So to the point, is this common?
Certainly it's not common. From the way you describe the change in weight it sounds as if you're saying your tandems slid forward which is really strange. The combination of the inertia of your loaded trailer and the forces of a hard brake on the tandems should put pressure on the tandems to slide backward.
It remains a mystery to me.
A set of axles spaced close together, legally defined as more than 40 and less than 96 inches apart by the USDOT. Drivers tend to refer to the tandem axles on their trailer as just "tandems". You might hear a driver say, "I'm 400 pounds overweight on my tandems", referring to his trailer tandems, not his tractor tandems. Tractor tandems are generally just referred to as "drives" which is short for "drive axles".
A set of axles spaced close together, legally defined as more than 40 and less than 96 inches apart by the USDOT. Drivers tend to refer to the tandem axles on their trailer as just "tandems". You might hear a driver say, "I'm 400 pounds overweight on my tandems", referring to his trailer tandems, not his tractor tandems. Tractor tandems are generally just referred to as "drives" which is short for "drive axles".
I think prior to your hard breaking, the four pins securing the tandems may not have been completely set. Whenever I set mine, I have the trailer brakes set (red button out). Tug on trailer forward once, shift into reverse and push back once, back to forward and tug, then back to reverse a final time. I then get out and do another visual of all four pins to ensure each has "popped out" completely.
A set of axles spaced close together, legally defined as more than 40 and less than 96 inches apart by the USDOT. Drivers tend to refer to the tandem axles on their trailer as just "tandems". You might hear a driver say, "I'm 400 pounds overweight on my tandems", referring to his trailer tandems, not his tractor tandems. Tractor tandems are generally just referred to as "drives" which is short for "drive axles".
A set of axles spaced close together, legally defined as more than 40 and less than 96 inches apart by the USDOT. Drivers tend to refer to the tandem axles on their trailer as just "tandems". You might hear a driver say, "I'm 400 pounds overweight on my tandems", referring to his trailer tandems, not his tractor tandems. Tractor tandems are generally just referred to as "drives" which is short for "drive axles".
Old School is right. The hard braking, or any braking, would slide the tandems to the rear. Now if you had done any backing, like into a spot at a truck stop, the tandems could have slid forward. But I would suspect they would have slid back again as you were braking to enter the weigh station.
But pins do not just pop out on their own no matter how severe the braking may have been. There would be devastating accidents on a daily basis if that was even the most remote possibility.
If you had stopped anywhere else, like a rest area or truck stop, it's entirely possible someone devious could have unlocked your tandems.
I don't know what happened, but I do know that properly locked tandem pins do not unlock themselves under any circumstances.
A set of axles spaced close together, legally defined as more than 40 and less than 96 inches apart by the USDOT. Drivers tend to refer to the tandem axles on their trailer as just "tandems". You might hear a driver say, "I'm 400 pounds overweight on my tandems", referring to his trailer tandems, not his tractor tandems. Tractor tandems are generally just referred to as "drives" which is short for "drive axles".
A set of axles spaced close together, legally defined as more than 40 and less than 96 inches apart by the USDOT. Drivers tend to refer to the tandem axles on their trailer as just "tandems". You might hear a driver say, "I'm 400 pounds overweight on my tandems", referring to his trailer tandems, not his tractor tandems. Tractor tandems are generally just referred to as "drives" which is short for "drive axles".
I'd have that trailer inspected asap. If you're positive your pins were fully locked, you may have some broken parts.. Possibly an air leak on your tandem release valve or worn springs that actually push the pins out to lock them. Definitely something not right or broken on your trailer.
A set of axles spaced close together, legally defined as more than 40 and less than 96 inches apart by the USDOT. Drivers tend to refer to the tandem axles on their trailer as just "tandems". You might hear a driver say, "I'm 400 pounds overweight on my tandems", referring to his trailer tandems, not his tractor tandems. Tractor tandems are generally just referred to as "drives" which is short for "drive axles".
The Substance Abuse Professional (SAP) is a person who evaluates employees who have violated a DOT drug and alcohol program regulation and makes recommendations concerning education, treatment, follow-up testing, and aftercare.
Sorry, should have said drive axles was over.
Unfortunately we don't keep our trailers for any length of time or I would have had it checked, but Safety knows about the incident. I can only hope they follow up on it.
*Side note, something else to check and I don't think it's emphasised enough because of the constant trailer hopping. Pre/Post trip your trailers!!!
In just the past month, I've replaced 2 side/skirt marker-turn lights, and had to zip-tie one trailer airline retention spring. until I got to the next TS for a replacement)
Somewhere some people have gotten the idea that the shop should fix everything, and or have no clue how to fix basic items. Some would waste hours to replace a bulb instead of the 15min it takes to do yourself. Don't get me started on worn glad hand seals...
