transmission retarder

[jack14r]

Jon,I think that the switch must be on and the lever in at least the #1 position for the brakes to activate the retarder as you describe.

[Jon Wehrenberg]

Not on my bus, Jack.

I leave the switch on all the time, so if I have to make a quick stop I have all the help I can get.

My vintage bus has the transmission oil temp gauge and retarder light visible all the time and I know every brake application is accompanied by retarder activation. I manually use the lever only on long downhills, because if I left it on while on cruise control the retarder would be cycling on and off.

Don't you have a dash light to indicate retarder activation?

[JIM CHALOUPKA]

The way I perceive mine to work is;

the retard push button on dash is on (all the time for me)

when you are off the throttle the retarder is activated, but only to the degree of which the steering column LEVER is set

Zero thru Six. Six being the highest degree of retard and

ZERO being a degree that has no retard

ONE is the first lever position that will retard the bus (mine anyway)

TWO thru SIX have successively higher degrees of retard
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I think Jon is saying he has a degree of retard at ZERO lever position.
I don't think that I do. (I can not feel it)
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I also don't think the ABS is directly affected by the retard any more than it is if say one is driving in 3rd or 4th gear and the engine is slowing you down as you reduce throttle.

I don't think the retarder will induce abs to activate any sooner than if you did not have retard button turned on.



JIM

[Jon Wehrenberg]

I did not say I have any retarding in the zero lever position. However, with the retarder switch "on" I have retarder application when the brakes are applied.

With the lever in any position but the zero position just lifting your foot from the accelerator applies the retarder. Two different things.

[sticks]

Well from reading your posts this isn't an open and shut case. But I think in normal driving conditions, I'll leave retarder in #2 position( with dash switched on at ALL times). If potentially slippery I'll go to #1 and if I'm stuck in SLIPPERY conditions and I'm just trying to nurse my way to a safe spot to pull over and wait it out, I'll put retarder lever in #0 position.

[JIM CHALOUPKA]

You've got it down Sticks, but don't be afraid to try the higher positions as conditions warrant.

You can work that lever a lot if you like to be involved in driving.


JIM

[Jon Wehrenberg]

Sticks, I come from the western NY snow belt and when I saw your post all I could think about is the ass end of your coach trying to take the lead.

Under normal dry road conditions I don't think the use of the retarder is a concern. It will certainly help a lot when braking, and in the #2 position, with planning it is going to assist in going downhill without speeding up.

But having any assistance from the retarder, and that includes leaving the lever in the zero position, but the switch on, when in slippery road conditions needs to be considered.

Unless you are braking with the switch on, the retarder will be off in the zero lever position. Letting your foot off the throttle in the zero position will not engage the retarder. Braking with the switch on engages the retarder, but the ABS shuts it down if wheel slippage occurs.

With the lever in the #1 position however, the retarder cuts in with braking giving more power to the braking on the drive axle. Without braking it still could cause the drive axle to slip because it also drops the coach down a gear. That sudden gear reduction could break the rear end loose, and without using the brakes the ABS does not kick into play.

We drove a lot on snowy, slippery roads and the bus is very good and stable. But like anything else you want to be able to regulate how quickly you attempt to turn, stop or accelerate so I would suggest you practice on lightly traveled roads to see what retarder position if any is best. When the bus starts skidding you will not have the time or thought to turn the retarder on or off.

The sky is not falling. It does take a lot to break the back end of the coach loose or to get it to plow on the front end. When stuff like that happens you have been pushing the envelope. But a retarder doesn't have the feel you have as a driver who can modulate the use of accelerator or brakes. I wouldn't worry about the coach stability, but be aware the use of a Jake or retarder on slippery surfaces is probably not the thing to do.

[jack14r]

I only have a light which is a stop light on the dash and can be activated by the retarder or the brake pedal.I have my manual in front of me and here is what it states.
OPERATING THE RETARDER USING THE BRAKE PEDAL
With the retarder activated(retarder switch depressed),the accelerator pedal released and the output retarder lever in the initial position,apply the brake pedal as if using the service brakes.The further the brake pedal is depressed,the more the output retarder is applied.

The manual has a chart which shows the efficiency of the retarder
position efficiency
initial 0%
1 16%
2 33%
3 49%
4 71%
5 89%
6 100%

I thought that the word initial meant position 1 but it obviously means the position before position 1.

[sticks]

maybe it would be less complicated to move my whole horse operation to Florida than I don't have to worry about any retarder position

[Jon Wehrenberg]

Now you are catching on Sticks. There is a reason we moved out of NY, apart from dumb ass politicians. The snow was not fun to drive in and most of our use of the coach was when it snowed.

Move to Florida and use the retarder as you see fit.