I know this has been covered before, but I was just wondering whether this system had gone out of favour… Twice in the last week I’ve picked up trailers with the legs wound right up (so far that I had a hell of a job getting the legs wound back) & (consequentually) the back mud-flaps caught & dragged on buffers. I have always partially dumped the air before dropping trailers so the next driver can be sure to not under-run the pin & not have ripped flaps, but it seems to be more common to just ‘unhitch & run’ - is this a case of just time-saving or lack of experience/training. I know the shunters often get the blame but if the legs are already wound down, they just raise & move without wondering if they are at the right height for connecting with a normal unit (I can’t believe I’m defending shunters!! )
nowt wrong with pulling slightly forward and dumping air, that way you know the weight is on the legs,before you pull completly out,also if the driver collecting the trailer does it the same way he(she) will go under just enough to lift the weight then drive to engage pin and slight tug without busting the legs,also makes winding the legs up easier at first cause there’s no weight on them.
Agreed Mark, always do it that way. Got into the habit in my last job where we had no run-up ramps.
The leaving the legs an inch in the air before dropping thing is a hangover from spring suspension IIRC, as the weight settles at the back forcing the front end up otherwise. That’s the way I was taught when I first started, anyway…up for springs, down for air. The units were on springs too, mind.
I always specify my trucks without run up ramps, they are pretty much redundant with air suspension on the unit, also does away with the need to leave the legs up an inch. I raise the air a little when dropping a trailer, then when I pull away from the pin I drop the air, raising it first means I don’t have to drop the air as much when I pull away from the trailer so the spray flaps aren’t dragging on the ground.
I am pretty new to this, but I tend to wind the legs to the floor at ride height and then pull out (which is what I was taught) - although as I come off the pin I dump the air to ensure the legs are on the floor before the trailer comes off the fifth wheel. That seems to leave it at a good average height… … …
… … … picking up I back the fifth under the trailer and then raise the suspension until I can see the trailer being picked up before I go the rest of the way under.
Driving a shunter I have come across trailers that are so low that you cannot get the fifth wheel under them without using the ramps and so high that you can’t get good clearance without winding the legs up a little - so ride height seems a happy medium.
The European way, is to dump the air of the trailer, (especially loaded) and then drop the trailer with the unit at normal height. If you feel better, lower the unit as you leave the pin to stop it bouncing up and bending the chassis rails.
Our trailers automatically put on the park brake if you do it this way. The Dutch lads cannot understand why the trailers have park brakes as well
at our place it depends on the trailor.
if it is the lowloader it is dropped at ride hight as adjusting up or down is done hydraulicly and as my tractor has steel suspension and no ramps it is the easyist way to hook up, unless it has been dropped by one of the stralis drivers then i have to adjust the height, usually down.
if it is the tipper trailors then they usually lift the backend of the tractor up and then drop it a bit, wind the legsdown so they touch, draw forward then drop the rear end. (also helps keep the grease under the pin as opposed to on the frount of the trailor where i usually end up covered in it when i hook up the suzies )
as they are left unsheeted when empty this helps the rain water run out.
is there a right way or a wrong way■■?
salut
chris
Anyhow, I always wind the legs down so its a fraction off the deck, then lower the unit suspension down so that when I drive out it won’t hit any bodywork or make holes in any plastic If all the units are the same, then it’s ok, but when I was at Wincantons in the Foden, when we dropped at Excel Safeway at Tamworth we had to lower the suspension a bit then wind the legs down as other wise their motors couldn’t reach up enough to couple up and they had to low gear wind the legs up
I don’t know why but it always bugs me when I see another driver just drive out and see the trailer bounce off the mudwings, when it is avoidable and I bet the parts aren’t cheap when they get holed!
when we dropped at Excel Safeway at Tamworth we had to lower the suspension a bit then wind the legs down
Those ERF’s there are a pain - since you can drop the suspension, but not raise it means that I had to wind every trailer I have used there (fortunately only had to suffer one shift so it was only the 3 !!)…
tallyman:
I know this has been covered before, but I was just wondering whether this system had gone out of favour… Twice in the last week I’ve picked up trailers with the legs wound right up (so far that I had a hell of a job getting the legs wound back) & (consequentually) the back mud-flaps caught & dragged on buffers. I have always partially dumped the air before dropping trailers so the next driver can be sure to not under-run the pin & not have ripped flaps, but it seems to be more common to just ‘unhitch & run’ - is this a case of just time-saving or lack of experience/training. I know the shunters often get the blame but if the legs are already wound down, they just raise & move without wondering if they are at the right height for connecting with a normal unit (I can’t believe I’m defending shunters!! )
Another ‘end of rant’ - it’s been a bad week!!
I’ve noticed this lately too. I wind the legs down and leave about a 2 inch gap. Then I dump the air. I personally think the trailer is then at the right height for any unit to get under without going straight under the pin. We employ a lot of east european drivers and they seem to drop them way too high, I’ve noticed.
tallyman:
I’ve noticed this lately too. I wind the legs down and leave about a 2 inch gap. Then I dump the air. I personally think the trailer is then at the right height for any unit to get under without going straight under the pin.
which is fine if you have ramps fitted for the 5th wheel!!!
some of us still drive tractors on steel suspension
salut
chris
CBR_SI:
I don’t know why but it always bugs me when I see another driver just drive out and see the trailer bounce off the mudwings, when it is avoidable and I bet the parts aren’t cheap when they get holed!
Don’t do the landing gear any good either, there not designed for shock loads. It damages the internals and can deform the leg itself.
You know when you have damaged landing gear, there murder to wind up & down.
Wheel Nut:
The European way, is to dump the air of the trailer, (especially loaded) and then drop the trailer with the unit at normal height. If you feel better, lower the unit as you leave the pin to stop it bouncing up and bending the chassis rails.
Our trailers automatically put on the park brake if you do it this way. The Dutch lads cannot understand why the trailers have park brakes as well
Wheel Nut is actually spot on. But i’m not sure that you all understand why, so i’ll explain. Forgetting for a minute about lowering your unit suspension etc. so it is easier (harder or what ever) for the next driver to pick up. When you drop a trailer with the air suspension fully “up”, then it’s all level. As the air drops out and the (rear, don’t forget) suspension falls down the angle of weight on the trailer legs can cause the legs to buckle. So the trailer legs will end up with a “kink” in them even though the trailer has never been “dropped” hard or anything like that. Most drivers are only concerned (or know about)what happens when they uncouple or go to couple up to a trailer but i can assure you that the air should be dropped from the trailer suspension before uncoupling and winding legs down as 30 odd tons resting on two thin legs at an angle does the legs and gears no favours at all. But hey what do truckers know!!!
)
