Another Thumbs-Up for the BrakeSwitch

[ronboc]

Hi -

As others have mentioned in various forum-posts, it seems like Homer Hawk's BrakeSwitch should be installed as part of a diesel-coach's main equipment - and not an add-on. It's that useful.

As I understand it, in all diesel-coaches with engine brakes installed, there's a driver-operated switch that inserts a restriction in the exhaust (creating backpressure) and also tells the transmission to begin downshifting, which then allows the engine to help slow things down. Diesels do not have much compression retardation by themselves, so they depend on that variable restriction in the exhaust system to create the back-pressure. Using the regular engine brake is easy, flip the switch on to slow and flip it off the release the engine-braking action. The rub comes in when you have to reach for that switch while doing other things... like holding onto the steering wheel and steering.

The BrakeSwitch, on the other hand, is set to engage the engine-brake whenever the regular brake is depressed, keeping it on until the accelerator is again touched. It also does not defeat cruise-control operation when 'armed', and acts like it's not there til it's needed.

It might help to point out that the BrakeSwitch does NOT by itself decrease the stopping distance or make any other improvements to the rv or toad brakes or other systems. What it DOES do is act like another hand by 'turning on or off' the existing engine-brake much faster than we can do when both of our other hands are already busy gripping the wheel.

Installation is simple with just a few wires but the wiring details can get a bit confusing, depending on your make/model. It retails for about $85 (IIRC).


I credit my BrakeSwitch to not making an even-bigger mess out of things last week inside the I-10 Mobile Alabama tunnel. A scrap-truck had dropped part of its load across both lanes and cars & trucks were slamming on their brakes as they came over the rise heading in, swerving all over the place and into each other. There was almost no time to react as I got on the brakes with both feet and edged us over as far as I could behind and next to the 18-wheeler in front. Between the ABS and BrakeSwitch, I managed to miss him but still got close enough to be able to reach out and touch his trailer. No way I would have been able to free up a hand or move fast enough to hit the regular engine brake switch and still steer almost 40,000 pounds to a safe but shaky stop. (By the way, anyone know how to get puckermarks out of leather seats?).


Homer, you've made a believer out of me!

Thanks!
Ron

Oh, and I have no allegiance to BrakeSwitch whatsoever. I'd bought one on someone else's recommendation and now want to pass it on.

[smlranger]

I've been considering getting one of those...your post here convinced me to do it.

[ronboc]

Glad I could help. Now let's hope you never are faced with the occasion to test the limits of it or your coach.

Although I have read that these things can save a bundle on brake-linings, even in regular usage.

Thanks!
Ron

[smlranger]

Installed mine a few days ago...did a test drive...this a sweet addition!

[ronboc]

TOLD YA!

Yup, well worth the money and effort involved in putting the thing in. Don't you feel like this is the way it should have been, in the first place?

[David K]

I know this is an old post but, thought I would add my comments. I bought the switch and it took all of about 15 minutes to install it. Now I can leave the brake switch on the dash board in the "on" position all the time and when I use the brakes, it switches on and then when I accelerate, it goes off. Also, when going down a hill with the cruse control on and the accelerator lifts, the exhaust brake does not come on. Great addition to my coach. I already had a brake controller that I had installed for my tow dolly so finding the brake light wire was not a problem at all.

[footdoc]

On Cummins engines, they can be reprogrammed for the engine brake..I have mine in 'Latch mode' and it works just as you describe, except mine was free at Cummins...had them do it while repairing a front seal leak...

[Pusherman]

I had my CAT C-7 reprogrammed to the 'latch' mode, and driveability is greatly improved. Works similar to the Brake Switch. With the engine brake 'on', and cruise control 'on', the engine brake only engages when the brake pedal is pressed. The engine brake will also engage when the cruise control is turned 'off'.

The CAT dealer reprogrammed this functionality for me at no charge.

The difference between the Latch mode and the Brake Switch, is the Brake Switch engages as described even when the engine brake switch is turned off (as I understand-press the brake and the engine brake engages). For me, I always keep my engine brake switch on.

Note: I also had my Allison dealer change the engine brake downshift from '2' to '4' th gear when the engine brake is engaged. I find this much better than the factory setting of '2'.

[Warpath]

Just to make a clarification. The BrakeSwitch does not come on when the engine or exhaust brake switch is off. It only works if the switch is on.

I guess you have to find the right shop to get the Latch Mode parameter changed. I tried to have that done when I had some motor work completed on the last rig and the technician could never find it in the over 400 perimeters available on these electronic diesel motors.

[lthrnk]

Just as Pusherman said, both CAT and Cummins can set the Latch on their engines. I spoke with Cummins today, they said just stop by with the un it and they will hook up the computer and make the change, should only take a few minutes. Allison says they think the unit should only drop to 4th when the engine brake is on. They said all of the newer models should be set up that way, if not, again only a simple computer hookup and flip the switch. Ain't technology grand.

[SCVJeff]

Don: I'm a little late to this thread, but I "think" mine is operating as yours does after your programming. When I let off the gas (OK, Diesel), the Allison will downshift to 4th, and stay there until the RPM's drop sufficiently to let the Allison into 2nd. What irritates me is that there are times that I don't really want all the shifting and braking, but rather a little coasting. With my present setup I have to lean forward and around the wheel to feel out the swx. If I understand the Brake Switch operation, all of this control moves to the foot: hit the brake and the exhaust brahe is on, hit the gas and let off, it's in coast mose. To me that might be worth the price.
BTW- What's the difference between "Latch" and not?

[diesellabs]

With exhaust brake switch "on" in all scenarios...

(1) in non-latch mode, releasing the accelerator will immediately initiate engine braking via the exhaust brake and transmission downshifting

(2) in latch mode, with cruise control switched "on" but not actively controlling speed, releasing accelerator will result in coasting...only when brake pedal is drepressed will the engine braking sequence begin

(3) in either mode, with cruise control switched "on" and actively controlling your speed, the coach will coast from time to time (as in going down a grade) until your speed exceeds a programmed threshhold (7 mph is CAT default) at which time engine braking will occur until back to set cruise speed.

Obviously, if exhaust brake is switched "off" there will be no engine braking sequence in any of the scenarios.

At the time CAT reprogrammed my setting to latch mode I also had them reduce the "auto cruise retarder" value from 7 mph to 5 mph to keep downhill speeds more to my liking...

[SCVJeff]

(2) in latch mode, with cruise control switched "on" but not actively controlling speed, releasing accelerator will result in coasting...only when brake pedal is depressed will the engine braking sequence begin

How does it behave in latch mode and cruise control off?

[Pusherman]

Jeff,

Latch mode works exactly as Steve described it above.

In Latch mode with crusie control off, and the engine brake switch on, the engine brake will engage when you let off the gas (diesel), as it sounds like yours is operating now.

Of course if you turn the brake switch off, no engine brake in any mode.

Latch will let you coast (with the cruse control on and not engaged) by taking your foot off the accelerator w/o engaging the engine brake.

I much prefer the Latch mode to how it came from the factory.