Rehash of Old Topics

SuiteSuccess · May 24, 2017

I raised the question five years ago about two topics that I would like to rehash and gain from others experiences.

Topic 1. Blowouts on truck steer tires, drive tires, or trailer. I know that on a steer tire blowout the first maneuver is to floor the fuel pedal to gain control, then slowly begin to slow down using braking only when under control. Avoid slamming on the brakes!. So what about drives or on trailer, same approach? So what is your understanding or experience since I've never had any blowout in the seven years of my HDT driving?

Topic 2. Impending jackknife situation. Anyone with any knowledge or experience? Can you "drive out" of the situation by accelerating or hitting the trailer brakes? What conditions are most likely to get you into a jackknife situation?

Alie&Jim's Carrilite · May 24, 2017

Type 1- For a steer, drive thru it, keep power applied, maybe not smash the skinny pedal, but don't back off. For a drive, it will be a loud noise, followed by vibration and a little loose/fishtail feeling. On your RV, you won't hear it or feel it. Only your TPMS or your mirrors will tell you there's a problem.

Type 2- Apply trailer brakes without truck brakes and try to straighten, it out. Usually, a jackknife occurs in slick conditions where by the time you see the trailer move, it will be too late to do anything but enjoy the ride and brace for impact. I would guess that most jackknife situations occur when the truck can out brake the trailer and the truck move out of alignment with the truck and wants to pass it. Just like you see on the northern icy roads. The other jackknife is when you're on a downhill, with a light rain, and the car next to you passes and pulls in front of you to be first in line. The truck can hold the trailer back as long as it's in a straight line, but once you start to change lanes, and you break the straight line to an angle, the trailer usually pushes the back of the truck sideways. If there's enough room, you can turn the truck out of it, apply trailer brakes, turn the steering wheel the same as you would too come out of a slide, and presto your straight again on the other side of the intersection, but usually, there is a light at the bottom of the hill with a school bus full of kids.....

Something to remember....

Since we all have dash cams now..... when your sliding down the hill sideways, appropriate, non-offensive language should be used.... You might have to repeat it in a deposition...

I'mdonewiththis forum · May 24, 2017

If I remember right, when I was driving for a living it was calculated that the point of no return of a jacknife was 17 degrees. That means anything over 17 degrees off of straight you were a goner.....

Far as blow outs, I have had drives and trailer tires blow, but no steers, so not much experience there. Jim is correct on his assessment.

Pete Kildow · May 24, 2017

I have pulled 2 out of jack knifes. My uncle years ago when I was riding with him. Had a grain Dump try to pass us. He give it fuel and pulled the hand brake. That moved the trailer back toward the line we were traveling. He got off the hand brake. And it almost went the other way. Stopped in line with the tractor.

I had one on ice, got it back in line doing the above. Then years later I had a empty 53ft trailer do it. And it also came back in line with the tractor. I may have gotten lucky on both. But feel being with Uncle Johnny and seeing it. Helped me out.

Blowout on anything other then steer tire. You will hear it then feel it. No issue on stopping. Steer tire blowout will stay standing up. Unless you hit the brakes, then the wheel will dig in. And the ride it on! but give it some fuel then start slowing down no brakes unless .. Your about to hit a bus load of kids. Only had 2 steer blowouts. Both were within weeks of each other. Michelin tires both were new. First one had around 1200 miles on it. First trip out and was within 3 miles of the shop. When it blew, and got it off the side of the 2 lane road. They put a new one on again. And I went to Memphis Tn and back. Pulled up to the fuel pumps at our shop. And it popped right there. Shop got in touch with the other 110 trucks. Had all of them that has gotten new steers. to stop and get them replaced right there. They had ordered 220 new steers and Michelin took off of them back. I was never told but feel they had a bad run on this. That was in 1986.

VegasFlyer · May 24, 2017

1 hour ago, SuiteSuccess said:

I raised the question five years ago about two topics that I would like to rehash and gain from others experiences.

Topic 1. Blowouts on truck steer tires, drive tires, or trailer. I know that on a steer tire blowout the first maneuver is to floor the fuel pedal to gain control, then slowly begin to slow down using braking only when under control. Avoid slamming on the brakes!. So what about drives or on trailer, same approach? So what is your understanding or experience since I've never had any blowout in the seven years of my HDT driving?

