use power steering line to drive other components
use power steering line to drive other components
(OP)
Is it legal to use power steering supply line to run a hydraulic motor before entering steering gear on a bus? Or to split the line to run a hyd motor as for another option? I'd appreciate any helpful input here.





RE: use power steering line to drive other components
In the automotive world (I'm not so sure about buses) P/s pumps are selected by capacity, at a particualr speed, often idle.
If the pump is not big enough, or you divert some of the fluid elsewere, then typically your driver will experience 'catch-up', where the steering wheel goes very heavy as he turns it as the pump tries to catch up.
However, on some pumps there is a bypass, used when the engine is running fast and the steering isn't moving. This returns oil direct to the reservoir, Perhaps you could pick up that feed and use it for something else.
Messing with the steering makes me very nervous.
Cheers
Greg Locock
RE: use power steering line to drive other components
Power steering pumps are carefully matched to steering requirements, and on many cars, even with everything exacty stock, if you really get into it on tight winding roads, you can easily get ahead of the PS.
I have also had experience replacing a power steering box from an identical model designation (bothToyota Soarer MZ20), but slightly newer car (1988 vs 1989).
I found that I also needed to swap pumps to overcome heavy steering while parking and catch up when cornering.
Regards
pat
RE: use power steering line to drive other components
RE: use power steering line to drive other components
Three types of setups I know of people using:
From the bypass on the PS spool to the motor spool on the winch to reservoir. It is simplest method but can overheat the fluid when winching + steering. The other problems listed above can occur too.
On some vehicles a flow priority valve is installed to shut the flow to the winch off immediately when steering occurs, there would be 2 returns to the reservoir
Last some people use are a simple selector to choose PS or winch operation.
I hope this helps.
Ken
RE: use power steering line to drive other components
pump with dual circuits which operate at substantially
different pressures and flow rates that power multiple
servos. For example, my Audis use this system which is
made by ZF, a German company. One pump circuit powers the
rack and pinion, the other powers the hydraulic brake
booster for the power brakes. Both circuits are
independent but use a common reservoir and fluid.
In a single stage pump system with multiple parallel type
hydraulic circuits, the servo that requires the least
pressure has the possibility of consuming a majority of the
flow unless you regulate the pressure/flow somehow. If one
unit fails, you'll lose hydraulic assist in the other
servos in the same circuit unless you use some type of
pressure accumulator.
See this link: http://www.zf.com/defaultz.asp?lang=1
Here's a link to the type of dual circuit hydraulic pump I
referenced
http://catalog.eautopartscatalog.com/gapa/wizard.jsp?partner=gapa&clientid=gapa.com&baseurl=http://www.gapa.com/&cookieid=0X310X5OK&year=1990&make=AU&model=200-T-001&category=M&part=P%2FS+Pump
You may have to copy and paste the URL to complete it.
Then click the thumbnail to see a larger picture.
Hope this helps.
Chumley
RE: use power steering line to drive other components
-Jon
RE: use power steering line to drive other components
Would the OE pressure hoses be up to handling the new press?
Would the pump bearing take the revs (but now without the belt tension load on it)?
Is there a pressure relieve valve built in it to cater for all this?
Power ram seals?
Steering control valve seals?
I intend to run the pump some 10" away from the main belt driveline using a pipe and shaft config. due to space unvailability. So the pump will be attached on the rear end of shaft so it sees no belt tension at all. This would be similar to the eaton's long nose s/c drive assy'. Pls f/back on this and thks.
cheers
Ganesan
RE: use power steering line to drive other components
Regards
pat
RE: use power steering line to drive other components
Are the external power ram typed systems different from the power ram built into the rack types? Where would pressure relieve be done then?
Still not very clear of how this thing should be put together. In any case, would an oriface (a pipe diam reducer) placed inside the high pressure metal pipe be of any use in reducing the system pressure developed by higher rpms?
cheers
Ganesan
RE: use power steering line to drive other components
I am not a steering systems expert, so I am not familiar with many details on various pumps.
I base my comments on the 3 times I have adapted the wrong pump to steering box when doing engine swaps, and more general work with fuel pumps in mechanical FI systems, speed boat water pumps, and when modifying oil pumps for hotrodded engines, and a fairly comprehensive broad band knowlege of applied physics.
The orifice will not necessarily reduce pressure, it will reduce flow. This may reduce pressure if some oil is bleeding of, so the input to output ratio changes, but will only slow the rate of buildup if flowing into a closed pipe.
The best way to control pressure is with a pressure relief valve that will bypass oil back to the reseviour at a certain pressure. This obviously needs to be sized correctly, and should be adjustable
Regards
pat
RE: use power steering line to drive other components
A steering valve bypasses fluid so the pump just circulates under no load conditions.
Ken
RE: use power steering line to drive other components
Ken, you had pointed out sizing the pump as important. But this is the very same system we are talking about, with the only difference being the pulley diam. I wasn't sourcing to fit a diff pump from some other model. I guess if a small diam pulley was used, then the 80bar bypass trigger would happen much earlier in the rev range than usual thus increasing the fluid temp. Would an inline oil cooler keep things together? On which line should this cooler be inserted?
cheers and thks
Ganesan
RE: use power steering line to drive other components
Less chance of leaks, less chance of bursting a cooler
Regards
pat
RE: use power steering line to drive other components
After all- this is positive displacement pump, meaning a certain volume per PUMP REVOLUTION.
May need pressurized reservoir to avoid cavitation?
Maybe want larger hoses to and from the ram?
and very good sized cooler...
Jay Maechtlen