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Air Brakes

Good morning,
I am getting used to driving our coach however, I am having difficulty getting the art of using air brakes down. I have often wondered why the brake pedal is so long; should I press on the top of the pedal or what? It seems to me when the brakes start to really engage I need to let off a little so I do not come to a hard stop and then I have to hit the brakes again, etc. etc. This is really annoying. I can imagine what it is doing to the people behind me.
What should I do differently to come to a nice smooth stop without having to do the "brake on - brake off" thing? I have tried with the retarder on and off; no real change.
Any suggestions?
OH
Rick & Deborah Webster
2002 3610 U320 #5964
2014 Jeep Wrangler Sahara JKU- 'Copperhead'
Richland Chambers Lake, East Texas

Re: Air Brakes

Reply #1 –
The test drive of our coach (maybe five miles total distance) was the first time I drove a vehicle with air brakes. For me, at least, the secret is don't stand on the brakes. I just put my foot on the pedal and gently push. My stopping distances are probably longer than necessary, but the deceleration is slower, which makes for an easier life inside the coach. So far I only have about 500 total miles experience, but that seems to work for me. We've got a longer trip coming up, with a variety of terrain, so I may learn to do things differently.

Re: Air Brakes

Reply #2 –
When we had our SOB (don't have any coach now, still shopping), I learned to use the transmission in conjunction with the exhaust brake (when legally allowed) to do most of the braking until the last 200 feet, then gradually come to a stop with the service brakes.

Anyone see a problem with that? I have been driving a DP for only about a year, so my experience is not extensive.
Royce & Denise, MC #17410
'01 U320 4220 ISM450 Build #5895 SOLD
Toad: '10 Honda CR-V

Travel makes one modest. You see what a tiny place you occupy in the world. - Gustave Flaubert

Re: Air Brakes

Reply #3 –
Quote from: BamaFan –
When we had our SOB (don't have any coach now, still shopping), I learned to use the transmission in conjunction with the exhaust brake (when legally allowed) to do most of the braking until the last 200 feet, then gradually come to a stop with the service brakes.

Anyone see a problem with that? I have been driving a DP for only about a year, so my experience is not extensive.

Yup, that is how you do it. 
Brett Wolfe
EX: 1993 U240
Moderator, ForeForum 2001-
Moderator Diesel RV Club 2002-
Moderator, FMCA Forum 2009-2020
Chairman FMCA Technical Advisory Committee 2011-2020

Re: Air Brakes

Reply #4 –
The disk brakes seem to have a very high temp set of pads that warm up and become very agressive. Lots of reserve capacity. 

For smoothness I recently in normal flat ground have turned off the xtarder and like the feel and smooth stopping of the service brakes by themselves.

As they heat up during their application they slow the coach faster and faster so I slowly let up on the pedal as I come to a stop. Like a rolls Royce chauffeur

The xtarder and service brakes together with my 320 and a 3,000 pound tow car is fairly abrupt in its application to me.

I use the xtarder for bigger hills and/or with my brake light disconnected system to hold speed in hilly areas for speed limit stuff.

Had a state patrol guy behind me in the Midwest and I bet he wondered how come I did not overrun the speed limit down grades without the brake lights coming on.

Seriously the xtarder can be too strong depending on its settings and cold disk brakes at the end of a retarded stop needed heavy pedal pressure. Then they warm up and are too strong.

Better braking progression if warmed up.  Almost fun to play with.  DW looks at me when I play with the brakes coming into little towns but warmed up a bit they are really impressive and for possible emergency stops I tend to Pre heat them in traffic use. 

As traffic increases again I do turn on the retarder switch as for emergency stops the combo of warmed up brakes and the retarder is impressive to say the least.

Loved the retarder since the first u300 GV showed up in my store.

Bob

"Riding and rejoicing"
Bob
1997 U320 40' Mid entry, build 5132,  wtbi ce27, 4th owner
2007 Solara convertible
2 prodeco tech outlaw ss electric bikes

1095 watts solar
08 Ls 460 and a sc430
2000 Ford F-250 superduty 4x4

Re: Air Brakes

Reply #5 –
 
Just went for my MR licence to drive my Grandvilla,

The instructor said the air brakes are on a one second delay, You just touch the brake pedal lightly, the brakes come on and slow you down, Then press harder to actually stop, It does work, I got my licence,

If you push the brake pedal on hard, one second delay, then a putty knife scrapes you of the inside of the windscreen,
Cheers,
Brian,

Toys, 1989 Grand Villa, 36 foot, ORED with 300 Hp Cat. 2002 Gemini 34 foot Sailing Catamaran, 2006 Honda Super Blackbird 1100XX, 2002 ZR7 750 Kawasaki,
25 HP Chinese tractor and Backhoe,