Topic 2. Impending jackknife situation. Anyone with any knowledge or experience? Can you "drive out" of the situation by accelerating or hitting the trailer brakes? What conditions are most likely to get you into a jackknife situation?

On Drive tires the answer is, "it depends". There are variables like a tandem versus single drive axle. Dual versus single tire per side. And the biggest variable of overall weight and loading or balance of that weight. Those factors, along with where the truck is or the state it is in, i.e. Going straight on level ground versus up or downhill and in a sharp curve all determine how the truck,will react when a blowout occurs. The overall goal is to try to keep the mass of the vehicle as stable, as possible, while decelerating.

On the jackknife scenario, IMHO it is dangerous to prescribe someone automatically apply trailer brakes. The reason the trailer is jackkhnifing is already due to the trailer tires losing traction and the resulting loss of traction allows the trailer to accelerate in front of the truck, thus swinging out to one side or the other. If you have full loss of traction to the trailer, the brake application will have no positive effect. If you apply brakes when there is already a large amount of traction loss to the trailer tires, you could increase that loss of traction and possibly speed up the trailer trying to pass you.

If you have a trailer swinging quickly to the side, in a jackknife and you accelerate too quickly, you could induce a whip effect that make the trailer move faster.

Everything I have seen, prescribed to try to accelerate the truck, SMOOTHLY, to bring traction back to the trailer tires slowly.

Anyone who has gone through a professional motorcycle course has probably been taught a similar technique to recover from a rear tire breaking traction in a turn. You are taught to try and get neutral power. If you crank the power, the bike will continue to yaw and lay down. If you chop the throttle to idle, the rear tire could quickly gain traction and violently launch you off the bike.

Sculptor · May 29, 2017

On May 23, 2017 at 8:04 PM, SuiteSuccess said:

Topic 2. Impending jackknife situation. Anyone with any knowledge or experience? Can you "drive out" of the situation by accelerating or hitting the trailer brakes? What conditions are most likely to get you into a jackknife situation?

Caught a nail in my rear tire once. It was a Honda 750. Not the same. ?

If a 3/4 ton pickup and a very large homebuilt trailer counts for a similar experience then yes I survived a close call, but neither truck nor trailer did.

When I graduated high school I went for a summer trip with my grandparents in a big Ford sedan and very large, to me, camper. Grandpa Joe was a troubleshooter and tester for Diamond Reo trucks during and after the war. He claimed either solution would work and I saw him use the trailer brakes or accelerator several times for that purpose. My total experience up to the next bit below.

Fast forward to sometime in the late 80's my uncle and I were doing a favor for a friend. Unk was driving the loaded pickup and very overloaded dual axle box trailer. I'm not sure how the orange barrels snuck up on us but Unk applied the brakes and suddenly the back end of the trailer tried to pass us. The tail wag got worse very quickly and we left the road. Fast. The truck limped out of the ditch but then had to be towed. Later both were sold at a big loss, since they needed repairs. That's a very short version of a very long 48 hours.

1. Either badly placed road signs or lack of alertness, failing to realize we should not be driving at the posted speed but much slower.

2. Sudden braking into a sudden lane shift.

3. Overloaded trailer, probably. Badly balanced load, probably.

If the trailer load was not balanced, as I suspect, the back end was going to sway even on a straight flat road. We had not been up to full highway speed yet. Braking hard into what I remember as a sudden lane shift in effect brought some of these problems together in a bad way. When the tail end wag got wider and wider all I could do is watch. I think the trailer brakes would Not have helped, and probably made it even worse.

Acceleration might have helped. With the sharp lane change we would have gone off the road anyway, maybe not as badly as we did.

Jackknife on a straight dry road and either one would probably help in my opinion. Our weather was hot and very dry. Add ice, then intentionally breaking the tires loose by braking or acceleration would end badly. Not noticing a road hazard like barrels or trash until it was too late, and IMO an unbalanced load, gave us our headaches that day.

Lessons? Yeah I'm full of them. I hope this is helpful.