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Accumulator cut out valve

A check of our accumulators has found the rear cut out valve is leaking fluid through a small hole the size of a match in the thin end of the valve. It's not corrosion, is there a breather hole?
Can this be repaired in situ or if not, does anyone know who can repair and/or supply a replacement. I tried Hebble, they don't do the valves...

My bus number (if any): RTL 960, RMC 1458, RM 1585 and several RTs

Re: Accumulator cut out valve

Sounds like the adjustment screw has fallen out of the end cap. With this missing if the valve has an internal leak then fluid will escape although I would expect other issues to be noticeable. Send the complete accumulator and COV to Imperial with a description of the fault.

Re: Accumulator cut out valve

Thanks for the reply Roy but no screw has fallen out, the hole isn't in the end cap

I have been told it could be a weep hole for fluid to drain off that has got the wrong side of the valve, which suggest dirt in the fluid perhaps which is quite possible or an internal problem in the cut off valve. Either way it will probably have to go to Imperial unless Mike Langley can look at it Thanks again

My bus number (if any): RTL 960, RMC 1458, RM 1585 and several RTs

Re: Accumulator cut out valve

Hi Brian,

I have a pair of rebuilt accumulators on the shelf if you are in desperate need of one.

My bus number (if any): RML2532

Re: Accumulator cut out valve

Thanks Roy, but accumulators themselves are Hebble overhauls and in good condition.

My bus number (if any): RTL 960, RMC 1458, RM 1585 and several RTs

Re: Accumulator cut out valve

Hello Mr Brian Watkinson.

Sorry for the 12hr delay in responding.

My original drawings of the Lockheed System don't show a bleed hole in existence but I would bet there is one.

The body of COV consists of a system of a valve stem, main sleeve, sliding valve, main sleeve & 2 sets of oil seals all wearable.

The vent or bleed hole will be a first warning that para 3 above is leaking oil from either the primary or secondary systems.

I would say age of the unit and not contaminated fluid is the problem.

I would also suggest setting up pressure test gauges and watch the readings too determine the severity of the loss of oil pressure.

Also a pressure check could prove that the COV adjustment has not been tweaked up a notch.

My bus number (if any): Ex LTE Bus Engineering

Re: Accumulator cut out valve

I've had overhauled unit that have leaked as soon as they've been put on a bus in the past. There is indeed a bleed hole.

Sorry to disagree Brian, but if the accumulator is leaking, then it's not in good condition.

My bus number (if any): RML2532

Re: Accumulator cut out valve

The tubes were overhauled not that long ago by a well known sub contractor Roy, who specialises in hydraulic equipment, and tested prior to despatch to us, but they don't apparently touch the cut out valves. The bus isn't used much and it seems ems the seals or sleeve in the valve may well have gone and it's also possible somebody may have interfered with the adjusting screw, the tubes itself is as new. It will probably go to Imperial, they overhaul them separately. Thanks for the replies.

My bus number (if any): RTL 960, RMC 1458, RM 1585 and several RTs

Re: Accumulator cut out valve

Very much the reason why accumulators should be overhauled by a company that DOES check the cut out valve or the non return valve. The cut out valve in particular controls the entire system. A bit like having a brand new tyre and not renewing the inner tube.

Re: Accumulator cut out valve

I've heard varying tales about who-overhauls what. I've not had dealings with Hebble so can't comment on them. I have had dealings with Imperial for a number of years now and have seen their workshops and watched various bits of kit being overhauled and tested.

I admit I have had problems with 2 or 3 accumulators over the years from them, and each time they've been replaced or re-done without question, even when one was well over the usual warranty date they give.

One was earlier this yer, a unit leaked air as it was fitted, replaced without question; one a couple of years ago leaked as Brian describes from the cut-out valve, that was changed without question, the other was so long ago I can't remember!

It really isn't worth just repairing half the unit, on a safety critical item like an accumulator or a foot valve, don't mess with them. I've tried overhauling one myself without much success. a lot of my work is abroad and the last thing I want is units failing abroad a short while after fitting them. There is no cheap option.

It's much like people who want gearbox parts. I won't supply any as I know that unless they know what they're doing the box will fail again soon after. Change the box for a factory recon unit. I know they're getting bloody expensive, the last couple I've had done were in excess of £1900, but they're done by a reputable firm, bench tested and should last along time..

My bus number (if any): RML2532