Emergency stopping (question)

Foot brakes!

Parking brakes are for parking.

 

Something that has not been mentioned, sometimes the spring wears out and applies less pressure than the application brakes do. So could have less brakes in addition to all the things that @AModelCat said.

 

Along with @Bean Jr. 's point. "Setting" the parking brake on the trailer tends to take a few seconds. By the time the brakes even engage then you've either wrecked or avoided the wreck.

 

A spring brake applied force (parking brake) is on average about half that of the service brakes (regular use brakes).
Translation: most trucks it takes about 50-60 psi to release the parking brake, as that is all the force that the spring brake has that can be over come by the air when you release them. The service brake (foot or hand valve) can apply up to full system pressure (100-120 psi) onto the push rod.
On a fully loaded truck the parking brake is not strong enough to lock up the wheels at highway speed, the parking spring only puts up to the equivalent of 60 psi braking pressure.
Using the foot brake you can get over 100 psi braking pressure. Plus as others stated, you are still in control.
So you did the right thing. Clutch in, stand on the brakes, and steer to avoid if possible.

 

plus more than likely. the springs wont just lock them down anyway.

 

ask that texas dude that was coming down the mountain grade in colorado. he has first hand experience.

 

First off all.. you need to be in gear to slow down more effectively and downshift accordingly..Not sure where you learned to push in the clutch and coast when stopping, but that's not doing you any good nor will it be good for those you crash into secondly.. the idea of pulling the brakes on the trailer while moving at highways speeds is just insane!

 

I have come over the hill at the 95 Tydings Bridge at Hav're De Grace Maryland Northbound at 90 loaded with a seacan approx 100K

In front of me presented all lanes of traffic stopped dead flat. By the time I finished mentally processing the Oh *& valuable seconds and space went away. In my lane presented a buick station wagon with 4 kids in the back in the old style before the spread of minivans.

I just put the service brake flat on the floor, popped both of the spring parking brake buttons and waited. 9 seconds she stopped all crooked because I forced the front end around the station wagon, I was not going to let it hit it or anything else.

Halfway during the stop I visually evaluated the median, it's a slope to the other side and will tip the truck and kill a thousand people etc. Just another morning news blurb. So that way is out. I evaluated the other bank, that is out too. Too many cars.

She stopped that day.

New rule was born as a addition to the truckers constitution.

"If they ALL stop, can YOU Mr Big Rig??"

Sometimes they dont stop. Once in memphis I was plodding along at 25 or so In deep traffic rush. A pickup with a small fishing boat with outboard on trailer stopped short because a idiot cut him off. Three in the cab.

Here I came. I stopped short but she did not stop. I had to turn the wheel into the right lane to get past the outboard and stop before hitting the transom of the boat. About 4 inches to spare over that additional 3 feet.

That little stop was probably the scariest for me. It was stupid and I needed a magic rabbit FAST and no hats around. What do I do? What do I do with the truck that wont stop. It was literally a brand new century with about oh 500 miles on the clock and the trailer was a reefer loaded.

That truck stopped near perfect. But if the boat was three feet bigger, it goes into the pickup cab and try the breaking of three necks.

Nightmares lasted about three years at night in various forms of that. One was a steamboat out of the mississippi. Captian hollard move you *&^% bad word. I didnt. Stern paddle wheels chopped the truck and me.

Boss? Yes Boss you wont believe this. (Flat stupid...)

I made many stops.

One was a problem. In Akron Ohio about the 94-95 construction season. I am tooling along at high speed in between two walls 8 feet high and 5 cars on my left with a policeman at my trailer. Alls well.

I see a grey/black Jimmy, a sort of a mini SUV with 4x4 in those days, we did not call that SUV then. 3 kids noses on the glass in the back, two parents in the front. Stalled. Not moving.

I knew I was going to kill em all. There was just no way.

So.. once I accepted that mentally (Distance is still closing... my mind is working the problem fast) I thought lets split the difference and see.

Foot went to the floor. Smoke instantly came off all my wheels except front axle. Locked all of the rest. Engine bucked,. slapped her out of gear. Then trashed the box looking for any gear. Decided I will split the difference. Get rid of these 4 cars and take that lane.

At about 31ish I horsed her left. (Speed reduction was about 40 or so mph above that.) I knew she will take a 28 mph Jug but I didnt know if she will accept a 31 without rolling and crushing everyone) From what I remember and think maybe my right steer touched the truck. The miss was too tiny to be seen. Trailer got crazy. I allowed it to rub the left wall, as long it's there it's GOOD. To hell with the damage. Police man was essentially full trunk into the sky completely compressed in a fearful emergency stop of his own he stopped about 8 feet short more or less. And that was the last I saw of them.

Those 5 get to have a future. I still have my job. Mr Fix it got some money today. Company knows nothing except Mr Fix it bills.

This was before monitoring systems. So... what did not happen did not happen in those days.

I would have many more braking in a semi.

So far the engineers of Bendix and company has done a good job building those trucks. It's saved futures and lives.

One morning Baltimore 13 news cast has a set of doubles with tractor on 70 east past the 3 deck bridge at 695 at speed. Driver slams a red button.

They were stopped in about 4 seconds straight on live TV.

What it was it button trips wedges that make all the double tires ride up on top. Then they are essentially rubber skid makers forcing a stop faster than braking systems can on rolling tires.

The Industry did not adopt that technology for one reason or another.

 

....

 

People are forgetting the ABS. You put the pedal to the floor and let the ABS bring the brakes to point of lockup. Because the ABS computers and do it faster then a person. So you still have control of the truck without actually locking the brakes up.

Remember the if you have more weight you should stop sooner. Because that what the truck was designed for. The hardest thing to stop is bobtailing. Because you have more tires then needed for the weight. The tires will just slide in top of the pavement. You need the weight to push all tires on the pavement so they can grave more. So I'd you had 44,000 LBS in the trailer you should have more traction and you can stop faster


The next thing people can to do stop even faster is spec a truck and trailer with Disc brakes. My company has Disc brakes on tractor. They definitely have more stopped power and now they are getting disc brakes on the trailers. Disc brakes can also take a lot more heat and no slack adjusters to worry about anymore !