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Trailer sway crash.
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Previously:
https://www.homemadetools.net/forum/...2673#post96840
https://www.homemadetools.net/forum/...447#post189143
https://www.homemadetools.net/forum/...659#post143520
https://www.homemadetools.net/forum/...907#post140572
https://www.homemadetools.net/forum/...738#post148031
Is there anything to be done, once the swaying first starts, to avoid the roll over?
I always heard that locking up the trailer brakes will help, but haven't seen that method tested.Quote:
Originally Posted by Karl_H
Step on the throttle. The driver saw a short opportunity to get around the slower vehicle, and mashed the throttle to the floor. Once he got clear, he backed off. Now the trailer is going faster than the truck, trying to push it down the road.{never works} Simple solution: step on the throttle {gently} until the truck is once again pulling the trailer down the road. Works with almost any combo of tractor/ trailer, on almost any surface.Quote:
Originally Posted by Karl_H
Watched this happen probably a couple dozen times in 12 short years in the trucking business.
The other thing to do is don't panic. Just walk into the throttle and drive on.
The trailer started swaying immediately once the back end of it neared the area where there was a transient disturbance in the air flow at the gap between the tractor and the trailer creating cross turbulence between the back end of his trailer and the transient disturbance generated in the gap. it looked like he was trying to accelerate out of the sway initially but then made the mistake of getting off the throttle too quickly. As has already been explained the trailer was pushing the tow vehicle. He may also have had too much rear loading on the trailer, either from not knowing or an attempt to reduce the tongue weight. RV trailers of that length should have 3 axles or a spread axle setup. It is nearly impossible to achieve a good 60/40 axle placement ratio on a trailer of that length without having more tongue weight than most tow vehicles can handle. The addition of load equalizing hitches and anti sway devices are a great help but they only help in reducing sway they can not totally prevent it from happening.
When sway happens accelerating gently until the sway is reduced or goes away while gently applying a small amount of braking to the trailer once it is in a straight line behind you, causing a little more drag resistance to gradually reduce your speed to a safer rate of travel, is an accepted way of getting out of a dangerous situation. However every sway condition will be different from the previous, heavily traveled roads may have wear ruts in them which can create a situation different than anything you have ever encountered
The occupants are “lucky” they didn’t exit the highway on the right hand side!!
The only way to stop that immediately, if the van has brakes fitted, is to apply the van brakes hard, that straightens it out and slows the whole vehicle down to an acceptable speed. Once it is pulled straight and some speed washed of, start using the go pedal sparingly and away you go with just a dirty set of undies and no broken van. If the van has NO brakes, then this will be the outcome just about every time this happens. The moron driving was giving it too much pedal and when he broke out of the windbreak caused by the truck, then 'Shits are trumps'. Been out on the road for over 30 yrs and seen this a few times, don't even bother to stop now-a-days, they caused it, so they can clean their own crap up.
In Europe we have the Al-Ko Trailer Control (ATC) system available that does that automatically https://www.alko-tech.com/uk/al-ko-trailer-control-atc, the other thing we have is their Delta axle, where the axle's angles change under swinging load to help cancel the movement, ridged straight axles don't help when things start swinging. https://www.alko-tech.com/uk/al-ko-s...weight-chassisQuote:
Originally Posted by greenie
You are correct, in most cases a quick short stab of the trailer brakes while applying pressure to the throttle will pull everything back in alignment long enough to regain control, allowing the driver to get further away from the currents created by the truck. The problem there is most new pickups now come with factory installed trailer braking and must be pre programed with the length and weight of the trailer entered into the trucks computer in order for them to function properly, there is no obvious lever to apply the trailer brakes separately. on some pickups it will be a slide bar but it is so well disguised in the dash it is hard to locate it may even be a goofy touch pad in the multi function view screen you slide you finger across like answering or hanging up many cell phones.Quote:
Originally Posted by greenie
everything requires familiarity with the vehicles systems, something too few drivers take the time to learn.
And then there are the trailers with inertia hydraulic braking systems on those there is no possibility of applying the trailer brakes without the truck slowing first, However a quick hard very brief stab on the tucks brakes and immediately stepping on the throttle hoping there will be spontaneous braking on the trailer and slow enough release to regain control.
Even newer Semi trucks have limited access to what we used to call the Johney bar for applying the trailer brakes. Gone are the days of the simple round steering column, with a turn indicator on the left and a trolly valve mounted on the right
Looks like the only attempt to right the trailer was with steering. I don't like long trailer like that either. With the axles in the center, to reduce the tongue weight, it magnifies every move of the steering wheel. Looks like this person was just trying to steer into the the direction of the sway which just made it worse.
Last year we rented a 5000lb roller and the trailer to haul it. When the guy loaded it on the trailer for us he drove it right up to a predetermined mark on the trailer. My friend complained all the way back to my shop about the tongue weight on his brand new F250. So when he returned the unit he had me leave it back about a foot from where the guy had put it when we rented it. The machine was still centered ahead of the centerline of the axles but not by much. I told him to call me when he had problems and I'd try to explain how to drive it so he can reposition it on the trailer. He looked at me like I had grown a 3rd eye. About half an hour later he calls up and askes how do I start this thing? I can't get over 40 MPH. I about fell over laughing.
Trailer sway bars help prevent swaying on the high way, and they can even save the vehicle from crash or rollover. Sway bars may make it hard to turn, but safety first, and it worth it.
Proper tongue weight and weight distribution in the trailer can all but eliminate this...I love how the semi/video truck moved right and slowed down just enough to be a safe distance then moved back to the left to keep the grand finale centered in frame of view.
Which is why anyone whole pulls a trailer should take the responsibility upon themselves to familiarize proper load distribution and securement procedures.Quote:
Originally Posted by bob_3000
Also another argument for installing stabilizer control bars and shock absorbers on trailers, which is almost never done on bumper pull trailers and rarely ever seen on gooseneck ball or fifthwheel camper trailers, but incorporated in one form or another in the suspensions of every Semi trailer