Hydraulic Capacity Calculations

[MysTiK]

quote:Originally posted by D-17_Dave

One simple way to increase the tank size on a power steering pump is to place a large diam. rubber hose over the filler spout instead of a cap. run the hose up as high as desired and add a tank to the hose as large as needed. the need then becomes proper venting so the large flow can move the oil in or out of the reservoir so as to not starve the pump. Most general hydraulics systems have 3 times the pumps flow rate in reservoir capacity.

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id="quote">Having read this approx 10 times, I get it. It's interesting because I was scheming similar reservoir in the case where we were considering using the Sundstrand pump, and it was deemed risking starvation. So we seem to be long past that now. This raised reservoir makes sense with a powersteering pump, extending the pumps capabilities, and likely would satisfy the need for dissipation of air bubbles, already mentioned, as well. My question: what would constitute "proper venting"?It seems the re-plumbed pump would be drowning in hyd fluid, essentally overfilled compared to it's original intended automotive application. I don't know much about pumps generally; but what is being vented? air? hyd fluid? pressure? vacuum? all of the above?I am wondering also if an automotive power steering pump has a 'properly vented' cap; and if that could be utilized as a cap for a reservoir like you describe here. (or something similar). It seems 2-way venting would be required. Something simple? or more complex?For me this really raises another question. Is the entire hydraulic system pressurized? or are only the active components pressurized? again perhaps a little of both?Also could a T-junction be used to effectively "vent"; rerouting fluid to other areas of the system? and acting like a "buffer" to minimize "load shocks" to the system?Yes, that's like multiple questions. 8)Brief comment will suffice - I clearly need further research. Any comment will do. sm01Thanks.

[Kenzen]

quote:Originally posted by HubbardRA

The subject was brought up about using a power steering pump with a built in reservoir. Most American power steering pumps, at least on Fords and Chevys have a removable reservoir. I have replaced some that did not come with a reservoir and you had to use the one from the previous pump.

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I'm used to the older RWD cars where the PS pump, reservoir, and even a little dipstick for checking the level were all one thing. If I remember correctly, my 88 SAAB 900T had a remote reservoir. Anyway, it seems these pumps run in the neighborhood of 1000-1500# and around 2 gpm. 2 gpm is a quart every 7.5 seconds, which is plenty to move a couple small bore cylinders in parallel pretty quickly for lifting or dumping a bucket. This seems to be a real practical way to go for a garden tractor scale loader.

[D-17_Dave]

The automotive pumps are "drowning" in oil anyway. Basically the pump intake is submerged much like a remote mounted pump where a pipe or sump is submerged and routed to the pump.

The venting is used to allow the difference in the oil displacement to come into or go out of the reservoir fast enough to not create pressure or vacuum as the cylinders are cycled. These tanked style systems are not pressurized in the tank. Some very large industrial machines are.

The type of cap Mystic mentions above is vented and would likely work. You'd need an extra metal reservoir to cut the neck off of and clean off the debris and clamp on the other end of the hose that extends the reservoir and use the oem cap.

Another comment on the above topic of sundstrand charge pumps, you won't starve the pump unless your intake side filter restricts the oil flow or you lower the oil level where you can draw in air. The pump doesn't care how much oil you want, it will only provide so much flow controlled by rpm. The key is understanding that a properly plumbed system the transmission gets the oil it needs and send the remaining flow to the lift valve or power steering then lift valve if so equipped. The pressurized oil flow never gets "Tee'd" into. It must perform a given task then move on to the next task via the power beyond feature found on some hydraulic components. As each task is performed the oil used is returned to the tank via a tee'd line under no pressure. The lack of flow comes into play when the pressurised oil flow is "tasked" off until there is not enough oil flow to do the task required.