Question for the truckers

M-MAN · Aug 31, 2016

Every now and then I get behind an 18 wheeler and the trailer isn't tracking the tractor. A couple of times like today on I40 the right rear trailer tire was almost
touching the white line while the left front tractor tire was almost touching the center line. There's no way a driver isn't gonna notice a two foot or more offset. I'm
curious as to why this happens and why a driver would even pull a trailer like this. It looks awfull dangerous. I followed one a few years ago up US 64 the same way. If
there wasn't any oncoming traffic the tractor was running about six to twelve inches over the center line and when traffic appeared the right rear inside would be barely
on the shoulder so he could get out of the other lane. If there was a sign or mailbox he rode the center line to keep from hitting them. My nerves counden't take driving
a rig like that.

MtMan · Aug 31, 2016

The reason for the trailer dogging off to he side is the trailer is out of line. Very simple to fix. You just have to line up the front axle on the trailer with the fifth wheel pin and the align the rear axle to the front axle and your good to go.

JD Seller · Aug 31, 2016

mtman is correct in that the trailer is not tracking correctly. If there are high cross winds that can cause the trailers to trail out of line. As for safety, it is more of a tire wear issue than a safety one.

As for the trucker doing anything about it. Most truckers do not own the trailers they are pulling. Most company drivers do not get to run the same trailers either. They usually drop and hook if they can to save time. So you have the load already on the trailer before you know how it is going to pull. So you deliver it and tell someone to get it fixed.

John M · Aug 31, 2016

We have all of our trailers at work aligned every 3 years. Most are still within spec, but since they guys are there they make it right. We do have 2 though, that even though they are perfectly aligned, they still track to the right. Alignment guys insist its the crown of the road and/or they way they get loaded that cause it. Its not bad, but if you were behind them, youd see it. These are older, like late 90s, Great Dane trailers, and the only ones that do that.

Texasmark1 · Aug 31, 2016

What about 96 inch groves in the pavement vs the "newly" allowed 102 or 105, whichever. Trailer can't make up it's mind which set of duals wants to ride the ditch?

mmfan55 · Aug 31, 2016

Alignment on trailer axles is very similar to alignment on any other unit. Reason for being out of line is also the same factors. Age, wear, abuse, indifference in maintenance, etc....

markct · Aug 31, 2016

102 has been allowed for decades now.

Bob Bancroft · Aug 31, 2016

I rode shotgun with a neighbor/friend Sun. and Mon. down to Bennettsville SC and back to pick up a new Kaufman detachable gooseneck equipment trailer. I noted how it pulled perfectly straight. Any vehicle can dog track if the rear axle(s) isn't square with the vehicle frame. The longer the vehicle, the more noticeable it will be.

I only drive a straight truck. But if I'm loading something like pallets, and don't have an even load, I always load it heavy on the high side, which is the left side, for the crown of the road. Then if you're driving interstate, and you will be in the left lane, it's a different story.

So, there are multiple factors to consider.

db4600 · Aug 31, 2016

Like a 70's Nova after a couple years of driving

sotxbill · Aug 31, 2016

Comes from running over too many curbs... and the right rear axles is pushed back a bit. That will do it everytime.

Lots of trailers with the right rear.. front dually having a axle bent and making the wallo wallo noise from running over curbs, holes, and small cars.. Its always the first axle on the rear that takes a beating.

dpendzic · Aug 31, 2016

I have found that a common problem is the spring shackles or center bolt being damaged and letting the axle slide back on one side

Janicholson · Aug 31, 2016

I built trailers (8 axle Steel Hauling Michigan Trains) when i was young for Obrecht trailers, Knox Indiana. We intentionally set the alignment for a 4 to 6" offset to the right on a 30' trailer, I was told by the suspension crew, that it was to allow the driver to see rearward down the road much farther. I helped measure brackets and hangers using a tape measure, so I know we did it. Jim

caterpillar guy · Aug 31, 2016

Slider axles like most box trailers and reefers have will sometimes do that from the slider being of of true with the trailer. I used to get some rail cans that would be real bad. If you had a lot were you could just crank it around to shift the axle slider on the trailer frame it would help track straighter some times.
The axles are out of line as mtman said. I get mine done when I start to see a difference in the tire wear and will go real slow if it has to get a curb. My detach will not clear much so it rarely gets a curb. Also no many things to hit going to dealers lots or farmers yards. If to small to get in I unload in the road.

guido · Aug 31, 2016

Hello M-MAN,

mtman got it right!. Fifth wheel pin is the measuring point for the front axle. Rear axle square to the front one. Properly adjusted mirrors is a must to see both axle. Easy to see if the axle are not tracking straight then,

Guido.

johnlobb · Aug 31, 2016

We always called that dog tracking...

Stephen Newell · Aug 31, 2016

He would be in a world of hurt if he had to drive Dallas streets. Many places in order to increase traffic flow they will take a street intended for two lanes and make it three, like nobody has a vehicle larger than a compact car. I followed an big rig on one of these streets the other day and the tires were literally touching the white line on both sides. I was nervous enough because I was dragging a utility trailer and there wasn't much room on each side.

RBoots · Aug 31, 2016

I pulled a log bunk double that had just been laid on its side and had just left the insurance repair shop. I was the "guinea pig" with it the first time out after being repaired. Was 3 in the morning and could see it wasn't real straight but had a 4 hour trip and was already underway. Once we loaded it up so where we were up 160,000+ it was a long ways from straight. Like you say, drive the left front steer tire on the center line and the right rear duals on the rear trailer would run right down the outside line. Kept the cars away from me thru Grand Rapids, but was VERY snug on the S curves through there. Got it fixed soon after that maiden voyage.

Texasmark1 · Aug 31, 2016

I remember it was a while back, but new considering the age of a lot of concrete.....and so it is the number is 102. Thanks.

We still have some WPA roads down here, narrow with the expansion joints every 20' or so. Want a real thrill get on that in a Volkswagen micro bus, 40 hp 4 banger with one cylinder on the free ride (short wheel base, 45 mph max) with a 1 month old baby and 3 siblings for a 250 mile trip....great sport.

M-MAN · Sep 1, 2016

Thanks guy's. It was a puzzle to me whether the driver could do anything about it or not.

Question for the truckers

M-MAN

Well-known Member

MtMan

Member

JD Seller

Well-known Member

John M

Well-known Member

Texasmark1

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mmfan55

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markct

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Bob Bancroft

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db4600

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sotxbill

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dpendzic

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Janicholson

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caterpillar guy

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guido

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johnlobb

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Stephen Newell

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RBoots

Well-known Member

Texasmark1

Well-known Member

M-MAN

Well-known Member

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