Jackknife!!!

Slow your roll and keep 'er straight... You could put yourself in a bad situation by pushing it to save what will just amount to maybe a few minutes....

 

On slick surfaces, it can be a matter of your wagon trying to outrun the tractor. Tractor braking will make it worse, so you'll either need to increase the tractor speed to compensate, bringing the wagon back in behind it, or you'll need to slow the trailer down. I've heard of drivers using the trolley brake to accomplish the second goal, but I'd not want to try it and see since you only have a few seconds to make a command decision and live with the consequences.

I started to jack-knife on a snowy / icy road a few years ago due to forgetting to set my Jakes down on the single stage. I looked out and saw my wagon trying to out-run me in my side mirror. It was easily corrected by shutting off the jakes and getting into the throttle gently, but enough to make the tractor speed be greater than the trailer speed, bringing it in-line.

 

Maybe hit the trailer brakes via the trolley handle? That'd be my guess if you couldn't correct it with acceleration.

 

I've been lucky enough to have never been in a serious jack-knife situation, just the smaller incidents such as skidding on ice or snow. The basics are the same - steer in the direction of the skid. The direction of the skid being the way the rear of your vehicle is skidding and in this case your vehicle is your tractor, not your trailer. The biggest lesson to get in your head is that a jackknife is less your truck skidding and more your truck being pushed out of the way by the forward momentum of the trailer behind you. It is the trailer pushing against your kingpin that typically is pushing the rear of your tractor. That said, the number one thing to do is to NOT drive so fast that you can't outrun your trailer, LOL! Pulling out of the skid is the most effective way to prevent it from getting worse, meaning have acceleration available to put power to your drive tires in hopes of resuming PULLING your trailer and not being pushed by it. That is why in bad conditions you should never be at the top of your power or acceleration. If you are governed at 65 and go into a curve in the road and the trailer's centrifugal force wants it to keep going straight, it will drag your tractor's end around. If you can't put your foot in it to pull the trailer around the curve, you are in trouble. This is the same factor that tells you to not use your jake brake in bad road conditions, if your traction is compromised and the jake slows your tractor, your trailer is going to still want to go at the faster speed.
In the good old days, the pros would swear to you that they could save any jackknife with keen application of the trolley (or trailer) brake. In concept, this sounds good, NOT using your service brakes means you aren't slowing your tractor and adding to the problem, using the trolley brake means you are slowing the trailer tandems themselves. I have no idea what the current belief is, but when I began 20 years ago, the trolley brake approach was NOT recommended by safety instructors, I think mostly due to the confusion that is going to add up as the trolley brake use carries a slight delay and that there is another delay after you disengage that brake. You need the real time ability of service brakes to evaluate what is going on in your mirrors at the same moment you are applying the brake (or the accelerator) to try and control the movement of the trailer. Best way to avoid a jackknife? Watch your speed especially in bad conditions. If you have to use a sudden braking maneuver, you want to do everything you did in your car - no stabbing the brakes, no quick jerks of the steering wheel, steer in the direction of the skid and if able, power your way out of the skid using the accelerator.
I DID use the trolley valve once in a situation but looking back, I think it was my steering, not the slowing of the trailer, that kept my rig in line. It would be GREAT if someone made some sort of skid pad amusement park for truckers to practice bad weather control of their trucks but I imagine the insurance would be astronomical! I've done skid pad work on a simulator, but it only helped make me queasy and I had no impression that the simulation was anything like the real event.

 

Anytime I have had one try to come around on me it has always been fixed by slowing... Namely the trailer... All situations are different though.. There is no magic pill in a jackknife.. slamming on the foot brake can make it a lot worse..

 

Remember, always try to out run your trailer. Whatever it takes, speed up the tractor, slow down the trailer, apply braking to the trailer only (slowly), keep turning the wheel left or right, but whatever you do, keep the truck ahead of the trailer.

Flashback, January 1989, eastbound I-80, Wyoming, mm 304, 3inch thick Ice, -10 degrees, wind blowing about 25 mph, all I wanted to do was get to Laramie and shut down. I had just come over Elk Mountain in a blinding ground blizzard. On flat ground there was only myself and a school bus about a quarter mile in front of me. I was slowly gaining on the bus when all of a sudden the woman driving it lost control after hitting a deep rut in the ice. She did a 180 and was going backwards while facing me. Split second decision, I never hit the brakes, I steered to the left of the bus and drove through the median strip, across the west bound lanes and came to rest on the right shoulder of the westbound side. All the while as this was taking place my only concern was the bus, kids and driver. I never hit my brakes until I cleared the bus and then it was to only get stopped. I kept thinking that if I touch my brakes I would jackknife and take out the only vehicle on the road near me, the school bus. I came to a stop, collected my thoughts then ran over to the bus to make sure everyone was safe. There was absolutely no damage to the bus, my truck or trailer, just a lot of gratitude no one was hurt. The highway patrol came, took everyone's statement called a wrecker and another bust to get the kids home safely, then thanked me for not hitting anyone or anything. I was then escorted off the westbound shoulder going east for 2 miles until I was able to get back the right direction on the highway.

That was 24 years ago, and to this day I have that episode engraved in my head. It's as though it happened just yesterday. I constantly think about the actions I took, the things I did to prevent an accident and the steps I took to avoid a jackknife. God for bid if it was to happen again tomorrow, I would do the exact same things.

 

You have to check your mirrors for trailer swing frequently whever you are driving on slick roads and if you notice that you're starting to jackknife you will need to quickly identify the cause. If the trailer wheels lose traction, you can increase your speed to allow the trailer to fall back in line. If the tractor loses traction you need to let up on the pedal until you regain traction. Its pretty simple to corrected a jacknife If you are not driving too fast for conditions. I speak from some experience. I did a complete donut one time and was able to correct with a jacknife and I am still accident free.