Brake failure behind RV crash and fatality.

[Lakesidelogger]

Retired commercial driver here.

In British Columbia there is a brake check at the top of every major downhill grade that commercial vehicles are required to stop at. A ticketable offense for not stopping.

One of the major reasons for these brakes checks is to have the vehicles start down a grade from a stop.

If you happen to start down a grade at highway speed then try to slow down to a descending speed a lot of your braking “reserve” is already gone.

[Benjamin]

This accident brings up the subject, but we don't know what happened, and probably never will.  Because of the fatality, the RV was probably hauled off to be inspected, but we're not going to get those results, and they wouldn't tell the whole story anyway.  I know the article doesn't tell the whole story, other than I'll have to trust the direct quotes from the troopers, and take everything else with a grain of salt. 

Regardless of what happened in this particular case, in general I'll guess "brake failure" (as in failure of brakes to perform to specs caused by mechanical malfunction) causing accidents is rare.  I would guess if we had access to all of the accident data that the state patrol accident investigator has, that the majority of "brake failure" are operator error, unsafe speed, improper technique, panic leading to bad decisions, etc. 

In a local overweight dump truck crash, the driver had pumped the brakes in panic, which theoretically could exhaust the air supply, especially if the vehicle was in way too high a gear, so the engine was at low speed.  One correct technique for stab braking is to slow down 5mph over about 3 seconds of brake application, then give the brakes a period to cool, if you speed up too fast, then you need to slow to a lower gear immediately.  Pumping is what you do to hydraulic brakes with a leak, not air brakes.  Following correct technique with the engine in the proper gear you won't run out of air pressure without a true mechanical failure.

Another commonly suggested "brake failure"  is fade.  Fade comes from lower friction of the hot brake material, but most importantly from the drums expanding past the stroke of the air cans.  I believe the drums expanding enough to lose more than half the force is only possible with improperly adjusted brakes, that is without automatic slack adjusters or stuck slack adjusters.  This is why a pretrip inspection requires examining the stroke length and linkage angle. 

Even a serious mechanical failure like loss of compressor, or loss of power steering flow for a hydroboost, should not result in a failure to stop.  The warning lights are there to tell you to stop immediately in those cases, and if you're under control with engine braking, then you'll have enough reserve to stop safely.  Similarly, loss of front or rear brakes, whether air or hydraulic, should leave enough braking to stop in the same situation. 

Here's one of a series of four videos with better explanation, all four are important, as well as an understanding of an air brake precheck, even if you're not going to do it every day, do it before the trip, and before each day of mountain driving. 

https://www.youtube.com/watch?v=B1jGncXcV0s

The brakes have plenty of redundancy and extra capacity to prevent runaways if the driver uses them halfway correctly.  And if you realize you're in trouble, slow down immediately and get into a lower gear.

[Jetjockey]

 I Use proportional braking on towed pickup, actuated by motorhome air brakes. Read where systems that are inertial require several seconds to activate. Where the average panick stop lasts 2 seconds. The crash may be over before the the brake assist activates.

[dl_racing427]

2 hours ago, amphi_sc said:

I'm always saddened by a preventable accident, especially one with a loss of a precious life. By the time the braking emergency has emerged things have gone too far.  It is much better to err on the side of safety early and use that engine brake AND transmission proactively.  Downshift and slow to your target downhill speed BEFORE the grade, and if that can't be held use that shift pad and go down another gear.  In Canada I've often come across major roadways with 14% to 17% grades that I go down and NEVER have to engage the air brakes, thus they are there in reserve should I need to slow even more or completely stop for some reason.  Your compressor should always be able to keep up but do remember it takes air each time you step on the foot brake. I remember a rule of thumb that some will argue against, but it was to always go down in the same or lower gear than it requires going up.  In my coach full engine brake & 4th gear may not hold speed but downshifting to 3rd often means I can toggle between 1/2 and full compression brake maintaining my target speed.  I'll go down the Priest Grade bypass outside Yosemite in 2nd and never use the foot brake.

I find it very counterintuitive that it is ILLEGAL to warn drivers behind you that you are going slow by using other safety measures such as your 4 way flashers to gain their attention.  Illegal to drive with flashers on in:

Alaska
Arizona
Arkansas
California 
Colorado 
Delaware
Florida 
Georgia 
Hawaii 
Idaho
Illinois
Indiana
Iowa
Kansas
Louisiana
Maine
Maryland
Massachusetts 
Minnesota
Montana
Nevada
New Mexico
Ohio
Oklahoma
Rhode Island
Tennessee
Virginia 
Washington 
West Virginia
Wisconsin

Enjoy the journey and arrive alive.

FWIW

I was pulled over when I had a family emergency.
I passed a cop at high speed, with my flashers on.  He pulled me over and quickly let me go when I explained the situation.

