when did high flow come into the picture, and what is the spec for high flow? how many GPM is it. what tools/attachments need high flow, or can all be used with high flow.
I don't know when "Hi-Flow" was coined nor am I aware of a generic specification. However, it has become the manufacturer's norm to have a Hi-Flow option or model on their existing line up. The GPM will depend on the size of the machine but in general...a Hi-Flow model with have about 30 to 50% more flow available than a standard model. Some (most) Hi-flow machines have two auxilliary circuits available, one being "standard flow and one being "Hi-Flow". Hi-Flow may also increase the operating pressure..generally from around 3000 psi to 4000 psi. Some "standard" attachments, such as after market augers, cannot handle the increase in pressure so you do need to be careful. The pressure can be adjusted by a competent technician but that may affect other circuits on the machine. Pickup brooms, some power rakes and slasher/brush cutters are examples of attachments that demand more oil...and are therefore deemed to be Hi-Flow. Sorry I can't be of more help. Cheers
Standard flow rates seem to range from about 16 to 25 GPM. High flow would be considered to be anything over 25 GPM. I'm not sure when it started, probably when higher powered attachments started being manufactured. My Cat 248 is rated at 33 GPM on the high flow side.
It is important to take note of flow and pressure requirements when matching attachments with skid steers. The older attachments were not made for the increased pressure of the newer machines. There is also a wide range of high flow rates in machines. The important thing is to read the specs of your machine and match it to the attachment. Example would be Bobcat until very recently had terrible flow rates. If memory serves me 28-30 gpm on their most powerful machines. CASE machines were specing two different systems one at 3000 psi and the other at 5000 psi both at 40 gpm. Hook up an attachment that is speced for the Bobcat high flow to a 5000 psi 40 gpm system and you will be purchasing a new hyd. motor for your attachment. The aux. hyd systems of most machines is around 20-24 gpm on the larger machines. That is a pretty good flow for standard flow. There are some attachments that run much better with more flow, stump grinders, planers, mulching heads, rock saws are some of them.
Just as KSSS said..the cutter heads I think are what brought Hi-Flow out in the main stream..the one we have is a Timber Ax www.loftness.com and it requires hi-flow to run our ASV hits 38gpm and the timber ax could take more because it still has some bogging in real thick stuff...