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Topic: Coach moving at idle despite parking brake (split from Re: Handling Comparison:36' U270/42' U320 ) (Read 1280 times) previous topic - next topic

Re: Coach moving at idle despite parking brake (split from Re: Handling Comparison:36' U270/42' U320

Reply #25 –
Quote from: littledubz –
Regarding creep, I think what Pierce said is relevant and logical (imagine that!). 

I have never driven a truck that has disc brakes.  I think the drum brakes that you tend to find on trucks have a lot of disadvantages.  Drum brakes are more likely to lock up than disc brakes.  When you're idling they are probably more likely to stay locked and not allow creep than disc brakes, even more so when they haven't been used or are cold. 

I would think that ALL truck drivers would have the same opinion on creep (i.e. there should be none).  But these are not trucks, they don't have truck brakes.  So the horror a truck driver would feel at the thought of creep is not relevant to a motor coach driver.

All that being said, putting your coach in to neutral is something simple that you should always do when you're not sitting in the drivers seat.


My turn..

NUTZ..  If this was true and it ain't, disc brakes on trucks would be the norm.  It is a fact that the swept  contact area of drum type brakes under all conditions makes a mockery of disc brakes.

I have had one trailer with disc brakes in over fifty years of driving OTR and could not be happier than the day I got back with good old fashioned drum brakes (thank you..)

Please note, I am not saying disc brakes are a bad idea.  On a four wheeler, they are great. Just that on heavy trucks, they are less than acceptable (& I'm not real happy having disc brakes on my FT, fwiw.)

Disc brakes' major contribution is in greatly reducing unsprung weight which does improve handling and overall ride comfort, an obvious improvement over drum brakes on any MH.  pc

 






S/W Houston 95" U320C SE/40' 
Build #4778  Cummins M11
Repairs & Covered RV Parking (BAO)
PPL is close..

Re: Coach moving at idle despite parking brake (split from Re: Handling Comparison:36' U270/42' U320

Reply #26 –
I have no experience or opinion as regards disc brakes vs drum on heavy duty OTR trucks, but I absolutely love the disc brakes on our coach. No squeals, very linear feel, easy to modulate and get to smooth stop. In spite of a few air horn inspired moments, never felt like I even tested the limits of the stopping power on our coach. The combination of the retarder and the air disc brakes on our coach is one of the features that sold me on Fortravels in the first place. Just curious, what makes you unhappy about the brakes on your coach, the performance of the braking system, or the idea that they are disc brakes?
Don
Quote from: pocketchange –

...I'm not real happy having disc brakes on my FT, fwiw.

Disc brakes' major contribution is in greatly reducing unsprung weight which does improve handling and overall ride comfort, an obvious improvement over drum brakes on any MH.  pc
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Don & Tys
1999 U270 3602 WTFE #5402
Xtreme Stage 1 w/Headlight, Step Conversion, etc.
2009 Honda Fit Sport with Navi
Freedom is NOT "just another word for nothing left to lose"... with apologies to Kris Kristofferson

Re: Coach moving at idle despite parking brake (split from Re: Handling Comparison:36' U270/42' U320

Reply #27 –
Quote from: Gary Bouland –
From experience with trucks..... If your service OR Park brake will not hold vehicle in drive at idle you have a MAJOR problem.  You should drive CAREFULLY to a shop that can inspect and adjust brakes , in the case of Disc's the calipers , and slack adjusters .
A DOT inspection that found that the vehicle would creep in drive would put you out of service and just common sense a MH driver should use the same air brake criteria as a trucker.
On second thought please DON'T drive it, tow it.

Gary B

Gary, I think he was saying at a slight throttle. I know mine will not move if i park it and put on the park brake but I do take it out of gear.  I do feel though that on the M11 it is just barely holding and that is over multiple motorhomes I have been in with the M11 and have driven. If you touch the throttle it will move with the park brake on.  My 8.3 did not come close to it.
2025 Wanderbox Outpost 32 on F600 Expedition Motorhome
2015 Born Free Royal Splendor on Ford 550 nonslide version  for sale
Former Coaches  covering. 360,000 miles
1999 34 U270
2000 36 U320
2001 42' double slide U320
2018 Jeep Rubicon

Re: Coach moving at idle despite parking brake (split from Re: Handling Comparison:36' U270/42' U320

Reply #28 –
Pocketchange

Please help me understand.  You've said two things that appears to me to be in contradiction

"I'm not real happy having disc brakes on my FT" and "Disc brakes' ...major contribution is in greatly reducing unsprung weight which does improve handling and overall ride comfort, an obvious improvement over drum brakes on any MH"

Are you saying that they are a major improvement in that one area, but they are worse in every other area and you would still not prefer to have them on your RV?

You're also saying "if this were true, and it ain't", but I don't know which one of the 9 statements I made you're disagreeing with. 

My point, which may have gotten lost in all that other stuff, is a truck driver would not find creep acceptable, and is trained to identify it and have it resolved, but that may not be relevant to a motor home driver because their vehicle has disc brakes.

I would love to hear if you agree or disagree with that one point.
Used to be 40' U300 1992 Build # 4087

Re: Coach moving at idle despite parking brake (split from Re: Handling Comparison:36' U270/42' U320

Reply #29 –
Before Crown and American LaFrance went to 10" drums, fire trucks had poor brakes. The big drums and putting a weaker spring in the treadle valve made smoking the tires pretty easy.

Disk brakes are much more expensive to manufacture so may be a big reason why big rigs don't have them. They are much easier to work on, and are much less likely to fade than drums. Depending on pad material, they may work better when a little warm. You will need a cherry picker to R&R drums they are so heavy.

Our U300 brakes work great even on the steepest grades. I have not experienced any fade yet with them. I have had to put the right side of an American LaFrance into a soft ditch coming down out of the Santa Monica mountains on a campaign fire. I was in first gear with the AnchorLoks on but brakes had completely faded out.

The vast majority of big rigs are manual transmissions so no worry about creep in drive.

Pierce
Pierce and Gaylie Stewart
'93 U300/36 WTBI
Detroit 6V-92TA Jake
1140 watts on the roof
SBFD (ret)

Re: Coach moving at idle despite parking brake (split from Re: Handling Comparison:36' U270/42' U320

Reply #30 –
Back to the beginning, IF you are new to the ISM....I had smaller engine before....the torque or whatever you call it, I found at a stop light, and I kept it in gear, it took goodly pressure on the brake.  Unlike the other coach, it would start moving, creep I guess you would say for perhaps so slow to not catch your attention if you looked away a moment.

So.....if I was getting an ISM from some other starting point, I think it a good admonition.  It may be different feel, may see some creep

As for moving with park brake on and in gear, I just think have not done.  So tried....see what I think John S said (?), hold on flat surface, no throttle, 725 rpm.  But if on much of an incline, I rather doubt it would hold?  Still, no plans to part in gear, far as I know.  Hmmm

Thanks Neal

mike
Mike
2001 U320 4010 Build 5878 (Gus)
Wrangle Unlimited Toad
Nacogdoches

Re: Coach moving at idle despite parking brake (split from Re: Handling Comparison:36' U270/42' U320

Reply #31 –
I hold a.CDL B with air brake endorsement also.
I was terrified when I first went to move.my coach in reverse cold. I had to put it in neutral to wrestle it to a halt.
It would not hold in either direction with the parking brake on. Not acceptable.
I replaced the rear spring chambers and.adjusted the slack adjusters front and rear as close as.I could, then monitored the discs with a remote thermometer after driving to make sure they were not rubbing.
Big difference.
If it won't hold with parking brake the rear springs in the chambers could be.fatigued.
1995 U320C SE 40'
Jeep 4x4 Commander - Limited - Hemi
"The Pack"  Yogi and Diesel our Airedales -  Charlie our Boxer/Akita mix. Gone but NEVER forgotten Jake our yellow Lab.
NRA Law Enforcement Firearms instructor - Handgun/shotgun
Regional Firearms instructor for national Armored Transp. Co.

Re: Coach moving at idle despite parking brake (split from Re: Handling Comparison:36' U270/42' U320

Reply #32 –
Well, it's very interesting that this thread has more opinions and less common sense of purpose than a room full of politicians.

Thanks Mike, you get the purpose of the post:

Quote from: Michael & Jackie –
Back to the beginning, IF you are new to the ISM....I had smaller engine before....the torque or whatever you call it, I found at a stop light, and I kept it in gear, it took goodly pressure on the brake.  Unlike the other coach, it would start moving, creep I guess you would say for perhaps so slow to not catch your attention if you looked away a moment.

So.....if I was getting an ISM from some other starting point, I think it a good admonition.  It may be different feel, may see some creep

As for moving with park brake on and in gear, I just think have not done.  So tried....see what I think John S said (?), hold on flat surface, no throttle, 725 rpm.  But if on much of an incline, I rather doubt it would hold?  Still, no plans to part in gear, far as I know.  Hmmm
Thanks Neal

I was making a comparison between the U270 36' and the U320 42' operating/driving characteristics.
 
These FACTs about the big blocks "creeping" against the strength of the parking brake spring force on the disc brakes and the additional "push" that a big block exerts, which requires additional service brake pressure at a stop light have been talked about for years on this forum.  Like many others, I sort of dismissed those thoughts because the 8.3's (most of my RV experience) properly adjusted and maintained, do not come close to showing alarming or "wake up call" type characteristics.
So during my comparison days,  I lived and learned quickly.  With the ISM-450, at least, it deserves your full attention and respect based on my "back to back" comparison.
 
It certainly seemed to be an appropriate topic to include in the comparison.

Look at a few of the threads from over the years:
 
Through various forum members (now including me, after posing the idle speed and parking brake questions last week), Foretravel (James Triana) has told us:

    • Properly set up and maintained, the U320 parking brakes are designed to hold the coach on level ground on up to a few degrees of grade, WITHOUT the engine and transmission engaged.
       
    • Greater than a few degrees of grade, also WITHOUT engine and transmission engaged,  one needs to ensure the use of chocks to prevent the coach from overriding the parking brake spring force applied to the disc brakes.
       
    • Also, the much larger torque values of the M11's will require significantly greater service brake pressure to counteract the greater "push" of the larger block engines.
Just a few of the many earlier threads that have discussed the same topic or closely related topics to this.
   
Effectiveness of Emergency/Parking Brake
AIR BRAKE CHAMBER
New to RVing
M 11 and parking brak
Parking Brake Effectiveness
Setting low idle
Motor Mount Replacement
Parking Brake
M 11 and parking brak
Breaks or Brakes
Parking Brake

The interesting diversions into discussions of "S" cam drum brakes on commercial vehicles, CDL training, individual brake system optimizations, proposed design experiments, Etc. stray quite a way from the RVIAA standards and the two primary purposes of our air brake system designs and their capacity:
    • Hold a non-operating vehicle in place on a level surface (Parking)
       
    • Bring a moving vehicle to a controlled stop in the case of  "loss of all service air" braking capacity (Emergency)
We are not heavy duty truck designs, with 80,000 Lb. payload capacities, we are not commercial carriers of freight or people, we are not regulated by 10 CFR 49, Subtitle B, Federal Motor Carrier Safety Regulations. 
Many of the principles, applied within reason, are appropriate to our safe operation and our thought processes,  but knowing where and how to draw the line is well beyond most RV owners, without special training.  That's part of why it is a federal offense to tamper with or redesign air brake systems on any vehicle over 26,000 lb. GVWR, without proper certification.
 
A bit of a side issue, but WRT to CDL training, CDL licenses must usually be surrendered when obtaining a license in another state (what I was required to do long ago), until recertification in the new state is achieved.  Most CDL holders prefer to surrender their CDL, if it is not being (or not planned to be) actively used, as local law enforcement and the legal system is far more strict on CDL holder infractions, and rightfully so.  CDL license holders should know that logic better than most.  It used to be illegal to have two types of licenses or to simultaneously hold CDL licenses in two different states.  I don't know about now.
All that doesn't mean that one shouldn't avail themselves of CDL training if one can come by it reasonably.  I have found that the quality of instruction varies widely and good research on the internet or in the library can be much more meaningful and less costly, unless one needs the "hands-on"or personal instruction to understand the topic.

So, I stand by the premise that there are stark differences between the U270, 36' and U320, 42'  operating/handling braking system characteristics........... that the uninitiated would be well served to know about.  Like most of the 8.3 owners, I dismissed them for years, but no longer.
Thanks, Mike, "for Getting It".
Neal
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Neal (& Brenda) Pillsbury
'02 U320 SPEC, 4200, DGFE, Build #5984
'04 Gold Wing
'07 Featherlite 24'
'14 Jeep Grand Cherokee Summit
MC #14494
Exeter, NH & LaBelle FL
Quality makes the Heart Soar long after Price is Forgotten
 

Re: Coach moving at idle despite parking brake (split from Re: Handling Comparison:36' U270/42' U320

Reply #33 –
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