Unlocking a fifth wheel that has accidentally tripped shut......

A guy with a torn up shoulder. Want trying to come off like billy ######. Was just saying ive never had to deal with one that required any effort at all to pull. If it gives resistance, i get back in the truck and back against it. If that doesn't give it enough slack to pull easy, it means it's improperly adjusted and i get out the handy dandy ratchet and extension. the snow and grime doesnt bother me cause my carhart jacket or coveralls are already filthy from tarping all winter.

 

So last week my trainee was coupling to a trailer. As part of the pre couple check (height, alignment, tandem pins) he thought the trailer was too low. I said it was too high, even though the 5th wheel would just barely get underneath. The ground was slopping down, so while it was a struggle to get under initially, by the time we passed the 5things wheel pivot point under the trailer a gap had started to open. Had we kept going it would have resulted in a high hook.

Later in the week we dropped a trailer and I made him give a couple extra cranks, then ,add him watch as I pulled out from underneath. The landing gear came back off the ground just before I got out from under it. Had I cranked the landing gear to the "correct" point the landing gear would have been 3 inches off the ground when I pulled out.

 

To be honest over my career I have backed under trailers at an angle. (because my loaded trailer was dropped too close to the trailer in front of it) I have backed under trailers where the landing gear was actually sinking into mud. I doubt there were many (perfect) situations. As the driver (picking up) you are at the mercy of the dropping driver and the yard guy. So to be honest it never really mattered how many inches I had, I was just concerned that the strike plate was touching the front part of the 5th Wheel. Sometimes I have been known to (dump) my air bags to get under a trailer.

 

EVERYONE of our older Freightliners have an angled rear-frame and no dump valve. Why do you suppose the frame is angled?

 

Exray, When its your trailer, your fifthwheel saddle bushings and your check book, you tend to get anal about these things.

 

Not for lifting trailers. Frame ramps yes. Frame rails no. Google steel frame structural strength, do some reading on the physics and then tell us how is ok to use the rear of the truck frame to lift the front of a heavy trailer.

 

With a 5th wheel that is close to the frame, deflection angle during a high center situation would pitch the frame rails up, could it be a old school protection against frame binding?

 

Look at the front of a step deck sometime, specifically the frame rails at the neck, and you will get it. A square frame would catch.

 

LOL and you think that is why the frame is angled? Like the others have said, it is to clear the trailer frame. Even a flatbed or van has the same issue where the area of the 5th wheel is thinner than the rest of the frame from just before the landing gear back.

BTW every truck is built this way. The only ones that I have seen with squared off frame rails are log trucks and straight trucks, unless someone has modified one.

 

Lifting a trailer is one thing but sliding a trailer down the frame rails is not a good thing as you already know. The frame of a truck is NOT a wear point. Heck is is thinner than the apron of a trailer.