| Author | Message | ||||
     Chris Miller Prolific User Username: cjm51213 Post Number: 191 Registered: 5-2013 |
Hi Folks, Pump to ACV/Accumulator to Reservoir. This cycle is pretty clear. On the low pressure circuit, downstream of the reservoir is the master cylinder which controls one set of pistons on the rear calipers. This is pretty clear and apparently self-contained. On the high pressure circuit, downstream of the accumulator are the distribution valves which control the calipers, and the height control valves which control the ride leveling rams. This is also pretty clear. Now I see there are other parts, which are not described. There is the “Roll Restrictor Valve”, the “Solenoid Valve and Restrictors”, and the “Deceleration Conscious Pressure Limiting Valve". What do these parts do? This has become interesting because today, I had an accumulator pressure switch exception. I parked the car and when I returned, I had a spontaneous red warning light that appeared while sitting during the course of an hour. This is unusual. I could see that the fluid level was correct in the reservoir, meaning there was fluid in the accumulator. When I did the “pedal test” the level increased considerably, demonstrating that there had been fluid under pressure before I released it into the reservoir. So, in general everything was fine, except for the pressure switch and the red light. I thought about the problem, and I think my distribution valves need some attention. There are only two ways out of the accumulator – back through the ACV and forward through the distribution valves. The ACV was recently re-built and bench tested, so I have confidence in it, but the distribution valves are unexplored territory. I suspect that due to the heat, they leak and not only bleed pressure from the accumulator, but do so faster than the pump can replace the fluid and rebuild pressure, hence the persistent red light. Once I moved to the shade and the car cooled a bit, the light extinguished, and did not reappear. So, “rebuild the distribution valves” has been bumped to a higher spot on the list, but now I see these other parts and I have no idea what they do or if any of them might explain or contribute to what I saw. Can anybody tell me where the “Roll Restrictor Valve”, the “Solenoid Valve and Restrictors”, and the “Deceleration Conscious Pressure Limiting Valve" are described? Or can you tell me what they do? Thanks for the help, Chris. | ||||
| Brian Vogel Grand Master Username: guyslp Post Number: 972 Registered: 6-2009 |
Chris, The solenoid valve and restrictors are part of the height control system and are described in the part of the workshop manual that deals with height control. The solenoid valve is to control whether leveling is fast (when sitting still and loading or unloading the car) or slow (while driving). The restrictors, if memory serves, controls the rate of fluid return from the rams to the reservoir when they're allowing fluid out to lower the car. The "Deceleration Conscious Pressure Limiting Valve" is often called the G-Valve, is in the "rat trap" (the plumbing that's collected together and activated when the brake pedal is pressed), and is a primitive anti-lock mechanism. If memory serves the roll restrictor valve is part of the front height control system, but I may be wrong on that. If it is part of that system your car is unlikely to have it unless its a very early car. In any case, all of these are documented in Chapter G of the workshop manual for both the SY1 series cars and SY2 series cars. This is an instance where looking at both workshop manuals may give you more details. Brian | ||||
| Chris Miller Prolific User Username: cjm51213 Post Number: 192 Registered: 5-2013 |
Hi Brian, Yeah... The manuals. They don't describe what these things do. They describe how to remove, replace, renew, and inspect. Sometimes they describe tests. But they don't explain what they do, at least not section G of the manual I'm reading, which says "June 1968". I just looked through the whole thing, which is where I got the names for these parts. However, you have explained them very well, and I have learned that one is height control, so not germane to my current project, one is probably not on my car, but is on the '66 cadaver car, and one is going to be part of the whole master cylinder/distribution valves overhaul. Thanks very much for the help, Chris. | ||||
| Bob uk Unregistered guest Posted From: 94.197.122.92 |
The distribution valves are very reliable. They cost £600 each used. There are no spares available. They are meant to leak slightly to lubricate and protect from corrosion the spool piston. These must not be dismantled because the front seal which cannot be removed will be damaged. The leak from the valve if wiped away will appear soon. It will drip onto the rat trap lid. But should not be enough to drip on the floor. The ride height is permanently switched on and if the rear springs are weak then the ride height will suck pressure from no 2 even with battery disconnected. I suspect that the system is fine as it is. The ride height constantly working will not damage anything and will exercise the rams which will prevent failure. Biggest killer of hydraulics is lack of use. There is no hydraulic or mechanical connection between the brakes and the ride height. Except the No2 pressure supply. (Message approved by david_gore) | ||||
| Brian Vogel Grand Master Username: guyslp Post Number: 974 Registered: 6-2009 |
