R Cubed Posted November 5, 2007 Share Posted November 5, 2007 Hi all, need some technical help regarding spool valves and relief valves etc on a hiab type crane........... Eagerly awaiting Quote Link to comment Share on other sites More sharing options...
N.O.S. Posted November 5, 2007 Share Posted November 5, 2007 Can you explain the nature of your problem? (It's a Health and Safety and Lifting Equipment Regs minefield out there :shake: ) Quote Link to comment Share on other sites More sharing options...
R Cubed Posted November 5, 2007 Author Share Posted November 5, 2007 Ok, bought a small truck crane 6 foot tall with hydraulic slewing and one main arm which stows straight down and raises on a ram to a horizontal position or where ever you want it, then 2 hydraulic extensions which push out from the main arm. Problem none of the hydraulics seem to work when the leavers are moved, have a combined resevoir/12volt motor/pump unit and a 3 leaver spool block, have fluid in tank and getting flow back to tank, pump will generate 150 bar in to a dead end before its relief valve opperates, when flow and return hoses connected to spool block get flow back to tank when pump runs but also when any one of the levers are moved I still get flow back to the tank, shouldn't the return flow stop as it is directed to the appropriate ram by the said leaver :dunno: AggHHHHHHH Quote Link to comment Share on other sites More sharing options...
N.O.S. Posted November 5, 2007 Share Posted November 5, 2007 shouldn't the return flow stop as it is directed to the appropriate ram by the said leaver :dunno: Yes. Sounds like you have tested the relief valve built into the pump unit. Often (and almost always on a crane installation) a spool valve block will have a relief valve combined, at the input end - you need to check this. If not, is there another seperate relief valve anywhere? Is the spool valve housing one casting, or assembled with seperate spools bolted together? Make? (Kontak by any chance?) Quote Link to comment Share on other sites More sharing options...
R Cubed Posted November 5, 2007 Author Share Posted November 5, 2007 Yes. Sounds like you have tested the relief valve built into the pump unit. Often (and almost always on a crane installation) a spool valve block will have a relief valve combined, at the input end - you need to check this. Good point, yes there is one right by the input to the block, I have had it out and all seems to be ok, but off hand I can't think of how to test it as when I opperate any of the leavers I still get flow back to the tank, something wrong there I think !!!!!!!!!! If not, is there another seperate relief valve anywhere? No Is the spool valve housing one casting, or assembled with seperate spools bolted together? Make? (Kontak by any chance?) The block is one casting, can't see a make, I can do some pics tomorrow night of the bits. Quote Link to comment Share on other sites More sharing options...
N.O.S. Posted November 7, 2007 Share Posted November 7, 2007 Just a thought - Even if relief valve is u/s, if you take off a ram pipe from the first spool after pressure inlet and work that spool, oil should flow. If it does, then hopefully problem is relief valve. But if nothing at all comes out - Are you absolutely certain the system is piped up correctly? A lot of spool valves have 1 inlet (marked with a P on casting) but 2 outlets (marked T), one by P end, other at far end. Just a chance you have got pressure going into a T by mistake?? If you need a relief valve cartridge, you will need to know what make/model or even just a part number from the relief valve as a starting point. How old is it? Try http://www.grouphes.com (Hydraulic Equipmenmt Supermarkets near Stroud) Tel. 01452 730774. Very helpful guys, if you can give them a make or number they should be able to fix you up, cost should be about £20 - 40 plus vat and post for cartridge). Should come pre-set at about 170 bar, which will mean your pump relief valve will be doing all the work - might want to adjust it so spool valve one is the limiter? Cartridge usually has o-ring seal at base - you removed the cartridge so was o-ring ok? If you cannot identify valve, you'll just have to take it to someone who can :dunno: local hydraulic supplier? Quote Link to comment Share on other sites More sharing options...
