A skid steer can have the right lift capacity and plenty of engine power, yet still struggle with the attachment you bought for it. When that happens, the cause is often the auxiliary hydraulics.
That’s why the standard flow vs high flow skid steer decision deserves more than a glance at the brochure. An attachment performs properly only when the machine delivers the right oil flow, at a pressure the attachment can handle, through connections that actually match.
At Worldwide Construction Machinery, we’ve been supplying and servicing machinery for contractors and farmers in Perth since 1982. Here’s how we suggest approaching the match before you spend money on either the machine or the attachment.
Standard Flow vs High Flow Skid Steer: What Is the Difference?
The difference is how much hydraulic oil the auxiliary circuit can send to an attachment each minute. A standard flow hydraulic system suits many everyday attachments. A high-flow hydraulic system delivers a larger volume of oil for attachments designed to need it.
The auxiliary hydraulic circuit is the set of lines and couplers at the front of the loader arms. It powers any attachment with its own hydraulic motor or cylinders.
Industry sources often quote indicative ranges like these:
- Standard flow: roughly 60 to 100 L/min
- High flow: roughly 110 to 170 L/min
Treat these as a loose guide only. Many brochures are written for the US market and quote hydraulic flow in GPM, where one US gallon per minute is about 3.8 L/min.
There’s no single industry standard behind either term. One manufacturer’s standard flow on a large loader can come close to another’s high flow on a smaller one. When comparing high flow vs standard flow skid steer options, read the actual L/min figure and the attachment’s requirements, not the label.
Three Hydraulic Specifications to Check Before Buying
Check flow, pressure and connections. A match on one or two of them doesn’t confirm compatibility.
Hydraulic Flow Rate: Does the Machine Deliver Enough Oil?
Flow largely determines hydraulic motor speed. More oil usually means a faster auger, rotor or chain, up to the limit the attachment was designed for.
A good attachment spec sheet lists some or all of these figures:
- Minimum hydraulic flow → below this, the attachment may perform poorly, lack working speed or stall under load
- Recommended hydraulic flow range → where it performs as designed
- Maximum hydraulic flow → above this, you risk overspeeding the motor and damaging components
Your machine’s auxiliary hydraulic flow rate should sit inside the recommended range. If the sheet only gives one figure, ask the attachment manufacturer what it means before assuming a match.
Also check how the machine’s flow figure was measured. Published figures are often taken at rated engine speed, and on many machines flow falls when revs drop. Ask the dealer how flow behaves at the engine speed you’ll actually use.
Hydraulic Pressure: Is It Within the Attachment’s Rating?
Pressure relates to the force and torque available under load. Flow affects how fast a post hole digger turns. Pressure affects whether it keeps turning when it meets hard clay or limestone.
Compare the machine’s hydraulic relief pressure with the attachment’s operating pressure and maximum rating.
- If the machine’s relief pressure is higher than the attachment’s maximum rating, treat it as not compatible unless the attachment manufacturer confirms an approved setup for that machine. Don’t improvise with aftermarket valves.
- If the machine’s pressure is lower than the attachment’s design pressure, expect reduced torque and a greater chance of stalling.
Hydraulic power depends on both flow and pressure working together. That’s why matching flow alone never confirms compatibility.
Couplers, Case Drain and Electrical Connections
Even with flow and pressure matched, an attachment won’t work properly if it can’t connect properly.
Skid steer hydraulic couplers: Many skid steers use flat face couplers, but type, size and thread vary. Undersized couplers or stacked adaptors can restrict flow and build heat.
Case drain: Some hydraulic motors leak a small amount of oil internally while they work. A skid steer case drain is a separate, low-pressure return line that carries that oil back to the tank.
A third hose on an attachment doesn’t automatically mean it’s a case drain. It could serve another function. Check the attachment manual and the port markings to confirm what each hose does.
If an attachment does require a case drain, don’t run it without the correct connection. Pressure can build inside the motor housing and damage the shaft seal. Never route a case drain into a pressurised return line, and follow the manual’s connection sequence. Many manufacturers advise connecting the case drain first and disconnecting it last.
Electrical connections: Attachments with more than one function may need a wiring harness, a specific connector or in-cab controls.
Check | Machine spec sheet | Attachment spec sheet | What to watch for |
Flow | Auxiliary flow (L/min) and the engine speed it’s measured at | Minimum, recommended and maximum flow | A machine near the bottom of the range may leave the tool underpowered in hard ground |
Pressure | Auxiliary relief pressure (bar) | Operating and maximum pressure | Machine relief pressure above the attachment’s rating is a red flag |
Return line | Case drain fitted? | Case drain required? | Confirm hose functions from the manual, not by counting hoses |
Couplers | Type, size and thread | Type, size and thread | Adaptors can work but may restrict flow |
Electrical | Connector type and cab controls | Wiring and control needs | Worth checking twice on used attachments |
How to Check a Skid Steer Specification Sheet
Start with the auxiliary flow figure, then confirm everything the sheet leaves out.
Our WS50H Wombat listing is a useful example. It shows an auxiliary flow rate of 64 L/min, along with a 50 HP engine and a Rexroth Danfoss pump and main control valve.
