Run the lift chart before trusting the carrier class
A published carrier class is a guide. The real check is the chart with 1,600 kg fitted at the reach and slew the work requires, on the ground conditions you will meet.
Where this machine sits
The ST90 is a mid-size stump shear for 12-20 tonne carriers: 1,600 kg, a 900 mm opening and up to 70 tonnes of cylinder force. Shearing is a different approach to stumps from grinding — it splits and lifts the stump rather than reducing it to chips, which suits site preparation and stump recovery rather than finishing a lawn.
The carrier class is the decisive specification. At 1,600 kg the attachment has to be held at working reach on ground that is frequently uneven, and the lift chart with the shear fitted is what determines whether a carrier in the stated class can actually use it.
Specifications
Indicative published manufacturer and distributor information. Confirm every figure, lift chart and hydraulic requirement with the manufacturer or authorised dealer before purchase.
What the published figures actually constrain
A specification table tells you what the machine is. This is what each of those numbers means for the work you would put it to.
The four checks that decide whether your carrier can run this
Each of these can fail independently, and passing one says nothing about the others. Weight class alone is the weakest of the four and the one most often relied on.
Where this machine earns its cost
Wrong machine when
- Urban finish work — stump shears are poor where excavation must be minimised
- Stump populations above the 900 mm opening, where the ST140 is the correct size
Verify these for this specific model
Beyond the standard buying criteria for the class, these are the questions this machine in particular raises.
What drives the cost of owning this machine
Shearing suits stump recovery and site preparation, where the objective is removing stumps across an area rather than finishing individual ones. Where the material has a biomass outlet, recovery can offset part of the cost — but stumps carry soil, which affects both wear and specification compliance.
Carrier utilisation is the commercial advantage of an attachment-based approach. The 12-20 tonne carrier earns in other work when stump removal is not running, which spreads its fixed cost far wider than a dedicated machine achieves.
Wear on shear blades and pivots scales with material and with soil contact. Rocky or gravelly ground is hard on the attachment in ways that a clean demonstration does not reveal.
Ownership considerations in Australian conditions
Match the opening to ground-level diameter
Stumps flare at the base. Measuring at breast height or from the standing tree understates what the shear has to engage.
Confirm hydraulic requirements with the carrier
Flow and pressure have to be met by the carrier's auxiliary circuit continuously. This is a separate check from the lift chart, and both have to pass.
Common questions about this machine
Alternatives to compare against
Other stump shears covered in this guide.
Fleet packages that use this class
Commercial land clearing
A deliberately flexible attachment-based system. Instead of owning six specialised purpose-built forestry machines, the same base excavator generates revenue across civil earthworks, demolition, vegetation clearing, log handling, tree removal, stump removal, road construction and drainage.
Plantation re-establishment
A sequence rather than a machine: stump treatment, then slash treatment, then tillage, scarification or mounding, then planting. Measured in hectares and planting spots, not cubic metres.