if we drop a trl on the bays at our depot we will place the handbrake on and place the chock under the axle (front).if we are dropping it in the trl parking bays then the rear doors get opened to show it’s empty, that way you don’t need to go and check it,we will put the trl brake on b4 dropping it. 
munibear:
If the trailer is well maintained and is free from defects like air leaks or in need of relining then it is or should not be nessarsary to apply the hand brake however the health and safety would want to know why it was not applied if anything went wrong anyway modern trailers come without hand brakes and taking the red airline off is the same as pushing or pulling the button!! ps i never put the hand brake on
Exactly! Im afraid 
The old ratchet brakes were a pig to release sometimes, so us seasoned professionals are guilty
With air suspension on a tractor there is no need to ram under trailers, if you end up chasing trailers with this then you should always ensure the brake is on
And in the old ■■■■■ defence on this subject!
A trailer will not roll away when it is dropped because the landing legs act as brakes.
However the correct way is to use the wheel chocks fitted to trailers & units.
Never ever drop a trailer without chocks in Europe if you are carrying ADR
As a newbie I learnt a couple of things from this thread.I didn’t know some trailers had an automatic brake. How do you know if they have, we have two new Montracon trailers but I hadn’t seen any signs on them. The other thing, when I first started driving artics a driver who was showing me the ropes when coupling said if you see it moving pull the red line off . I assumed he meant the trailer not the unit. Thanks to Ladytrucker I now know its the unit, I would have jumped off and tried to get in the unit.
To get back to the thread I always use the brake. I always double check the unit handbrake as well.
Thanks everyone
knight:
To get back to the thread I always use the brake. I always double check the unit handbrake as well.
Thanks everyone
You keep doing that, Knight and you will never be responsible for a death!! Remember a fully loaded trailer can weigh anything up to 36 ton gross!!! Not nice to be hit by one of them. My unit has air suspension so i always pick the trailer up by dropping the air, sliding under the trailer and then levelling the air suspension once the fifth wheel is under. (One bonus of doing this is you keep the front of the trailer clear of fifth wheel grease and your susies keep cleaner as a result). Now not all trailers have dead brakes so if I am in that position with the traileer just sat on the fifth wheel plate and connect my red line, I could be in big trouble if the brake isn’t on. If the park brake is on, then I can comfortably connect my lines, and then finish reversing under the trailer. IT TAKES NO TIME TO WALK ROUND AND RELEASE THE PARK BRAKE.
Not trying to be a smart so and so 
BUT
Someone said that pulling off the red line is the same as pulling the parking brake on,
WRONG! 
Trailer with automatic park brakes have a system on it, when you drop the red line a valve operates and puts the service brake on full, as if you have got you foot on the brake, This is NOT a Parking brake, If the air in the trailer tanks drops then the service brake is released as the spring brakes come on, if you pull the park brake then the spring brakes are applied, this point can be proved if you drop a trailer then push the blue shunt valve, the service brake is taken off and the trailer is free to do what it wants, with no airlines connected!
When you just drop the trailer you park the trailer on air rather than springs, if someone walks past and pushes the shunt valve the trailer is NOT parked, so you roll up and back under and the trailer rolls back,
IS THERE SOMEONE OR SOMETHING BEHIND IT?
There is a fail safe on then because if the park brake is on then the shunt can not be pushed as it feels spring loaded,
If the trailer has been sat with nothing but gravity stopping it from moving and you back under and couple up the red line the brakes are OFF, if its heavy on a slope it will push the unit along, because the shunt valve is down you put the red line on and the fail safe finds fresh air pressure there the the button pops out, and because the park brake is not on your now possibly rolling across the yard,
Please remember, Pulling the red line is NOT the same as Pulling the red button, There have been some nasty accidents because of this, the reason all you who don’t park it properly have not had an accident is just pure luck, nothing else
Play safe!
Maybe it’s cuz i’m still relitively new to this, but I ALWAYS put the trlr brake on…
Except… Yesterday when I had a rental and couldn’t find the brake for love nor money… 
Luv
Chrisie… 
I have had that, Rags lolol especially at night!!
You walk round and round looking for it and think you’re going mad lol.
In fact just two weeks ago, I had this. I found it in the end though
Discopete:
Please remember, Pulling the red line is NOT the same as Pulling the red button, There have been some nasty accidents because of this, the reason all you who don’t park it properly have not had an accident is just pure luck, nothing elsePlay safe!
All fair comment but if you find yourself rolling whilst coupling up it is the safest way to imobilise the vehicle so that you can apply the brakes properly.
Linux-user:
Am i correct in guessing that split coupling is when you back under the trailer but don’t hitch leaving a gap to connect airlines and then reversing back and hitching?
yup, its someting I hate to do but its nessesary due to the trailers we run having fridges, unless your built like twiggy and can squeeze into a tight space.
though sometimes you come across trailers with the suzies on a slider. I`ve also seen asda and safeway trailers with the the suzies on 1 corner
All this talk of a red button for a trailer brake , what you on about i,ve never seen one!!!;);););)…
Only joking but got to say i have never put one on yet but it does ■■■■ me off when some shunter has put it on and ive got to get out the cab again to put it off.
Not putting the handbrake in your unit on, when hooking up to a trailer is something else all together. If your rig starts to roll away when you put the red line on, pull it off straight away. Do not jump off the catwalk and try to put the unit handbrake on. Far to many people have been injured or killed attempting that. Far to many innocent bystanders have been injured or killed as well.
But that isn’t what this thread was about.
What I was posting about was answering the question “Do I apply the trailer brake, when unhitching a trailer”. The answer to that is :- Normally no.