Shearex VM-35SK excavator mulcher

Why the 8 to 12 tonne class is the crossover point

The VM-35SK exists for the contractor who does not mulch full time. An 8 to 12 tonne excavator is the largest machine that still moves cheaply and the smallest that carries a serious attachment, which is why this head, rather than anything above or below it in the Shearex VM excavator mulcher range, tends to be the one that gets bought by businesses whose main income is civil work, fencing, farm contracting or council maintenance. The machine hangs a bucket on Monday, a tree shear or grab on Wednesday and this head on Friday, and the mulching contract is an addition to the year rather than the shape of it.

That crossover is the whole argument. The VM-25SK below it is bought for reach into places a larger machine cannot go, and the VM-40SL above it is bought because clearing has become the business. The VM-35SK is bought because a general-purpose excavator can be made into a credible vegetation unit for a few weeks at a time without being rebuilt around the attachment.

What one carrier and several tools actually costs

Multi-attachment fleets fail on details rather than economics. Three of them decide whether this arrangement works. The first is the coupler: every tool has to come on and off in minutes with the same hitch, or the changeover eats the flexibility that justified the purchase, which is the subject of quick couplers and attachment changeover. The second is the circuit set. A mulcher needs a double-acting auxiliary with a case drain to tank, which happens to be the same plumbing a rotating grab or a shear wants, so one well-specified auxiliary kit serves the whole tool list if it is specified once and properly. The third is hours. An attachment that works three hundred hours a year carries its purchase price differently from one that works two thousand, and total cost of ownership is the place to test that before signing.

The 95 cm rotor and the 15 cm target in mixed work

Twenty-five centimetres more rotor than the VM-25SK sounds modest and is not. The head sweeps wider arcs from one stance on a boom with the reach to use them, and the mass barely moves: 522 kg against 499 kg, a difference of 23 kg that disappears entirely once bracket and hoses are counted. The choice between the two heads is therefore about hydraulics and access, never about lift.

The published optimal target material diameter of 15 cm is the number that should govern quoting. On mixed contracts it comfortably covers regrowth eucalypt coppice, wattle thickets, shelterbelt understorey and the woody weeds that come with old farm ground. A stand that is consistently heavier is a signal to price the job on a bigger head or to subcontract it, and maximum diameter versus production diameter shows why the occasional 20 cm stem is not evidence that the head will hold that rate.

Flow, not tonnage, sets where you land in the window

Continuous flow of 87 to 144 L/min is a wide window, and where a given carrier falls inside it is what decides the production rate. The published minimum carrier power is 54 hp (40 kW) and the VM range runs to a maximum operating pressure of approximately 410 bar, which the carrier’s auxiliary relief setting has to respect. What the buyer needs measured is continuous flow under load, the pressure available at the same moment, return back-pressure and the presence of a case drain.

Put those measured numbers, not the brochure ones, through the hydraulic power calculator; the full worked arithmetic is on the VM-50SR page. The short version for this class is that a 12 tonne machine with a proper auxiliary circuit gets a great deal more out of this head than an 8 tonne machine that merely clears the published minimum. Mulching also holds the pump at high demand for hours with none of the natural pauses digging provides, so read hydraulic matching and hydraulic cooling and heat before the cooler becomes the surprise.

Where a part-time mulching head pays

The work that suits this class is road corridor clearing on rural reserves, firebreak and asset-protection work in bushfire fuel reduction programs, and farm clearing, shelterbelts and orchards where old rows are being removed. All three are seasonal, which suits an owner who needs the carrier back on other work in between.

Old farm ground, table drains and batters are where tooling gets destroyed, and buried wire, star pickets and stone are more common there than in any forest. Carbide is usually the safer commitment on that ground; blades belong on clean green material where finish quality is being sold. Blades versus carbide teeth makes the comparison in detail.

Stepping either way

Go down to the VM-25SK only when access, not production, governs the work, since the smaller head costs almost nothing in mass but gives up a quarter of the swath. Go up to the VM-40SL when stems regularly exceed 15 cm or when the fleet has moved to 12 to 15 tonne machines with strong auxiliary circuits. Go sideways, to a front-mount head such as the HM-70, when the ground is flat and open enough for a loader to drive continuously, because forward travel beats sweeping from a stance every time the terrain allows it; excavator mulcher versus skid steer mulcher weighs that properly.

Owning consumables you use in bursts

Part-time use creates its own parts problem: a belt or a bearing set that would be replaced on schedule by a full-time operator instead sits half-worn through a quiet quarter and fails in the middle of the one week that was booked. Get the consumable list priced with Australian stock levels at quotation rather than at the first failure, and treat the wear parts to price before buying list as the minimum. Between jobs, store the head with the belt housing blown out and the rotor bearings greased, and put daily blow-down and leak checks into the operator’s routine during the season; see fire risk in clearing operations. The circuits the door and any option need are set out in full on the VM-25SK page.

Building a rate when the carrier has two jobs

A mulching head on a shared carrier creates an accounting problem that a dedicated machine does not. The excavator’s finance, insurance, registration and major service costs belong to the whole year, while the head’s purchase price, tooling and belt life belong only to the weeks it is fitted. Contractors who ignore that either quote mulching too cheaply, by treating the carrier as already paid for, or too dearly, by loading a full machine rate onto a few hundred hours.

The workable method is to carry the carrier at its normal hourly rate, add a separate hourly figure for the head that recovers its purchase price and tooling across a realistic annual utilisation, then add mobilisation as a job cost rather than an hourly one. Building a tender rate sets out the structure, and total cost of ownership covers the inputs. The number that decides whether the arrangement works is annual mulching hours, and it is worth writing down honestly before the order rather than optimistically afterwards.

Hire, buy, or subcontract

There are three ways to service a mulching contract with an 8 to 12 tonne carrier, and the right answer changes with the shape of the work rather than its volume.

Hiring a head for a defined block of work suits a contractor testing whether the service sells, because it converts a capital decision into a job cost and reveals the real hours before any money is committed. Buying suits scattered, recurring work where mobilisation dominates and the head needs to be on the truck whenever the carrier is. Subcontracting the mulching to a specialist with a wider machine suits large continuous blocks, where the specialist’s production advantage is bigger than the margin being given away. Hire versus buy works through the comparison in detail.

The trap is the middle case: buying a head for a single large contract that will not repeat. A 522 kg attachment does not depreciate quickly, but it does sit idle, and an idle attachment on a busy carrier is a reminder of a decision rather than an asset.

Changing over without losing the morning

The flexibility that justifies this class only exists if the changeover is quick, and in practice that means three things being right at once. The coupler has to be the same across the tool list, so the operator is not carrying pins and spacers for one attachment. The hydraulic connections have to be dry-break couplers that can be connected with residual pressure in the lines, because a hot mulcher circuit will not connect otherwise and an operator who has to crack a fitting to relieve pressure will eventually stop bothering with the mulcher. And the electrical connection for the door diverter has to be a plug rather than a set of terminals.

Get all three demonstrated at handover with the machine hot, not cold in the workshop, and time it. Quick couplers and attachment changeover covers the options. A changeover that takes twenty minutes is a tool that gets used; one that takes an hour and a half is a tool that stays on the trailer until the job is big enough to justify it, which defeats the reason the VM-35SK was bought.

Buying used from a mixed fleet

Heads from mixed-fleet owners are often in better condition than their hours suggest, because they spent whole seasons in a shed rather than in windrows. The things to check are the ones that suffer from storage rather than work: bearing condition after long idle periods, belt condition where it has sat under tension in one position, and corrosion at the case drain and door fittings. Ask what the head was run on and whether the carrier had a case drain, since a head that lived on an undersized circuit will show heat damage at the motor even with low hours. Inspecting used forestry attachments sets out the sequence.

Confirm before ordering

• Continuous auxiliary flow and pressure measured under load on the actual carrier, and where that sits in the 87 to 144 L/min window
• One auxiliary specification that suits the mulcher, a rotating grab and a shear, so the kit is built once
• Coupler type and changeover time for every attachment in the fleet
• Case drain to tank and the carrier's return pressure limit
• Quoted head mass in the ordered configuration, checked at working radius
• Cooler capacity for continuous summer running, given the carrier's normal duty is digging
• Australian stock and price of teeth, holders, belt and bearings, and the delivered price with bracket and hoses

Frequently asked questions