum with a pram we would have been locked up . ( and rightly so . ) We now grease the ball hitch on a regular basis to make sure it is properly located .

 

Test the security of the hitching every time you hitch up.

 

Use the jockey wheel to see if you can lift the trailer back off the vehicle. You should see the vehicle rise to its pre hitched level & feel the extra strain on the jockey handle.

 

This simple check would have saved Freddies life.

 

In this case the hand brake was released prio to hitching. THE lever was then in the way of the hitch locking handle so it was never actually attached properly. Then either the brakes did not work or the brakeaway cable was not fitted (not in the publicly available details).

 

The company involved were very lucky not to be directly chased re this as it does appear that the hitch, coupling & hand brake came from different makers so were not compatible. Plus employee training seems not to have been carried out (you do all train your towers regularly dont you?) or they would have known to test the hitch security.

[Justme]

Your probably right I will check a few of ours out over the next few days. I am guessing it does not take much wear in thevbrake shoes before the travel on the handbrake becomes to much to be effective in reverse. Either way there has been many reports of modern caravans running away over the last few years.

 

 

I would guess most are due to user error or lack of maintenance.

 

As you can imagine my work trailer covers some mileage, fully loaded & driven by people that tend to over brake to start with.

 

It gets checked twice per year.

 

It only needs adjustment about every 18 months.

[gensetsteve]

I would guess most are due to user error or lack of maintenance.

 

As you can imagine my work trailer covers some mileage, fully loaded & driven by people that tend to over brake to start with.

 

It gets checked twice per year.

 

It only needs adjustment about every 18 months.

 

May be that should read my trailer only needs adjusting every 18 months because it's not loaded to full capacity.

I don't run great mileages but always loaded to near capacity and mine always need adjusting before 6 months and often replaced within two years. The other thing we are very hot on is replacing the cables on every service if the outer covering shows stone chip damage.

The cables are cheap and when they get seized the shoes stay on cook the drum shoes and bearings eventually leading to to the wheel falling off

[Goaty]

Always makes me cringe when I see people un hitch caravans and push them towards a cliff using the hand brake to stop them

 

 

Sounds like a top gear moment. You hope they would value their lives more than the caravan, if push comes to shove.

[Matthew Storrs]

Sounds like a top gear moment. You hope they would value their lives more than the caravan, if push comes to shove.

 

Could be unfortunate for any unsuspecting sun bathers down below:laugh1: