Go Back   iRV2 Forums > MOTORHOME FORUMS > Class A Motorhome Discussions
Click Here to Login
Join iRV2 Today

Mission Statement: Supporting thoughtful exchange of knowledge, values and experience among RV enthusiasts.
Reply
  This discussion is proudly sponsored by:
Please support our sponsors and let them know you heard about their products on iRV2
 
Thread Tools Search this Thread Display Modes
 
Old 04-10-2015, 07:45 PM   #29
Senior Member
 
Ray,IN's Avatar
 
Join Date: Aug 2001
Location: North America somewhere
Posts: 13,675
Quote:
Originally Posted by falconman View Post
I think this should lead to a discussion of how to use air brakes vs conventional hydraulic brakes. When coming down a steep hill with conventional brakes I would routinely use short heavy braking to slow the rig and allow time in between for the brakes to cool. I've been told and it makes sense to me, that air brakes should be applied with a steady heavy pedal till the desired speed in reached. Repeatedly applying the brakes or stabbing, may overcome the ability of the compressor to maintain enough pressure. This of course in conjunction with the proper gear and engine/exhaust braking. I know people hate the idea of requiring an air brake license endorsement but I wonder how many out there really know how these things work? I learned a lot when studying for my Class B. How many know what happens if there is a rapid air loss?
I disagree with your air brake constant pressure method, air brake shoes/pads and drums get just as hot as hyd brake shoes/pads and drums. I've never noticed my air gauges dropping with frequent use of the brakes while descending a grade.
What happens with a rapid air loss__ your spring brakes engage because something broke.
__________________

__________________
2000 Winnebago Ultimate Freedom USQ40JD, ISC 8.3 Cummins 350, Spartan MM Chassis. USA 1SG, retired;PPA,Good Sam Life member,FMCA."We the people are the rightful masters of both the Congress and the Courts - not to overthrow the Constitution but to overthrow men who pervert the Constitution. "Abraham Lincoln"
Ray,IN is offline   Reply With Quote
Join the #1 RV Forum Today - It's Totally Free!

iRV2.com RV Community - Are you about to start a new improvement on your RV or need some help with some maintenance? Do you need advice on what products to buy? Or maybe you can give others some advice? No matter where you fit in you'll find that iRV2 is a great community to join. Best of all it's totally FREE!

You are currently viewing our boards as a guest so you have limited access to our community. Please take the time to register and you will gain a lot of great new features including; the ability to participate in discussions, network with other RV owners, see fewer ads, upload photographs, create an RV blog, send private messages and so much, much more!

Old 04-10-2015, 08:09 PM   #30
Senior Member
 
docj's Avatar
Official iRV2 Sponsor
 
Join Date: May 2011
Posts: 3,712
Regardless of what you call it, my CDL instructor told us that when going downhill to apply our brakes firmly until our speed was ~5 mph below our target speed and then to release. When speed increases again to ~5 mph above the target speed reapply brakes and repeat the process. This gives the brakes a chance to cool between application. FWIW with the 2-speed compression (Jake) in my MH I hardly have to use my brakes on most highway grades.
__________________

__________________
Joel Weiss--WiFiRanger RV Ambassador
RVParkReviews administrator
2000 40' Beaver Patriot Thunder Princeton CAT C-12
docj is online now   Reply With Quote
Old 04-10-2015, 08:15 PM   #31
Senior Member
 
flaggship1's Avatar


 
Fleetwood Owners Club
iRV2 No Limits Club
Join Date: Sep 2012
Location: Rainbow Riding
Posts: 18,385
Quote:
Originally Posted by docj View Post
Regardless of what you call it, my CDL instructor told us that when going downhill to apply our brakes firmly until our speed was ~5 mph below our target speed and then to release. When speed increases again to ~5 mph above the target speed reapply brakes and repeat the process. This gives the brakes a chance to cool between application. FWIW with the 2-speed compression (Jake) in my MH I hardly have to use my brakes on most highway grades.
There ya go... I only have the tranny retarder but I do whatever you describe is called. How about braking...
__________________
Steve & Annie (RVM2)
2008 Fleetwood Bounder 38F ~ 325 ISB Turbo ~ Freightliner XC 2014 CR-V ~ Invisibrake / Sterling All Terrain
Sioux Falls, SD (FullTime Since Nov 5th 2014)
flaggship1 is offline   Reply With Quote
Old 04-10-2015, 11:41 PM   #32
Senior Member
 
slickest1's Avatar
 
Monaco Owners Club
Join Date: Jul 2011
Location: B.C.
Posts: 3,705
Quote:
Originally Posted by docj View Post
Regardless of what you call it, my CDL instructor told us that when going downhill to apply our brakes firmly until our speed was ~5 mph below our target speed and then to release. When speed increases again to ~5 mph above the target speed reapply brakes and repeat the process. This gives the brakes a chance to cool between application. FWIW with the 2-speed compression (Jake) in my MH I hardly have to use my brakes on most highway grades.
What he should have told you is that after the first slow down you should downshift to a gear that will hold you without having to use your brakes so much. If you keep using your brakes like that on a long down hill grade it won't be long until they are hot and become useless.
__________________
Dennis & Marcie & Captain Hook The Jack Russell,aka PUP, 04 Dodge/Cummins 01 Citation 29.rk fifth wheel.RVM59
slickest1 is offline   Reply With Quote
Old 04-11-2015, 01:04 AM   #33
Senior Member
 
