Shearex VM-50SR excavator mulcher

Where the VM-50SR sits in the range

The VM-50SR is the 15 to 20 tonne head in the Shearex VM excavator mulcher range, and it is the point at which the carrier’s hydraulics, rather than its tonnage, become the whole conversation. Below it, the VM-40SL suits 12 to 15 tonne civil machines with a 20 cm target diameter; above it, the VM-60SR shares the same continuous flow window but demands 130 hp and takes on 40 cm material. The VM-50SR is the natural head for a contractor whose 20 tonne excavator is already the workhorse on transmission easements, pipeline corridors and firebreak construction, and who wants serious vegetation capacity without moving to a dedicated mulching carrier.

What the published figures mean on site

The 123 cm cutting width clears a corridor edge or a firebreak strip in wide, overlapping sweeps from a single stance. The optimal target material diameter of 25 cm is the commercially honest figure: the stem size the rotor keeps processing at a productive rate, which now covers most regrowth eucalypt, wattle and pine understorey on an easement. Larger stems can be worked from the top down as occasional events, but the tender should be priced on the target figure; our guide on maximum diameter versus production diameter shows how quickly wood volume climbs with diameter.

At 975 kg the head is close to a tonne before bracket, hoses and any options, and it must be checked against the lift chart at the working radius. The defining figure is continuous flow of 159 to 238 L/min. Many 20 tonne excavators can quote a pump total above that, but what the buyer needs is the flow that can be dedicated to the attachment and held at pressure for an hour of continuous work. The published minimum carrier power is 80 hp (59 kW), and the VM family’s maximum operating pressure is published as up to approximately 410 bar.

Carrier matching

Excavator tonnage is only the entry ticket, and this is the model where that stops being a slogan. Confirm how much continuous auxiliary flow the carrier can dedicate under load, what pressure is available at the same time, the allowable return pressure and the presence of a case drain to tank. Then ask what the oil temperature is after an hour of continuous mulching on a 38 degree day, because excavation includes natural pauses to slew and dump while a mulcher does not. Our guides on hydraulic matching and hydraulic cooling and heat cover the questions to ask.

Theoretical hydraulic power is flow in L/min multiplied by pressure in bar, divided by 600, and it is the quickest way to expose a pairing that looks fine on tonnage. As an illustration only, the head’s upper figure of 238 L/min at an assumed 300 bar gives 238 × 300 ÷ 600, about 119 kW, which is at or beyond the engine output of many 20 tonne excavators; at the lower 159 L/min the same assumed pressure gives about 79.5 kW. A carrier that merely meets the published 80 hp (59 kW) minimum will therefore live at the bottom of the window. Substitute the carrier’s own measured figures in the hydraulic power calculator before ordering.

Typical work and production considerations

The head is well matched to powerline and transmission easements, mining and pipeline corridors and firebreak construction in bushfire fuel reduction programs. Corridor work exposes the rotor to cuttings, rock and buried debris, which favours carbide teeth; blades cut faster and cleaner in clean green vegetation. See blades versus carbide teeth.

Limitations and when to step up or down a size

On flat, traversable ground a front-mount head such as the HM-88LV runs nearly twice the width and will usually produce more area per hour. The excavator head wins on batters, around structures and wherever material must be reached rather than driven over; excavator mulcher versus skid steer mulcher sets out the trade. Step down to the VM-40SL if the fleet is lighter and stems are under 20 cm. Step up to the VM-60SR when 40 cm material is regular rather than occasional and the carrier is a 20 to 25 tonne machine with 130 hp or more.

Options and hydraulic circuits to settle at quotation

The hydraulic door is standard, and the circuits it needs are set out on the VM-25SK page. On a 20 tonne machine

Wear parts and support

Price the consumable set with Machinery Specialist before signing and confirm what is held in Australia. Easement and pipeline work is usually remote, so the question that matters is not the price of a belt but how many days it takes to reach a crew camped two hours from the nearest town.

Confirm before ordering

• Continuous auxiliary flow the carrier can dedicate to the head under load, not the pump total
• Pressure available at that flow, the return pressure limit and a case drain to tank
• Oil temperature behaviour after an hour of continuous work, and any cooler upgrade required
• Circuit plan and diverter wiring for the door and any tilt, grapple or heel option
• Head weight with options against the lift chart at working radius
• Blade or carbide tooling for the corridor's rock exposure
• Australian stock and price of teeth, holders, belt and bearings
• Delivered price including bracket, hoses, commissioning and operator training

Frequently asked questions