Chris, If the appropriate section of the Workshop Manual doesn't include a "System Operation" section then my suggestion is always to go to the Tee-One Topics Master Index to find articles on the thing in question in one of the issues in the RROC-Australia Tee-One Topics Archive. Also, a search of the forums often reveals your question (for any you) has been answered many times in the past. I do this even before looking at Tee-One Topics (and I'll take this opportunity to thank Bill Coburn prodigiously and again). Brian | ||||
| Bob uk Unregistered guest Posted From: 94.197.122.92 |
Roll restrictor valves are only fitted to cars with front ride height which my car does not have. Solenoid valve sends fluid to the ride valves which opens up the valve more to give slightly faster than quite slow lift. The solenoid is energized by park and drivers door open or park only I think. The ride valves have four ports in ram return and signal pressure from the solenoid. There are two restrictors not roll ones, one is upstream of the solenoid valve and the other is in the solenoid return pipe. I have found that because every bit has a return the ride height system will more or less bleed it self once activated a few times. To bleed load boot car lifts in about five minutes open ram bleeders car drops and that will do and any small slugs of air will find the return wwhile driving. On my car I found bleeding every last scrap of air from ride height used lots of dot. I never reused fluids. (Message approved by david_gore) | ||||
| Bob uk Unregistered guest Posted From: 94.197.122.76 |
It is important to note that removing the brake valves may upset the settings in the rat trap. The three hoses to the ride height are signal, pressure and return. These never get changed and ate often why systems are slow and difficult to bleed. (Message approved by david_gore) | ||||
| Bob uk Unregistered guest Posted From: 94.197.122.84 |
Chris, I wrote the 3 posting above quick because my bedtime is you getting up time. And I feared you was about to mess about with the brake valves. If you go back about a month I wrote a posting called brake valves, read that and digest Important if the ride height is working ok then do not fix what is not broke. So far the Work you have done is the easy simple stuff. The ride height is a step more complicated. Before go any further you must read and understand chapter g. RR brakeology. Don't think that you can just Work on this system without the knowledge because otherwise you can easily cause lots of problems. I suggest that you go to the circuit schematic in the bible chapter g. There are two schematics. If the master on your car is connected to the top larger pistons. Then the early circuit is the one. Draw the circuit out on A3 paper in colour using felt tips. I have AutoCad so mine is better than RRs. It is laminated. By the time you have drawn this out you will know how it works. Use RR colour codes. This system is meant to be slow and there are no adjustments for speed. I repeat you must not work on the system until you know how it works because mistakes have been made by trained personal and valves have been expensively damaged beyond repair. I have read the bits many times. I know that you haven't because of calling these parts mysterious. READ CHAPTER G IN FULL (Message approved by david_gore) | ||||
| David Gore Moderator Username: david_gore Post Number: 1438 Registered: 4-2003 |
Some years ago, Tord Samdal, a Norwegian member of the UK RREC devised a model of the Shadow Hydraulics system and published it for the benefit of those needing to understand the system. It is my understanding Tord approved publication of his work with attribution and accordingly, I have attached the file below:
If you click on the file, you will get a message to save the file as hydraulics-16176.unk. Save the file to an appropriate location and rename it hydraulics-16176.exe. For those who may be concerned, I have virus and malware checked the file with no adverse results as well as having it run on my computer many times over the years without any problems. Run the file as normal and the system schematic will appear, do the brake pump test until the accumulator pressure drops to zero and then start the engine and play to your heart's content. | ||||
| Chris Miller Prolific User Username: cjm51213 Post Number: 199 Registered: 5-2013 |
Hi Bob, I'm in the middle of some measurements and experiments, the outcome of which will help me determine my next steps. I'll have some questions and remarks on your three posts after I have completed this. I'm pretty sure that I have one ride leveling ram that is not working because yesterday I took my staff out to lunch and I noticed in the parking space that the '72 was listing a bit to starboard. This is either a failure to sense correctly, or a defective ram and this is one of the assessments I need to have before I decide what to do. Hi David, I am a fan of this web site: Hydraulic System. Your presentation is downloadable for me, and pretty clear. I'm not sure what the component is on the yellow line, downstream of the distribution valves, between the fore calipers and the aft calipers. I'm not yet familiar enough with the ride leveling system to understand it very well, but this animated diagram is pretty helpful. The site I referenced has the drawback that it uses multi-image video animation and I can't stop the animation long enough to compare the states shown, however I have gotten some useful advice from it nonetheless. The benefit is that it is showing the internal workings of the hydraulic components, like the ACV, ride leveling rams, the some of the other valves. Thanks for the help, Chris. | ||||
| David Gore Moderator Username: david_gore Post Number: 1439 Registered: 4-2003 |
