just like to point out these 45 footers with a self correcting back axle arenot rear steer trailers.they are basically trailers with a rear axle that moves when going forward but locks off when going back. proper steer trailers are steered independently from the cab via a wanda lead or remote. a lever is usually pulled on trailer to make the axles NOT respond to cab and be in complete control of the attendant steering it. as mentioned above an extra lead is needed from cab to trailer,usually a nato lead which gives power for the steering
Thanks for clearing that up mate from a post made 7 years ago. It’s been keeping me awake.
rhudson:
I recently did some CoOp deliveries around North Wales with a twin axle rear steer trailer (including Wrexhan centre). I did quite a lot of maneuvering (including reversing) and was amazed at the level of maneuvarability it had. The same run with a six wheel rigid would have been much more of a challenge. It seems to me that a rear steer axle trailer would offer a big advantage in a LGV C+E test scenario. Can a rear steer trailer be used a test or is there some restriction ?
I much preferred the twin axle rear steer at the co-op than the single or a rigid , the twins were good fun in and around Glasgow/Edinburgh , pulling the cages full of irn bru wasn’t though 
shame you couldn’t use a tug and turn the seat round too , the reversing would be easy and a piece of what uktramp posts 
how do these work 
do you need a special unit to haul one as how does the trailer know which way the unit its turning, guessing its some sort of rod that is attached from the trailer to the back of the unit
cheers.
I was gonna ask this yesterday, but forgot by the time i got home from work. 
We have a couple of them here at Keystone. The units used are bog standard units, so not even I know how these trailers work, even though I pull them.
I have never used one so I’ll GUESS that they are electronically controlled by some sort of sensor ■■?
There is a couple of systems, a mechanical and hydraulic
bubsy06:
There is a couple of systems, a mechanical and hydraulic
Thanks for that
I did not realise that they can also be used in reverse !!
Are you talking “command steer” or trailing axles?
Command steer works on a wedge mounted on the rubbing plate on the trailer that slots in the “V” on the fifth wheel just in front of the king pin hole , as the unit turns it turns it moves the the “wedge” and via, normally hydraulics but sometimes via rods, the rear axle is steered. One advantage of this is on large trailers (e.g. Long or lowloaders), the hydraulics can be disconnected from the fifth wheel wedge and the trailer indepndantly steered via a hand control
A trailing axle is basically loose(in terms of direction of travel) and will naturally turn in the direction the trailer is turning
for both with a standard trailer no modifications are needed to a normal tractor unit.
With the Heavy/long trailers a power lead to power the hydraulic pump when the trailer is being hand steered maybe needed.
It is important to make sure that the wedge is tight against the fifth wheel, on some trailers a bolt at the back of the wedge can be adjusted that “spreads” the wedge to sit tight against the fifth wheel, anny play in the wedge/fith wheel may lead to the trailer wandering from side to side as you travel, or crabbing down the road
I think it’s something similar to the solution used in this Ikarus bus (very popular in Eastern Block, but I’ve seen them also (on Pics) in Kanada and in RHD versions)
The trailer turns as it’s suspension have a system quite similar to what you can find in skateboard… The result is funny, as when bus is full of people, trailer makes sharp turns following the bus, while when it’s empty, the bus stays almost rigidl and bus swings half of the junction with trailer… 
Anyway, I don’t think that you need any connection to the front steering.
ROG:
I have never used one so I’ll GUESS that they are electronically controlled by some sort of sensor ■■?
blimey i’ve stumped ROG 
i guess not even your book would have the answer either, once you’ve found it that is…
]
Rikki-UK:
Are you talking “command steer” or trailing axles?Command steer works on a wedge mounted on the rubbing plate on the trailer that slots in the “V” on the fifth wheel just in front of the king pin hole , as the unit turns it turns it moves the the “wedge” and via, normally hydraulics but sometimes via rods, the rear axle is steered. One advantage of this is on large trailers (e.g. Long or lowloaders), the hydraulics can be disconnected from the fifth wheel wedge and the trailer indepndantly steered via a hand control
A trailing axle is basically loose(in terms of direction of travel) and will naturally turn in the direction the trailer is turning
for both with a standard trailer no modifications are needed to a normal tractor unit.
