EP-THOR ST grondstabilisatiemachine – Wegverharding, 200 mm diepte
PTO-driven soil stabilizer for rural road rehabilitation — mills and mixes existing road material to 200 mm depth, injecting water from a connected water truck. 92 Kennametal RK4 bits. CVT tractor is mandatory. 250 CV minimum.
0.5–1.5 km/h · 1000 RPM · 5,300 Kg · Transport: 2,960×2,745×2,615 mm · Korea local stock.
THOR ST — Engineered for Rural Road Improvement
The Watanabe THOR ST is a PTO-driven soil stabilizer built specifically for the construction, rehabilitation, and recycling of rural roads. Connected to a water truck via a distribution hose, the THOR ST mills existing road surface material to depths of up to 200 mm and mixes it uniformly with water and chemical stabilizing agents — converting degraded road material into a structurally improved, stabilized base layer in a single forward pass. The result: improved traffic flow for heavily loaded trucks, reduced fleet maintenance requirements, and significantly lower construction costs compared to conventional road reconstruction.
The THOR ST operates at 0.5–1.5 km/h at 250 CV minimum PTO input. CVT (Continuously Variable Transmission) tractor is mandatory — this is the only tractor transmission type that can maintain the required slow working speeds while delivering full 1000 RPM PTO output. A conventional-transmission tractor cannot replicate this operating condition regardless of gear selection.
For projects where significant surface rock requires processing before soil stabilization, the THOR 2.4 stone crusher pre-processes surface boulders to aggregate size in the pass preceding the THOR ST. For the lime or cement binder distribution step that precedes the THOR ST milling pass, the DCW 2.2 binder spreader front-mounts on the same CVT tractor as the THOR ST rear, enabling single-pass combined binder spreading and soil milling.
Complete Technical Specifications — THOR ST
All data from Watanabe official product documentation (February 2026).
TRANSPORT DIMENSIONS
| Length | 2,960 mm |
| Width | 2,745 mm |
| Height | 2,615 mm |
MACHINE DIMENSIONS (WORKING)
| Body length | 1,794 mm |
| Total length (incl. hitching) | 2,400 mm |
| Body height | 1,086 mm |
| Total height | 1,740 mm |
| Rotor drum width | 2,200 mm |
| Total width (incl. side covers) | 2,744 mm |
MANDATORY TRACTOR REQUIREMENTS
| Min. Power Rating | 250 CV |
| Transmission Type | CVT — MANDATORY |
| Operating Speed | 0.5–1.5 km/h |
| PTO Input | 1.3/8" — 21 splines |
| PTO Speed | 1,000 RPM |
MACHINE DATA
| Milling Depth Range | 0–200 mm |
| Number of Bits | 92 |
| Bit Type | Kennametal RK4 |
| Operating Weight (approx.) | 5,300 Kg |
ⓘ 250 CV = 250 metric horsepower (cavalo-vapor). CVT tractor is a non-negotiable hardware requirement — confirm before ordering. All specifications from Watanabe official product documentation February 2026.
Machine Component Breakdown — 7 Integrated Systems
The THOR ST's soil stabilization capability comes from the integration of 7 functional components working in coordination during the forward pass. Understanding each component explains how the machine achieves simultaneous soil milling, water injection, and material mixing.
Liquid Reservoir
Holds the water supply for the soil stabilization mixing process. Connected via distribution hose to the water truck travelling alongside the machine. The reservoir acts as a buffer between the water truck supply flow and the continuous application nozzle demand — smoothing any flow variation from the truck supply line.
Cover Adjustment Cylinder
The hydraulic cylinder that controls the position of the adjustable cover (Component 3), which in turn determines the milling depth. Adjustment from 0 to 200 mm is a "practical and fast operation" — the operator sets the target depth from the tractor controls before the working pass and the cylinder holds the cover position precisely throughout.
Adjustable Cover
The rear cover plate of the milling chamber, positioned by the Cover Adjustment Cylinder (Component 2) to set the milling depth. As the cover is raised (away from the ground), the effective penetration depth of the rotor increases. Lowering the cover reduces the effective cutting depth. This is the primary depth control mechanism — simple, mechanically robust, and field-adjustable without specialist tools.
Rotor with RK4 Bits
The central working component. Carries 92 Kennametal RK4-type bits across the full 2,200 mm rotor drum width. Driven at 1000 RPM by the CVT tractor PTO via the gearbox (Component 5) and chain protection (Component 6), the rotor shatters and pulverizes road surface material to the set depth. Designed for milling applications in various soil types — granular road base, clay, laterite, and mixed recycled asphalt and aggregate road materials.
