Hydraulics Guide

Does Your Skid Steer Have Enough Flow to Run a Mulcher?

The answer is probably no — and this is the most important thing to figure out before you spend $15,000 on a mulcher attachment that your machine can barely turn.

Mulcher attachments are the most common source of machine-attachment mismatch in the Canadian market. The sequence goes like this: someone has land to clear, they price a drum mulcher, they buy it, then they discover their skid steer produces 22 GPM and the mulcher needs 38 GPM. The drum spins slowly, the cutting chips are oversized, and the machine gets hot. Then they're either renting a different machine or reselling a barely-used mulcher at a loss.

This guide is specifically about hydraulic flow requirements for mulching attachments — drum mulchers, disc mulchers, and the lighter-duty brush cutter category. If you want a full drum-versus-disc comparison, read the drum mulcher vs disc mulcher guide. This guide is about whether your machine can run either type at all.

What Mulchers Actually Need: The Numbers

Hydraulic motors require two things to produce power: flow (measured in GPM, gallons per minute) and pressure (PSI). Flow determines how fast the motor spins; pressure determines torque. A mulching head needs both — high flow to keep the drum or disc at cutting speed, and high pressure to maintain speed under load (when you push into wood).

Attachment Type Typical Flow Required Typical Pressure Cutting Capacity
Drum Mulcher (full-size) 30–45 GPM 3,000–3,500 PSI 6–12" diameter trees
Drum Mulcher (compact) 25–35 GPM 2,800–3,200 PSI 4–6" trees; dense brush
Disc Mulcher (full-size) 28–42 GPM 3,000–3,500 PSI 6–10" trees; fast on large material
Brush Cutter (rotary) 15–25 GPM 2,500–3,000 PSI 2–4" stems; heavy brush
Standard-flow skid steer 17–25 GPM output 3,000–3,200 PSI typical (machine, not attachment)
High-flow skid steer 35–45+ GPM output 3,000–3,500 PSI (machine, not attachment)

The overlap problem is clear. A standard-flow machine producing 20–22 GPM has enough flow for a brush cutter, but is genuinely underpowered for any serious drum or disc mulcher. Running a 35 GPM drum mulcher on a 22 GPM machine means the drum is spinning at roughly 60% of design speed. At that speed, the cutting tips don't have enough velocity to chip wood cleanly — they tear and compress instead. The material comes out in chunks, not chips. And the motor overheats under sustained load.

How to Check What Your Machine Produces

How to Find Your Machine's Hydraulic Flow

  1. Check the operator's manual or spec sheet. Most manufacturers publish "auxiliary hydraulic flow" in GPM or LPM (litres per minute; multiply LPM by 0.264 for GPM). Look for "standard flow" and "high flow" specs separately — they're often listed as two separate options even on the same machine model.
  2. Find the machine model number (on the door frame or frame rail) and search "[make] [model] hydraulic flow specs" — manufacturer sites publish this.
  3. Ask your dealer. If the machine has a high-flow option installed, the dealer can confirm it. High-flow requires a different hydraulic pump or pump output setting — it's not something you can improvise.
  4. Look for the high-flow switch or lever. Machines with the high-flow option have a dedicated control in the cab — usually a toggle or rocker labeled "high flow." If your machine doesn't have this control, it's not high-flow.

Common machines and their typical flow output as examples:

Machine (Example Models) Standard Flow High Flow (if equipped)
Bobcat S650 ~24 GPM ~37 GPM
Bobcat S850 ~27 GPM ~40 GPM
John Deere 330G ~25 GPM ~37 GPM
Kubota SVL75-2 ~24.9 GPM ~37 GPM (HF option)
Cat 262D / 272D2 ~26 GPM ~40 GPM
New Holland L228 ~25 GPM ~38 GPM

Verify these against your actual machine spec sheet — model year and options affect the numbers. These are representative examples, not specifications to rely on for purchasing decisions.

What Happens If You Run a Mulcher Underpowered

Three things, in order of severity:

Poor cutting performance. The drum or disc spins below design speed, so cutting tips don't have enough velocity to chip wood. You get tearing instead of mulching — the material comes out irregular, stringy, and sometimes large enough to create a fire hazard in dry conditions. This isn't a performance inconvenience; it makes the attachment produce a worse result than a bucket and chainsaw.

Thermal overload. A hydraulic motor running at reduced flow generates heat. The machine's hydraulic system is designed to handle its own flow output — not necessarily to dissipate heat efficiently when the motor is working hard at the wrong speed. Extended operation risks overheating the hydraulic fluid and degrading seals over time. Many operators run their machine hot for a season and then discover they've shortened the life of hydraulic components.

Motor damage. Under high cutting load with insufficient flow, the motor can stall momentarily — then restart under load. This creates pressure spikes that can damage the motor's internal seals, shaft seals, and in extreme cases, the case drain line. A damaged motor on a mulching head runs $2,000–$8,000 to replace. This is a real outcome, not a theoretical risk.

The "it kind of works" trap: Undersized machines often run light mulchers without immediate obvious failure — until they don't. Dry summer conditions, hard wood species, or sustained use at full cutting depth is when the damage shows. If it feels marginal, it probably is.

Standard-Flow Options: What Actually Works

If you have a standard-flow machine and you need to clear brush and light wood, you have two practical options:

Option 1: Rotary Brush Cutter

A brush cutter (sometimes called a rotary cutter or disc mower) runs on 15–25 GPM. On a standard-flow machine, a well-matched brush cutter handles brush, stems up to about 3–4 inches, and light saplings cleanly. It's not a mulcher — it cuts and knocks down material rather than chipping it — but it handles vegetation management on standard-flow machines. Price range: $3,000–$8,000 CAD new for a 60–72" unit.

The limitation: a brush cutter doesn't reduce material volume. Cut brush still needs to be picked up and hauled out (grapple job) or burned. A drum mulcher chips material in place, eliminating the haul. On a big clearing job, that's a significant productivity difference.

Option 2: Rent a High-Flow Machine

If the mulching job is large enough to justify a drum mulcher, rent a high-flow machine for the project rather than buying a mulcher for a machine that can't run it properly. High-flow skid steer rentals in Canada run $500–$800/day or $1,800–$3,000/week depending on region and machine size. That's expensive but much less expensive than a $15,000–$35,000 mulcher sitting unused or damaging itself on an undersized machine.

Alternatively, subcontracting a specialized land clearing contractor with their own high-flow equipment is often the most economical path for a one-time large clearing job. They show up with the right equipment and you avoid the capital and risk entirely.

Adding High-Flow to an Existing Machine

Some machines can be retrofitted with a high-flow pump or a high-flow auxiliary circuit. This is typically a dealer-level modification that costs $2,000–$5,000 CAD depending on the machine and what's involved. It's worth asking about if you have a machine you want to keep and genuinely need high-flow capability.

Not all machines support the retrofit — some standard-flow machines have pumps that physically can't produce the higher flow rate. Others have the provision for high-flow built into the platform but the pump is sized down from the factory for the standard-flow option. A dealer familiar with your machine's architecture can tell you whether the upgrade is feasible and what it costs.

Buying a Mulcher: What to Verify First

Before purchasing any mulching attachment in Canada, have these numbers confirmed in writing:

Then confirm against your machine's actual spec sheet — not someone's estimate, not the dealer saying "it'll probably work." The mismatch scenario is common enough that sellers are occasionally optimistic about compatibility. Verify it yourself.

Browse Mulcher Attachments in the Catalog

Verified product pages on mulching attachments available through Canadian dealers — with flow requirements listed.