Shearex VM-40SL excavator mulcher

The model where mulching stops being a sideline

Every family has a model where the purpose changes, and in the Shearex VM excavator mulcher range it is this one. The heads below the VM-40SL are maintenance tools bolted to machines bought for something else. The VM-40SL is a clearing tool: 107 cm of rotor, a 20 cm published target diameter and 757 kg of mass say plainly that the carrier will spend whole contracts doing nothing but vegetation. That is also why it is the first head in the family a buyer should stop comparing only with its siblings and start comparing with a different kind of machine altogether.

The VM-35SK beneath it serves 8 to 12 tonne carriers on 15 cm material and keeps the excavator general-purpose. The VM-50SR above it moves to 15 to 20 tonne machines and a flow demand that rewrites the carrier conversation. In between sits the 12 to 15 tonne class, the most heavily populated tonnage band in Australian civil fleets, which is exactly why this model is the one most owners look at first when a corridor or solar contract adds mulching to the scope.

Excavator head or front-mount carrier: the comparison to run now

At this size the honest question is no longer which VM head to buy but whether an excavator head is the right architecture for the work on offer. Answering it before the order is much cheaper than answering it after two seasons of tendering.

Excavator mulcher versus skid steer mulcher works through the decision in full, and a front-mount head such as the HM-70 is the realistic comparison at this budget. The short answer is that mixed terrain and infrastructure favour the excavator, while continuous open ground favours forward travel.

What 107 cm and 20 cm cover

A 107 cm swath clears a table drain or a fence line in one sweep and lets the operator work down a batter in overlapping arcs rather than chasing individual stems. Twenty centimetres of published optimal target diameter is the figure to build a rate on: it takes in most regrowth, invasive woody weeds and shelterbelt species, but not mature eucalypt. Working occasional larger stems from the top down is possible and slow, and pricing a contract on that possibility is the specific mistake maximum diameter versus production diameter exists to prevent.

Mass is the other change. At 757 kg this head is roughly half again as heavy as the VM-35SK, and on a 12 tonne machine reaching over a batter the margin that existed on the smaller heads is gone. Read the chart at the radius the work actually happens at, with bracket and hoses included in the figure.

One tonnage band, many different hydraulic systems

The trap in this class is uniformity of tonnage disguising enormous variation in hydraulics. A 13 tonne excavator with a shared single-pump auxiliary and a 14 tonne machine with a dedicated high-flow circuit are not the same proposition for this head, even though both look right on a fleet list. The published requirement is 114 to 167 L/min continuous with a minimum carrier power of 65 hp (48 kW), and the VM range’s maximum operating pressure of approximately 410 bar has to be confirmed against the carrier’s auxiliary relief rather than assumed.

Measure continuous auxiliary flow under load, the pressure available at that flow, the return pressure limit and the case drain arrangement, then run those figures through the hydraulic power calculator rather than treating the 65 hp minimum as evidence of anything. The worked arithmetic behind that sum is set out on the VM-50SR page. Mulching also removes the natural pauses that let a digging machine shed heat, which is covered in hydraulic matching and hydraulic cooling and heat.

Corridor, rail and solar work

The contracts that suit this head are road corridor clearing, rail corridor vegetation inside possession windows, and solar and wind farm site preparation, where the same carrier can also cut drainage and pull stumps between vegetation passes. Possession work deserves particular care, because possessions are priced in hours rather than area: a head running at the bottom of its flow window may simply not finish the booked strip.

Ballast shoulders, rail cuttings and old farm formations are hard on tooling in a way green timber never is. Carbide is the defensive choice on that ground and blades are the productive choice on clean material, a trade set out in blades versus carbide teeth.

The heel, and the other options

The hydraulic door is standard and its circuit requirements are documented in full on the VM-25SK page. The option that earns its money on this particular head is the heel, because a 12 to 15 tonne machine working a batter spends much of its day holding material into the rotor rather than pursuing it across the ground. Tilt is next most useful on sloping corridor work, and a grapple mainly suits operators who also stack or feed. Settle all three at quotation, since each one adds mass to the figure that has to clear the lift chart and may add a circuit to the auxiliary kit.