With the Heavy/long trailers a power lead to power the hydraulic pump when the trailer is being hand steered maybe needed.
It is important to make sure that the wedge is tight against the fifth wheel, on some trailers a bolt at the back of the wedge can be adjusted that “spreads” the wedge to sit tight against the fifth wheel, anny play in the wedge/fith wheel may lead to the trailer wandering from side to side as you travel, or crabbing down the road
thanks for that Rikki , the ones which i refered to in my question are the ones supermarkets use, hadnt actually thought about low loaders ones 
. so would they be trailing axles
I first came up against rear steer when i was on agency for Salvesson. After ten minutes having a good laugh at my efforts to back on to a bay the shunter came over and put me out of my misery.
The automatic locking mechanism only worked when you engaged reverse while the wheels were straight. If they were even slightly off it just didnt work and, as soon as you pulled forward (for another shunt) it released anyway. Sometimes (because of its exposed position) the solenoid that worked it would fail and the only solution was to have a pin (I used a ½" bolt) to drop into the locking hole while you were manouvering.
Going forward, the idea worked well once you got used to it. Reversing - grrrrr
They’re fun to reverse, and as already said, any unit can pull them. Just make sure your dead straight when coupling up so you dont smash into the ‘cheese wedge’, then you’re screwed.
We wouldn’t get into half the farms we do without rear steer. Fortunatley i’ve got used to them now, so dont make as many ■■■■ ups, but when i go out with a normal trailer, i’ll probably struggle 
ive used some command type ones like ricky mention with the small metal wedge that slots in to the fifth wheel and this one had chain system that ran to the front axle on the tandem trailer which was bolted to a turntable. bloody thing could get in anywhere ( as long as you thought about it).
There are several types of steering axles on trailers.
There are the steering dolly type,which is probably the type you have seen on supermarket trailers,where the axle is mounted to a sub frame that turns in the oposite direction to the unit.This type is operated from a wedge in the fifth wheel and can be operated by mechanical linkage or hydraulics.
The same system is used on those multi axle trailers used to carry the counter weights for cranes,they run at about 100 tonnes on a 6 axle trailer.
If you look closely,you can see that each axle is on a separates sub frame and when the unit turns,all the axles turn at a slightly different angle.
I used to run with a tri axle that had a rear steer,but on this type,the wheels turn on the axles,much the same as the front axle of a truck.
They follow in a straight line because of the “Castor action”,caused by the “King pin inclination”,much the same as your truck steering will self centre when coming off a lock if you let the steering wheel go.
However,just like a truck,in reverse they will tend to go to one lock or the other.That is unless as on most there is a lock,to lock them in the straight ahead position.
Some years ago,there was a muck shifting firm round here that had twin steer tractors with a steering back end on the trailer that was also driven!
Both of the trailer axles were on one dolly that was steered from the king pin by way of cables.
There was also a propshaft from the rear of the tractor unit running in support bearings under the trailer to the front trailer axle,then from the front axle to the rear.
I pull a Tri axle trailer with a front and rear steer wheel. The rear wheel locks off and the front wheel lifts out the way when you stick it in reverse 
We use twin axle 10 meter ones for some places, the axle right at the back steers. Use any unit to pull them…
I think they’re great anyway, it’s unbeliveable some of the places you can get them in! you’d struggle with a rigid in some places.
Just got to be careful onto bays etc, they come round sooo fast you end up miles short of where you need to be… can be hard to get the lock off quick enough.
philmots:
We use twin axle 10 meter ones for some places, the axle right at the back steers. Use any unit to pull them…I think they’re great anyway, it’s unbeliveable some of the places you can get them in! you’d struggle with a rigid in some places.
Just got to be careful onto bays etc, they come round sooo fast you end up miles short of where you need to be… can be hard to get the lock off quick enough.
tell me about it, not look for about 3 seconds and the back of the trailer is in front of the cab…(slight exageration but you need to watch for where it goes.)