R Cubed Posted November 7, 2007 Author Share Posted November 7, 2007 Not sure if relief valve on spool block is any good looks like it was ok when I took it out, all O rings etc ok and was seated on its base and valve part shut !! flow and return hoses are correct as there are "IN" and "OUT" words cast in to the block one at each end and also an arrow pointing from in to out, which is how I am running it ! About taking a ram pipe off the spool block you are right when leaver is moved there is oil flow from that connection on the block but not at any great pressure also there is still flow back from the return hose on the out point of the block, AGHHHHH there is only 1 "IN" connection ( top left ) but there are 2 "OUTLETS" ( bottom right ), one in use, the other is capped off, I assume these are just linked internally ?? The spools themselves will hold the rams under weight so they seem to work ok but can not work out why when a leaver is opperated there is still flow to the tank !!!!!!!!!!!!!! The red eyeball valve with small steel tube round the back of the ram hoses, I think is an emergency bypass valve to allow flow from inlet to outlet.. See attached pic please. Quote Link to comment Share on other sites More sharing options...
Richard Grosvenor Posted November 7, 2007 Share Posted November 7, 2007 I'm not an expert on hydraulics by any means but have you tried operating/closing the red valve while operating the spool valves? Maybe it could by some sort of safety device in so much as you have to use two hands to operate the crane. :dunno: Richard Quote Link to comment Share on other sites More sharing options...
R Cubed Posted November 7, 2007 Author Share Posted November 7, 2007 Yes I have tried that and it seems to make a bit of difference but not much only a slight note change in the pump but still not enough pressure to do anything with the rams, I will have to have a better look at the spools at the weekend ............. Quote Link to comment Share on other sites More sharing options...
Richard Grosvenor Posted November 7, 2007 Share Posted November 7, 2007 Hmmmmm...... I don't know then. I've got an old digger that fits on the back of a tractor and that has weird hydraulics, to slew you have to be using one of the other functions at he same time. I wondered if yours might me similar. There's no mechanical locks on the arm is there? Richard Quote Link to comment Share on other sites More sharing options...
R Cubed Posted November 7, 2007 Author Share Posted November 7, 2007 No mechanical lock all rams are free to move, there is one spool valve for each ram so it should be one for one but then it does not seem to do what it should :angry: :angry: Time will tell once I get it a bit more appart..... Quote Link to comment Share on other sites More sharing options...
N.O.S. Posted November 7, 2007 Share Posted November 7, 2007 Haven't you got a nice simple problem we can help you with? :whistle: The bypass valve is a bit odd - could be some form of pressure "carryover", used when you need to use full pressure in another valve (e.g. for winch) beyond the spool valve. Trouble is most valves like this are not designed to "carry over" pressure without special adaptors, if you do, a gallery between pressure and return side in the spool valve casting may break resulting in the symptoms your valve is showing. This bypass valve looks like it might be a bodge attempt to do this :shake: Can't think what other purpose it would be for :dunno: On the other hand, connecting these two ports may be the proper way for this make of spool valve :dunno: This bypass valve should most certainly be SHUT when operating the crane. Reckon this might have caused your trouble :-( If when it is shut (assuming it is not bxxxxxxd up) there is still quite a it of oil in return pipe when you take a pipe off and operate a spool, almost certainly the valve casing is split internally. The centre spool has an extra block on top - If this is the slewing spool they are "cross line relief valves", to prevent anything bursting should the crane arm be knocked sideways (by allowing oil to move from one side of slew to the other without going through spool). Sorry, but can't help much more with info to hand. Quote Link to comment Share on other sites More sharing options...
R Cubed Posted November 8, 2007 Author Share Posted November 8, 2007 <qoute> Haven't you got a nice simple problem we can help you with? :whistle: Yea can I have a new spool block :-D This weekend I am going to strip down the spool block and remove all the hoses and test through the valve block, dont rearly want to remove the spools yet..... Dont seem to have problems with the actual rams as I can bodge them and they work ok. The block on top of the centre spool is for the 2 telescopic extensions !!! so dont know why this would be on that, hoses connected wrong maybe, the slewing is achieved by a motor and worm gear to rotate a larger gear on the main upright, this is the far right spool, Far left spool is for the main arm ram and the middle spool is for the 2 extensions as in the pic. Quote Link to comment Share on other sites More sharing options...
