Trailer Brakes while parked backwards down hill

[htb]

Easy answer NO

[Stephen Blair]

For me something has to work 100% to work.

That humble pie an stay in the oven 😀

[monkeybusiness]

Sometimes heavy trailers pointed backwards downhill need a bit of extra handbrake lifty lifty to really engage the brakes in my experience. Mr Blair - if your trailer handbrake can foul on the headboard at or near full application then I would think that there is something wrong with the design/construction of the trailer. If the handbrake is restricted in its movement then full braking force can't be applied and your trailer may well run away backwards downhill. Heavily laden trailers with not enough handbrake application can creep back a bit until the handbrake settles and is pulled on further by the mechanism, but they shouldn't run away more than a few inches if correctly constructed and maintained.

There are many adjustments required to properly set up trailer brakes - it isn't just a case of winding up and then backing off the shoes as the amount of play in the cables is equally important. It's a bit of a dark art which is why I leave all of my trailer/trailed plant running gear servicing to an expert every 3 months. Engines, vehicles, tractors and chippers are a piece of cake in comparison!

[Stephen Blair]

handbreak comes up to say 45 degree( this is a guess) the only time it came right back is after it shot backwards, hit my house and pulled the break cable, the break cable pulled the bottom of the break lever hence sending the handle away further back than usual.

If it hadnt hit the house( i had 1 side chalked) it would of snapped the cable and kept going.

as i said, trailer had recently been serviced and the trailer will stop the towing vehicle on a downhill when breaks applied with force.

I ill get trailer booked in and get it tested after

[gensetsteve]

At times I run with about 16 trailers. I have new ones, serviced ones and not so serviced . I would not trust the hand brake in reverse on any of them they simply don't work. If your not confident your chocks will hold don't un hitch. We don't use the hand brake in the yard as when left for a few weeks the shoes will bond them selves to the drums especially if cleaned new or well serviced.

[mendiplogs]

At times I run with about 16 trailers. I have new ones, serviced ones and not so serviced . I would not trust the hand brake in reverse on any of them they simply don't work. If your not confident your chocks will hold don't un hitch. We don't use the hand brake in the yard as when left for a few weeks the shoes will bond them selves to the drums especially if cleaned new or well serviced.

 

HI STEVE yes your right about shoes bonding mate we use a large log that stops trailer thanks jon

[WeFixIt]

FORWARD BRAKING

The actuating force for the wheel brake is generated during braking of the towing vehicle, as the trailer tends to overrun and pushes the drawtube in. This force is transmitted to the expander devices in the wheel brakes via the overrun lever, brake rod, compensator and brake cables.

As a result, the brake shoes are pressed against the brake drum. The resulting friction from contact of brake linings and drum produces the required braking.

On releasing the brake on the towing vehicle, the drawtube returns to its original position and the brake shoes are released from the drums by means of the tension springs.

AUTO-REVERSE

During reversing the drawtube is pushed in and the brake shoes press against the drum (as in forward braking).

When the trailer wheels are in reverse, the reverse rotation, combined with the friction generated from drum and lining contact, causes the sliding shoe to slide on its carrier towards the adjuster.

This displaces the sliding shoe radially inwards away from the drum. The drawtube may then travel fully to its end stop without applying further force to the brake shoes and the trailer can be reversed without any difficulties.

Changing direction from reverse to forward travel results in the drawtube being pulled out, allowing the sliding shoes to be returned to the forward braking position by means of the tension springs.

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.

[Dean Lofthouse]

FORWARD BRAKING

The actuating force for the wheel brake is generated during braking of the towing vehicle, as the trailer tends to overrun and pushes the drawtube in. This force is transmitted to the expander devices in the wheel brakes via the overrun lever, brake rod, compensator and brake cables.

As a result, the brake shoes are pressed against the brake drum. The resulting friction from contact of brake linings and drum produces the required braking.

On releasing the brake on the towing vehicle, the drawtube returns to its original position and the brake shoes are released from the drums by means of the tension springs.

AUTO-REVERSE

During reversing the drawtube is pushed in and the brake shoes press against the drum (as in forward braking).

When the trailer wheels are in reverse, the reverse rotation, combined with the friction generated from drum and lining contact, causes the sliding shoe to slide on its carrier towards the adjuster.

This displaces the sliding shoe radially inwards away from the drum. The drawtube may then travel fully to its end stop without applying further force to the brake shoes and the trailer can be reversed without any difficulties.

Changing direction from reverse to forward travel results in the drawtube being pulled out, allowing the sliding shoes to be returned to the forward braking position by means of the tension springs.

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.

 

We have already established this apart from the last paragraph in bold

 

My argument is that the full surface of the brake lining on the shoe does not contact the drum once the auto reverse mechanism has been activated, so the "full braking effectiveness" cannot be achieved. So the question is, what percentage of braking effectiveness is achieved ?

[TimberCutterDartmoor]

I thought your trailer brakes disengaged going backwards, but the handbrake worked.

 

This is correct. Parked a trailer for years rear facing downhill, handbrake on, no issues.

[WeFixIt]

If auto reverse has been activated then you may have on a good day 2-3% drag on the non sliding shoe

 

It makes no difference the area of contact if it has no force behind it it won't have any effect

 

In simple terms auto release activated means you brake shoe pressure has been released and your brakes no longer work until till the auto release is reset!

 

Also what some are saying the park brake works in reverse because a law states it has to have energy store?? This means it has a gas strut pushing your park brake lever up !!

 

The auto reverse will still activate in a backward direction

 

Trailer park brakes don't work backwards ( if fitted with auto release)

 

If it does hold in reverse then your brakes are in poor maintenance and not working correctly and unpredictable !