Is retarder activated by brake pedal?

[Scott & Heather]

Trying to sort out my retarder wiring and wanting to know if it's typically activated by brake pedal? I have a dash switch for Automatic or off I think. Can't read the label. But it's on constantly. I disabled the air to the retarder because the solenoid opens when my
Ignition is on and never closes so I have constant air pressure to the retarder thus activating it nonstop. I need to figure out what is sending power to the solenoid keeping it open and letting air through. Anyone have schematics? Allison 748 ATEC 1992 MCI 102C3

[buswarrior]

I would wire it so that it may be engaged separately too, and be prepared to disable to brake pedal activation.

These things were famous for poor ride quality when engaging, more stop than you wanted, encourages you to drive like a possessed transit driver to get it smoothed out.

An engineers dream, brake life extension, little to no consideration for the passengers, and the guy who was getting blamed for rough operation..,

Happy coaching!
Buswarrior

[blue_goose]

It depends on how it is programed in the ECU.  I can be programed to come on when you take your foot off the throttle or when you apply the brakes.
Jack

[Scott & Heather]

Ok good info to know. I can wire it up any way I want at this point since I have access. But what is the best/easiest? Foot switch? Lever? A switch on the dash doesn't seem like a quickly accessible spot for panic stops or constant engagement or disengagement when in the city stop and go or a mountain grade.

[luvrbus]

Scott do you need the wiring diagram for the transmission you don't have many options with the ATEC ,wire 211 is a input and wire 213 is for the output and 213 goes from open to ground if wired right

[Scott & Heather]

Cliff yes that would be wonderful to have.

[TomC]

Because of long down grades west of the Rockies, my bus is wired with a toggle switch on the dash with off-one-both heads. Then the only requirements for activation is to release the accelerator. It will continue to work if you press the brake pedal.

I would suggest against wiring it through the brake pedal. Then that means you have to have your foot on the brake coming down a hill-which with a 5 or 10 mile down hill going 25 mph, that's a long time to have your foot on the brake. Plus you'll extend your brake life if you're not touching the brakes. Good Luck, TomC

[buswarrior]

A retarder or jakes are not emergency stopping devices, their access needs to be convenient, no more.

When the poop hits the fan out front, the brake pedal is the Alpha and the Omega.

Please do not follow false prophets. Few of them have engineering degrees.

Happy coaching!
Buswarrior

[richard5933]

I think that the only way I'd consider wiring through the brake pedal would be as an auxiliary in-between step - something between 'off' and 'on'. Put the toggle in off, they don't come on at all. Put it in the middle position, and the retarder works only in conjunction with the brakes acting as a brake assist. In the full 'on' position the retarder would work any time the rack is in a no-fuel position.

As said earlier, if it only come on with the brakes, then the retarder will not be able to do its primary job - keeping the speed down without having to apply (and overheat) the service brakes.

[TomC]

Very smart, Richard. Good Luck, TomC

[sledhead]

A two or three stage jake works nice  as well so you can control the amount of slowing power . I have the 3 stage now and use all 3 stages rather then just on and off with the jakes

dave 

[luvrbus]

I have 3 stage Jakes on my Cummins ISX even coming down from Golden Valley I can only use the first stage 33%,the ISX Cummins uses the turbo for braking power also,I have had some reprograming done so it don't drop to 4 th gear now from 6th it goes to 5th.Never found a grade steep enough to use the 3rd (high) yet 

[sledhead]

I have used the 3rd stage a few times on a 9 % grade but I had to cycle between 3rd stage and 2nd stage or I would slow down to much . nice to have and makes a great noise if you turn them on when in a tunnel

dave

[buswarrior]

Luvrbus, that diving to 4th was incredibly irritating in a seated coach.

The same vintage prevost didn't do anything different with the transmission. Lovely to drag the jake in 6th, when you have a slight downgrade and an electronic tattle tale reporting on speeding.readily shift yourself for anything else you desire.

Any ideas why suck divergent strategies with the same drivetrain?

And the customers knew nothing in the prevost. They questioned the marriage of your parents in the mci.

Happy coaching!
Buswarrior

[6v92FireFan]

I realize this is a dead post at this point, but I'm installing Jake's on my 6v92/HT740 fire truck and would love a copy of that ATEC wiring diagram if anyone still has it.