N.O.S. Posted November 8, 2007 Share Posted November 8, 2007 the slewing is achieved by a motor and worm gear to rotate a larger gear on the main upright Motors do not like normal spool valves which totally shut off oil when closed - can get a high pressure spike 'cos motor is still turning and trying to overrun. A motor spool is normally open centred (i.e. both lines to return line), but allows creep, so no good for this application. I suspect this shock valve unit is intended to work as a cushion valve for the motor, whilst preventing creep. Cannot think it would serve any useful purpose on the extension rams unless it is to limit max. pressure (why?). The crane looks good, well worth the cost of a new spool valve if you have to, but lets hope not. A bit of o-ring stuck in a valve might be all it is :whistle: If you cannot move rams, spools themselves should be fine. If you do need to spec up a new valve, you'll just need to know if spools are 3/8"BSP or 1/2"BSP size (look like 3/8, fair bit cheaper) to enable you to get a quote - my guess new is £150-300 from HES, but they sometimes have really good offers on, which I've taken advantage of in the past. Fingers crossed! Quote Link to comment Share on other sites More sharing options...
Richard Farrant Posted November 8, 2007 Share Posted November 8, 2007 <qoute> Haven't you got a nice simple problem we can help you with? :whistle: Yea can I have a new spool block :-D This weekend I am going to strip down the spool block and remove all the hoses and test through the valve block, dont rearly want to remove the spools yet..... Dont seem to have problems with the actual rams as I can bodge them and they work ok. I am looking at your picture of the whole crane and reckon I may have the answer. Have you connected the electrics up? It will not operate until the electric solenoid valve is activated. Richard Quote Link to comment Share on other sites More sharing options...
N.O.S. Posted November 8, 2007 Share Posted November 8, 2007 I am looking at your picture of the whole crane and reckon I may have the answer. Have you connected the electrics up? It will not operate until the electric solenoid valve is activated. Richard Trust you to be first to see the obvious :rofl: :rofl: :rofl: :rofl: And there was me begining to think it might be something simpler, like the strap holding it back :whistle: Quote Link to comment Share on other sites More sharing options...
Richard Farrant Posted November 8, 2007 Share Posted November 8, 2007 Trust you to be first to see the obvious :rofl: :rofl: :rofl: :rofl: And there was me begining to think it might be something simpler, like the strap holding it back :whistle: Ah well, I was just waiting to see the whole picture............if you see what I mean :-D Richard Quote Link to comment Share on other sites More sharing options...
N.O.S. Posted November 8, 2007 Share Posted November 8, 2007 Well, if that's the sort of wisdom that age endows you with, "Bring It On" :-D Quote Link to comment Share on other sites More sharing options...
R Cubed Posted November 9, 2007 Author Share Posted November 9, 2007 :goodidea: :goodidea: :goodidea: :goodidea: Nice one I will wire up the electrical bits and bobs now they are disconnected and in the garage and I never thought of taking the strap off....... Typical me always goes for the most complicated first... We will see what the weekend brings. Thanks for the help R3 Quote Link to comment Share on other sites More sharing options...
R Cubed Posted November 30, 2007 Author Share Posted November 30, 2007 Update..... I have used another spool block, and the crane itself works fine, so no problems there. The red valve, links the main inlet of the block to the outlet of the block ? also the handle was in the wrong position in relation to the position of the opening in the ball, this is now disconnected and the ports on the block caped off. I have stripped the original spool block down, all spools are unworn and free to move, no chips or marks on them, using an air line at low pressure to test the block I get flow from main inlet of block to outlet side when all levers are in neutral ( centred position ). When a lever is operated the flow stops and does not exit through the actuator port ( A ) ! the other port ( B ) is vented to tank as you would expect, this is the same for all levers in all positions ? Agggghhhh whats going on....... The centre spool with the extra block on the top of it as in the pic, I have removed and there are 2 inlets on the bottom, A and B and 2 outlets on the top A1 and B1, there is at each end of the block what looks like adjustable nuts, ( to adjust pressure ) ? but there is no flow through it from A to A1 or to B1 or B, and vice versa ?? using low pressure air line, what is this for and how does it work ? can someone explain ? I will investigate more this week end if the rain stops...... Quote Link to comment Share on other sites More sharing options...
