High flow means the machine's auxiliary hydraulic circuit sends far more oil to the attachment, commonly around 30 to 40 gallons a minute against 17 to 24 on a standard unit. Attachments with a hydraulic motor doing continuous work need that flow or they stall. The machine costs more to hire, in the region of $100 a day over a standard skid steer, and it is not optional for some tools.
Flow does the work, pressure holds it
Gallons per minute is how fast the attachment motor turns; pressure is how hard it pushes before it stops. A mulcher head fed standard flow will spin up empty and bog the moment it meets timber. Ask the yard for the auxiliary flow figure in gpm, not just the phrase high flow, because the threshold varies between makes.
The attachments that demand it
Forestry mulchers, brush cutters on heavy growth, cold planers, wheel saws, stump grinders and snow blowers are the usual list. Augers, breakers, grapples, sweepers and pallet forks all run happily on standard flow. If your attachment is on the first list, the machine choice was made for you before you started comparing rates.
Check the couplers before the truck leaves
High flow circuits often use larger flat face couplers than the standard ones, and some attachments need a case drain line back to tank or the motor seals fail. Confirm coupler size and case drain with whoever supplies the attachment, especially when the machine and the tool come from different yards.
What the day rate comes to with the attachment
The machine itself commonly runs about $100 a day above the equivalent standard unit, and the attachment is a separate line that can exceed the machine on a mulcher. High flow units are a smaller part of most fleets, so book early in clearing season. Delivery is priced the same as any tracked machine, out and back.
Questions people ask about high flow skid steer
Can I run a high flow attachment on a standard machine slowly?
No. Starved of flow the attachment either will not turn under load or overheats the oil trying, and either way you risk damaging equipment that is not yours. Hire the machine the attachment was specified for, or hire a different attachment.
How do I know if a machine is high flow?
There is usually a second set of couplers and a switch or menu setting in the cab, and the spec sheet gives an auxiliary flow figure. Ask the yard to confirm the gpm on the exact unit going out, because two machines of the same model can be built differently.
Does high flow mean a bigger machine?
Generally yes. High flow is normally offered on the larger frame sizes with more engine power, so the machine is heavier and wider than a mid frame unit. Check gate widths and ground protection before you upgrade for the flow alone.