fbekholden.com

Hi all,
don't read any further if you have little or no interest in what goes on with the electric braking system as fitted to caravans etc......

We are about to retire and recently (4 months) purchased our "tug".....
We are now searching for the "tow" for it to haul a number of times "laps" around the "block".... Oz..

I have been mystified as to just how the electric brake system works and did a fair bit of research in the last week and a couple of "field" trips.

Below is a "cut and paste" of what I put up on another forum this morning...

frats,
Rosco

Hello again - serial "post" pest here....

I don't know if there is a technical section for this thread - if so kindly advise and move this post..

Our intended van will have "electric" brakes and it is probably an excellent opportunity to glean some knowledge from the membership regarding both operation of the system and practical use.

My understanding (ignorant or otherwise) is that the brake controller fitted to the tow vehicle "dictates" the amount of voltage/current to the brake units on the van...

I do not fully understand how this is accomplished, but am aware that this varies from different make/models of controller.

I note in posts on other forums that this varies from a constant "on/off" application dependent on brake light switch, to that of a variable increase/decrease of voltage/current from the controller according to incline, rate of deceleration and sensitivity control.

I am unaware of how this is relayed/effected to the van braking system, but logic (to me) would suggest this is accomplished by a "devoted" wire and pin connection through both vehicles.....?

If this is so, then the brake light wire on the tow vehicle would serve only to "energise" the brake controller - as in binary code.. on/off.....?

With variable brake controller units, does this provide ability to increase/decrease the voltage/current and also afford some "control" of application/releasing of the van brakes.....?

A manual application "slider" also allows the van brakes to be applied independently of the tow vehicle - serial braking, correcting sway - are there other uses for this independent control?


Van

If am correct in my understanding of what goes on within the brake drums of the van - an electro-magnet fitted to the end of a mechanical brake "lever" receives this voltage/current and is attracted to the rotating "wall" of the brake drum.....
The attraction of the electro-magnet to the rotating wall effectively provides the "leverage" to force the brake shoes apart - imparting friction braking force to the working shoe/drum surface of the brake drum.....

The greater the voltage/current from the brake controller - the greater resultant "attraction" of the magnet to the brake drum wall ...... and ultimately more leverage on applying the brake shoes to the brake drums .....?

I believe some form of anti-wear material is provided between the electro-magnet and brake drum wall to prevent/subdue wear to both components.....?

This is the way I understand the system to work and would be most appreciative of any correction or enlightenment.....

Some aspects of the system are still a total mystery to me - does the van battery have anything to do with activating the system?
Does the "break away" switch between van and tow work independently or in combination with the brake controller system?
Does the brake system fitted to the van need to be calibrated at any time?
When setting up the tow vehicle controls (we have an HR "Guardian" pendulum unit fitted) - how exacting is it to effect proper/efficient combined braking?

I hope members do not feel I am trumpeting all over this forum as a newly joined member....

All responses to these questions greatly appreciated..

frats,
Rosco

Hi Rosco,
I read your above post with interest, as at work we have several trailers controlled by electric, air or mechanical means and this is what i have found over the years, Mind you ours is Hire Industry standard so we have to be flexiable in our setups so any customer can legally haul our gear.

To answer some of your q's;
Brake controller regulates current from tow vehicle to the trailer, by use of an internal resistor, the regulation of the current as you state later on in your post controls the attraction force of the magnet to the drum strong the attraction, stronger braking force as lever is pulled further placing more pressure on the shoes inside the drum.

Some applications (Like work's) has the brake controller mounted on the trailer, so any one can tow without the need for a controller inside the vehicle. (External controller is not ideal as brake force is fixed and you cant regulate on the move.)

In the controller mounted inside vehicle applications i am familiar with, trailer wiring circuit is from brake light switch, through the controller to the trailer socket at the back of the vehicle. Hence the variable control. So a blown brake light bulb has no effect on your brakes, etc.

Not sure of what you mean by the slider controlling sway, etc. But in my experience the slider is used to balance brake force between tow vehicle and trailer depending on load, weather conditions, etc.

The antiwear on the magnet to drum, The magnet block is actually a resin block set around a wire coil (Magnet) on the end of the actuator lever. Its hard to explain but suffice to say magnet block with out last your brake drums,

does your van have anything to do with activating system, yes if fitted with "override" brakes, Ie: Van shunts your car as you break heavily forcing tow coupling (on van) back in on itself either actucting the mastercylinder mounted ontop or pulling the cables to actuate the brakes on the van.
(Sometimes your park brake is part of the override system.)

Your break away system uses a battery on the trailer or van to actuate. basically its full lock up application of trailers brakes. The break away is usually a switch mounted on your draw bar thats wired from your van battery to the trailer brake wiring on your van/trailer. There is a lead from the break away hooked onto your vehicle that actuates if ever seperated. (Basically pulls the guts out of breakaway switch, completes the contacts from van battery to van brakes.

Dont need to calibrate controls, but adjust brakes in normal fashion to ensure efficent actuation.

Adjust your controller to suit load of trailer, trailer braking should be in balance with your vehicle, not pushing it forward nor pulling it back under normal operation. Not to hard, just do it by feel when you first pull out onto your street, apply brakes from low speed and see if van wants to hold you back or push you forward. my preference is to err on the side of holding back. As personally i would prefer to flat spot a set of trailer tyres than force a car into a dangerous unbalanced situation.

Hopefully this answers some of your questions?

Cheers, A.

Thanks Anthony,
yes very much indeed - questions answered.

We don't have the "tow" yet - but am itching to play with the unit on the "tug"....

