Thank you for visiting the Routemaster Owner and Operator's Forum (ROOF). Please feel free to use this forum for the mature discussion of any issues of interest and relevance to Routemaster owners. Please do not use this board to publicise your feelings about individuals, National or Local Government or TFL policy. Owners of other London bus types in service during the 1950s, 60s and 70s are also welcome to contribute to this forum.

Please note, the ROOF website no longer exists. The link from the Forum does not work anymore.  Useful information and links from the website has been posted to the Forum.

Please do not respond to abusive posts but notify ROOFmoderator

Start a New Topic 
Brakes failed - Thankfully before I moved her!

*** Help Needed ***

So after a successful day refitting glass to my bus after turning it on to put it away the brake flag goes up and I give it another 30 seconds.

I press the break and the flag drops and shoots up - okay maybe not pressured yet (weird normally spot on time) - leaves it another 30 seconds and the same again and again and again.

I then notice when I press the brake and flag drops after 2 seconds the flag rises but at the same time I feel the brake pedal fighting back against my foot.

I stop the bus' engine, press the brake till the flag stays down, turns engine on again but now flag won't rise even after 5 mins of idle!

1) Is any one able to advise what may have failed in the braking system. (Clayton Delwandre)

2) Is the hose circled in the photo mean to be able to be squeezed when engine is running? - the other is rock solid.

So I'm guessing this one job to far for me to fix so...

3) Can anyone recommend a good reasonably priced recovery company to use to send her off for repair? Collection would be from near St Neots.

4) Can anyone advise a place to diagnose/repair her
i'm guessing this will be send her off to ward jones commerical vehicles?

My bus number (if any): RMF2771

Re: Brakes failed - Thankfully before I moved her!


Talking to a mechanic else where says i may have lost a clayton accumulator bag, which tallies up with me loudish pop sound when i first pressed the brake, at the time i just assumed it was the farmer with his shot gun whichd i often hear but this sounded slightly different.

(i have a spare clayton accumulator)

Or could be to quote "non return valve/cut out valve is playing up"

My bus number (if any): RMF2771

Re: Brakes failed - Thankfully before I moved her!

My bus suffered identical symptoms to yours and it was one of the accumulators that had failed.
I had the Clayton system on my bus also but after making inquiries i changed both accumulators as "Murphys law has it that if you replace one then the other will fail shortly after".
Hebble hydraulics can supply very similar accumulators but you will need to make up new brackets to hold them.
I can send you pictures of how they look if you need them and I can also get a pair of brackets made if required.


My bus number (if any): rml2478

Re: Brakes failed - Thankfully before I moved her!

Pictures would be great,

Yeah I been told to try charging them, I happen to have a spare Clapton type so if one has failed I can at least get to ,y two day event this weekend then can look at doing your conventions

Re: Brakes failed - Thankfully before I moved her!

I am not trying to be facetious or unkind, but you really do need to get yourself a Walker manual and read it so that you understand the vehicle's systems ,otherwise you are going to be in real trouble taking the bus on an overland to Japan. You will be very lucky to find anyone on your journey able to help you unless you understand the vehicle yourself.

Yes it sounds like an accumulator problem, but don't take my word for it, get the manual and the necessary test and charging equipment and familiarise yourself with it - because you are probably going to need it in deepest Ulan Bator.

On balance I probably wouldn't be attempting the trip with a Clayton Dewandre braking system, since if the nine way valve packs up then you will probably end up abandoning the vehicle and thumbing it home. That opinion being expressed only because there simply aren't any valves floating around.

As for the suction hose, it needs renewing because if it was proper hydraulic return hose you would not be able to squeeze it.

If you are near St Neotts then you are on Rob Duker's doorstep.

Re: Brakes failed - Thankfully before I moved her!

Have the manual and read it, ( I actually have two, one in my bus and one at home)but the problem arose as I was leaving and no time to investigate more.
I needed further clarification on a point the manual wasn't clear on which has been clarified by a few people now off forum. Just because the diagram says low pressure on the plessy pump on one side doesn't mean it's low enough to squash it with my fingers, it's surprising how strong 10psi can be.
As for the test equipment I don't have access to the right guage till morning - yes I've used them before.

My suspicion is a accumulator has blown but I also wanted to see what other suggested so of my plan provides no results then I know what else to try next. So far all the other inputs have been recharge the accumulators or one has blown, confirm my suspicion, not just to prove it.

My explanation of what happened may seem simplistic and like I don't know how the bus works, but from my day job I know how explaining things to people and taking notes can be tricky to get a point across and some times the best way is just to be simple.

I happen to have spare accumulator for Clapton type so if it is blown I can change it, it recharge again and check to see if there is any other issues.

If it turns out to be more then the accumulators, I want to be already have a plan in place for a truck to ship iit and to know where it's being shipped so I can act straight away, so I'm not scrambling to find details on farm that has little phone signal and no internet.

Re: Brakes failed - Thankfully before I moved her!

You should not be able to squash hydraulic low pressure hose regardless of flow. The hose is either life expired or more than likely not hydraulic hose. Hose deteriorates internally with age reducing the bore and thus restricting flow. The high pressure hose illustrated is known to suffer from this condition. This will cause the Plessey pump to run hot.

At present we suspect that the vehicle has lost pressure in an accumulator, but not which one, or whether both are affected. While it is possible to diagnose this using the test switch, it is not unknown to find that the microswitches have been connected to the wrong circuit. Since you have the three test gauges then this is an ideal opportunity to put them to use and discover what test results mean without the stress of a roadside incident.