Thanks for the replies, I'll mark it as a one off/random event.
Okay, it sounds like what happened is your load shifted or slid forward. But I'm still confused because you said it was a "quick fix."
Sorry, should have said drive axles was over.
So then your tandems slid to the rear? Is that what happened?
A set of axles spaced close together, legally defined as more than 40 and less than 96 inches apart by the USDOT. Drivers tend to refer to the tandem axles on their trailer as just "tandems". You might hear a driver say, "I'm 400 pounds overweight on my tandems", referring to his trailer tandems, not his tractor tandems. Tractor tandems are generally just referred to as "drives" which is short for "drive axles".
A set of axles spaced close together, legally defined as more than 40 and less than 96 inches apart by the USDOT. Drivers tend to refer to the tandem axles on their trailer as just "tandems". You might hear a driver say, "I'm 400 pounds overweight on my tandems", referring to his trailer tandems, not his tractor tandems. Tractor tandems are generally just referred to as "drives" which is short for "drive axles".
Sorry, should have said drive axles was over.
So then your tandems slid to the rear? Is that what happened?
Yes, tandems, popped and slid to the rear. Actually to the stops.
Quick fix at the scale, because all I had to do was slide them forward again.
Yes the load shifted as well, I reset to the previous 9 hole, and could see from the air gauge I was still heavy, so went to the 6 hole, and then weighed.
11600/33600/33700 approx DOT doesn't give scale sheets.
A set of axles spaced close together, legally defined as more than 40 and less than 96 inches apart by the USDOT. Drivers tend to refer to the tandem axles on their trailer as just "tandems". You might hear a driver say, "I'm 400 pounds overweight on my tandems", referring to his trailer tandems, not his tractor tandems. Tractor tandems are generally just referred to as "drives" which is short for "drive axles".
A set of axles spaced close together, legally defined as more than 40 and less than 96 inches apart by the USDOT. Drivers tend to refer to the tandem axles on their trailer as just "tandems". You might hear a driver say, "I'm 400 pounds overweight on my tandems", referring to his trailer tandems, not his tractor tandems. Tractor tandems are generally just referred to as "drives" which is short for "drive axles".
A department of the federal executive branch responsible for the national highways and for railroad and airline safety. It also manages Amtrak, the national railroad system, and the Coast Guard.
State and Federal DOT Officers are responsible for commercial vehicle enforcement. "The truck police" you could call them.
Well, as I had said before, I don't know why those pins popped out but they certainly should not have. Either they weren't in properly in the first place or something is broken on the trailer. That's the only two possibilities. There is no third possibility that I am aware of.
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Wondering if this was a one off/freak occurrence or something to be aware of.
Recently had a hard breaking incident. Came upon an accident just past the crest of a hill with vehicles scrambling every which way to avoid.
So, I'm on the brakes hard enough to smoke and hop the tandems (45k in the box) and manage to avoid all the crunchies.
Next place to pull over and do a proper visual is, just my luck a weigh station. Bing! Red light of doom... The tandems had popped to the stops and I had 36k registered on the rear axles. Quick fix, and I had my scale ticket from just 20 some odd miles previous. DOT cop was aware of the incident, so I didn't incur a fine, just the overweight violation. *Safety guy said don't sweat it, was doing everything legal, stuff happens.
So to the point, is this common? Or just possibly a worn trailer?
*And yes before anyone asks, the pins were out and locked. Yes I tug test every time before rolling after a stop which isn't the same as an emergency stop 62 mph.
Tandems:
Tandem Axles
A set of axles spaced close together, legally defined as more than 40 and less than 96 inches apart by the USDOT. Drivers tend to refer to the tandem axles on their trailer as just "tandems". You might hear a driver say, "I'm 400 pounds overweight on my tandems", referring to his trailer tandems, not his tractor tandems. Tractor tandems are generally just referred to as "drives" which is short for "drive axles".
Tandem:
Tandem Axles
A set of axles spaced close together, legally defined as more than 40 and less than 96 inches apart by the USDOT. Drivers tend to refer to the tandem axles on their trailer as just "tandems". You might hear a driver say, "I'm 400 pounds overweight on my tandems", referring to his trailer tandems, not his tractor tandems. Tractor tandems are generally just referred to as "drives" which is short for "drive axles".
DOT:
Department Of Transportation
A department of the federal executive branch responsible for the national highways and for railroad and airline safety. It also manages Amtrak, the national railroad system, and the Coast Guard.
State and Federal DOT Officers are responsible for commercial vehicle enforcement. "The truck police" you could call them.