The wear item this head eats

On corridor and solar contracts the Hardox 500 bolt-on liner and the skid shoes wear faster than most tooling budgets allow, because the head spends its working life in contact with the ground rather than above it. Price those as a recurring item alongside teeth, holders, the belt and rotor bearings, and ask Machinery Specialist to confirm Australian stock before signing; wear parts to price before buying lists the full set.

Programme work changes what the head has to do

The contracts that bring this head into a fleet are rarely priced by the hour. Road, rail and solar programmes are built around a schedule owned by someone else: a possession window, a lane closure calendar, or an EPC construction sequence that has piling crews arriving on a date set months earlier. That changes the specification conversation, because the question stops being how fast the head cuts and becomes whether it can cut the agreed area inside a window that will not move.

Two consequences follow. The first is that reliability and parts availability are worth more than marginal production: a head that runs at 90 per cent of its best rate every day beats one that runs at full rate and loses a shift to a belt. The second is that the carrier’s hydraulic headroom matters more on programme work than on day work, because a machine running at the bottom of its flow window has no capacity to catch up after weather.

Approvals, retention and selective treatment

An excavator head is often chosen over a wider front-mount machine for a reason that has nothing to do with production: it can treat vegetation selectively while leaving specified trees, understorey and habitat intact. On road, rail and renewable projects that capability frequently appears in the approval conditions rather than in the scope of works.

Clearing on those projects can require approval under state and local rules, and conditions commonly specify retained trees, root zone exclusions, seasonal restrictions and reporting. None of that is legal advice and all of it is worth reading before the machine is priced, because it determines how much of the site can be treated in continuous passes and how much has to be worked stem by stem. Native vegetation approvals sets out what to look for. Where retained trees are dense, the reach and selectivity of this head is worth a considerable production penalty, and that trade should be visible in the rate.

Operator technique on a batter

Most of the difference between a good and a poor production rate on this head is operator method rather than machine specification, and batter work is where that shows most clearly.

1. Set the stance
2. Work top downlet material fall away from the rotor
3. Hold with the heel
4. Finish the face
5. Track and repeat

The common errors are working uphill, which feeds material into the rotor against gravity and stalls it; reaching too far to avoid a track move, which costs both stability and control; and pressing the head into the ground to improve finish, which converts tooling into dust and adds nothing the client asked for. The finish class should be agreed with the client before the first pass, and the operator should be told what it is, because a crew chasing an unspecified standard will always chase the finest one.

What the second-hand market tells you

The 12 to 15 tonne class is where used mulching heads turn over most often in Australia, usually because a contractor bought one for a single contract that did not repeat. That makes it a reasonable place to buy and a demanding place to inspect, since the machine that was bought for a corridor programme has generally had a hard, short life rather than an easy, long one.

Look at the liner and skid shoes first, because they record the ground; then at holders, since replaced holders in a pattern suggest a rock strike rather than fair wear; then at the rotor bearings and belt. Ask what carrier it ran on and what the auxiliary circuit measured, because a head run below its flow window will look under-used and have worked harder than its hours suggest. Inspecting used forestry attachments covers the full sequence, and the wear parts to price before buying list doubles as an inspection list.

Confirm before ordering

• Whether an excavator head or a front-mount carrier suits the contract pipeline, decided before the order
• Continuous auxiliary flow and pressure measured on the specific 12 to 15 tonne machine under load
• Auxiliary relief setting against the range's approximate 410 bar maximum, plus return pressure and case drain
• Heel, tilt and grapple decided now, with their mass and circuits included in the quote
• Head mass with options read off the chart at the radius used on a batter
• Cooler capacity for continuous summer running
• Liner and skid shoe replacement cost treated as a recurring line, not a one-off
• Australian stock and price of wear parts, and the delivered price with bracket and hoses

Frequently asked questions