question Where to get Palm Couplings?

[daz76]

Mornin' all. Can someone advise me where to get the correct palm couplings for the front of the Explorer please? I have looked on T'internet but can't see the correct (old style) ones. Any help appreciated. Thanks. Darren

[marvinthemartian]

Hi Daz, I may have a couple spare in my shed that I got spare for my Leyland. If not, I'm hoping to do a bit of stripping on another Martian in the next week or two, so will see if it has any.

Simon

[Plantters]

Most good Commercial vehicle factors carry them.

Truck and Trailer components list them in their catologue in all colours and differing thread sizes, male and female.

Nigel

[Plantters]

Most good Commercial vehicle factors carry them.

Truck and Trailer components list them in their catologue in all colours and differing thread sizes, male and female.

Nigel

 

If you have problems let me know, checked today and my local factor has the common thread sizes and can get the unusual ones usually next day

Nigel

[antar]

If you have problems let me know, checked today and my local factor has the common thread sizes and can get the unusual ones usually next day

Nigel

 

Ah but they will be modern ones that are aluminium, the Explorer ones were cast steel.

 

John.

[marvinthemartian]

This is true, coz I'm sure the ones I have somewhere have got surface rust on them. I still haven't ventured that far, will make it one of todays jobs.

Simon

[N.O.S.]

I've got a really good modelling article showing how to replicate surface rust - highly realistic it is, if that is any help.

 

:coffee:

[Tony Graves]

hi all, i agree, original palm couplings are very hard to come by, modern couplings are not the same. i was led up the garden path for a year by a chap in belgium and nothing came of it, i finally found a diamond t rolling chassis which did the job, perhaps someone out there is breaking a similar vehicle or hopefully nos will help you out, good luck, all the best tony g.

[gritineye]

Just to clarify, this is the type we Darren needs. I have three more like this fitted to my towing air hoses, all bought at Beltring iirc.

 

 

 

 

Sent from my iPhone using Tapatalk

[marvinthemartian]

Guess what I found eventually after 1/2 hour looking through umpteen boxes and bins. Only lacking in the seal, but I think these can still be picked up at commercial motor factors.

What I had to wade though to find them.

Lo and behold rusty as thought.

Also found spare dummy couplings if required.

Simon

[N.O.S.]

Sorry guys, but can one of you please advise the differences between old and new? This is a problem I will face soon.

 

I take it the main problem is you cannot mix new and old coupling halves?

 

I assume there would be no problem changing both truck and hose ends to the new type?

 

Thanks.

[daz76]

Sorry for the late reply. Just catching up. Thanks for the all the info about the couplings. Marvin and Gritineye, those are exactly right. Mine on the front of Thor have been replaced with modern compressor fittings. IIRC there is some issue to do with braking if the correct couplings aren't used, as there needs to be a breather hole so the lorry doesn't think it's on tow? How easy would it be to obtain new rubbers for the original items? Would it just be easier to update to modern ones as long as the airline ends were changed to match? TBH most of the time I don't think they'll be used for trailers etc, so the dummy ends will be in place. DO modern couplings affect the air braking system in any way the originals would not?

Sorry. So many questions, but I have no idea of the differences between old and new. :red:

[N.O.S.]

... IIRC there is some issue to do with braking if the correct couplings aren't used, as there needs to be a breather hole so the lorry doesn't think it's on tow?....

 

Is this something to do with the blanking cover? Shouldn't there be a very small bleed hole in the coupling blanking cover to ensure the pressure at the coupling end is always slightly less than the last valve upstream (usually an equalising valve?) - which should always think there is less pressure on the external (hose) side or it will allow air to bleed through to brake lines?? e.g. as on Scammell Constructor?

 

We sort of got very near to nailing this eternal problem a while back - but not quite!!