The "slider" I refer to is an "over-ride" control on the brake unit - for independent application of the trailer brakes by moving the slider towards the application position - it is spring loaded so when you release it - so too, do the brakes on the van.
By using this control, the van brakes can be applied to hold back the tow vehicle using its gears (this is a little more critical with an auto and a heavy tug - our diesel auto just not have the "retard" in S to do much braking - and L is extreme!) ...... it is probably worth considering on long descents - as in using the van to hold back speed and keeping the brakes on the tug mainly in reserve (although still using tow vehicle brakes lightly to assist) should need arise for heavier braking (unexpected etc.).
I am of the opinion this procedure negates the need to re-adjust the combined balance between the two....

Ummmmm... next... sway control..
In the "good books" that I am currently reading - it is emphasised NOT to apply the tow vehicle brakes if a "sway" develops - the "accepted" procedure is to either pull away by slight use of power or by applying the trailer brakes lightly.... this is one advantage of the independent "slider" control....
Of course, good loading procedure and a little "common sense" - something which in recent times just doesn't come "naturally".... in driving conditions should prevent sway from occurring ...... but......

We will not have a hydraulic system fitted to our van at all...... thank goodness the authorities have "raised" the bar and put into place certain "essentials" which hopefully will prevent many mishaps.... and this applies to the size of van we are contemplating....ie - all wheel braked and "break-away" in-line braking switch.... we are opting for the electric system.
Thanks for the "heads-up" on how the break away works - I was a little confused when it came to how the two systems would inter-act with each other.....

We have a DVD from HR (Hayman-Reece) which suggests how to set the adjustment.... but, I would much prefer feedback from people here in Oz - the DVD is an American production and sometimes does not readily lend itself properly to Oz applications...
The unit we have is an HR "Guardian".... although I have learned from the van forum that it is in fact a Tekonsha unit - with features in between that of the basic and premium pendulum units from Tekonsha.

I am comforted to learn that the resin of the electro-magnet will outlive the drums - from what I saw of the unit, it did not appear to have "service pads" fitted.....

Thanks again, Anthony - for your response to my questions...
with your permission?.... I may update my post on the caravan forum...

frats,
Rosco

Please feel free to use any part of my post for any purpose you need.
Cheers, A.

Thanks Anthony - seems someone put this up on the van forum a few years back - I seem to have "re-invented" the "wheel".... (excuse pun)..

frats,
Rosco

Hi rosco doing the same thing as you (4 wheel drive and van) and going half way round next year just had the controller put in the car for the brakes and when towing you have a little light that comes on. red for more brakes green for less the idea is to have the light glow a orange colour when braking. you adjust it when you brake buy using the little wheel thing.the slide thing i was told to just slide it across if the van starts to sway to much and it would help correct its self. it is the best brakes i have used.
i dont no if this is any help to you.
good luck with it all

Without reading all of your post Rosco and the replies, but having had a few touring vans over the years with hydraulic,overide and electric brakes I can definately vouch for electric brakes as being the best and most reliable braking system for a van,trailer etc.

The controller unit sits under your dash and works off the brake light switch and is adustable to suit the braking requirements of the towcar/tow load and the brake habits of the driver.

Once it is tuned to the brake load that it is required to deliver to the electric servos/magnets in the brake assembly it really doesn't need to be tuned again.

I've got a "Tekonsha" brand control unit fitted underdash in my XR8 Flacon towcar and it has been great, would recommend this brand if you can still get it.

It is adjustable from a very severe brake application ( near lockup ) to a very light feather touch application and everything in between.

Have had it fitted for near 14 years now and apart from initial tune/setup I have not had to tuoch it since and has never let me down.

Oh, and if you get van sway, don't hit the brakes, could be terminal.... .

Hasn't happened to me for a while but if van sways best thing to do is just back off the throttle.

Thanks Terry and Basic,
got some big responses from the van site and have just about filled in the gaps from there.
Mine is a Tekonsha unit - but marketed by Hayman-Reece - under the Guardian label.... it doesn't have lights -but uses a digital readout instead... it indicates the voltage which is "supposed" to be going into #5 pin on your trailer socket......
The unit doesn't actually change output voltage - what it does is proportion a "pulse" to the electro magnets in the van drums ..... the "on" time during each "pulse" is increased as the shown voltage increases....

It has been stated many times on these van forums that to correct sway not to apply the tow vehicle brakes.... but to either slightly increase power or to apply only the van brakes by use of the independent control on the unit.....

Not looking forward to finding out what does/doesn't work..... better to load and operate the "rig" (tug and tow) so that this doesn't eventuate.....

Basic, it would appear you are closer than us to making a "run" for it.... we're still up in the air as to what van we will end up with...... I want "practical" - ummmm... and I have to be careful here..... the other option is "comfort"....... think that might better explain the junction in the road......

frats,
Rosco

hi rosco we went with practical and got a 15 footer dont wont to drag a big thing a round. i have sent a pm with are plans
good luck with it

yes BG - sent a couple back - just updating this thread.....

Larger vans are known as "gin palaces" on RV forums.....

We are currently in a "divided house" (excuse pun) sort of cunundrum.... I'd be happy with probably the smallest tandem - but the "balance of power" believes we'd be cramped .....

I have this "strange" feeling we'll be touring Oz - not "holing up" somewhere in it .... but ......

as I mentioned in another thread this afternoon

- happy wife = happy life.....

Off to look at more on Friday - going down east of state to the Royal Flair "stealers"......

I believe we are creating some considerable "interest" in the RV forums in our "debate".......

If van manufacturers are watching this - there could be a "new" line waiting to be designed which may very well become "the" tourer/ste sitter".......

Tandem - you ask? .... seems combined shower/toilet are almost "not negotiable" - but there has been "movement" (excuse pun) on this of late...... and I believe two large tanks are probably a big ask for a single axle......

frats,
Rosco