What initiates the retarder??

Topic: What initiates the retarder?? (Read 1408 times) previous topic - next topic

What initiates the retarder??

August 15, 2010, 10:57:39 am

So I may be asking an obvious question, but you know the saying "there is no such thing as a stupid question"; well so I hope anyway. I drive at least 50% of the time; at times when I am expecting the retarder to kick in, I look down and while the retarder is switched on, the light isn't on nor is it initiated. Now I know that if you have the cruise on, the cruise needs to be "off" before the retarder will initiate. But there have been times, normally just starting up, say from a fuel stop, where I have the retarder on and I touch the brakes and the retarder does not initiate. DH says he never has that problem. (Lucky him)..

I am really trying to avoid using the brakes as much as possible; but I have no choice when I can't get the retarder to activate.

Can anyone think of what I may be doing wrong? Your help is greatly appreciated. I am still a Newbie and don't want to make any costly mistakes.

Thanks!

Re: What initiates the retarder??

Reply #1 – August 15, 2010, 11:09:47 am

Quote

normally just starting up, say from a fuel stop, where I have the retarder on and I touch the brakes and the retarder does not initiate.

If you have the joy stick all the way up to the 1st position, try pulling it all the way back to the last position.
The retarder works in degrees & you may not be going fast enough from a stop.
Does it work the same way when you are driving the open road.

Re: What initiates the retarder??

Reply #2 – August 15, 2010, 11:12:01 am

In my experience, when it does not come on, the switch is off. I have had this happen a couple of times... I must accidentally and unknowingly hit the retarder on/off switch while adjusting the transmission gear or retarder. I keep an eye on the retarder switch (glows red when working) just to make sure that has not happened when I start down a hill.

In my experience, the retarder will come on when you back off of on the throttle or hit the brake (providing the switch is on!). It will usually kick off the cruise control going down a hill if I have forgotten to take it off when going on cruise.

Re: What initiates the retarder??

Reply #3 – August 15, 2010, 11:26:12 am

If you're coasting slowly the application of brakes or joy stick may not engage the retarder. Try this, with the retarder switch on & coach stopped, place the joy stick in the 1st position (so you don't get too much braking action). Start off accelerating very little to about 10 MPH...let off the throttle & notice if the switch light comes on. Continue this until you have enough speed so when you let off the throttle the light comes on...meaning the retarder is engaged.

Do the same procedure with the joy stick off & using the service brakes to determine when the retarder engages.

Re: What initiates the retarder??

Reply #4 – August 15, 2010, 11:58:25 am

Sandy, you mentioned for example just starting from a fuel stop. You have to be going at least 10 mph, I believe for the retarder to activate.

Re: What initiates the retarder??

Reply #5 – August 15, 2010, 12:07:34 pm

Thanks for your responses.

Barry, no I don't have a problem when on the open road and want to use the retarder. It is usually just at the start up speeds, so I must not be going fast enough to initiate. Next time driving, I will try what you suggested and move the joystick all the way back. For sure whenever I have had problems initiating, the retarder button was in the "on" position. It is always the first thing that I have checked.

Thanks Felix, about the 10 mph info. For sure when I had issues I was well under that speed.

I feel much better knowing that it isn't a "driver error" that I am making.

Re: What initiates the retarder??

Reply #6 – August 15, 2010, 02:30:30 pm

Retarder only activates when coach is moving above 10 mph or so, and throttle is at idle position.
This holds true when only using joy stick or only using brake pedal or both together.
Joy stick positions 1-6 all activate the retarder at the same time. Side electric master switch must be on.

With cruise control on, and joy stick is on 1-6, retarder will activate when throttle is at idle position, like when going down any hill, no matter how slight.
When retarder activates, the brake lights come on. When brakes lights come on, cruise control is turned off.

Which means coach will not automatically accelerate at the bottom of the hill because cruise was turned off by brake light.

If a mod is made to optionally not turn on brake lights with retard, cruise will stay active.
This can be helpful if joy stick is accidently or purposefully not in off position.

We wired a small Radio Shack LED from the side retard light, and mounted it in the dash, so the driver can easily see if retard is activate without having to look down at side panel.

Re: What initiates the retarder??

Reply #7 – August 15, 2010, 03:55:16 pm

Barry & Cindy:

Thanks for the retarder information. Your explanation was very helpful and makes a lot of sense to me. I appreciate your response.

Re: What initiates the retarder??

Reply #8 – August 15, 2010, 05:17:04 pm

From what you are saying, it is your cruise control that is keeping the throttle at more than idle. It can be just a hair so you do not notice it. IF that is the case it is an easy experiment to test. When you look down and do not see the light, hit the cancel button on the cruise control and see if that makes the light come on....

Re: What initiates the retarder??

Reply #9 – August 15, 2010, 06:36:58 pm

RE: "From what you are saying, it is your cruise control that is keeping the throttle at more than idle."

No, I am not saying that...

Cruise never keeps throttle from reaching idle position.

Cruise works just like your foot. Need to go, cruise pushes throttle down. Come to a downhill of any size, cruise lets up on throttle and pedal returns to idle position. At bottom of hill, cruise pushes down again. The 'problem' is when retard joy stick is not in off position, when pedal temporarily returns to idle during downhill run, brake lights come on and turn off cruise, so at bottom of hill, one must manually accelerate and reactivate cruise control.

