Passed Class 1 6 weeks ago and have managed to get a start on containers 
. Went out the other day with another driver and delivered to Argos RDC at Stafford. My reverse onto bay caused some amusement 
but got there in the end.
Anyway lad I was with mentioned I might, on rare occasions, have to āstretch the trailerā depending on size of container. 
Never heard of that before and not sure how itās done.
Anyone got any advice on it please ?
When you have a 20ā box on and carry it in the middle you will need to shorten the trailer so as to get the doors to the back for unloading.
You take the red air line off and put it on a valve next to the normal air line valves. This then locks the trailer brakes whilst also releasing the trailer slider pins. You then pop your truck in reverse and slowly back up. The front section of the trailer moves over the locked rear end so the box is now at the back accessible for unloading. Then pop the airline back on the red valve.
Some trailers donāt require having the red line removed, just push a button which does the same job, depends on the trailer.
When finished, do the same but drive forward to pull box to the middle again.
When changing between 40ā and 45ā boxes you are also change the trailer so the 45āer sits on the front pins closest to the cab, do this the same as above but just shunt a little as there is only a small difference between these to locating slots, but you can sit a 45ā box on the pins for a 40ā box. Donāt forget to pull the rear bar out though when carrying a 45āer.
Just ask the other drivers if your not sure, get a demo off them.
Same as above but before you get in and reverse back donāt forget to drop down twist lock arms on rear!!
Also donāt forget to slide so for a 20ft so you are using the 20ft position. Modern trailers are so lightweight they are only braced for the weight of a 20ft in this position. Using the 40ft position will bend the chassis and result in you being one of the poor fools who has to spend half an hour trying to get the pins out every time he wants to slide. Worse case scenario, the trailer can completely seperate into itās two subframes - it happened to one of ours a few years ago, which is why weāre now ā ā ā ā about it. Cost a fortune getting a crane out to re-assemble it for recovery, and the trailer was basically beyond saving when they eventually got it back.
Also, when you are slid to unload for a 20ft, DO re-engage the pins so the chassis is locked together, rather than hitting the shunt button to go the last bit onto the bay. Again, avoids chassis bend.
Iāve never had much to do with boxes, but out of curiosity how much does a skelly weigh?
Was always told to put the park break on the trailer even if itās ment to do it automaticly
About 4.5 tonnes these days, Harry. Hence it being far tooo easy to bend if misused.
Would agree with that as well, Nick. Some do, some donāt, but most of them donāt even if theyāre supposed to (ālock and goā trailers). You have to in order to be able to select the middle positions anyway, unless you want to spend all afternoon trying to line the holes up just so before letting the pins back out. 