[gritineye]

Mine on the front of Thor have been replaced with modern compressor fittings. IIRC there is some issue to do with braking if the correct couplings aren't used, as there needs to be a breather hole so the lorry doesn't think it's on tow? How easy would it be to obtain new rubbers for the original items? Would it just be easier to update to modern ones as long as the airline ends were changed to match? TBH most of the time I don't think they'll be used for trailers etc, so the dummy ends will be in place. DO modern couplings affect the air braking system in any way the originals would not?

Sorry. So many questions, but I have no idea of the differences between old and new. :red:

 

The breather hole is in the 'keeper' or dummy that fits on when not using the coupling, it is covered by a leather washer with a split pin through it which rusts then gets covered in paint causing odd braking symptoms. Can be seen on Marvin's pressed dummies with the washer missing. The correct dummies for an explorer are cast iron.

 

The rubbers are the same as in air hoses for pneumatic drills and such, I got some from a plant hire place.

 

Only real use I can think of for them is nosing trailers and when being towed by a vehicle fitted with correct air system, from experience this works very well.

 

TBH the originals look right and that would be the only reason for using them.

[gritineye]

Just checked and believe it or not there are different original dummies types!

 

The rear dummies do not have any holes, but the fronts do, one of my fronts has the remains on a rubber grommet in one chain eye and there seem to be two tiny holes, one central pip and one on the flat part, curiouser and curiouser, will look further tomorrow!

[daz76]

Thanks Bernard. Sounds like I've opened a can of worms there! I would prefer a matched original looking pair, as they won't be used much. Appreciate all the replies. Daz

[daz76]

We sort of got very near to nailing this eternal problem a while back - but not quite!!

 

The fun and games you can have with the Scammell air system. Part of mine is missing which makes it even more fun :nut:

[N.O.S.]

Just checked and believe it or not there are different original dummies types!

 

The rear dummies do not have any holes, but the fronts do, .....

 

And it was the fronts which gave me problems (because the couplings were missing and pipe was sealed by a large steel ball in the union therefore no chance to breathe. Interesting.

 

If I've got this right - there is a simple 3 way shuttle valve (equalising valve??) in the front lines, which - if more pressure in the connecting hose - will move across and allow air from connecting hose to connect with brake lines. Slightly less pressure on the front hose side of the valve compared with the vehicle side and the valve moves the other way and isolates the hose line. If pressure is equal the shuttle valve which is not sprung can work its way across and gradually cause air to bleed through to brake lines.

 

Or something like that....or maybe not ...:nut:

[daz76]

That makes sense NOS. I hadn't realised there were different dummies available though.

[utt61]

Not sure if they are the same, but railway vehicles use steel air line couplings (not aluminium). They look (from memory) pretty similar.

[gritineye]

As most of you who have combed through every Explorer image you can find will know by now, :rolleyes: that the majority have the pressed steel type of dummy fitted. Presumably an in service mod to overcome various problems.

 

This is what is on Forceful, which was not a REME vehicle it was run by FVRDE so may well have missed any updates.

 

Rear emergency coupling dummy, very smooth casting, looks to be original chain too, no hole.

 

 

 

Rear brake coupling dummy, different rougher casting, chain hole is shaped to accept rubber grommet, no hole.

 

 

 

Front emergency coupling dummy, same type as rear brake, has smaller chain and has one hole in centre. What I thought was a second hole is just a casting defect

 

 

What I thought was a second hole is, I think, just a casting defect.

 

I thought this gap coincided with the 'non hole' but it i think it is just a casting defect, or broken.

 

 

Front brake coupling dummy, same as front emergency, with smaller chain and remains of grommet still adhering to

 

chain and casting, has one hole in centre.

 

 

It seems the grommet is supposed to act as a one way valve after a certain pressure is present, wonder who thought nothing could ever go wrong with that?

 

 

So it seems the original cast ones caused problems in service and most REME ones (a couple of RAF ones still have cast type)where replaced with the pressed steel type with improved breather valve, or not, will we ever know?

Edited March 14, 2012 by gritineye

[diamond-t-steve]

Railway couplings connect the same way they are just 2 or 3 times the size.