QUALITY is one most difficult words there is. Because the definition of quality depends on so many factors....like preference, expectation, consistancy, cost, lifespan, reliability, etc etc....
A good quality hydraulic pump could actually be oine with a shorter life spasn than one with a longer life span.....because who wants to pay extra for a pump on a splitter, that have many years left, when the rest of the splitter is so worned out so it is worth less????
I concider McDonalds have very high quality food, because I can get exactly what I expect, every time I buy that Big Mac!!
With only one word, I would say, QUALITY is when you get exactly what you expect or better (GOOD QUALITY) for your money!!
This is of course just my opinion on this word Quality, I think it is easy to call a lot of stuff bad quality, when stuff in reality is just as good as you could have expected, if you checked it out before the purchase.....I can't answer all your questions,
but I will give it a try on a few of them....
I thought I'd toss out a question as to what constitutes quality in tractor hydraulics. This was triggered by reading several posts recently opining that MF had "better" hydraulics. I asked about that in a recent thread, and a local (NH) dealer responded that MF runs their hydraulics at higher pressure.
Well, IS higher pressure "better"?
You pay extra for higher pressure, but also for lower pressure....
Higher pressure takes less material (weight/mass), if you design for the same power/force rating....this is usually confusing for most people because, higher pressure should take "thicker" material...example...a 1/2" RA2 hose can take more pressure than a 3/4" RA2 hose, even though the 3/4" have bigger diameter and contain more material....but the fact is that both are 2 wire hoses....
A 3000psi/10gpm pump, is heavier/more expensive than a 2000psi/10gpm pump.....but a 3000psi/30hp pump is lighter than a 2000psi/30hp pump.....
Hydraulic systems are inefficient when it comes to power, and the reason is internal leakage and flow restriction. Internal leakage increases with higher pressure, and flow restriction increases with higher flow.... with no doubt, allways, high pressure comes out more efficient than high flow.
So the answer on your question, about "if higher pressure is better", it depends on preferens....with higher pressure allows lighter/less mass equipment, that cost less fuel to run. But it will cost a little extra to get it...so if you are purchasing a tractor for 2000hrs usage per year in 5-6 years....I definately would go high pressure, but for a tractor that are going to sit cold most of the days....I might concider a cheaper low pressure piece...
It seems that too many variables come into play to make this a determining factor - like the quality of the components, size & flow vs. pressure, circuit design, etc.
What do you look at when evaluating quality in a hydraulic system?
I would first look at how I plan to use the tractor, commercially or occationly??
Intensive commersial usage will take higher "quality" in terms of reliability, maintenance down time, cost of operation, warranty, maneuverability, control system, flexibility etc....and that usually means a constant high pressure, load sensing system with joy stick controls etc....
Another factor is manufacturer reputation on hydraulic components....and that is usually a matter of preference.....REXROTH or PARKER?? etc etc..
Hope other fill in on this one!!:thumbsup:
