Unhooking a semi-trailer for the purposes of a CDL road test is a required skill.
How to Unhook a Semi-Trailer for CDL Licence | Truck Driving School
Closed Caption
Introduction
Hi there smart drivers Rick with Smart Drive Test talking to you today about how to unhook a semi-trailer for the purposes of a road test.
This is not for drivers who are going out and working after they get their license.
However saying that, the sequence is the same regardless of whether you're preparing for road test or you're working--L.A.P (landing gear, airlines, pin).
Do it in the same order every time, and you won't drop the trailer on the ground, you won't rip the airline's off, and you won't bend the dollies.
And let me tell you, you bend the dollies on a semi-trailer, and every truck driver from here to Mexico is going to make fun of you for the rest of your career.
So we're going to be right back with that information.
Stick around.
L.A.P.
- Landing Gear, Airlines, Pin
Hi smart drivers, Rick with Smart Drive Test talking to you today about how to unhook a semi-trailer for the purposes of a road test.
L.A.P.
- landing gear, airlines, pin.
Do it the same order every time!
Dollies
Just a little note on the landing gear - there's a crank handle here - in is low, and out is high.
You can be a little rough with this.
And then you need to lock the handle in.
I've seen people do this sort of thing here...really screw around with it.
Actually what you need to do is lock that handle in and crank it down ok.
So one of the ways you can remember it, you crank it this way to put the dollies down and you crank it this way for the dollies to go up.
Okay, just a note when you're winding the dollies down, two fingers on the handle here--out here the end-- put your hand on the side of the trailer and tuck your chin in because you don't want to get smacked in the face with the handle on here.
So bring it down - when it goes taunt like that, then you put it into low gear and keep cranking it down until you hear the air out of the air ride suspension begin to exhaust.
So right there you can hear the air exhausting out of the suspension.
Drop the handle.
Any time that you're not having the trailer on the back of the truck you don't have to stow it, you just drop the handle like that.
Air & Electrial Lines
Now we go up to the airlines.
So the next thing we want to do is unhook the airline.
So L.A.P.- landing gear...we drop the landing gear and crank it down until we can hear air escaping from the air ride suspension.
Now we take our lines and electrical lines off.
It doesn't matter what order you take them off, however I do suggest that you work outside to in, that way you're not reaching over and you're not getting grease on yourself and all sorts of things.
Dummy Couplers
Now when you take these off put them in the dummy coupler on the back of the tractor.
Some guys will have a bungee cord on the deck - you can just put them into the bungee cord, but you get dirt and grit and that kind of thing in the lines.
So if you've got dummy couples on the back you can take that 30 seconds it takes and you to put them in the dummy couplers.
And put them in there.
So to unhook the glad hands on the trailer, just grab on the bottom here, pull up on them.
They come up like this - so pull this one off first, pull this one up - you have to lift up on this because there's a catch on this.
You gotta lift up on the electrical lid and pull out on the electrical line - lift up on this.
You got all of them in your hand like this, and then come up and put them on the dummy couplers on the back of the truck.
So the electrical has a groove on the top of it here you can see, and in the dummy coupler there's a groove that it matches up with.
You stick it in the top there like that.
And then the 2 gladhands 90° degrees, push it down.
90° degrees and push it down.
So your lines are stowed.
There isn't any dirt or grit going to get into your airlines, so that's a good place for them.
And this too is not hanging down [PULLING ON THE AIRLINES & ELECTRICAL] near the drive shaft or any place like that that's going to get ripped off and whatnot.
So the next thing we do - so that's the second step - Air Lines and electrical disconnected and stowed.
And the next step is to pull the pin on the fifth wheel.
So the last step of the uncouple - L.A.P - landing gear, air lines and electrical - disconnect that.
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Pin - 5th Wheel Handle
And then we're going to pull the pin.
Now most of the time you're going to have a pin puller, unfortunately I don't have a pin puller today.
Use a pin puller because what happens is the fifth wheel is covered in grease and all that grease is going to go up on your arm and eventually going to get into the cab and you don't know where the grease comes from.
So try and use a pin puller.
Go to the truck stop and get one or just make one - you can bend a piece of steel up to hook onto this handle here.
And pull this out you can see that it's a bit gnarly.
If you've got a pin puller, it's a lot easier.
So you can see that the handles out and also this particular fifth wheel has a bolt - an adjusting bolt on the front of it - you can see that the adjusting bolt has come out as well.
So that you know that it's unlocked and for the purposes of a road test you're gonna have to go in underneath and make sure that the jaws in fact are open.
And it depends on where you are, which licensing center you're going to.
Some of them will want you to go and check the jaws, others will not.
I personally don't think you have to because if you pull the tractor forward and it doesn't come unhook, you know that the jaws aren't open.
Check the 5th Wheel Jaws
But we're gonna go in and check them underneath the truck here.
You just look up into the fifth-wheel there and you can see that the jaws are open.
And all you do is you just come in here have a quick look and say: "the jaws are open."
And you're ready to go to finish unhooking the trailer.
So we finished everything outside - L.A.P.
- landing gear - we cranked down the landing gear until we heard air exhaust from the air ride suspension.
We've unhooked the airlines and we pulled the pin.
Now we're ready to finish uncoupling.
Pull Forward & Drop the Air Suspension
We get in the truck and we pull forward a foot (20 centimetres).
And the reason we want to pull forward a foot is because we want the kingpin out of the fifth wheel.
And the reason we want the kingpin of the fifth wheel - there's a flange on the bottom of the kingpin - you can see that in the image here.
And that flange will hang up in the fifth wheel when you drop the air suspension if you don't move the kingpin out of the 5th wheel.
Ground is Supporting the Weight of the Trailer
We've got to drop the air suspension because we want to make sure that the ground is supporting the weight of the trailer.
And we know that by dropping the air suspension and putting all the weight on the dollies of the trailer.
So that's what we're going to do next.
When you get in the truck and pull forward, drop the air suspension, and come out and check that in fact the trailer is being supported by the ground.
Because if it's not being supportive by the ground and you drive out from underneath the trailer and it sinks [CHUCKLING], your employer doesn't like you because it's really, really tough to get that trailer back up off the ground.
So we're going to do that - pull forward, drop the air suspension and check to make sure that the weight is being supported by the dollies on the trailer.
Use Low Gear or Bull
So we get in the truck, we move the truck forward and the other thing that I suggest when you move the truck forward, use bull (low gear), that way you've got a bit more control when you're pulling out from underneath the trailer.
So we pulled forward 12 inches (20 centimetres), we get the kingpin out of the fifth wheel and then we drop the suspension.
And you can see here in the shot that there is now daylight between the trailer and the fifth wheel, which indicates to us that the trailer dollies are actually supporting the weight of the trailer.
And it's unhooked.
[MUSIC: MEAN STEETZ] Quick review of unhooking - we're all done unhooking.
Conclusion
You can basically drive the tractor away at this point.
So L.A.P.
- landing gear, airlines and electrical, and pin.
So crank the landing gear down.
There's two gears on the landing gear:
1) there's a high;
2) and a low
And make sure that you lock the handle, otherwise you look like a rookie.
Remember, being a veteran isn't really knowing more, it's simply looking like you know what you're doing.
So make sure you lock the handle in when you crank the dollies down.
Crank the dollies down until they touch the ground, put it in low gear and continue to crank it down until you hear air escaping from the air ride suspension on the truck.
Then you disconnect the lines from the trailer and work out to in.
Hook them onto the dummy couplers on the back of the cab.
so L.A.P.
- last one is pin.
Pull the pin - the handle is out and the bolt is out on the front of the fifth wheel.
Some jurisdictions will want you to actually get under and visually look to make sure that the jaws on the fifth wheel are open.
After you've done that, you get in the truck, roll down your window so you can hear.
Always when you're working in yards and backing up and those types of things, always roll down your window so you can hear.
Put the truck into bull, pull forward 12 inches.
You pull forward 12 inches, dump the suspension, get out and make sure that there's daylight between the trailer and the fifth wheel.
That way you know that the ground is supporting the weight of the trailer.
Because you don't want the trailer to sink into the ground if the ground is unstable.
Because your employer gets pretty excited when they have to get a huge forklift or a crane out there to pick that trailer up off the ground.
So that's the reason you don't pull out from underneath the trailer right away.
You want to make sure that the ground is supporting the weight of the trailer.
Then you pull away.
Rehook
Now oftentimes on a road test what they're going to get you to do is uncouple like this, and than you're going to back up beside the trailer so that you're offline with the front of the trailer.
They're going to get you to pull forward and they're going to get you to rehook to the trailer.
So that's what they're going to do for the purposes of a license.
And as I said, once you start working, just keep it in that same order all the time: L.A.P.
- landing gear, airlines, pin.
If you doing it in the same order every time, you're not going to rip the airline's off, you're not going to drop the trailer on the ground, and you're not going to damage the landing gear.
So make sure you keep it in that order every time.
As I tell students, semi- trailers are easy to hook up and they're also easy to screw up! So make sure you do it the same way every time.
Question for my smart drivers:
Have you ever ripped airlines off a semi- trailer when you've been unhooking a trailer.
Salutations
Leave a comment down in the comment section there.
All that helps us out.
I'm Rick with Smart Drive Test.
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Check out all the videos here on the channel if you're working towards getting a license or endeavouring to start a career as a truck or bus driver.
Thanks again for watching.
Good luck on your license.
And remember pick the best answer not necessarily the right answer.
Have a great day.
Bye now.
