Has anyone used the Direclink controller braking system. Saw it in the Sept issue of Trailer Life. Tired of having to reset my current system to stop the grabbing brakes when I come into town after being on the highway.
I sent DirectLink an email asking some questions. I am interested to learn what is the sensing method used for this braking system. I am not aware of the information being in the PCM of Ford to determine the braking demands. Even Ford IBC uses a pressure transducer for sensing brake fluid pressure.
They do have a brake actuator to provide Electric/Hydraulic braking.
First the Kelsey-Hayes went away . . then the Jordan2020 . . then the BRAKESMART . . and now the MAXBRAKE
DirecLink appears to offer advantages, and I remain hopeful they will get their Anti-Lock Actuator on the market soon (or, before I'm ready to buy one).
I received a reply from DirectLink but it doesnt explain how it works. They mention a "...parameters...proprietary...".
If I were to make a "swag" it seems that there is some existing varying signal proportional to the braking which makes me wonder why other brake controller mfgs have not taken advantage of this. It must exist in Ford, GM/Chevy and Dodge as they dont seem to identify a model specific controller. What took the big 3 so long to develop their own IBC for example?
From a referenced link:
Quote: It links with your tow vehicle's computer network and uses multiple data parameters in a proprietary way to create amazingly proportional trailer braking.
Easy Installation and Set-up
DirecLink automatically syncs to your tow vehicle - just plug it in and let it do the configuring for you. Raise or lower the level of braking and you're ready to go. No holes to drill, no directional mounting.
Supported Vehicle Networks
1997 - Present
Ford
General Motors
Chrysler
2008 - Present
Nissan
Toyota
Maybe a good time for a controls discussion for trailer brake controllers
First, it has to 'sense' several things in order to be able to 'intelligently'
control the trailer brakes
1...when the brake pedal is pressed
2...when the TV decelerates
3...the rate of deceleration
4...that the trailer brakes are 'on'
5...amount of current or power being delivered to the TV connector
6...there might be more and will add them as this thread goes
Then how it manages those inputs (sensed) vs the dialed in or presets
Now how the TV brakes work in a very basic sense
Press the brake pedal
actuates the brake pedal switch to power the TV brake lights
Pedal push rod to the master cylinder (MC) moves
as the MC input rod moves, it pushes a piston inside a cylinder filled with brake fluid
that brake fluid then transmits pressure/flow into the brake lines going to #1ABS, #2 line A that goes to one front and one rear brake, #3 line B that goes to other front and other rear brake
brake fluid PSI raises as the brake pedal continues to move downwards
Note that on most/some TV braking systems, the brake pedal switch will
be initiated BEFORE the MC rod is moved, so there is NO
TV braking, yet.
Now a fork in this. #1 is for those that sense MC fluid PSI. #2 is
for those that sense the brake pedal switch initiation.
#1 will have the controller do NOTHING till the hydraulic sensor at
the MC outlet port (a T fitting) senses MC brake fluid PSI. This will
then decide to send braking power to the trailer via the harness/connectors
The amount of power sent is then calculated based on the MC PSI and
rate of change (that is my guess) and then decide to change the amounts
of power sent to the trailer brakes accordingly
#2 will have the controller initiate braking the same time the TV brake
lights are told to go on. This is BEF0RE the MC ever see's any
piston movement, therefore before any TV braking occurs
Some or most all have accelerometers, which sense rates of change
in speed (deceleration). That then tells the brake controller to look
up the dialed in preset and the factory presets. Do the math and then
proportionally send more power to the trailer brakes
Some have a boost function, which is to have a bit more (dialed in both
by the OEM preset and whatever the driver has dialed in). That boosts
the amount of power sent to the trailer brakes BEFORE there is any
deceleration and is to get the trailer brakes to 'lead' the TV's brakes
Meaning that the trailer brakes will come harder to slow it down at
a faster rate than the TV...till the accelerometer senses some level
that is also preset by the OEM (don't know of any that has driver
input for this)
Intriguing that this new controller plugs into the OBII (or whatever
era it capable of plugging into), but don't know if I'd want an
after market anything to be able to 'control' my vehicle's computer
systems until I've thoroughly investigated what is is programed to
and potentially do during a failure mode
-Ben Picture of my rig
1996 GMC SLT Suburban 3/4 ton K3500/7.4L/4:1/+150Kmiles orig owner...
1980 Chevy Silverado C10/long bed/"BUILT" 5.7L/3:73/1 ton helper springs/+329Kmiles, bought it from dad...
1998 Mazda B2500 (1/2 ton) pickup, 2nd owner...
Praise Dyno Brake equiped and all have "nose bleed" braking!
