Allison trans retarder

[lavocat]

I am new to the trans retarder. Have one onmy new to me 06 Foretravel Phenix. Would like to know if there is anywhere to go for good info on how to use it.

[Ray,IN]

Hi lavocat, welcome to irv2.com! Without any personal knowledge of MH Allison's, the best I have to offer is the Allison transmission publication page. Knowing your exact transmission model #, you may download several publications. Hopefully some are usefull.

[Tom N]

If by Trans retarder you mean the Allison Grade Brake I leave mine on most of the time.

I had it on for our trip from PA to FL last Fall. I rarely turn it off.

When I slow down and brake the Allison will automatically downshift. On accelerating it does not come into play.

-Tom

[dbarton291]

Quote:

Originally Posted by lavocat I am new to the trans retarder. Have one onmy new to me 06 Foretravel Phenix. Would like to know if there is anywhere to go for good info on how to use it.

The transmission mounted output retarder is a hydraulic retarder that consists of an output shaft mounted rotor with a clutch. When it is activated, the external accumulator fills the retarder cavity with oil and the vehicle slows. It is normally manually activated by the driver. It turns horsepower into heat. So, on a long downhill grade, watch your trans temp gauge. Don't let it get over 330F.

This should be covered in the transmission operators manual that should have been in the coach. It's a little 5x8 book.

[dbarton291]

Quote:

Originally Posted by Tom N If by Trans retarder you mean the Allison Grade Brake I leave mine on most of the time. I had it on for our trip from PA to FL last Fall. I rarely turn it off. When I slow down and brake the Allison will automatically downshift. On accelerating it does not come into play. -Tom

What you probably have is an exhaust brake that is activated by the trans ECU. Those normally go to a preselect downshift schedule to either 4 or 2 when activated. The exhaust brake needs engine RPM to be an efficient brake.