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.
  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 05-13-2016, 11:21 AM   #15
Senior Member
Sweetbriar's Avatar
Thor Owners Club
Ford Super Duty Owner
Join Date: Jul 2011
Posts: 2,048
Use it as a weapon of last resort. Better to burn up and destroy the brake them plow the coach into something or someone. Its not a very stout break and in a down hill emergency you'll probably get one use out of it.

Don't hit the peddle and floor it. Remember there's no antilock on the brake and if by chance you do lock up the rears the back of the coach will probably become the front of the coach, then they will switch, and switch, (wash-rinse-repeat). You get the idea. As other have mentioned you'll need to hold the release while pushing on the peddle. Steady pressure to get the speed down so you can start down shifting the transmission. The driver is going to be a one legged man in an a__ kicking contest but you'll have a camp fire story that will have everyone's attention.

Sweetbriar is online now   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 05-13-2016, 11:44 AM   #16
Senior Member
MRUSA14's Avatar
Entegra Owners Club
Join Date: Nov 2012
Posts: 4,992
I'm sure it is a diffent story with different type vehicles. I did it once in a Beaver which was rolling because some dumb a$$ (who shall remain nameless to protect the guilty) had forgotten to set the parking brake. The coach was rolling about 5 mph and I jumped in and pulled the yellow knob. The coach stopped instantly, with so much force that the nose dove and the retractable steps hit the ground. It was a violent stop, and I hate to think about what the result would have been at a highway speed.

Marc and Jill, Wellington FL
2013 Entegra Anthem 44SL
MRUSA14 is online now   Reply With Quote
Old 05-13-2016, 11:51 AM   #17
Senior Member
69Stang's Avatar
Join Date: Jul 2015
Location: Valdosta, Ga
Posts: 759
I have. In Oct 15, I was taking the off-ramp in McDonough Ga. after sitting on the interstate for an hour with hot brakes. I thought they had cooled enough, but once I hit the ramp and applied the brakes (at about 35 MPH) they went to the floor. I pulled the yellow knob and it slowed enough to drop it down a couple gears. Thankfully the light was green and was able to make the corner and pull over into a gas station until a wrecker arrived. I was able to change my shorts before the wrecker arrived.

Did an op's check on the parking brake later and they still work fine.
1998 Southwind Storm 34S
2015 Ford Focus Hatchback SE
Retired Air Force 1981-2006
69Stang is offline   Reply With Quote
Old 05-13-2016, 12:42 PM   #18
Senior Member
Join Date: Jul 2014
Posts: 11,779
With air brakes, the parking brake is applying your service brakes, with the equivalent of 60 psi pressure.

Quicker then the pedal, explaining the quick stop at low speed, but with less force then the pedal, explaining the lack of stopping, when the brakes are overheated while at a higher speed.

The spring in the chamber needs to be able to be compressed with the air system. They release at 60 psi.

Pop them on, at 20 mph, and you will just stop quickly.

Drive shaft mounted parking brakes have an advantage of the gear reduction of the rear differential ratio.
That's how a relatively small brake can lock you up. They also use high friction material.
twinboat is online now   Reply With Quote
Old 05-13-2016, 02:34 PM   #19
Senior Member
ChasA's Avatar
Join Date: Mar 2007
Location: Apex, NC
Posts: 1,857
Wrong. With air brakes, the parking brake is applied by very strong springs. When you push the yellow button on the dash, air is applied to overcome the force of the springs and release the brakes. A separate air cylinder operates from the brake pedal to apply the brakes (service brakes). The same brake shoes are operated by two separate systems and two separate cylinders.
With air brakes, if you don't have air pressure, the rig ain't going to move.
2010 Winnebago Journey Express 34Y
2010 Freightliner XCS (mfd 9/'09)
'07 Saturn Vue V6
ChasA is offline   Reply With Quote
Old 05-13-2016, 02:55 PM   #20
Senior Member
Join Date: Jul 2014
Posts: 11,779
Originally Posted by ChasA View Post
Wrong. With air brakes, the parking brake is applied by very strong springs. When you push the yellow button on the dash, air is applied to overcome the force of the springs and release the brakes. A separate air cylinder operates from the brake pedal to apply the brakes (service brakes). The same brake shoes are operated by two separate systems and two separate cylinders.
With air brakes, if you don't have air pressure, the rig ain't going to move.
Here is an explanation of parking brakes.

twinboat is online now   Reply With Quote
Old 05-13-2016, 03:10 PM   #21
Senior Member
Join Date: Jul 2014
Posts: 11,779
More on spring brakes.

Spring brakes for emergency braking and parking


All vehicles with air brakes must have a way of stopping if the service brake system fails. Most vehicle manufacturers combine this emergency braking system with a parking-brake system using spring brakes.

Spring brakes are not air applied like service brakes. They apply when air pressure leaves the brake chamber and release when air pressure builds up in the chamber.

