Shearex HM-90SV front-mount mulcher

Where the HM-90SV sits in the range

The HM-90SV is the heavy-vegetation head in the Shearex HM front-mount mulcher range, built for purpose-built mulching tractors of 170 hp and above. It runs 230 cm of cutting width and a 40 cm optimal target diameter on the same 178 to 288 L/min flow window as the HM-88LV, but with a heavier build at 1,938 kg and a much larger appetite for timber. Above it sits only the HM-100SV2, a 250 hp dual-motor head that belongs in a different category. On the excavator side, the VM-60SR shares the 40 cm target and is the reach-based alternative for the same material.

What the published figures mean on site

The 230 cm cutting width is only a little wider than the HM-88LV, so width is not the reason to choose this head. The optimal target material diameter of 40 cm is: it is the stem size the rotor processes continuously at a productive rate, and it moves the head from regrowth and scrub into mature stems on right-of-way, mine site and plantation rehabilitation work. Because wood volume rises with the square of diameter, a 40 cm stem holds roughly four times the wood of a 20 cm stem, so density decides whether a block is economical to mulch even when every stem is inside the target; see maximum diameter versus production diameter.

At 1,938 kg the head needs a carrier built to carry it, and at 170 hp minimum with 178 to 288 L/min of continuous flow it is well outside skid steer and compact track loader territory. The distinction between this head and the HM-88LV is largely rotor mass and build, which is why it takes more power to swing the same flow.

Carrier matching

Carrier horsepower is the first filter and the high-flow circuit rating is the deciding one. Confirm continuous L/min and bar, the case drain and return arrangement, the motor build supplied with the head, and the cooling capacity of a carrier that will hold the rotor near relief in 40 cm timber through a summer afternoon. Weight against the carrier’s rated capacity and attachment guidance still has to be checked, even on a purpose-built machine, because a front-mounted 1,938 kg head governs ground pressure and stability on slopes. See hydraulic matching, hydraulic cooling and heat and the skid steer and track loader class page.

The published 170 hp minimum is 30 hp above the HM-88LV’s on identical flow, and the reason is pressure: heavy timber holds the rotor near relief, and hydraulic power is flow multiplied by pressure. Worked through the hydraulic power calculator with an assumed 350 bar, the bottom of the flow window alone accounts for roughly 104 kW, leaving a 170 hp carrier a modest margin for travel, cooling and driveline losses, and the top of the window is out of its reach.

Typical work and production considerations

The head fits mining and pipeline corridors, heavy powerline and transmission easements and plantation thinning and re-establishment where windrows and residual stems must be reduced in place. Windrows, spoil and mine-site ground carry rock and buried debris that favour carbide teeth, while blades cut faster and cleaner in clean green material. See blades versus carbide teeth.

Limitations and when to step up or down a size

A front-mount head cannot work batters, drains or ground the carrier cannot traverse, and on steep or wet corridors the VM-60SR on a 20 to 25 tonne excavator will produce where this head cannot; excavator mulcher versus skid steer mulcher sets out the trade. Transport of a 230 cm head on a large carrier is a permit and float question to answer before tendering. Step down to the HM-88LV where material is under 25 cm and the job is measured in hectares. Step up to the HM-100SV2 only for genuinely industrial clearing on a 250 hp carrier.

Options and hydraulic circuits to settle at quotation

There is a single HM-90SV variant, so the quotation decisions are tooling, motor build, the case drain and return arrangement, and the electrical control on the carrier’s harness. Specify the motor build against the carrier’s real circuit rather than its brochure figure, because a head geared for flow the carrier cannot supply will simply run at lower rotor speed in the timber it was bought for.

Wear parts and support

Heavy timber consumes tools, holders and bearings quickly, so budget tool cost per hectare rather than per set and confirm Australian stock and lead times for the critical items with Machinery Specialist. Holder damage, not tooth wear, is usually what stops a head working in windrows.

Confirm before ordering

• Carrier meets 170 hp minimum and its high-flow circuit sits within 178 to 288 L/min continuously at pressure
• Case drain, return pressure and motor build matched to the carrier
• Head weight of 1,938 kg against the carrier's capacity, stability and ground pressure on the intended terrain
• Cooling capacity for continuous summer work in heavy timber
• Transport width and permit implications
• Blade or carbide tooling for the site's rock and debris exposure
• Australian stock, lead time and price of teeth, holders, belt and bearings, budgeted per hectare
• Delivered price including mounting plate, hoses and electrical harness

Frequently asked questions