Disk Brakes - Electric over Hydraulic???

[JJW_ND]

I kind of jumped in on another thread (Brakesmart) and thought it might be helpful to just start a new thread for someone else.



We are looking into upgrading several of your transport trailers from standard electric brakes to Dexter Hydraulic Disk brakes. The trailers have 8K torsion axles riding on 17. 5 tires.



From what I have been told, Dexter makes a direct bolt on disk brake assembly that runs about $400 per side (or $800 per axle) as compared to $250 ($500 per axle)per side for just the inner brake assembly less the drum for electric. The axles must be Dexter and there is a minimum drop requirement for clearance. A hydraulic line kit for about $70 and the electric over hydraulic controller is all that is required. Dexter and Masterbrake both make a controller. Dexters is about $700. This all sounds very expensive to most of you, but when you are running 20K miles in less the three months and lots of gravel roads, the upkeep, maintenance costs, and down time gets old. Not to mention the feeling when one or more brakes quit (wires torn, magnets, springs... . ).



There are also restrictions on what in cab brake controller can be used. Dexter wrote me stating Tekonsha Prodigy, Sentinal, and 9055 are on the DO NOT WORK with there EH1600 Electric over Hydraulic controller. They also said the new 2005 factory trailer brake controller is not compatible either.



What I am interested in as any comments for those of you with trailer disk brakes: How they are working out? What size are yours? what in-cab controller you are using? What trailer setup you have (Dexter controller - Masterbrake controller - Dexter Disks)?



Thanks for any comments and advice?



jjw

ND

 

[jelag]

I own 3 trailers with electric brakes. . they are 6K lb dexters and one trailer with 2 12K lb dexters that are power disc... . with the brake smart its really a great set up... .



The power disc's have 2 to 3 times the stopping force of the electric's... and there smooth... ... pleanty of reserve even with the trailer at 25K..... I always have problems here with long posts... and this could take some space... would you be so kind as to look up my other posts or email me at -- email address removed -- and I'll send you a couple of pages...



Jim

 

[rweis]

jelag,



Could you email me the long discussion as well? I am looking ot do this to my 5er (Dexter 8k axles, BrakeSmart controller)).



Email is



-- email address removed --



Thanks,



Bob Weis

 

[LEPage]

Pick up a copy of the Feb. '05 Trailer Life magazine. There is a good article on doing this swap. The conversion they used was from

Tow Brake International, and the Prodigy is recommended, but seems like any control will work. The before and after test numbers are unreal. You should find the kit at www.towbrake.com

 

[JJW_ND]

Links.....

Here are some of the links I ran across or recieved from others:



Dexter stuff:

http://i.b5z.net/i/u/1080235/f/Mounting_Instructions_8.0K.pdf

http://dexteraxle.com/inc/pdetail?v=1&pid=1126



Masterbrake: http://masterbrake.com/



Carlisle (same as Dexter ??):http://www.carlislebrake.com/spec_tbp.html



Towbrake: http://towbrake.com/hypowered_disc_trailer_brakes.html



Here is some info Dexter sent me directly on their products: "The Dexter Axle 8K disc brakes will retrofit to any Dexter 8K axle with minimum overhang dimension of 8. 0" for leaf spring axles and 9. 0" for Torflex axles. The 8K disc will not retrofit to Dexter Axle 4" drop spindles manufactured prior to January 2003.

The track dimension will remain the same with the disc brakes.

We recommend using the Dexter Axle electric brake controller model DX2 because we know it is fully compatible. There are many other controllers that are also compatible. Of these we do not recommend the "Time Base" type. These are essentially voltage ramp generators and do not respond proportionally to the tow vehicle brake inputs. We recommend using "Proportional" type controllers. Most of these use "Pendulum" type technology to sense the deceleration of the tow vehicle and send a proportional signal back to the trailer so that the trailer brakes respond with the same effort of the tow vehicle.

We know that there at least 4 controllers that are not compatible with the Dexter Axle E/H 1600.

The Tekonsha Prodigy, Tekonsha Sentinel, Tekonsha 9055 and Red Line TA1200. Ford Motor company has also informed us that the Ford integral controller is not compatible with E/H systems. "





jjw

ND

 

[RustyJC]

I've been watching this with interest as well. One key aspect of these systems to examine closely is the pressure rise time - how long does it take from the time the system receives a signal from the brake controller to begin braking until the system pressure is at its maximum? To date, I've seen figures of 1-3 seconds. Consider a panic stop situation - can you afford to wait 3 seconds for the trailer brakes to check in for duty?



Once someone gets smart and designs an accumulator-type system where maximum braking pressure is always available and is modulated as required by a control valve that takes its input from the brake controller, sign me up!



Rusty

 

[JJW_ND]

It is all in the controller....

Rusty..... I going to clip some of what Jim ("Jelag") has been emailing me. Here are his commments on brake delay.



"... with the simple controllers in the cab it was always 3-5 seconds before the brakes would set on the trailer and than you couldn't really vary the amount of brakes...