Spring brakes use a different type of brake chamber from service brakes. A brake chamber that includes both service brake and spring brake sections is called a spring brake chamber. (See Diagram 4-1.) Spring brake chambers apply the brakes by means of a large coil spring that provides enough force to hold the brakes in the applied position, instead of using air to apply the brakes.

Spring brake chambers are different in appearance from service brake chambers. To accommodate the large coil spring, a section must be added to the service brake chamber that is clearly visible and adds significantly to its size. The spring brake section is “piggy-backed” onto the service brake section and these two sections function as two separate chambers. The portion nearest the pushrod end is the service brake section and it works in the same manner as a separately mounted service brake chamber.

To release the spring brakes, normally about 414 kPa (60 psi) of air pressure must be supplied to the spring brake chamber to compress or “cage” the spring. If system pressure is below 414 kPa (60 psi), the spring brakes start applying because there is no longer enough pressure to keep them released.

Many vehicles can still be driven even with the spring brakes applied because they do not have the braking power of the full service brake application. Before driving the vehicle, it is important to ensure that the air brake system has enough air pressure (normally 414 kPa (60 psi)) to keep the spring brakes from applying. Due to the way most spring brake chambers are currently constructed, it is very difficult to unintentionally release the spring.

The large coil spring used in the spring brake chamber is compressed under very high tension. Tampering, damage or corrosion can cause the spring to release, resulting in sudden violent motion of parts of the air brake chamber. Since this can be hazardous, never attempt to service or repair any air brake chamber.

twinboat is online now   Reply With Quote
Old 05-13-2016, 08:56 PM   #22
Senior Member
Rich-n-Linda's Avatar
Join Date: Nov 2011
Posts: 884
I have applied the parking brake on our Mandalay at about 50 mph. I did this to test its braking force. The coach came to a stop with the equivalent braking force of a heavy stop with the service brakes. The final stop is a bit abrupt because the brake stays fully applied right down to the stop. It doesn't feather off as you would do when braking normally with the pedal.

Overall, it was a non-event and gave me a good idea of what to expect should I ever have to use it in an emergency.
Rich-n-Linda is offline   Reply With Quote
Old 05-14-2016, 02:05 AM   #23
Senior Member
Join Date: Aug 2014
Posts: 133
Originally Posted by CJ7365 View Post
I have done some practice on my Jeep CJ7 before, not on the highway but out in the desert, using the same procedure you described, holding the handle and manipulating the pedal.

It was challenging but could be done, rear drums are not the best by themselves though
On a small 4x4 with part time transfer case if you put it in 4wd the rear drums now slow all axles... handy if you ever lose a hydraulic brakes off road...
thedjjack is offline   Reply With Quote
Old 05-14-2016, 06:48 AM   #24
Senior Member
Freightliner Owners Club
Join Date: Apr 2004
Location: Apache Junction, Az
Posts: 747
Rich-n-Linda stated it correctly, as this is how it is explained in Camp Freightliner. So, if a DP requires you to pull the P-brake go ahead and do it. It will take time to stop 32,000 lbs or larger of a moving force. No need to change shorts.
Dale&Susan, 08 Alfa Gold, DaGirlsRv Blog
2015 F-150XLT_1600W Solar_880 AmpHr
gatorcq is offline   Reply With Quote
Old 05-14-2016, 08:25 AM   #25
Moderator Emeritus
Gary RVRoamer's Avatar

Join Date: Jan 2000
Location: Silver Springs, FL. USA
Posts: 18,635
I used the Emergency Brake on our DP to stop when we experienced a brake pedal failure and could not apply the brakes any other way. Fortunately we were only going about 40 mph at the time, but we were in traffic and we hit two cars in front before finally stopping. Only the rear brakes get applied, so the stopping distance is rather longer than usual.

On a DP, the emergency brake button dumps air from the brake system and allows the brake springs to apply pressure to the brake. It works.

Gary Brinck
Former owner of 2004 American Tradition
Home is in the Ocala Nat'l Forest near Ocala, FL
Summers in Black Mountain, NC
Gary RVRoamer is offline   Reply With Quote


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
Visone RV ? Has anyone used these folks for used parts ? johnboy2 Monaco Owner's Forum 15 11-05-2014 03:49 PM
Does anyone still have their first RV as their Primary? ie2special Class A Motorhome Discussions 31 02-18-2014 09:50 PM
Has Anyone Run Their Surround Sound Through Their Coach Speakers? zabooda Technology: Internet, TV, Satellite, Cell Phones, etc. 8 02-27-2011 04:44 AM
Who has used GS Emergency Assistance Plus ? Scooter iRV2.com General Discussion 9 12-24-2010 03:53 AM
Auto Parking Brake/ emergency brake??? HD tech Workhorse and Chevrolet Chassis Motorhome Forum 6 03-11-2005 02:04 PM

» Featured Campgrounds

Reviews provided by

Copyright 2002- Social Knowledge, LLC All Rights Reserved.

All times are GMT -6. The time now is 02:28 PM.

Powered by vBulletin® Version 3.8.8 Beta 1
Copyright ©2000 - 2018, vBulletin Solutions, Inc.