N.O.S. Posted December 1, 2007 Share Posted December 1, 2007 The centre spool with the extra block on the top of it as in the pic, I have removed and there are 2 inlets on the bottom, A and B and 2 outlets on the top A1 and B1, there is at each end of the block what looks like adjustable nuts, ( to adjust pressure ) ? but there is no flow through it from A to A1 or to B1 or B, and vice versa ?? using low pressure air line, what is this for and how does it work ? can someone explain ? These, as explained earlier, are most likely pressure / flow control valves of some sort. 1) for cushioned slew protection (cross line relief), If the crane boom is knocked sideways (or when slewing the crane a heavy swinging load tries to keep it turning when spool is suddenly closed), the spring controlled relief valve will resist oil flow (and hence movement of boom) up to the preset pressure only. Above that, the valve will lift, allowing oil to flow possibly from A1 to B1, and thus the boom will be able to swing sideways a little, rather than bend / break something. One valve controls flow A1 to B1, other valve controls B1 to A1. In order to work they require a certain pressure in the oil line from spool to build up before allowing normal flow to service, hence apparent blocked line A to A1 when using airline. 2) for slewing lock and movement precision (in line) Another possibility, is that these are intended to act as a pressure restriction for the slewing motor movement. The slew motor will not behave like a simple slew ram (which will instantly stop when spool is shut) - instead it will slow to a stop, and can also allow creep slowly if crane is not absolutely level, thus giving an imprecise response to slew commands. By requiring a pressue valve to be overcome before oil can flow (e.g. from A to A1 and from B1 to B), it may be that the motor (depending on type :dunno:) becomes more like a ram in response, i.e. much crisper movement and resistance to creep. 3) hose rupture check valve (in line) If hose bursts e.g. between pump and spool valve, the boom might fall sudenly. The valve (in cartridge form behind hex plug) permits a certain oil flow but if greater flow occurs then it "locks out". These valves also require a back pressure to work correctly, again an airline might not be enough to overcome this minimum setting to allow flow. 4) pressure limiting valves Where presure to service should be limited below relief valve setting. Any excess is dumped to tank via cross line. Unlikely to be these, as no back pressure required, so air flow would be A to A1 no problem. As to trouble with main spools, what happens to air flow when spool is operated in other direction? ?Could be spool and housing is assembled back to front. ?Might be wrong spools in block (e.g. single acting spool in double acting block). ?Might be a Closed Centre unit (where pump builds up max pres. in spool valve line and then stops pumping, when you operate a spool the pressure drops and pump starts flow - older John Deere tractors (1970's / 80's) were all like this, but not commonon application on truck cranes). I can't help anymore without playing about with it - why not ask Santa for a new spool valve assembly ;-) Quote Link to comment Share on other sites More sharing options...
R Cubed Posted December 2, 2007 Author Share Posted December 2, 2007 These, as explained earlier, are most likely pressure / flow control valves of some sort. Ok I think I have got that bit. As to trouble with main spools, what happens to air flow when spool is operated in other direction? The same thing happens, flow to respective spool stops, no flow out from ram connection and the return from the ram connection to tank has free flow? Could be spool and housing is assembled back to front? I did think of that but it does not seem to have been disturbed ever. ?Might be wrong spools in block (e.g. single acting spool in double acting block). Is a possibility but dont think so. ?Might be a Closed Centre unit (where pump builds up max pres. in spool valve line and then stops pumping, when you operate a spool the pressure drops and pump starts flow - older John Deere tractors (1970's / 80's) were all like this, but not common application on truck cranes). Not closed centre as I get flow through the spool block when all valves are in their central position. I can't help anymore without playing about with it - why not ask Santa for a new spool valve assembly ;-) Thanks again with the helpful advice on this problem. Might need a new spool block, but I want to understand why this one does not work !!! Quote Link to comment Share on other sites More sharing options...
R Cubed Posted December 3, 2007 Author Share Posted December 3, 2007 Last update.................. I have got the spool block working, must have been the red valve with the handle in the wrong place, so eyeball was always a bit open, this has now been removed, I have refitted the spool block to crane and all works fine so I am now a happy bunny, just have to sort out a few of the finer points and it will be a well useful bit of kit, thanks for all the advice and especially the bit about removing the strap must have been that all along :-D :-D Merry Christmas ;-) ;-) ;-) ;-) ;-) ;-) ;-) Quote Link to comment Share on other sites More sharing options...
Tony B Posted December 3, 2007 Share Posted December 3, 2007 How about testing it lifting a certain landy out at Maidstone? :-D Quote Link to comment Share on other sites More sharing options...
R Cubed Posted December 4, 2007 Author Share Posted December 4, 2007 :dunno: Lifting it out of where ??? Quote Link to comment Share on other sites More sharing options...
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