Yes…I guess you are assuming it as being so obvious…unit handbrake!
It does happen that it is left off. Trailer brake off and away it can roll…maybe that is why they want you to stay by the trailer brake button as the air goes through for ten seconds. If you cocked up you can pull the button and rescue the situation. Good idea.
And I would say never rely on turning the engine off to apply brake automatically.
One day you’ll be a vehicle that doesn`t have such safety devices. (Driver aids are not meant to be driver replacements) A bad habit to get into.
Raising the trailer legs a whole 2 inches? If it has missed the pin then the trailer has a long drop when the unit shoots forward on the tug test!
No need to raise the unit front wheels off the ground, but a gentle touch isn`t enough in a tug test.
Check trailer lights after connecting electric suzies.
And another wee habit I have is to do a quick brake check after moving off…not a full stop, just a touch to make sure they are there!
i did forget the handbrake but mainly because my habit in any vehicle is handbrake neutral engine off.
how high do you have the legs off the ground then before you do the tug test. I go that much because the feet swivel and i imagine would easy catch on the ground putting pressure on the weakest point
Legs just enough to have some slack in the legs. No need (IMHO) to have daylight under the feet.
Habit is a funny thing. (I’m not singling anyone out here.)
We do things time,after time, aftertime, all correctly then summat happens…not always a big thing, and we break our own habits.
Pilots who fly for many hours still use paper (or i-pad) check lists every time they fly.
When doing safety critical stuff elsewhere I was obliged to use a paper sheet signing off all stages in the procedure. At first others would check my work, but later I would sign my own work, but it was part of the procedure to do it as each stage was done. It concentrates the mind. It wasn`t acceptable to do the whole job and sign all the checks at the end.
It might sound like unnecessary bureaucratic stuff but it does make a difference.
That is why I stand still and double check everything in my head before getting back in the cab.
And it has been mentioned in other threads but not in this one yet…if someone comes up and starts talking to you tell 'em to leave you alone until the job is done.
Yes…I can walk and chew gum at the same time. … so let’s get that out of the way.
i didn’t think for a moment you couldn’t. It very rarely happens to me but if someone does come to talk to me or asks a question i physically go back to the beginning and start again. (if i have already picked up the pin i go back to checking its home correctly as described above)
By your own admission, your first attempt at hookup, you had the trailer too high. The flange of the king pin set the lock off. On your second attempt, the flange has snagged on top of the jaws. The pin will hold there, at low speed or in a straight line. As the prime mover turns, the turntable oscillation at a different angle, in relation to the trailer, allowing the pin to slide off the side of the turntable.
Not what you want to hear, but this was 100% driver error.
Before completing the kingpin engagement, ensure the skidplate is resting firmly on the turntable. I like to lift the landing gear an inch or two off the ground before engaging the pin. Listen for the clunk, clunk. Check that there is no gap between the skidplate and turntable, then get under with your torch and make sure the lock had engaged and you cannot see the kingpin. Perform a tug test, then wind up the legs and connect air and electrics. Drive off slowly, covering the foot brake while applying the trailer brake.
Used to occasionally drive a CF with a Fontaine 5th wheel that you had to be cautious with. No latch fitted to them so you really need to be using the dog clip. You could couple up and give it a good tug and all seemed well but it wasnt fully home as you couldn’t fit the dog clip, although the arm had clearly moved.
Like someone said they don’t just fall off, usually down to driver error. Cant think if a 5th wheel failure I’ve encoutered.
If course they happen but very rare. I’ve seen some well and truly shagged ones but trailer stayed on
Not all fifth wheel manufacturer’s mechanisms include a bar or wedge to the rear of the jaws; SAF have designs which don’t. I have never seen one apart from in a catalogue, however SAF axles are a very (un) popular fitment in the UK, so I don’t see why a company might not have their fifth wheels as well. As can be seen in the link these may be found fitted to Mercedes tractor units. Products: SAF-HOLLAND United Kingdom Quite why anyone would specify one I don’t know since they are rated at 14t when most trailers are plated to impose up to 15t on the tractor unit.
Trailers with a rear steering axle may have the operating block/triangle for the steering mechanism obscuring view of the wedge, which might at first sight look as if it is actually the wedge. These have a slightly different ‘feel’ when coupling up. There is a higher incidence of requiring a second attempt especially if not absolutely in line with the trailer, or if the steering axle is not straight.