He did explain that in VA, it is illegal to use flashers when driving ABOVE 35mph.  They can, and should be used to warn if you're driving slowly.

[Ivylog]

It was likely a Beaver Monterey or similar based on the Cat engine, oval Alcoa rims, and 8 airbags…you can see the rear H frame crossmember. Also it uses an aluminum house bolted to the Roadmast chassis. Such a rig is capable of using Teton pass safely by manually downshift to a gear that maintains the same speed with only using the exhaust brake… no need to use the air brakes except to downshift to an even lower gear because of the slow moving dump truck. Clearly operator error!

Edited September 9 by Ivylog

[Bill R]

I find it amazing how the house seems to be completely separated in the background.

[Jdw12345]

A person should be able to look a the Wyoming Highway Patrol report, I believe that they are public records, to verify the make and model.

[Tom Cherry]

Random comments…..added to my first post…having driven that stretch…..NOT in a MH.

10% of UNBELIEVABLE….could add an expletive….  Eisehnhower (I - 70 WEST) is 7% for 7 miles.  Black Mountain is 6%….with a few stretches approaching 8%.  The Teton pass, per the article is 10%.  NEVER, EVER would I have attempted it with a standard Cummins VGT exhaust brake,

Good observations and comments on the MH.  It is a 2008 or older.  The SLOTTED rims or wheels were last used in 2008….at least on the lower ends….  It is a SIDE RADIATOR, so  NOT an Endeavor or Diplomat.  Appears to have an Aquathot.  Tires are Toyo….unless my eyes deceive me,

Even with ON!Y a VGT Exhaust Brake….gearing down and sporadic but intelligent and judicious use of service brakes would have been WHITE KNUCKLE…but NOT reequiring it to have a Brake Job at the end.

[RVerBob]

Priest Grade in a RV, I'm Impressed.

That would pucker my you know what.

[dl_racing427]

On 9/7/2024 at 1:48 PM, throgmartin said:

I know from experience, pulling the emergency brake at speed will bring the rear end around on a DP. I was teaching my ex-wife how to drive the coach when we first bought it. On an exit I told her to hit the exhaust brake. She thought I meant the emergency brake and pulled it. We were at around 55 mph and the rear end started coming around. She quickly released the emergency brake, steered out of the skid and got the coach going straight again. She never panicked and handled it like a Pro.

I have no idea what the brake bias ( front to rear percentage ) on our coaches is but with the way the rear end came around it is obvious the percentage is higher in the front similar to a car. I would caution anyone about pulling that emergency brake switch when at a high rate of speed. I always start down a long grade at 55 mph or less, use the exhaust brake and if I get close to exceeding the RPM's, stab the brakes and release after 15 seconds and continue that action till my RPM/Speed drops so the exhaust brake resumes in helping to slow the momentum. It is all about managing speed and RPM's early on, not half way down a big grade.

Wow.  Kudos to your wife for controlling that situation.  Many people would have panicked and lost control.

[jacwjames]

When I visited Cuyahoga NP in 2021 main access road was closed and they directed me to a detour, no real warnings.  My GPS popped up a warning about truck access but that's not unusual if you get off the beaten path.   So as I descended the grade it started to get steep.  I had my exhaust brake on and I was in 1st gear, I stobbed the brakes to maintain a slow speed but at some point I had the brake pedal pressed with more and more pressure.  At one point my TPMS alarmed to high temp on one of the wheels.   I doubt that I could have actually stopped on the worst part of the grade even doing it a slow speed, my only recourse would have been to try the emergency brake (which I had in the back of my mind).  Luckily I made to the bottom which leveled out and allowed me to stop.  

I parked the coach and unhooked the Jeep to explore the park, I also looked for a better route when I left. 

I did scope out my route prior to getting there but did not know the main access road was blocked.  

Live an learn.  So last year when I traveled quite a bit in CO & UT I used google earth to look at all my routes and even changed plans if there was a viable alternative but in Southern Colorado you have to resign yourself you'll have to tackle some pretty steep grades both up and down.   On descents when cars started to pile up I didn't speed up, I kept my speed down knowing that that was what I had to do to keep my speed under control. 

 

Edited September 10 by jacwjames

[Scotty Hutto]

This topic will either be in Frank’s Coach Safety presentation of a discussion for Saturday’s Roundtable at the Gathering.  

[amphi_sc]

23 hours ago, RVerBob said:

Priest Grade in a RV, I'm Impressed.

That would pucker my you know what.

Priest Grade BYPASS.  The twisty way down on the right headed down (or left as heading up) that adds a couple miles to the route.  It twists so much it's pretty much a 2nd gear climb or descent. I wasn't talking about the original route straight up and down!  Even in just a car I would still choose the bypass going down...we'll, maybe I'd do the straight descent in my Jeep: 4 wheel low manual tranny downshifted...