Tony Lee's Avatar
 
Join Date: Sep 2012
Location: Peru heading for Brasilia, Brazil
Posts: 2,115
I think a few posters should look up snub braking and practice it next time they go down a hill.
There are three alternatives regarding the interaction between braking force, duration and interval and the actual speed down the hill.
First, safest and most painful is to select lower and lower gears until the auxiliary brake (term covers all such devices) holds the vehicle at a terminal speed so no braking is required. Trouble is this will often be ridiculously slow and it will change as slope changes and may even be so slow that the auxiliary braking disengages until the speed picks up.

The other is to let the dumb auto gearbox do the thinking for you and sail downhill on a wing and a prayer not realising that the gearbox and engine are working together for one aim and that is to keep the engine from overspeeding. Passenger safety is secondary to that.

The right way is to select gear and adjust speed so you can maintain speed within a comfortable (mentally) and safe band with periodic use of reasonably firm braking force at regular spaced intervals. Not really possible to specify how firm and how long and how often that snub braking application should be but given modern brakes, it is fairly safe to rely on your own level of concern as to whether it is time to select a lower gear and make the next brake application hard enough and long enough to allow the gearbox to drop into that lower gear.

One thing that isn't all that intuitive is that sometimes it is possible to reach a terminal (steady) velocity that is just a bit higher than what you selected as target velocity by relying on the non-linear relationship between velocity and drag. Even if you don't reach steady velocity, sometimes you do reach a state where by going 10mph faster the increased air drag and the increased performance of the auxiliary brake at the higher revs result in vastly reduced brake application force and frequency. Sounds wrong I know but we all know that an object in free fall does reach a terminal velocity that isn't all that much higher than the speeds some drivers sail down steep roads at. Of course only the driver in consultation with the copilot who usually gets final say, can know whether that higher stable speed is right for them and the road conditions.
__________________
Tony Lee - International Grey Nomad. Picasa Album - Travel Map
RVs. USA - Airstream Cutter; in Australia - MC8 40' DIY Coach conversion & OKA 4x4 MH; in Germany - Hobby Class C; in S America - F350 with 2500 10.6 Bigfoot camper
Tony Lee is offline   Reply With Quote
Old 04-11-2015, 08:05 AM   #34
Senior Member
 
docj's Avatar
Official iRV2 Sponsor
 
Join Date: May 2011
Posts: 3,712
Quote:
Originally Posted by slickest1 View Post
What he should have told you is that after the first slow down you should downshift to a gear that will hold you without having to use your brakes so much. If you keep using your brakes like that on a long down hill grade it won't be long until they are hot and become useless.
Yes, downshifting was part of the lesson also, but for this discussion I was only addressing the braking aspects. Unless you downshift (or use your retarder) the vehicle will speed back up too quickly and the brakes won't have had enough time to cool.
__________________
Joel Weiss--WiFiRanger RV Ambassador
RVParkReviews administrator
2000 40' Beaver Patriot Thunder Princeton CAT C-12
docj is online now   Reply With Quote
Old 04-11-2015, 09:46 AM   #35
Registered User
 
mel s's Avatar
 
Join Date: Mar 2010
Posts: 8,777
Quote:
Originally Posted by slickest1 View Post
What he should have told you is that after the first slow down you should downshift to a gear that will hold you without having to use your brakes so much. If you keep using your brakes like that on a long down hill grade it won't be long until they are hot and become useless.
slickest1
When descending grades I always use my PacBrake and I use "snub braking" if/when it's needed.
Because my coach is programmed to "select" 2nd gear whenever I activate my PacBrake... if/when shifting is necessary my Allison automatically down-shifts, (and up-shifts), at the proper road speed/engine rpm... (no manual shifting is necessary).
Mel
'96 Safari. 140k miles
__________________
mel s is offline   Reply With Quote
Old 04-11-2015, 10:48 PM   #36
Senior Member
 
Rich-n-Linda's Avatar
 
Join Date: Nov 2011
Posts: 884
Stab braking is an improper term for slowing descent on hills

It should be called CYCLE BRAKING.

As a previous poster said, you allow the speed to build to 5 mph above your target speed, then firmly apply the service brakes to slow down to 5 mph below your target speed. Then repeat the CYCLE. Simple. This basic principle of CYCLE BRAKING applies equally to air or hydraulic brakes.