With the BrakeSmart controller there is part of the program that allows for up to 2 seconds of full voltage to the hyd unit (hydrastar) to power up the brakes than the brake smarta backs off to the amount of pressure based on the hyd pressure in the truck brake system, and a chart of presets in the set up program... . this allows you to very whats going on with the load on the trailer... . so each time we change the load more than 2 or 3K lbs we reset the controller... actuator (hydrastar) takes the digital signal from the truck and converts that to a power setting and powers up the brake system comes up to that setting and holds it... .

it takes a couple of seconds for that to happen with a normal controller as the pump in the actuator (hydrastar)works at 50% when it sees a 6 volt signal from the controller

in the truck. . etc... hope this makes some sense... . when you push your brake harder in the truck the brakes on the trailer work harder.....

I have mine set so that the brakes on the trailer do most of the work... . but the key feature is that for the frist 1 to 2 seconds based on how you have the Brakesmart set... . it gives a full 12 v signal to the hydrastar to power it up... . and than drops back to what ever level is needed based on the brake pressure on your foot in the cab of the truck... . so the time delay is about 1/3 with the brake smart compared to the other controllers we have in the other trucks... . and when you want full brake power..... you just press on the pedal in the cab and get it... .

In a panic brake the brake smart and actuator (hydrastar) bring the trailer and truck under control in about 1/2 the time of the standard controller and electric brakes used on the other trailers we have... The large trailer I've been talking about usually runs for us around 18-22K lbs... and we've gotten about 85K miles on the brake pads... .

with over 100K on the pads on the 04 that pulls this trailer the most... .



There might not be a delay with the TowBrake actuator and standard in cab brake controllers. I can NOT verify this, but I have that impression based on what I read on it. It has a total different design then the Dexter, Masterbrake, or Carlisle actuators... but more expensive also. The above three appear to loose the delay with the Brakesmart controller.



jjw

ND

 

[RustyJC]

Rusty..... I going to clip some of what Jim ("Jelag") has been emailing me. Here are his commments on brake delay.



"... with the simple controllers in the cab it was always 3-5 seconds before the brakes would set on the trailer... . it (the Brakesmart) gives a full 12 v signal to the hydrastar to power it up... . so the time delay is about 1/3 with the brake smart compared to the other controllers we have in the other trucks.

OK, 1/3 x 3-5 seconds = 1 to 1-2/3 seconds. My point remains - under a panic stop, the trailer brake hydraulic unit receives no signal from ANY controller until you apply the truck brakes, right? Now, if the trailer brake hydraulic unit is starting from 0 PSIG pressure, there's going to be a delay while the pump comes on and builds pressure. Some take more time, some take less time, and (to give BrakeSmart the benefit of the doubt) the 12 VDC signal from the Brakesmart controller may cause the hydraulic unit to build pressure as quickly as possible. Irrespective of the foregoing, the fact remains - if the pump has to start from ground zero, there will be a delay.



Now, think of the water system in a 5th wheel RV. If you're pumping from the fresh water tank, when the faucets are closed the fresh water pump will run until it builds up system pressure and then shut off at a pressure switch setting - the pressure is held within the system, and if it drops, the pump comes on again to restore it. The water piping volume itself acts as the accumulator, and some individuals have even added a bladder-type true accumulator to the piping to minimize pump cycling with the added system volume. If someone opens a faucet, the pump runs in response to the pressure drop, but the pressure was there immediately due to the pressure being maintained in the piping when the faucet was opened, right? No delay in getting water flow.



That's precisely how an accumulator-type hydraulic unit would work. The pump would cycle as required to maintain maximum required braking pressure in the hydraulic system ahead of a control valve. When the brake controller in the truck calls for trailer braking, the control valve would open just enough to provide a system pressure to the disc brakes that is proportional to the output signal from the brake controller. Any excess pressure downstream of the control valve, and all pressure when the brakes are released, would be vented back to a reservoir on the suction side of the pump. This wouldn't even require a valve - just an orifice on the return line whose flow capacity is substantially less than the pump's capacity, but is large enough to bleed off the pressure quickly when the control valve closes.



Now, if someone has a hydraulic unit like the one described above, they've resolved the only complaint I had with the electric-over-hydraulic system. If such a unit exists, however, I haven't found it - not that I've spent every waking hour looking for it.



Rusty

 

[Ross]

I have a big living quarters horse trailer that has 2 8000 Dexter axles with Elecdraulic (electric/hydraulic) disk brakes. They are awesome. This trailer will stop you so fast it's hard to describe. I use the Brakesmart controller. I had a voyager at first, but didn't like the way it seemed to "hang on" at stop signs. The Brakesmart combined with the elecdraulic disk setup is as good as it gets, IMO.



By the way, my trailer weighs 23K, loaded with horses, gear, etc, and stops easier than any trailer I've ever towed, even those weighing 1/4 the weight. You never, never feel it push you. In fact, I had the Brakesmart adjusted incorrectly at first, and the trailer would grab so hard, that it would throw you forward into the seat belt catch. I had the gain adjusted too high. After a few adjustments, I can't tell a difference loaded or empty (stopping, at least).

 

[rweis]

Master Brake Systems



Computer Controlled - Capable of 4 million instructions per second.