I think alot of issues arise due to inexperience and poor training. I myself passed my class 1 nearly two years ago and as I mentioned above i have never looked for or even thought about the 5th wheel being flat against the trailer. All i was taught in my lessons was “black” When i queried if there were any other checks or procedures i was told no long as you follow the procedure exactly as taught nothing can go wrong. First night out on the job shadowing someone i was taught to split couple.
Few months in i cant remember what i did but something stupid luckily i realised straight away but somehow i had got the pin jammed in the 5th wheel. Admittedly that time i didn’t follow procedure exactly as i did something silly. The shunter came and helped me sort it.
Point im trying to make is I have heard many people in the office/training school say do this it will be fine well unfortunately it isn’t always
I think that if you do as trained, exactly, then little can go wrong. The word “exactly” is the key here.
The 5th wheel will be flat against the rubbing plate if you bang-under at the correct height. (maybe raising the unit or winding the legs shorter a little)
Lots of us say to check and double check because we do not always go under at the correct height.
The instructions/training are good, but although we think we are doing it correctly, we should check that we are doing it right.
As you say if correctly trained we would never go under at the wrong height, but we do. I certainly have.
The checks we have been talking about should catch the errors we as human beings make.
The training sequences are good but we are dealing with fallible humans.
I agree the system of black provides a easy to remember method provided that everything is fair and even unfortunately in the real world it isn’t always. For example I was taught to line the unit up so that i could see equal amount of the trailer in each mirror. That way i knew the 5th wheel was lined up at least fore and aft. All very well when you have plenty of space around the trailer etc. However one yard i went to regularly the trailers tended to be less than a shoulders width apart. Suppose two trailers are slightly angled towards each other and someone is picking up the other one you now either have to wait until they have finished and hope they don’t decide to have a 30 min break or come in at an angle relative to the pin. Obviously a piece of cake for an experienced driver but for a newbie it could be a challenge.
Obviously the thing to do is keep getting out and checking that your lined up but with the “stress” of the job and nerves i would suggest there is a strong possibility that they might not think of that.
Exactly, I always approached the trailer so that as soon as the leading edges of the ‘V’ entered under the trailer I wanted to see it touching. If it wasn’t then I would lower the legs till it did (I have never had a tractor with air suspension that could be raised or lowered). Then, when I continued to push, the trailer slid up the 5th wheel lifting the legs slightly from the ground until I heard the click.
But before all that I made sure the trailer brake was on and that no airlines were attached. The latter I saw with horror here when, for the first time in my career, because I had never had a frigo before, I saw that drivers would connect the suzies before the trailer was attached because of the limited space to stand.
On one occasion I saw the trailer slowly start to roll backwards and only my shout to disconnect the suzie halted a disaster.
That’s why split coupling is not permitted at some places.
It’s not that it is inherently unsafe, it is that there are more points at which the driver can get it wrong.
I have driven fridges where it was physically impossible to reach the couplings with the tractor unit attached.
As far as I am aware, there is no other way to connect or disconnect a trailer like that, but as every day I learn something new, I am happy to be corrected.
One supermarket has mavis rails that come right out and drop in an arc to about waist height making it easy to connect the lines. If for some reason you cant use the mavis rail they also have sliding 5th wheels with 2 positions so you can pick the pin up as “normal” press the button and pull forward so its effectively the same as split coupling but the pin is already connected to the 5th wheel.
However i agree with ncooper with out these facilities it is impossible to hook up a fridge trailer without split coupling unless your jeff capes
Well I’m certainly not Jeff Capes but I managed it every time. There wouild be no issue if the stupid law makers would concentrate on trailer lengths rather than overall lengths, like the Yanks do. It wouldn’t lead to stupidly long vehicles because of the space restrictions encountered on a daily basis. The same laws have always limited decent sleeper cab space. No haulier on general haulage is going to sacrifice load space to please his drivers.
I well remember seeing, but not driving, those wagon’n’drags that Vos, Murfitts and others used. I don’t think anyone over average height could squeeze behind the steering-wheel of one.
But the EU has recently changed the rules which allows for bigger sleeper cabs.
The DAF XG is the first, but Scania now has one out.
I used to split couple tautliners. Being close coupled it was difficult to stand squarely behind the air lines, (carrying full air pressure , no taps) to get them on otherwise.
… so let’s get that out of the way.