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Old 04-09-2015, 06:20 PM   #1
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Stab braking is an improper term for slowing descent on hills

Per CDL training documents, stab braking involves locking the wheels, controlled braking does not lock the wheels.
I have been guilty of recommending stab braking as the preferred method of reducing speed during a descent. Now I know that is not the best; controlled braking should be the proper terminology, using an on/off method of applying the service brakes to reduce the chance of overheating the brakes.
This is a terminology thing, but hopefully everyone understood applying the brakes to lockup is not the best option.
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Old 04-09-2015, 06:24 PM   #2
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When you lock up a brake, the tire loses 30% of it's braking friction.

I learned that in racing school.
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Old 04-09-2015, 06:28 PM   #3
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Stab braking is an improper term for slowing descent on hills

I learned it in 65 on a frozen MN lake.
Also how to spin and slide sideways at 60mph
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Old 04-09-2015, 06:28 PM   #4
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We call it "stubbing the brake" in Canada.
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Old 04-09-2015, 07:12 PM   #5
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I can't believe any training document would recommend locking brakes as a technique for downhill braking, or most any braking. Once the brakes lock, you lose control. Hence the addition of "anti lock braking" devices on all cars of recent mfg. I have heard of stab braking to the point of near lockup on older non ABS cars, but releasing before then.
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Old 04-09-2015, 08:03 PM   #6
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I assume this is in relation to Class A MH too. When we take 18 down the hill toward Lucerne it is about 7 to 8 miles of grades up/down to 16%, with hairpins and cliffs. About two years ago, pulled over on the wrong side of the road was a 40+' DP. Smoke was pouring from all axles, couldn't even make out the make. Now this is not how you drive down a hill.

Before heading down, not true of the new Ford 53 chassis, downshift to first or second or another gear to keep your speed safe and under control. Hairpin speed for a car is posted at 10 mph, MH <10 is a good idea because you may have to stop. Brake firmly prior to the turns to reduce your speed below the minimum then let off and let the brakes cool, hoping the engine braking holds the MH at a safe speed. Keep doing this, finding the appropriate low gear and your down, your cool.

On our new ACE, the tranny responds to your brake pressure, speed and decline doing the downshifting job for you. I have done this a couple times and have done the Tehachapi Grade on 58 with a toad, amazing.

The Grade to Lucerne:

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Old 04-09-2015, 08:16 PM   #7
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This is from the Florida CDL.
What they are saying is apply the brakes hard enough to cause the wheels to lock, then release as soon as they lock.
This would not apply to ABS systems...and in thinking about it, this is exactly what ABS systems do...except they sense the locked wheels and release the brakes very quickly.


Stab Braking
  • Apply your brakes all the way.
  • Release brakes when wheels lock up.
  • As soon as the wheels start rolling, apply the brakes fully again. (It can take up to one second for the wheels to start rolling after you release the brakes. If you re-apply the brakes before the wheels start rolling, the vehicle won't straighten out.)
Regards,


Dan
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Old 04-09-2015, 08:27 PM   #8
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Did this grade earlier this year towing a jeep with class c. Readybrake on jeep was dragging to much but MH was doing just fine. 1st and 2nd gear all the way down. Readybrake is like a mechanical surge brake. Pulls a cable to the jeep brake pedal.
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Old 04-09-2015, 08:32 PM   #9
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Quote:
Originally Posted by falconman View Post
I can't believe any training document would recommend locking brakes as a technique for downhill braking, or most any braking. Once the brakes lock, you lose control. Hence the addition of "anti lock braking" devices on all cars of recent mfg. I have heard of stab braking to the point of near lockup on older non ABS cars, but releasing before then.

DITTO!

No way would I ever contemplate locking up my tires going down hill. As flacon man said "near" lockup. IMHO way too easy to loose control by locking up the brakes...makes me shiver just thinking about it.
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Old 04-09-2015, 08:40 PM   #10
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Basically it is only terminology.

I have never used the term "Stab" braking however I do use the term "Trounce" when talking about descending a grade and keeping the coach and PacBrake Exhaust Brake working well together within the useful speed range.

For those that have a true Compression Brake they seldom have to even touch the brakes when descending grades. The will have either a 2 step or 3 step switch to engage different cylinders to control the braking during the descent. I wish I had one.

My coach has ABS brakes so you can never lock them up. Only once did the ABS activate when I was descending a grade in Alaska and quickly decided to enter a turn-out. Before actually stopping the ABS activated. It may have been some loose gravel on the paved turn-out that caused the ABS to activate.

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Old 04-09-2015, 08:42 PM   #11
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Yep. I have ABS. Topic is moot AFAIC
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Old 04-09-2015, 08:47 PM   #12
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You should post the entire section, it is for trucks with air brakes and emergency stopping.

5.4.3 - Emergency Stops
If somebody suddenly pulls out in front of you, your natural response is to hit the brakes. This is a good response if there's enough distance to stop, and you use the brakes correctly.

You should brake in a way that will keep your vehicle in a straight line and allow you to turn if it becomes necessary. You can use the "controlled braking" method or the "stab braking" method.

Notice this is not a method for descending hills. Using this method you will not have steering control and you will crash.
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Old 04-09-2015, 08:47 PM   #13
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Damn Suri.

I meant to say "Snubbing" the brakes or "Snub Braking".

Pota'toe potatoe.
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Old 04-09-2015, 08:52 PM   #14
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Quote:
Originally Posted by dpinvidic View Post
This is from the Florida CDL.
What they are saying is apply the brakes hard enough to cause the wheels to lock, then release as soon as they lock.
This would not apply to ABS systems...and in thinking about it, this is exactly what ABS systems do...except they sense the locked wheels and release the brakes very quickly.


Stab Braking
  • Apply your brakes all the way.
  • Release brakes when wheels lock up.
  • As soon as the wheels start rolling, apply the brakes fully again. (It can take up to one second for the wheels to start rolling after you release the brakes. If you re-apply the brakes before the wheels start rolling, the vehicle won't straighten out.)
Regards,


Dan
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