Gearbox
Transmits power from the PTO input shaft (1.3/8" - 21 splines) to the rotor drive train. Sized for the 250 CV continuous input load that the THOR ST requires during sustained milling operation. The gearbox is positioned at the machine's centre to distribute drive load symmetrically across the full 2,200 mm rotor width. Designed for easy maintenance and low operating cost — one of the principal design criteria for the THOR ST's Kennametal RK4 rotor system.
Heavy-Duty Chain Protection
Encloses the drive chain between the gearbox and rotor shaft in a heavy-duty protective housing, shielding it from stone fragments, abrasive dust, and the chemical exposure of the lime or cement stabilizing agent environment inside the milling chamber. Chain protection inspection and lubrication access is provided without major disassembly — supporting the THOR ST's design intent of low operating cost and easy maintenance in field conditions.
Application Nozzles
Spray water from the Liquid Reservoir (Component 1) into the milling chamber during the rotor pass. The nozzles are positioned to distribute water uniformly across the full rotor width — ensuring every portion of the milled soil column receives the moisture required for the chemical stabilization reaction. Application rate is controlled in relation to forward speed to maintain the target moisture content in the finished stabilized material.
Kennametal RK4 Rotor System — Fixation Block + BIT-RK4
The THOR ST rotor uses the Kennametal RK4 bit system — the same bit series used in professional road reclamation, cold milling, and soil stabilization equipment internationally. The RK4 system consists of two components:
FIXATION BLOCK
The steel holder welded to the rotor drum that receives and locks the individual BIT-RK4. The fixation block design allows each bit to rotate freely within the holder during operation — this rotational freedom distributes wear evenly around the bit's circumference, extending bit service life compared to fixed-position bit systems. When the bit wears out, only the bit is replaced; the fixation block remains on the rotor. No rotor removal is required for individual bit replacement.
BIT-RK4
The individual Kennametal-manufactured milling tool with a carbide tip and a cylindrical shank that fits into the fixation block. The RK4 bit geometry is optimised for milling applications in granular road base materials, compacted soil, and mixed material road structures. 92 bits cover the full 2,200 mm rotor drum width of the THOR ST. The bits are individually replaceable in the field — a critical operational advantage for remote Korean rural road projects far from workshop facilities.
Adjustable Milling Depth — 0 to 200 mm
The THOR ST's milling depth is set by the Cover Adjustment Cylinder (Component 2) controlling the Adjustable Cover (Component 3). The Watanabe design description: "a practical and fast operation — simple concept for adjusting the milling depth — 0 to 200 mm." The depth is set before the working pass begins and is held by the hydraulic cylinder throughout the pass without operator monitoring.
Choosing the Right Milling Depth for Korean Road Projects
The milling depth for a specific project section is determined by the condition of the existing road structure, assessed through visual inspection and trial pits before the stabilization pass:
| Road Condition | Recommended Depth | Rationale |
|---|---|---|
| Surface rutting only, sound base | 80–120 mm | Treats the wearing course only — preserves existing base |
| Moderate base deterioration | 120–160 mm | Includes part of the degraded base layer |
| Severe base failure | 160–200 mm | Full structural reconstruction to sub-base level |
| Thin asphalt over failed base | 150–200 mm | Processes asphalt + base together as recycled material |
ⓘ Depth selection is a project engineering decision. These ranges are indicative guidance only — consult a geotechnical engineer for project-specific depth specification on formal road contracts.
The Complete Soil Stabilization System
The THOR ST is the central milling machine in a coordinated four-machine soil stabilization workflow. The system shown in the official Watanabe documentation:
Applications — This Machine Is Designed For
From the Watanabe official THOR ST product documentation:
Construction, rehabilitation, and recycling of rural roads — with the objective of improving traffic flow, particularly for heavily loaded trucks. The THOR ST's 200 mm milling depth allows the complete structural treatment of deteriorated rural road base layers, not just surface scarification.
Reduced fleet maintenance requirements — a chemically stabilized road base reduces rut formation, pothole development, and surface deterioration under heavy agricultural and commercial vehicle loads. Lower road maintenance frequency means lower overall infrastructure cost for county governments and farm cooperatives responsible for rural road networks.