Whoever suggested that you should lock the wheels in this process should have his drivers license taken away. That is absolutely nuts and TOTALLY WRONG.
__________________
Rich-n-Linda is offline   Reply With Quote
Old 04-12-2015, 10:41 AM   #37
Senior Member
 
Tony Lee's Avatar
 
Join Date: Sep 2012
Location: Peru heading for Brasilia, Brazil
Posts: 2,115
Quote:
Originally Posted by Rich-n-Linda View Post
It should be called CYCLE BRAKING.

As a previous poster said, you allow the speed to build to 5 mph above your target speed, then firmly apply the service brakes to slow down to 5 mph below your target speed. Then repeat the CYCLE. Simple. This basic principle of CYCLE BRAKING applies equally to air or hydraulic brakes.

Whoever suggested that you should lock the wheels in this process should have his drivers license taken away. That is absolutely nuts and TOTALLY WRONG.
Since "cycle braking" in the context of this post doesn't appear at all in a Google search and "snub breaking" appears 45,000 times, I'd suggest sticking to the term used by transportation experts.
__________________
Tony Lee - International Grey Nomad. Picasa Album - Travel Map
RVs. USA - Airstream Cutter; in Australia - MC8 40' DIY Coach conversion & OKA 4x4 MH; in Germany - Hobby Class C; in S America - F350 with 2500 10.6 Bigfoot camper
Tony Lee is offline   Reply With Quote
Old 04-12-2015, 10:59 AM   #38
Senior Dude
 
Dogpatch's Avatar


 
Forest River Owners Club
Join Date: Sep 2010
Location: Somewhere, BC.
Posts: 5,584
Blog Entries: 8
"Snub Braking" is the "cycle" of periodic use of the brakes in a controlled manor for the reduction of speed in the decent of a hill.

Everybody happy? LOL
__________________
Les (RVM12), Bonnie, Morgan and 4 leggers Bella & Bruce
2010 Forest River Cardinal 3450RL 40' Full Body Paint- 2015 Ram 3500 Laramie 6.7 ltr Turbo Diesel, 68RFE Trans. 4x4 SRW SB Pullrite 2900 18K FMCA-420438 Good Sam
Dogpatch is offline   Reply With Quote
Old 04-12-2015, 11:56 AM   #39
Registered User
 
Monaco Owners Club
Join Date: Oct 2009
Location: Varies Depending on The Weather
Posts: 8,517
Quote:
Originally Posted by Dogpatch View Post

"Snub Braking" is the "cycle" of periodic use of the brakes in a controlled manor for the reduction of speed in the decent of a hill.

Everybody happy? LOL




I love it!

Now let's not to death!

Dr4Film ----- Richard
__________________
Dr4Film is offline   Reply With Quote
Old 04-12-2015, 12:25 PM   #40
Senior Member
 
wa8yxm's Avatar
 
Damon Owners Club
Workhorse Chassis Owner
Join Date: Mar 2009
Posts: 22,787
Ray you reminded me of last DEC-18....Just as I got up to speed after a turn some 1-D-Ten-T (IDIOT) hung a left in front of me..... I STABBED (I usually say Spiked) the brakes..Missed him but about 30 miles later got a soft pedal.... Yup, blew a wheel cylinder... At least it was only my car.

Still managed to get everywhere I needd to go (With seconds to spare) good thing I was bringing a cheesecake to the pot luck (HAS to be made day before) Sang my Solo,,, Delivered a bunch of gifts.. Had a good meal.

But that is one reason to avoid "Stabbing"brakes
__________________
Home is where I park it!
wa8yxm is offline   Reply With Quote
Old 04-12-2015, 02:38 PM   #41
Senior Member
 
Redapple's Avatar
 
Join Date: May 2006
Location: SoCal
Posts: 538
Every year we take the Rv up the CA 395. Right out of Bishop is a 12 mile 6 -7% grade. Heading into Mono Lake. On the return trip, I always downshift first and set my speed before I hit the gra de. I hit the brakes until I an 10 mph below target speed then cruise until 10 over before I hit then again. In the Ford F53 chassis with the 5 speed Torque flight the Trans grade braking works great.
__________________

__________________
2006 Damon Daybreak 3272 w/F-53 @ V10
Redapple is offline   Reply With Quote
Reply



Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)
 
Thread Tools Search this Thread
Search this Thread:

Advanced Search
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Similar Threads
Thread Thread Starter Forum Replies Last Post
Peak Braking Definition? Romeo Cummins Engines 4 07-12-2014 09:03 PM
aux braking with a dolly RayR Toads and Motorhome Related Towing 3 04-29-2014 06:52 AM
Braking - auxiliary braking system for tow r cogburn Toads and Motorhome Related Towing 1 04-24-2014 10:43 AM
Using Jake Brake and long term damage on trans. tom chelbana Allison Transmission Forum 8 04-19-2014 08:26 AM

» Virginia Campgrounds

Reviews provided by


Copyright 2002- Social Knowledge, LLC All Rights Reserved.

All times are GMT -6. The time now is 07:13 PM.


Powered by vBulletin® Version 3.8.8 Beta 1
Copyright ©2000 - 2017, vBulletin Solutions, Inc.