Our coach's cruise control does not have a cancel feature. Why jam brake pedal just to cancel cruise as it adds some wear to the braking system. So we have a "cancel cruise" momentary push button on the retard joy stick that flashes the brake lights.

Re: What initiates the retarder??

Reply #10 – August 15, 2010, 08:51:44 pm

I am saying that the cruise is on and it is preventing the throttle from going to idle as it is slightly increasing the throttle. You may not realize it but you can see it on the silverleaf as load on the engine but you do not feel it when you are driving.

It will prevent the retarder from engaging.

Re: What initiates the retarder??

Reply #11 – August 15, 2010, 09:00:30 pm

John,

Are you saying that "the fast idle setting on the cruise" will affect the retarder? Can you drive-off with the "fast idle" set and it will continue to stay on fast idle?

Re: What initiates the retarder??

Reply #12 – August 16, 2010, 01:14:16 am

I can only set "Fast idle" when our throttle pedal is at idle position. When I press throttle pedal fast idle goes away

Re: What initiates the retarder??

Reply #13 – August 16, 2010, 04:39:39 am

You can set your idle speed with the cruise control on my 01. It was low and that is how cummins increased it for me. It might be the same on George's unit too.

Re: What initiates the retarder??

Reply #14 – August 17, 2010, 06:37:37 pm

My retarder takes 3-4 seconds to engage when I let off the throttle. Is that normal? When I hit the brake pedal it engages immediately. I drove a similar coach as mine (I have 1998 U295 & I drove a friends 1997 U320) and his retarder engages immediately when the throttle is released.

Re: What initiates the retarder??

Reply #15 – August 17, 2010, 08:01:32 pm

Are you saying the retard light has a delay when off the throttle , but not on the brake pedal? When you say engage, do you mean when the light comes on?

Re: What initiates the retarder??

Reply #16 – August 17, 2010, 08:20:41 pm

When I say engage, I mean when I feel the braking force of the retarder. However, the light does not come on until the retarder engages either. I have driven 20,000 miles in the past year and used the retarder extensively in all positions and all situations and it has functioned this way the entire time. I thought it was normal until I drove the 1997 U320 and the retarder (and the light) engaged immediately upon releasing the throttle. Now I am not sure. The two coaches have different transmission models so maybe that is part of it.

Re: What initiates the retarder??

Reply #17 – August 18, 2010, 09:24:56 am

From my experience, yes, you can set the idle speed within a range. Before I had enough experience with it, I found my self on solid ice patch and needed to move a small amount, so at idle, and holding brake, put into forward, and started moving, problem was that I did not want to move at that moment. Front wheels were sliding and drive wheels pushing me along, so needed more brake effort. That woke me up to the faster idle I had set, was set about 850RPM, I then backed the idle down to 690RPM and was then controllable .

I am not the most experienced nor the brightest, but hope I live long enough to learn and remember all the little things that are going on in these beautiful contraptions.
Many differences from a 18 wheeler many very similar.
Very few similarities with a car, we all need to honestly evaluate out skills

FWIW
Dave

Re: What initiates the retarder??

Reply #18 – August 18, 2010, 05:07:47 pm

Here's how the retarder behaves on our 1999 U-270:

The retarder engages immediately (you can feel it) when either the retarder lever is pulled back or the brake petal is pressed (with the retarder enable rocker switch on). With the retarder lever in any position back from the front (off) position, the retarder will engage immediately when the throttle is closed, and will disengage when the throttle is pressed. The light on the rocker comes on whenever the retarder is engaged.

Re: What initiates the retarder??

Reply #19 – August 18, 2010, 05:38:50 pm

Quote

Here's how the retarder behaves on our 1999 U-270:

The retarder engages immediately (you can feel it) when either the retarder lever is pulled back or the brake petal is pressed (with the retarder enable rocker switch on). With the retarder lever in any position back from the front (off) position, the retarder will engage immediately when the throttle is closed, and will disengage when the throttle is pressed. The light on the rocker comes on whenever the retarder is engaged.

It works exactly like that on my 2003.

Re: What initiates the retarder??

Reply #20 – August 18, 2010, 10:03:03 pm

I realize I have a much older coach but if I have sped up the idle with the cruise control it drops to normal once I apply the brakes. Also, don't the new dash units show the RPM?

Re: What initiates the retarder??

Reply #21 – August 20, 2010, 04:37:22 pm

So if my retarder takes 3-5 seconds to engage does that indicate a problem? As an aside, my joystick does not have an off position, I have a toggle switch near the boost switch on the panel near the retarder.

Re: What initiates the retarder??

Reply #22 – August 20, 2010, 10:38:10 pm

The front position of the joystick is off, but if the toggle switch is on, the retarder is triggered by the brake pedal even with the stick forward.. Are you saying that your retarder engages (throttle closed) whenever the toggle switch is on and the stick is in the forward position?

Sounds like something wrong.

Re: What initiates the retarder??

Reply #23 – August 21, 2010, 12:38:42 pm

Yes, the retarder will engage with the toggle switch on and the joystick in the most forward position. Sounds like I need to get it checked out. Has worked this way for 20,000 miles since I purchased coach. Retarder has worked well the whole time too, just that pesky delay in engaging.

Affiliate Notice