Chris, If the item you are referring to is the component tilted at 45deg on the RHS of the distribution valve just above the Green dotted line leading to the rear calipers - this would be the Pressure Limiting Valve located immediately behind the master cylinder on the rat trap body however this should be on the Low Pressure circuit [Green] for Shadow 1 vehicles; I do not recall it acting on the high pressure circuit or the inclusion of a similar valve in the high pressure circuit of the Shadow 1 series. This may be a mistake that was not picked up by us when Tord was working on this schematic. | ||||
| Chris Miller Prolific User Username: cjm51213 Post Number: 202 Registered: 5-2013 |
Hi David, Yes. I agree. I think that is what it is supposed to be. I was surprised, because as an "anti-lock" device, I would have expected to see it on all wheels, not just the rear wheels, and only on one set of calipers, at that. My other diagram also shows it downstream of the distribution valve on the rear wheels, which means that 1) it is on a high pressure line (distribution valve) and 2) it is on the forward accumulator (rear wheels). Apparently this move from low-pressure to high-pressure was a modification that happened around serial number 1899. Thanks for the help, Chris. | ||||
| Bob uk Unregistered guest Posted From: 94.197.122.79 |
Dave, The g valve is in series with the upper larger pistons on all cars. Early cars the master was connect to g valve and then big pistons. Later cars the master goes to small lower pistons. The g valve is always big piston. The schematic in Chapter G is bad because the colours are so muddled around the solenoid valve. I have a better one which has many colours make makes things very clear. And the circuit is very simple. Chris, The height valves are connected to the suspension by 2 inch long rods. These are adjusted to get the height correct. These are easy to adjust. Do not turn control shaft in ride height valve because it can be come disengaged inside. I think the shaft has a flat on it. So compare the ride valves to each other. If one side is working then it must be the height valve. Also on the rear inner seal are each side bleed nips for the rams. Load boot with 50kg of whatever, a person will do or water. Wait 5 mins for car to rise. Open nipple and car should drop. If light comes on start engine. Doing this will not damage anything. The rams can leak which is about all that can go wrong with rams. Dot running down the damper. Read my sticky rams post. You said car parked for an hour. If someone is in the car the movement of the car will cause the ride height to suck pressure. The 3 hoses are common to both sides. The ride valves are as complicated as the acv. With addition of signal pressure extra bit. It might just be the links. RR brakeology manual. What happens is that the system is slow so people don't give the system time and when nothing happens they leave the adjusters where ever they gave up. And or they have turned the valve ccontrol shaft and it is disengaged. Advice from others needed. Correct level is sill trim in line with wheel centres. Front system is virtually useless and not needed. If the front is not leaking then leave alone. (Message approved by david_gore) | ||||
| Bob uk Unregistered guest Posted From: 94.197.122.80 |
Chris, The g valve is NOT a antilock device and thinking it as such will confuse your thinking of the system. Inside the is a ball rolls forward and cuts pressure to half the caliper so that when under heavy braking the back doesn't slide. In slippery conditions the brakes will lock if heavy footed. Although people call it a antilock gizmo. It isn't which is why it is on rear wheels only. Lots of cars including American have similar before ABS was invented. (Message approved by david_gore) | ||||
| David Gore Moderator Username: david_gore Post Number: 1440 Registered: 4-2003 |
IMHO the correct description of the "G valve" is "Pressure Limiting Valve" as this is all it does using gravity to activate and deactivate restriction of fluid pressure to the rear calipers. Very helpful in minimising the back of the car overtaking the front on wet roads...... | ||||
| Bob uk Unregistered guest Posted From: 94.197.122.92 |
Deacceleration pressure limiting valve. Dave, My understanding is that it does two things that have more or less the same effect. The first is if the pedal is stamped then the pressure will spike and the fast rise will force the ball in to the seal and limit the pressure. The other is that if the pedal is pushed down slowly and heavy as in last minute braking from quite fast then the ball will roll forward and limit the pressure. I use g valve because it is easier to write on a mobile. Found some good photos of cycle guards I made for a rolling chassis road test. (Message approved by david_gore) | ||||
| Bob uk Unregistered guest Posted From: 94.197.122.71 |
Dave, I called it a g valve because my understanding is that the valve is angled and the ball inside rolls forward up hill under braking. If a sudden pressure spike occurs such as emergency braking then pressure will snap the ball on to the seat and cut pressure to zero to the big pistons leaving master only on rear wheels So I think the deceleration bit in the name is the g bit. This g pressure conscious valve is about the best of its type. Because it senses both g and pressure. Where as other ones only do one or the other. The more this system is examined the more I realize how good it is. (Message approved by david_gore) |
Tord Sandal Hydraulic Simulator Description
Tord Sandal Hydraulic Simulator Programme