Are there any " Warning signs" for A Jack knife?

I've noticed that my truck / trailer combination acts differently than what you've described. When I depress the treadle valve, my trailer brakes apply first, followed by the tractor brakes. I'm thinking that this is done by design, but perhaps someone who knows can weigh in on this?

 

thats called brake bias

 

Usually when you feel your bunghole pucker up.....that always seems to be the first sign.

 

I've only come close once back in 1999 or so. I was coming up to construction in Kentucky just before the I-71/75 split near Covington. I had grabbed the left lane as the right lane was ending. A Blazer zoomed by at the last minute, as ######## tend to do. I looked in my mirror to check to make sure nobody else was pulling the same stunt and as I looked back, traffic had come to a stop. I hit the brakes. I was pulling one of Steven's old 48' trailers sans ABS and they locked up. The trailer started sliding to the right and came to a stop up almost parallel to the cones merging the right lane to the left. A driver behind me got on the CB "Stevens, you alright?". I said "Yes, got caught off guard here, I'm ok."

 

Once your tractor breaks traction, you have the potential for a jack-knife. The odd, and suicidal sounding, solution is to apply power, which will draw the trailer back behind the tractor. Paying careful attention to your speed and proper braking for weather conditions are the best preventative actions.

 

To avoid a jack knife:

1.) I would start by trying to configure your tractor trailer tandem weights to match as close as possible. Most commercial vehicles have ABS now but that doesn't mean that it's working correctly. A tandem with less weight will lock up before a heavier one.

2.) Keep that music way down or off when you know that you are in icing conditions. Use your ears and listen. The first sign is hearing the engine rpm going up. When this occurs, you simply get off the accelerator and let the wheels coast. this will stop the entry of a jack knife but you can't do this if you can't hear those wheels due to other noise.

3.) Increase your following distance. If you have to keep hitting your brakes, you're going too fast and following too close. The way I adjust my following distance is with the road stripes or other marks. I will pick a spot where the vehicle ahead of me crosses and start to count off one thousand one, one thousand two etc; I count to 6 under dry conditions and 7 in the winter. The idea is that if I cross that line before I'm finished counting, I'm following too close.

4.) When you start hitting your brakes don't hold the pedal down, use a stabbing motion with your foot and give yourself much more distance for stopping.

5.) Use your mirrors when you are braking.


6.) Get rid of "Get There Itus." Screw the appointment. You get there when you get there. It's also exciting when we are going home but once again we need to do it safely.

7.) Lastly, Think beyond the jack knife or accident. This will have consequences that will take some time to pass and greatly affect your potential to be hired as a commercial driver. I know because I had a head on collision with another truck in 1982. I was this hammer down kind of young hot shot driver with my radio blasting all the time, it was icy out that day and I was empty passing everything in site. When I woke up, I was being rushed to the hospital and don't remember anything. I recovered and was out the following day but I lost my job and no repituble company would hire me for at least 3 years. It was a hard lesson and one that I will always remember.

 

^^^^^^ number 6 and 7 ^^^^^^

good post!

 

When your trailer is no longer in line with your tractor, and you dont have a trailer dogtrack, then you have your first sign of a jackknife about to occur. Gently accelerate should bring you out of it. Then again if your trailer can be seen by looking out your side window it is a bit too late, just bend over and kiss your ### goodbye.

 

know your vehicle. speed, and equipment keeps you driving down the road.

 

Bunch of us drivers were driving and came upon Freezing rain. the pavement turned to glass real quick. We were all going 5 mph or less. the truck beside me pushed in his clutch and hit the brakes. It caused a Drive tire Jack. (when the drives stop spinning) He nearly side swiped me, I was in the Grass half way as he folded in half in my mirrors. So remember on ice. slow down and don't hold the clutch in. those tires need to be turning.