Integrated Self Diagnostics - Runs diagnostics and reports system problems to the BrakeSmart™ Unit.

Hydraulic Disc or Drum Brakes - Functions on either platform.

Axle Capacities - Easily supports axle capacities from 3,500 lbs to 15,000 lbs (up to 4 Axles).

Communication mode - Automatically communicates with BrakeSmart™, and relays any error messages as well as Trailer Brake Information for true proportional and safe trailer braking.

Anti-Lock Braking Optional - Optional ABS kit is available.

Automatic Load Proportional Braking Optional - Braking is proportional based on the load contained on the many air suspension trailers.

Extremely Fast Brake Actuation Timing - (0. 3 Seconds into 1 cubic inch)

Integral Breakaway System - Automatically applies trailer brakes

Bleed Mode - Electronic aid to help bleed the brakes





Now what does that mean? IF it means . 3 seconds, while not an accumulator is fairly quick. But again what does it mean? However, if it is accurate, it is significantly faster than a lot of other systems. But NOT an accumulator type system.



The ABS concept is interesting.



I like the RV water system analogy.



Bob Weis

 

[RustyJC]

Extremely Fast Brake Actuation Timing - (0. 3 Seconds into 1 cubic inch)



Now what does that mean? IF it means . 3 seconds, while not an accumulator is fairly quick. But again what does it mean?

Bob,



You're right - without knowing the volume of the braking system in cubic inches, I don't know what the actual delay would be. 0. 3 seconds is an impressive number, though, even if it's meaningless!



Rusty

 

[JJW_ND]

Towbrake....

Towbrake told me their system (http://www.towbrake.com/hypowered_disc_trailer_brakes.html ) has a 0. 3 of a second delay. They have alittle different design actuator (no pump) which might account for the difference.



I might not have captured the jist of Jim (jelag) point on braking but he pretty much said any brake delay was unacceptable especially in rush hour traffic grossing 20K+. He said the delay was LESS then standard brake controllers (other then Brakesmart) and electric brakes he has previously used. I have the impression there is no more delay (and maybe even less of a delay) then any electric brake setup.



Hope this helps!



jjw

 

[RustyJC]

Yep, their "HD3000 HYPOWERED" controller looks interesting. It appears to be a conventional 2-circuit master cylinder that's probably driven by a linear electric motor/actuator. An interesting approach!



Rusty

 

[TX Gooseneck]

We build a fair amount of trailers with the hyd. disc brakes. There are two things you need to look for, dexter makes two models one for drums one for disc. The drum unit is 1000psi and the disc is 1600psi, if you swap them, it will roast the predator unit. Then the brake controller, we recommend the tekonsha voyager. Looks ok and works good.



As for feel, these brakes are great, very linear feel. You can crank them down to the point they will lock up with a load. Make sure you use a heavy gauge wire as well. We're running 10 gauge (as opposed to others using 14-16g) on our brakes. Makes a big difference.

 

[Loren]

Here are some numbers that may interest readers:



60 mi. per hour = 88 ft. per sec.



If the brake delay is 0. 3 seconds, you will travel about 26 feet before you get any trailer brakes. That's slightly more that one car length.



If the delay is 1. 0 seconds, you will travel 88 feet before you get trailer brakes.



Most sports cars or motorcycles with excellent brakes can stop from 60 mph in 100-125 feet, not counting driver reaction time. I don't know what the stopping distance is for an empty Dodge diesel, but I'd guess it's something close to 175-200 feet. An additional 26-88 feet will seem like an awful lot when you need to avoid hitting a pedestrian or minivan full of kids.



Loren

 

[Loren]

I thought that I would like electric over hydraulic disk brakes until I got my BrakeSmart brake controller. I no longer feel any need to improve my standard electric drum brakes.



With a BrakeSmart controller the trailer brakes produce exactly the right amount of braking force to match the truck. You really cannot tell that the trailer is back there (at least not because of the brakes). I don't know how they build such a great controller, but it's so much better than whatever is in second place there is no competition.



Compared to retrofitting an entire trailer brake system, a BrakeSmart controller is cheap. You should try one before deciding to spend all that money on the trailer.



Loren

 

[JJW_ND]

Just a followup....

Thanks to some of you for sharing your experience and taking the time to email me directly. To summarize what I have been able to find out on hydraulic disk brakes:



-disk brakes stopping ability is as good as when you have four new electric braking assemblies all working at their maximum ability... . all the time. No change in braking performance between wheels, axles or as the braking pads wear.



-sliding tires much reduced as all wheel, brake proporional all the time.



-maintenace cost are a fraction of what electric brakes require to maintain functional brakes on all wheels.



I think the cost and use is similar to justifying the higherend brake controllers. If you put 15K miles or more on a year with a loaded trailer in tow, and do this in mountains, lots of gravel, or rush hour driving; disk brakes will perform better and be cheaper to operate.



Regarding the stopping ablity (distance until stopped), I have not found anything that did not state disks stopped in a shorter distance then the same load/trailer with electric brakes.



About mid summer we should have 30K miles on two trailers that are being converted to disks to report on.



jjw

ND