Engine brake usage

[Roadking]

Old trucker: I agree with you about having a manual switch so I installed one, however, the factory engineered and designed system still works better and I still use it more often than I do my manual switch.

In my Cummins exhaust brake when the brake switch is applied the computer does the downshift and applies 12VDC to an air solenoid which then releases regulated air to a small air cylinder that pulls the exhaust brake flapper. I used a heavy duty diode to isolate the 12volts from the stock exhaust control circuitry and wired a manual switch into the circuitry. I used a brake light isolation diode that is used to isolate the lighting circuitry used in "toad" towing.

The manual switch works nicely for very minor downgrades or when you want to slow just a little as the engine does not offer much deceleration braking unless the RPMs are up over 2000. To get stronger deceleration which is needed on bigger hills you need more RPMs to get more compression, which means you have to downshift to get the RPMs up. As a result, in any steep declines the factory engineered braking system works a lot better than my manual switch. So... unless you really think you need something different that offers very little, stay with what the engineers designed....

[Dr4Film]

Quote:

Originally Posted by Roadking Old trucker: I agree with you about having a manual switch so I installed one, however, the factory engineered and designed system still works better and I still use it more often than I do my manual switch.

Roadking,

Truthfully, a manual switch for the PacBrake won't do anything unless it works in unison with the transmission.

I totally agree with your statement regarding the factory engineered system. I find that it works as advertised and that's exactly how I use it. I have almost 24 tons pushing me down the hill. Depending on the steepness, I keep the rpm's up and speed down to a safe level. I prevent the Allison from up-shifting by watching my tach. When the mph creeps up to the shift point, I give the service brakes a good hard jab to lower the speed keeping the rpm's up.

I also use the upgraded PacBrake PRXB. I want to have everything available to me when needed. I also drive with the PacBrake switch on ALL the time. I never have to think about or look to see if it's on.

Dr4Film ----- Richard

[rmmpe]

On my 330ISC, I designed a system that, when activated, isolated the regular Pac Brake system to preclude back-feed to the system and allowed manual selection of Pac Brake and gear.

There was not much braking when in 6th but it did provide some slowing. If I selected 5th and triggered the Pac Brake there was a noticable slowing.

The system also activated the Pac Brake in 1st if I chose to do that, which would drag the Alpine down to idle speed quickly.

The the standard system, which shifted to 4th, was left untouched so it could be used in the regular mode.

There was also a parallel momentary switch under the bed so I could excercise the Pac Brake for lubricating purposes.

The new owner of the Alpine may want to offer comments on the system.