Previous trucks/offroaders: 40's Jeep restored in mid 60's / 69 DuneBuggy (approx +1K lb: VW pan/200hpCorvair: eng, cam, dual carb'w velocity stacks'n 18" runners, 4spd transaxle) made myself from ground up / 1970 Toyota FJ40 / 1973 K5 Blazer (2dr Tahoe, 1 ton axles front/rear, +255K miles when sold it)...
Sold the boat (looking for another): Trophy with twin 150's...
51 cylinders in household, what's yours?...
Oh...ABS does NOT work well with shoe/drum setups. The shoes do NOT release
quickly, nor can they be modulated quickly enough
Disc brakes can be, but not many trailers have disc brakes, yet
Then the trailer disc brake controller (in the trailer) interface with the
standard TV/trailer connector needs to understand that there is an ABS capable
controller in the trailer
You point out many things steps that apply to any braking.
One thing I would add with electric brakes is the time element of electro-magnetic devices to react. This area is where I question whether you could ever develop an anti-lock brake system that would work properly with electric shoe or disc brakes.
With standard electric brakes the magnets must be energized, move to the drum and I there must be movement of the arm before the shoes move outwardly toward the drum.
With E/H you have to power the brake actuator which I believe is a motor that must build pressure to supply the brake system.
There is a lot going on and it seems it would be difficult to apply as an ABS system.
Many talk about the speed of some brake systems and controllers being faster than others. I believe your post clearly shows the proper way to evaluate brakes is add up the pieces of information and the mechanical change that must occur before the brake shoe or pad actually makes contact with the drum or rotor.
Yes, and that the time frame for each in the food chain is where I think many
who have problems are from
Super tuning and constant maintenance is key
Even the electrical runs from the controller to the trailer brake magnets contributes
to the time delays and even amount of current delivered
Another is that all friction materials operation in their sweet spot of temp
and that when outside of that range, poor friction or poor braking
One reason why I ALWAYS touch my brake pedal to initiate the trailer brakes often
to keep them 'warm'...or whenever I think see a potential in front will likewise
touch my brake pedal to warm up the trailer brakes...just in case will nee to
nail them
This also why I always carry trailer brake rebuild kits, even when
I don't own one right now, but borrow many. 'Trained' their owners
to have a spare setup and I always replace any that I've changed
out on the road (yea, do that often enough to be able to do it almost
blindfolded)
wittmeba wrote: I sent DirectLink an email asking some questions. I am interested to learn what is the sensing method used for this braking system.---
Since you didn't get a DirecAnswer from DirecLink -- I'll offer some SWAGs of my own.
To be "truly proportional", the braking force produced by the TV tires and the braking force produced by the TV tires must be in the same proportion as their respective weights. IOW, if the TV weighs 6000# and its tires generate a braking force of 3000# and the TT weighs 8000#, then the TT brakes must generate a braking force of 4000#.
The ratio of braking force divided by the weight of the vehicle is equal to the deceleration espressed in Gs. A braking force of 3000# acting on a 6000# vehicle results in a deceleration of 0.5G.
If a brake controller can sense the deceleration of the TV, it can, when properly adjusted, provide a current to the TT which can generate proportional braking.
It's possible the DirecLink uses the TV's available speed data to calculate the TV's deceleration. If the brake light switch is activated and the TV is decelerating, the DirecLink then could produce a TT braking current proportional to the TV's deceleration.
The DirecLink might also use the TV's speed data to reduce the braking current output at lower speeds.
OTOH, if you want your TT braking current to be proportional to how hard you're pushing on the brake pedal, I don't know of any TV which generates such a value which can be accessed via the OBD-II system.
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