Take that figure straight to the attachment’s spec sheet. Here’s a hypothetical example. If an attachment recommends 45 to 75 L/min, 64 L/min falls inside that range on flow. If another attachment needs a minimum of 90 L/min, it isn’t a match, however capable the loader is otherwise.
Flow is only the first check. Ask about the details a flow figure can’t tell you:
- Auxiliary relief pressure
- Coupler type and size
- Whether a case drain is fitted
- Whether a high flow option is available for that model
Don’t classify a machine as standard or high flow from one number alone. Confirm the exact configuration with the dealer.
For an example of how auxiliary flow appears in a specification sheet, see the WS50H Wombat skid steer loader. Always confirm the machine’s configuration and the attachment manufacturer’s requirements before deciding on compatibility.
When Standard Flow Attachments Make Sense
Standard flow is often enough for property maintenance, farm work, fencing, landscaping and general site work.
Attachments such as post hole diggers, trenchers, grapples, pallet forks, 4-in-1 buckets, rotary hoes and many slashers are commonly run on standard flow machines. Each still needs to suit your machine’s flow, pressure and connections.
Our range of skid steer loader attachments includes many of these, and our team can check them against your machine.
A standard flow attachment is designed around a lower oil volume. When it’s properly matched, it can do solid, reliable work. On demanding jobs, it may work more slowly than a high flow equivalent.
Some attachment types, including mulchers, are made in both standard and high flow versions with different performance capabilities. Check which version a particular attachment is before assuming it suits your machine.
The practical upside is that you aren’t paying for hydraulic capacity you’ll rarely use.
When a High Flow Skid Steer Is Worth Considering
High flow is worth considering when your regular work involves attachments specifically designed for it. Industry examples include:
- High flow forestry mulchers for dense scrub and standing timber
- Cold planers for asphalt and concrete surface removal
- Stump grinders for regular clearing work
- High flow brush cutters for heavy vegetation
These attachments are built around higher oil volume to maintain working speed under load. Skid steer mulcher flow requirements in particular vary widely between models, so always check the exact figures.
Flow isn’t the whole picture. Engine power, hydraulic pressure, cooling capacity and machine weight all need to support the attachment.
If high flow work only comes up occasionally, hiring suitable equipment for those jobs may be better value than buying a machine around them.
Why More Hydraulic Flow Does Not Always Mean Better Performance
An attachment is designed for a specific flow range. Going above it doesn’t add performance and can cause damage.
Pushing more oil into a motor than it’s rated for can make it spin too fast, straining seals and bearings and risking hydraulic motor damage. Excess flow can also generate heat, which contributes to skid steer hydraulic overheating over time.
Too little flow is a problem as well. An attachment that needs more oil than the machine can supply may perform poorly, lose speed, stall under load and run hot.
Whether a high flow machine can run a standard flow attachment depends on the machine’s actual specifications, the hydraulic mode selected and the attachment’s maximum ratings. Selecting the wrong mode with the wrong tool connected is where problems often start. Our guide to efficient skid steer operation covers good habits in the cab.
If hoses run unusually hot or an attachment sounds strained, stop and get it checked. You can book a service at our Maddington service centre.
The goal is simple: match the machine to the work and the attachment, not to the biggest flow figure available.
Skid Steer Attachment Compatibility Checklist
Before buying a machine or an attachment, confirm the following:
- Auxiliary flow sits within the attachment’s recommended range
- Auxiliary relief pressure doesn’t exceed the attachment’s rating
- Coupler types, sizes and threads match
- Each hose’s function is confirmed from the manual, including any case drain
- Electrical connections and controls are compatible
- Engine power, operating capacity and cooling suit the attachment
- Compatibility is confirmed with the dealer and the attachment manufacturer
Get the Right Match with Worldwide Construction Machinery
Choosing between standard and high flow is easier when someone checks the numbers with you. At WCM, we’re a family-owned Perth business with more than 40 years in the industry. Tell us which attachments you plan to run, and we’ll talk you through how our machines line up.
After you buy, we support you with parts and servicing at our Maddington workshop or on site.
Explore our skid steers for sale in Perth and speak with WCM about matching a machine to your intended attachments.
FAQs
How can I tell if my skid steer has high flow hydraulics?
Check the spec sheet or operator’s manual for a separate high flow rating. A high flow switch in the cab or extra couplers can be clues, but confirm with the manufacturer.
Can you add high flow to a standard flow skid steer?
Sometimes, but it usually involves pump, valve, line and cooling changes. It’s often costly, so confirm feasibility with the manufacturer before planning around it.
Does a skid steer slasher need high flow?
Not always. Many slashers are built for standard flow, while heavier high-flow versions exist. Check the slasher’s recommended flow range against your machine’s auxiliary flow.
What size hydraulic couplers do skid steers use?
It varies. Smaller flat face couplers are common on standard circuits, and larger ones often appear on high flow circuits. Confirm sizes against your machine and attachment.
Does a case drain mean a skid steer is high flow?
No. A case drain only provides a low-pressure return for motors that need one. Some standard flow machines have it, so confirm the flow rating separately.