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Topic: MD3060R - Retarder Control (Read 410 times) previous topic - next topic

MD3060R - Retarder Control

Hello All,
  My '95 U240 has a MD3060R Alison Transmission.  My retarder is controlled by the brake peddle.  Works just like using the service brake.  These pics are looking up under my front at the brake and throttle peddles.  My retarder is intermittent, sometimes it works and sometimes it does not.  When it works the red light on the enable rocker switch will light up.  Other times the light on the rocker does not light up and just the service brakes work.  I want to change the parts that are connected to the brake peddle the make the retarder work.  It is variable, the harder you press the brake peddle the more retarder action you get.  Whats What???
Pat/Blue Angel
1995 U240 36ft
MC# 16511
Build# 4653

Re: MD3060R - Retarder Control

Reply #1 –
If like others, there are 3 separate air pressure switches that close when their pressure setting is reached, activating 3 levels of retard.

I guess you could temporarily jump switches closed to see if retard always comes on when off the throttle or put a mechanical spst switch, all to test to see if air pressure switch is the problem.

Not sure of correct psi, but it may be something like 1st closes at about 2 psi, next at 4 psi, and third at 6 psi

So to speak, the brake pedal does not mechanically close retard switches. Only air pressure does the job.

Re: MD3060R - Retarder Control

Reply #2 –
Good Morning Barry,
  Thanks for the response.  I agree with what you suggest.  I don't know where the point of failure is.  I don't know where the troubleshooting should start.  I just know that some times the retarder does not work.  If it works, the retard is smooth at any level.  The change between levels is also smooth.   

Pat,
Pat/Blue Angel
1995 U240 36ft
MC# 16511
Build# 4653

Re: MD3060R - Retarder Control

Reply #3 –
Pat,

With you last statement I would think you need to look at the "Retarder On/Off" switch. It could be that the contacts are pitted or the plug on the back of the switch is loose or corroded.  It could also be ground wire problem.

Mike
Pamela & Mike 97 U 320

"It's not what happens to you, but how you react to it that matters."