pugwash Posted September 28, 2007 Share Posted September 28, 2007 This has been touched on before but i haven't beeen able to work out the right answer. The PAS pump on the engine pumps at 2.7USgpm (just over 10l/min). To work out the size of the ram needed i guess you start from the speed required to turn from lock to lock (lets say 30 seconds). You then need to work out what length stroke on the cylinder you need- plus an inch for safety- which i presume is as simple as working out the length of the arc subtended by the movement of a point on the steering arm- the further out you are from the pivot point on the steering arm then the more power you have transmitted by the ram but the slower the ram moves. So at first i need to work out performamce curves for the steering arms. Now that i know how much stroke on the ram that needed, how do i work out the bore? is it as simple as working out the swept volume Lets say it's 1l- does this mean that if i have a 10l/min pump that as long as my steering box doesn't reduce the flow then the ram will sweep from one extreme to the other in 1/10 of a minute- ie 6 seconds? does any of this make sense to anyone? lets presume that i need a 10" (25cm) swept volume and i can have any bore i want. As i have a 10l/min pump what size bore is the best trade off between speed and power? of should i just buy a 1.5" bore and stop worrying? if i can fill this ram at 10l/min at 2000psi, how much power am i adding to the steering system and how can i compare the results to a non ram-assisted setup to make sure that i have chosen the right ram? one thing i seem to have taken absolutely no account of is the power drag from the power steering box- what am i missing? or does the ram assist basically take over steering duties? would anyone else be interested in 8-10" stroke rams which have jonny joint (or whatever they are called) ends and are double acting. Probably get them into the UK for about £90 in VAT and shipping i would have thought. any help and advice much appreciated. Quote Link to comment Share on other sites More sharing options...
Lewis Posted September 29, 2007 Share Posted September 29, 2007 would anyone else be interested in 8-10" stroke rams which have jonny joint (or whatever they are called) ends and are double acting. Probably get them into the UK for about £90 in VAT and shipping i would have thought. Whithout seeing the joint you are refering to I cannot say for certain, but you most probably mean a spherical bearing as this is what most rams are fitted with, not a jonny joint. £90 isnt a good price, I just ordered 2 x 8" stroke double acting rams for £48 each (cash sale - no VAT) Quote Link to comment Share on other sites More sharing options...
Astro_Al Posted September 29, 2007 Share Posted September 29, 2007 Am I reading this right? To work out the size of the ram needed i guess you start from the speed required to turn from lock to lock (lets say 30 seconds). 30 seconds lock to lock? So its going to take you 1 minute to turn the wheels to drive round a tree? Maybe I misunderstand, but that seems kinda slow... (Perhaps you can have a screen showing movies or something to keep the co-driver awake?) Length of travel is straightforward once you've figured where you want the ram and got your steering arms sorted. ...the further out you are from the pivot point on the steering arm then the more power you have transmitted by the ram but the slower the ram moves. So at first i need to work out performamce curves for the steering arms. No, the ram moves at the same speed, but the tyres turn slower. I'm sure you don't need 'performance curves' for the steering arms (what are you on about, moment arm increase with length of arm? - its gonna be a mighty dull plot!). What are you running - have you gone for custom hi-steer on the on the Mog knuckles? (Did you consider ackerman, or reverse ackmn. or just not bother?). Once you've got your beefy arms, just mock it all up and measure the distance. I suppose if you go wild on arm length and still place the ram on the axle body, or close, you're gonna introduce some noticeable non-linearity between ram movement (steering wheel input) and change in steering angle of the front wheels. So just keep it sane. The ram is providing the power, so you don't need huge arms. how can i compare the results to a non ram-assisted setup to make sure that i have chosen the right ram? Disconnect your ram and see the difference! Al. Quote Link to comment Share on other sites More sharing options...
dollythelw Posted October 1, 2007 Share Posted October 1, 2007 bear in mind..... as its a ram assist you have the volume of the PAS box to factor in as well single ended ram swept volumes are easy.. (bore surface area x stroke) - (rod surface area x stoke) = SV1, in the other direction it will be simply; bore surface area x stroke = SV 2 double ended rams are balanced and require the same fluid volume for both sides, single ended rams require more fluid in on direction than the other but in reality if your pump is shifting enough fluid it wont matter and lag wont be noticeable. in a perfect world the ram will be perfectly matched to the rod movement from the PAS box meaning you can pull the heim pin out and after moving the wheel the pin will just drop back in....... but thats not going to happen.. so dont tie your head in a knot trying to figure it out power from a ram = surface area x pressure (remember you will get more power in one direction than the other with a single ended ram) lock to lock times to calculate fluid requirements; I work on sub 2 seconds Lock to Lock, this just makes it crisp and mondo useful for 28 point turns, are you sure about the 2000psi bit? thats pretty high I agree with Lewis - you are being tucked up for your rams, try Steerforth - good value and they custom built anything you want. Ackerman isnt going to be affected by a ram assist - its is affected by full hydro or hybrid hydro setups. sorry if thats simplistic or teaching to suck eggs but Ive not had enough coffee yet Quote Link to comment Share on other sites More sharing options...
