shunt button

UK PROFESSIONAL DRIVERS FORUMS THE UK PROFESSIONAL DRIVERS FORUM (INTERACTIVE)
1

i know im gonna get a load of abuse for this one but i might get the odd answer chucked in amongst it :laughing:
an artic trailer has 2 buttonts (blue and red if i remember correctly) but which one is which and what does the shunt button do exactly?

when i worked for ranks, it was on the docks and therefore flat so no one used the trailer brake. now im in Scotland, i need to know this stuff before my first day out. its time to do it right :exclamation:

2

red is normally trailer brake

3

When dropping a trailer,pull the red button out.As Neil46 says this is the park brake.If you just need to move a trailer a short distance hitch up but dont connect the airlines.Just push both buttons in and this releases the brakes on the trailer.Remember though that you will have no trailer braking.Also remember to pull both buttons out again when you drop the trailer :unamused:

4

scanny 77

Red one is trailer brake, blue is shunt button, which when you
pull it out will release trailer brakes, so you can shunt trailer
about without connecting up air lines. Soon as red airline is
put on shunt button goes back in automatically.

P.S if you move trailer using shunt button donā€™t forget to
push it back in when dropping trailer. Or when you
pull unit away it might run away, or when somebody
else picks trailer up they might end up chaseing it
round yard :laughing: ( Brakes are still off )

cheers Bob.

5

oops see Highlander beat me to it
it took me that long to type that out :blush:

Bob.

6

just another thing Richie, if you break your red airline while
turning round, backing in etc. if you kink airline over to stop it leaking
secure with cable tie or something, then push shunt button, so you can
carry on , or move truck out the way.

cheers bob

7

now to put the cat amongst the pigeons

forgetting the buttons for a mo if you put the red airline on you get to move the trailer without brakes

if you stick the yellow on nothing happens til you release the shunt button
you can then move the trailer until the air is drained from the tank

i am ā€˜wasā€™ of the opinion that you shouldnt be able to release the shunt button unless the yellow airline was on. if you can it must be faulty

8

i asked this because i did shift trailers around at ranks out of boredom between loading trailers. i wasnt sure about the buttons so i connected both air lines and moved the trailer wherever it was going. the buttons werent an issue there but things are much less level up here and i dont want trailers rolling around after i drop them. thanks for the replies :smiley:

9

You only need the red line to drag a trailer Scanny and the axles up to save winding the legs up. :wink:

10

Ladytrucker679:
You only need the red line to drag a trailer Scanny and the axles up to save winding the legs up. :wink:

bloke at our place got a disciplinery for that as mercedes blamed people driving in yard with air up for why the bags burst!!!

so maybe not do it in front of boss :wink:

I always remember push to park , pull to shunt. obo on the 2 different buttons if that makes sense. It does to me. lol

11

Recently been doing deliveries to Ikea @ Thurrock & we are instructed to remove all lines & use the shunt button in order to get onto the bays - thereā€™s only just enough room to jack-knife a trailer around - doing it with the lines connected can over-stretch them (I know, I tried it without before being told of the ā€˜standing ruleā€™ & I had a split suzi at the next drop). As long as you donā€™t try it on the open road or on a steep slope you can use the shunt button for manouvering with no problem.

12

errr guys its push to shunt pull to park (still at work and just looked at trailer) hehe

using the shunt button only works if there is air in the trailer usually its easier just to connect the red line to shunt trailers though you as said earlier you have be aware that only the unit is braking for the whole outfit if heavy take is steady is a good rule of thumb. personally I would run roun with the back end of the truck jacked up as the run up ramps (if fitted) can catch the tralers neck and cause damage as well as very rarely blowing air bags if bad one is fitted

13

so everyone is in total disagreement. excellant, thanks very much :laughing:

14

hitch:
now to put the cat amongst the pigeons

if you stick the yellow on nothing happens til you release the shunt button
you can then move the trailer until the air is drained from the tank

i am ā€˜wasā€™ of the opinion that you shouldnt be able to release the shunt button unless the yellow airline was on. if you can it must be faulty

I havenā€™t heard that one before.

The yellow line is a ā€˜controlā€™. A rheostat, a dimmer, something akin to the knob on your gas hob. Compare it as you will. It provides a signal to the RE6 valve to supply air from the trailer mounted tank to the wheel actuators.

On the other hand, the ā€˜shunt buttonā€™ allows the reservoir of air in the trailer mounted tank to be directed to the ā€˜releaseā€™ chamber of the spring brakes on the trailer. Once that reservoir of air is depleted, either through leakage or due to compensating for suspension changes, the brakes will re-apply.

I have come across newish trailers where (not using the shunt button) not only did the Red air line need to be connected, but also the Aux electrical lead, before they could be moved.

Different manufacturers seem to interpret the same rules in different ways. Perhaps the only consistent fact that I can establish is that, on connecting the Red Line, the Shunt Valve is disengaged. i.e. returns to normal operating position.

15

do renaults still have the lever on the brake so when air is low you push the lever to get it moving on rigids

16

hitch donā€™t you mean the broms brake that volvos have

17

I seem to remember coming across trailers, where when you take off the red the trl brake applies itself. Might have been Tescos ones. :confused:

18

The shunt button is nothing new, only cleaner. :stuck_out_tongue:

The old way was to crawl under the trailer and drain the air tank.

You should never use the shunt button to move a loaded trailer

19

And bear in mind that using the shunt button will only give you a small amount of air to move a small distance,if your not the best at reversing then it might be a good idea to put red line on. :wink:

20

a lot of these things as mentioned above seem to be more trailer-specific, as thereā€™s experiences Iā€™ve read above I canā€™t relate to, and others Iā€™ve had Iā€™m sure some wonā€™t see as matching theirs.

for example, at the live-haul firm I drive for sometimes, the trailers are all parked in a row, pick the one you want and drive under it, legs up a turn or two, shunt button in and listen for brakes to disengage (and often lurches a little as weight ā€œrelaxesā€ hence initial leg-winding to prevent strain) - and legs up a turn or two more for clearance at normal ride-height.

brakes will now remain disengages until I use the button to change itā€™s state.

onto the weigh-bridge, shunt button disengaged, legs down, unhook, drive out, wait for green light, then couple up as normal.

some drivers ignore the shunt button completely and simply connect the red air-line which allows the brakes to be operated on the trailer in a normal manner via pedal and handbrakes, and when disconnected the brakes are applied automatically. I canā€™t be bothered with climbing up to couple up when on this job though since thereā€™s several trailer-swaps in a day and I have a dodgy shoulder. the less climbing the better.

in fact IME the only use of the red park-brake is as a fail-safe in case they donā€™t engage when you disconnect your airline. otherwise even that would be redundant.