don schad wrote:
Hi all,

Thanks for all the help/suggestions. It's very much appreciated.

I'll take the liberty to ask another question while we are he

There has been a lot of talk about having things sized properly such that
the system is controllable. Is proper sizing just a question of making some
assumptions and doing the math?
For example, lets say that I wanted the loader to go from the ground to the
full-up position in 3 seconds (is this too fast? too slow?).
Assuming:

Two hydraulic cylinders with a bore of 2", and a stroke of 14" to go from
down to full up.
3 seconds to extend ram 14"

To compute flow:
Speed (in/min) = flow (in3/min) / area (in2)
flow = speed (in/min) * area(in2) = 14"/0.05min * 3.141in2 = 880in3/min *
1g/260in3 = 3.4gpm
and since we have two cylinders, we need 6.8gpm?

This estimate seems to be reasonable based on what I have seen for other
loaders regarding pump size. Is this (basically) all there is to it? And
from there should I pick the lowest pressure which will (a) operate all the
parts and (b) give me the force which I need to do what I want? So if I
want to have the loader capacity be 1000#, I would have two cylinders which
could produce (minimally, since I guess there is geometry to consider and
the loss of usable lifting force - haven't gotten there yet ) 500# each
at a given PSI (seems like 1500 is the lowest common on, and this will
produce a force 500#)?

Easy...so what am I missing?

As always, thanks a lot for your help.

don


Hi Don
I think Nick had a lot of sound points well worth listening to . Common
Hydralic systems these days tend to run from 2500 to 4000 PSI . The rams
, pump , controls and hoses all have to match the maximum setting to
be safe . This is controled by a relief valve somewhere in the system .
Most controls have stepped spools , this allows you to feather them ,
but not all have this . For a loader you will want to be sure you get
this feature . The speed you mentioned , well as others have posted I
would say that is too fast . I might have missed it but you do not say
what tractor this is for . A loader capable of lifting 1000 lbs plus the
weight of the loader hanging out front of everthing is a lot . You
should call up a dealer and ask them what size loader this tractor is
rated for . You also have to be able to steer it after the loader is on
it . Will your steering take it ? I mention this as I have a tractor
with a factory loader that snapped the front spindles off . Yep the
engineers got it wrong . It is a real jolt to the heart when that
happens driving with a loaded bucket . Good reminder to carry the load
low to the ground which I wasn't at the time . Hey factory system has to
be safe right ? ha ha . I will point out that this little 25HP tractor
has a foolishly wide bucket on it . Maybe it would be ok lifting saw
dust or snow but anything else is more then the tractor can handle .If
you can find the same model tractor with a loader it would be well worth
trying to copy . Might save yourself a lot of grief down the road .
there are lots of companies that sell aftermarket loaders . Phone one
and ask them what they recomend for your tractor . At least you would
know what limits you should be planning for .
Ken Cutt