Bush65 Posted October 1, 2007 Share Posted October 1, 2007 ...power from a ram = surface area x pressure... No, that is force from a ram (although that may be what pugwash wanted). Power is pressure x flow or force x velocity. Pugwash, it is possible to modify the steering pump on a 300Tdi to improve the flow a little and increase the pressure (up to about 1500 psi). Increasing the pressure can help if the ram dia is a little small. Quote Link to comment Share on other sites More sharing options...
dollythelw Posted October 1, 2007 Share Posted October 1, 2007 eek - force was the intended, coffee intake insufficient during post Quote Link to comment Share on other sites More sharing options...
pugwash Posted October 1, 2007 Author Share Posted October 1, 2007 thanks for the replies chaps. Trying to work out the ram size needed when using an LS1 pas pump, a range rover box and a set of mog axles is not the easiest in the world! still got to tap my box yet- grrr Quote Link to comment Share on other sites More sharing options...
dollythelw Posted October 1, 2007 Share Posted October 1, 2007 still got to tap my box yet- grrr fnarrr what size tyres Jim? Quote Link to comment Share on other sites More sharing options...
pugwash Posted October 1, 2007 Author Share Posted October 1, 2007 undecided- 38.5 or 40 by 12 or 13 big enough to warrant the assistance and there is capacity to spare in the pump! Quote Link to comment Share on other sites More sharing options...
landrovermanuk Posted October 1, 2007 Share Posted October 1, 2007 Hi, I'm new to this so if I say/ask something stupid feel free to laugh...... I'm thinking of putting hydro assist on my 90. It's got pas and I'm running on 33x12x15s BFG MTs. The problem I've got is that the steering keeps going loose. The steering wheel has 3 or 4 inches of play in it. I had the steering stripped and rebuilt last year...I was told that nothing needed replacing but it was all loose. Now a year and 5000 miles later it's loose again. I was thinking of rebuilding and adding hydro assist... 1) What do people think about this? 2) Does any do a kit or is there a supplier I could ring and order all the parts from here or in the USA? 3) Please keep replies simple.... Thanks.... 3.9Efi Auto. Now fitted with winch bar and winch.... Quote Link to comment Share on other sites More sharing options...
GBMUD Posted October 2, 2007 Share Posted October 2, 2007 Hydro assist is not a solution for a worn steering box or other existing problems. With your tyres I would suggest a new steering box is the ideal solution from a value for money and practical perspective. Try an Adwest one for best quality. Chris Quote Link to comment Share on other sites More sharing options...
LandyManLuke Posted October 2, 2007 Share Posted October 2, 2007 I run 255/85R16 (33"x 10") with a standard adwest steering box and that's doing the job fine. the original failed about 3 years ago (when i was still on 205/80 tyres). Quote Link to comment Share on other sites More sharing options...
Bush65 Posted October 2, 2007 Share Posted October 2, 2007 thanks for the replies chaps. Trying to work out the ram size needed when using an LS1 pas pump, a range rover box and a set of mog axles is not the easiest in the world! still got to tap my box yet- grrr If power assist and not full hydro steering, use a 1-1/2" ram. My best guess for stroke is 8", but i don't have experience with mogs, so may be a little out there (I have considered the greater steering angle mogs have, but still a guess). Not necessary to tap the box. Use the bleeder port on top of the box for one line. Cut the hyd line that goes around the outside and fit a tee fitting for the other line. However if you tap the box, you can use larger fittings. Quote Link to comment Share on other sites More sharing options...
landrovermanuk Posted October 2, 2007 Share Posted October 2, 2007 Thanks chaps.... I did realise that I would need to sort out the exsisting steering first, I just thought hydro would make it last longer and add strength.... I'll try the Adwest box first though.... John Oh and thnaks for keeping it simple... Quote Link to comment Share on other sites More sharing options...
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