Saracen accumulators - changing/rebuilding

[trophy160]

Right, I've got my cylinder of nitrogen, regulator and a spare accumulator (plus seals to rebuild the others). I'm pretty sure I have at least two accumulators that don't hold pressure that long so I want to swap one with my spare and remove/refurbish the other one.

 

My question asked in total ignorance is (once I have dropped pneumatic and hydraulic pressures) when I swap out an accumulator, i.e. broken into the hydraulic system do I then have to bleed the hydraulics to that accumulator. Sorry if it is a really dumb question.

 

thanks

Nic

[robin craig]

Nic,

 

The only dumb question would be not to ask, this is a hugely smart question. Your safety is always primary.

 

Others will chime in soon, I dont know

 

R

[Hoseman]

Nic,

 

The only dumb question would be not to ask, this is a hugely smart question. Your safety is always primary.

 

Others will chime in soon, I dont know

 

R

Hi mate

I'm a hydraulics engineer, depends on your system. Most modern one's are self bleeding, just run them up for 5 min to warm up and get things circulating then operate slowly. What does that system control?

Is it a Single Acting system or Double Acting? Ie . . Brakes are single acting ( no return to tank line, just primary pressure line) or wheel drive motor will be double acting Bi-Directional, meaning it can move in both directions.

Does it operate a hydraulic cylinder or drive motor?

 

Paul

[trophy160]

Hi mate

I'm a hydraulics engineer, depends on your system. Most modern one's are self bleeding, just run them up for 5 min to warm up and get things circulating then operate slowly. What does that system control?

Is it a Single Acting system or Double Acting? Ie . . Brakes are single acting ( no return to tank line, just primary pressure line) or wheel drive motor will be double acting Bi-Directional, meaning it can move in both directions.

Does it operate a hydraulic cylinder or drive motor?

 

Paul

 

Hi Paul,

 

All I can tell you is that there are three circuits (accumulators) two of them are for brakes and the third is for steering. I have attached the hydraulics schematic here, not sure if there is enough information for your question to be answered.

 

[robin craig]

Hopefully Nic from the Cold War Collection will come along and comment soon

 

R

[Richard Farrant]

Hi Paul,

 

All I can tell you is that there are three circuits (accumulators) two of them are for brakes and the third is for steering. I have attached the hydraulics schematic here, not sure if there is enough information for your question to be answered.

 

 

 

Hi Nic,

When you refit the accumulators, the oil side can be bleed at the adjacent check point on each pipe, No. 4 on your diagram. You may need to make up a little pipe to do this as it is the point where pressure checks are carried out, the cap is removed and fitting released slightly to open up. Without a pipe you might get a soaking! Obviously, this is done with engine running and there will be little air in the system.

 

regards, Richard

[Cold_War_Collection]

Hi Nic,

When you refit the accumulators, the oil side can be bleed at the adjacent check point on each pipe, No. 4 on your diagram. You may need to make up a little pipe to do this as it is the point where pressure checks are carried out, the cap is removed and fitting released slightly to open up. Without a pipe you might get a soaking! Obviously, this is done with engine running and there will be little air in the system.

 

regards, Richard

 

Sorry for the late reply! I was pulling a cooling system out of a Goat (less fun than it sounds!!), anyway, yes, I agree with Richard about the process. The little tubes that you can make up and place on the bleeders are a very good idea, as there is considerable pressure

 

have fun!

 

Nick

CWC Canada

[Hoseman]

Sorry for the late reply! I was pulling a cooling system out of a Goat (less fun than it sounds!!), anyway, yes, I agree with Richard about the process. The little tubes that you can make up and place on the bleeders are a very good idea, as there is considerable pressure

 

have fun!

 

Nick

CWC Canada

Hi

Yep,schematics are ok, nice and basic, way I like them . . !!Lol

As mentioned,run engine to build up system pressure, make sure you got your tube on test points as mentioned handlers out air,just like bleeding brakes on car. Obviously put tube into a container otherwise you will oil the inside of your hull!!! Without seeing the system I think operating that relevant system while bleeding would help get rid of air in system,but ask the relevant experts first as I am not familiar with these!

Have fun

 

Paul

[Richard Farrant]

Hi

Yep,schematics are ok, nice and basic, way I like them . . !!Lol

As mentioned,run engine to build up system pressure, make sure you got your tube on test points as mentioned handlers out air,just like bleeding brakes on car. Obviously put tube into a container otherwise you will oil the inside of your hull!!! Without seeing the system I think operating that relevant system while bleeding would help get rid of air in system,but ask the relevant experts first as I am not familiar with these!

Have fun

 

 

 

With respect, I am experienced in Saracens, having worked on them since the Seventies. I would not post up on an issue such as this unless being very familiar with the equipment. The braking system is unlike any car, and has a hyd pump producing constant pressure. The brakes or steering do not have to be worked to bleed air if only the accumulator is removed and refitted, due to this circuit being the constant pressure one.

 

regards, Richard

[trophy160]

Thanks everyone for your help. I've pressurised my spare accumulator which looks like it has been rebuilt, to check that it holds pressure for a reasonable time. If it looks OK, I'll then swap this one out first. I'll take a peek under the check point caps tomorrow to see what sort of pipe I need to make up. Just one final question, is it always necessary to bleed air out? The reason for asking is that I was reading about changing accumulators on the Routemaster earlier today, I understand that it has a generally similar accumulator set up to the Saracen and the author commented that these were self bleeding in most instances.

[Richard Farrant]

Thanks everyone for your help. I've pressurised my spare accumulator which looks like it has been rebuilt, to check that it holds pressure for a reasonable time. If it looks OK, I'll then swap this one out first. I'll take a peek under the check point caps tomorrow to see what sort of pipe I need to make up. Just one final question, is it always necessary to bleed air out? The reason for asking is that I was reading about changing accumulators on the Routemaster earlier today, I understand that it has a generally similar accumulator set up to the Saracen and the author commented that these were self bleeding in most instances.

 

Hi Nic,

What I stated re. bleeding is from the EMER, but to be honest you will loose very little oil if you remove the pipe from the accumulator and plug it and any small amount of air will do on harm in this line and no more than the air from a leaking seal within an accumulator.

[trophy160]

Thanks Richard, that all makes very god sense

[Grasshopper]

Having changed numerous Routemaster accumulators in a previous career, I don't recall bleeding them afterwards but we did pressurise (run up the engine until the relief valve cut in) and discharge (shut off engine and pump brakes until the brakes no longer worked) the system a few times after the job.

[datadawg]

To jump on this thread and hopefully I'm not hijacking it b/c of its age, but I am buying a Saracen in UK and having it overhauled by Baz from Trackfix. Are the accumulators something that should be serviced? I am an absolute virgin with Saracen and don't want to get it to US to find problems. On the other hand, I'm paying per hour, so don't want to do unnecessary work. Any thoughts would be appreciated.

[Starfire]

Easy way to test - charge 'em up and then check them in a month or so. If they're still holding (most) of their charge, they should be fine. Don't forget that they should be checked and topped up regularly - no hydraulic pressure on a Saracen means no brakes!

 

Cheers,

Terry

[datadawg]

Easy way to test - charge 'em up and then check them in a month or so. If they're still holding (most) of their charge, they should be fine. Don't forget that they should be checked and topped up regularly - no hydraulic pressure on a Saracen means no brakes!

 

Cheers,

Terry

 

I take it there is no PSI gauge to warn of pressure loss? So how does one check them and top up the contents (nitrogen??).

[Starfire]

The procedure is detailed in the user handbook, workshop manual and service schedule but the short version is to relieve any hydraulic pressure (by working the brakes/steering without the engine running), and then pump them up to ~550 PSI with dry air or nitrogen.

 

As a new Saracen owner, the first thing you will need is manuals. Get all of them that you can find. I can send you a digital copy of the service schedule (PM me your email address), but I don't have soft copies of the others.

 

Cheers,

Terry

[datadawg]

The procedure is detailed in the user handbook, workshop manual and service schedule but the short version is to relieve any hydraulic pressure (by working the brakes/steering without the engine running), and then pump them up to ~550 PSI with dry air or nitrogen.

 

As a new Saracen owner, the first thing you will need is manuals. Get all of them that you can find. I can send you a digital copy of the service schedule (PM me your email address), but I don't have soft copies of the others.

 

Cheers,

Terry

Thank you Terry, PM sent.