Shearex VM-25SK excavator mulcher

Where the VM-25SK sits in the range

The VM-25SK is the smallest head in the Shearex VM excavator mulcher range, built for 5 to 8 tonne carriers. It suits council contractors and small vegetation businesses working narrow road reserves, drain lines and batters that a front-mount machine cannot reach, on a carrier that travels on a light float and fits inside a lane closure without the traffic-control cost a 20 tonne machine attracts. Above it, the VM-35SK moves into the 8 to 12 tonne class with a 95 cm rotor, and the VM-40SL begins the commercial land-clearing end of the family. The VM-25SK is an access tool rather than an area tool.

What the published figures mean on site

The 70 cm cutting width sets the swath, about what a 5 to 8 tonne boom sweeps without constant repositioning. The optimal target material diameter is published as under 13 cm, and that is the commercially honest number: the stems the head processes continuously at a productive rate, not the largest stem it will eventually get through. Regrowth, saplings, lantana and woody weeds sit inside it; a stand of 20 cm wattle does not, even if the head copes with the occasional one. Our guide on maximum diameter versus production diameter explains why tendering on the occasional maximum loses money.

At 499 kg the head is light for the class, but it should still be checked against the lift chart at the working radius. Continuous flow of 57 to 83 L/min is modest in absolute terms yet demanding for this carrier size, and the minimum carrier power of 50 hp (37 kW) rules out the lighter end of the 5 tonne market. Across the VM range the maximum operating pressure is published as up to approximately 410 bar, so the carrier’s auxiliary relief setting belongs in the conversation alongside its pump.

Carrier matching

The limit on a carrier this size is rarely the pump’s headline figure. It is what a small tank and cooler will hold once the oil is hot, and whether a case drain runs back to tank at all, since many 5 to 8 tonne machines leave the factory without one. Ask for continuous auxiliary flow measured under load, the pressure available at the same time and the return pressure the carrier imposes, then read hydraulic matching and hydraulic cooling and heat.

Put those measured figures through the hydraulic power calculator before committing. The published minimum of 50 hp (37 kW) leaves almost no margin at the top of the flow window, which is why a lightly powered 5 tonne machine stalls the rotor in anything dense.

Typical work and production considerations

The natural homes for this head are council parks and urban vegetation, tight-reserve road corridor clearing and small-scale bushfire fuel reduction around assets. Measure output in hectares per productive hour and record the first knockdown pass separately from any second pass, because moving the finish class from rough knockdown to fine mulch can roughly double the time on the same block. Road batters and drains frequently carry exposed stone, which argues for carbide teeth on most corridor work, 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 70 cm rotor on a mini excavator is not a hectare machine. On flat, traversable ground a front-mount head such as the HM-60 covers more than twice the width per pass and will outproduce it; excavator mulcher versus skid steer mulcher sets out when each wins. If typical stems regularly exceed the 13 cm target, or the sites are open, step up to the VM-35SK. There is no smaller Shearex head, and if the work is mostly grass a slasher is the cheaper tool.

Options and hydraulic circuits to settle at quotation

The hydraulic door is standard on every VM head, and Shearex’s guidance is that the door runs on the pressure and return lines plus a case drain, with an electrical diverter for control. Grapple, tilt and heel are optional. Tilt is better served by a second double-acting auxiliary line, and tilt plus grapple together is best done with two double auxiliary circuits plus case drain. On a 5 to 8 tonne excavator that may mean an auxiliary kit the machine does not yet have, so settle the circuit plan and wiring before the head is ordered.

Wear parts and support

Price the consumables before you sign: teeth or blades and holders, the Poly-Chain carbon belt, rotor bearings, the Hardox 500 bolt-on liner and skid shoes. Ask Machinery Specialist what is held in Australian stock and what has to be ordered from the factory, because a small contractor waiting on a belt loses a week. Mulching packs dry fines around the belt housing and the carrier’s engine bay, so a daily blow-down and a check for hydraulic weeps are part of fire housekeeping; see fire risk in clearing operations.

Confirm before ordering

• Carrier make, model and year, with continuous auxiliary flow measured under load at operating temperature
• Auxiliary relief setting, return pressure and a case drain line to tank
• Circuit plan for the standard door and any tilt, grapple or heel option, including diverter wiring
• Head weight in the ordered configuration checked against the lift chart at working radius
• Cooler and tank capacity adequate for continuous summer work
• Blade or carbide recommendation for the expected rock exposure
• Australian stock of teeth, holders, belt and bearings, and delivered price including bracket and hoses

Frequently asked questions