Re: Air Brakes

Reply #6 –
I use the retarder most of the time when I need to slow down whether I'm in traffic or not and the service brakes the last 50ft or so - depending on speed.  Turn it off in rain.  Having just gone down some steep grades in the Montana mountains - I can't say enough good stuff about the retarder.  I thought the Allison trans in my Duramax was good - this is so much better.  If I use the service brakes while the retarder is on my braking seems too severe so I just use the brakes when I'm going 5 to 10 mph right before I stop. 
Scott & Carol Seibert
2001 42' double slide U320 - Sold
Previous - 2002 36' U320

Re: Air Brakes

Reply #7 –
I believe the retarder anly works above 15 mph.
Felix and Gail Mathieu
99 U320
Jeep Liberty CRD
Build number 5522

Re: Air Brakes

Reply #8 –
One phenomenon of an auto trans/retarder coupled to a diesel engine is that the engine will seem to push the vehicle when the retarder releases when stopping.  That may be what you are feeling.  Try a few non retarder stops to get the feel of the brake system.  With the retarder engaed you will have to finesse the pedal as the vehicle slows then press a little harder when the retarder releases then ease off to give a non jerking stop.  It's all a matter of getting used of it.

Continuous use of the retarder to stop the vehicle with only a light brake application at the end can cause the pads to glaze increasing stopping distance.  Turn off the retarder and do a few brake only stops to deglaze them.

Here are a couple of links that may help:

Air brake operation video (Posted by Barry Beam).  It shows drum brakes but it's basically the same as disc brakes up to the calipers.

Stopping with Air

Retarder operation:

Transmission Retarder Operation - How Does It Work



Keith
Keith, Joyce & Smokey the Australian Cattle Dog
1995 U320 SE Extreme 40' WTBI Build # 4780, with a Honda CR-V hopefully still following behind.
Motorcade # 17030
FMCA # F422159

Re: Air Brakes

Reply #9 –
Thanks Keith, Very informative,
Cheers,
Brian,

Toys, 1989 Grand Villa, 36 foot, ORED with 300 Hp Cat. 2002 Gemini 34 foot Sailing Catamaran, 2006 Honda Super Blackbird 1100XX, 2002 ZR7 750 Kawasaki,
25 HP Chinese tractor and Backhoe,

Re: Air Brakes

Reply #10 –
Quote from: MR B2 –

Just went for my MR licence to drive my Grandvilla,

The instructor said the air brakes are on a one second delay, You just touch the brake pedal lightly, the brakes come on and slow you down, Then press harder to actually stop, It does work, I got my licence,

If you push the brake pedal on hard, one second delay, then a putty knife scrapes you of the inside of the windscreen,


Nature of wedge cam drum brakes. Bigger primary brake pad, smaller secondary pad.  As the brakes heat up the bigger shoe is "screwed"(leveraged around the pivot?) into the drum.

That's why they squal  in reverse.  Under the dash is an lq4 valve that disables the front brakes until 60 psi is applied to them.  Stopped the squealing in reverse.

Had a few knowledgeable trucker customs disconnect the valve and replumb the system.  so the front brakes worked at all times.  Better stopping but a shudder backing up. Loud.

Different cans are available to spread the brake shoes as are "pills" in the pedal assembly.

You are a tinkerer so you will like picking my brain.  Careful down hills as the rear brakes are the only ones working at moderate brake applications.  Seen smoke out of the rear wheels many times. 

Front were cool.  Never on.  Ored drum brakes only.  Not disks.


Bob
"Riding and rejoicing"
Bob
1997 U320 40' Mid entry, build 5132,  wtbi ce27, 4th owner
2007 Solara convertible
2 prodeco tech outlaw ss electric bikes

1095 watts solar
08 Ls 460 and a sc430
2000 Ford F-250 superduty 4x4

Re: Air Brakes

Reply #11 –
Bob, the brake lights come on with the retarder.
1999 U320
Mount Dora Fl

Re: Air Brakes

Reply #12 –
Quote from: philtravel –
Bob, the brake lights come on with the retarder.

He has an ored.  No retarder.  My brakes lights do not come on with retarder use or kick off the cruise. 

Bob
"Riding and rejoicing"
Bob
1997 U320 40' Mid entry, build 5132,  wtbi ce27, 4th owner
2007 Solara convertible
2 prodeco tech outlaw ss electric bikes

1095 watts solar
08 Ls 460 and a sc430
2000 Ford F-250 superduty 4x4

Re: Air Brakes

Reply #13 –
On my '95 U320 they come on with the retarder.  Seems some do some don't.

Keith
Keith, Joyce & Smokey the Australian Cattle Dog
1995 U320 SE Extreme 40' WTBI Build # 4780, with a Honda CR-V hopefully still following behind.
Motorcade # 17030
FMCA # F422159

Re: Air Brakes

Reply #14 –
Quote from: Keith and Joyce –
On my '95 U320 they come on with the retarder.  Seems some do some don't.

Keith

Somehow the wire to the brake light relay must have fallen off mine
"Riding and rejoicing"
Bob
1997 U320 40' Mid entry, build 5132,  wtbi ce27, 4th owner
2007 Solara convertible
2 prodeco tech outlaw ss electric bikes

1095 watts solar
08 Ls 460 and a sc430
2000 Ford F-250 superduty 4x4