Dust reduction, enhancing operational safety — stabilized road surfaces generate significantly less dust under vehicle traffic than unsurfaced compacted soil roads. For Korean agricultural zones where roads pass alongside ginseng fields, vegetable operations, and orchards, dust suppression is a direct operational benefit for the farming community adjacent to the treated road.
Significant reduction in transportation time and operational costs between field and factory — all-weather access roads that remain passable under heavy load after rain and frost events are a direct enabler of reliable supply chain logistics for Korean agricultural producers who depend on on-time delivery from field to packhouse, processor, or cooperative.
Korean Application Zones
Primary Korean application areas for the THOR ST include: 농어촌도로 (rural agricultural road) rehabilitation programs administered by county governments; mountain farm access road improvement in Gangwon-do, North and South Gyeongsang, and North Chungcheong; forestry bureau road upgrading for timber transport in highland regions; plantation internal road networks in South Jeolla, South Chungcheong, and Gyeonggi-do; and village connector road construction in highland agricultural communities where conventional aggregate supply is expensive due to distance.
In-Place Stabilization vs. Conventional Road Reconstruction
Soil stabilization with the THOR ST delivers multiple advantages over conventional road reconstruction — from the official Watanabe product documentation: "reduced vehicle maintenance, shorter construction timelines, optimized resource usage, and lower CO₂ emissions."
| Factor | In-Place Stabilization (THOR ST) | Conventional Reconstruction |
|---|---|---|
| Material import required? | No — existing road is the raw material | Yes — crushed aggregate, asphalt |
| Old material removal? | No — milled and reused in-place | Yes — excavation, haulage, disposal |
| Construction timeline | Short — days to weeks | Extended — weeks to months |
| CO₂ emissions | Significantly lower | Higher (haulage + production) |
| Typical project cost | 40–60% lower (typical range) | Baseline (100%) |
| Prerequisite | Soil type must suit chemical treatment | None — works in any condition |
ⓘ Cost comparison is a general estimate from road rehabilitation literature. Site-specific engineering assessment determines actual cost benefit for each project.
Watanabe — Road Stabilization Equipment Since 1970
Why Brazilian Rural Road Experience Applies to Korea
Brazil's rural road network conditions — particularly in the highland agricultural states of Paraná, Santa Catarina, and Minas Gerais — closely parallel Korean 농어촌도로 conditions: decomposed granite and laterite clay road base materials, heavy agricultural truck loads, seasonal weather extremes, and limited aggregate supply at distance from major quarries. The THOR ST's specification for this Brazilian operating environment makes it directly applicable to Korean rural road rehabilitation projects without material modification.
Korea Local Stock and Service
Korea Watanabe maintains the THOR ST and DCW 2.2 in local inventory in Ansan-si, Gyeonggi-do. Korean-language technical support covers CVT tractor configuration, milling depth setting guidance, binder type selection for Korean soil conditions, RK4 bit supply, and operational troubleshooting. Kennametal RK4 bits and fixation blocks stocked locally for next-day domestic dispatch. Warranty terms confirmed at purchase.
Frequently Asked Questions — THOR ST
Why is CVT mandatory — can I use a conventional tractor?
The THOR ST requires 0.5–1.5 km/h working speed while maintaining full 1000 RPM PTO output. No conventional transmission tractor can achieve speeds below approximately 2–3 km/h at the engine RPM required for full PTO output — the lowest gear ratios of conventional tractors simply cannot produce the required creep speed. CVT tractors decouple ground speed from engine speed, enabling any speed from 0 km/h with full PTO output. There is no workaround — CVT is a hardware requirement. Confirm CVT specification on your tractor before ordering.
How are individual RK4 bits replaced in the field?
Each BIT-RK4 inserts into its fixation block on the rotor drum. Bit extraction uses a standard chisel and hammer or a dedicated bit extractor tool — the bit is knocked from the side until it disengages from the fixation block. A new bit is driven into the block until it seats. No rotor removal, no welding, no specialist workshop equipment required. The field replacement capability is a key operational advantage for remote Korean rural road project sites. Carry a set of spare bits on site during multi-day projects to avoid downtime for parts delivery.
Can the THOR ST mill existing asphalt surfaces?
Yes. The Kennametal RK4 bit system is rated for milling in asphalt, recycled asphalt base, compacted aggregate, and soil. For Korean rural roads with thin existing asphalt wearing courses over deteriorated base layers — a common condition on roads resurfaced in previous improvement programs — the THOR ST processes both layers simultaneously at the set depth. The resulting mix of recycled asphalt and granular base material is suitable for lime or cement stabilization treatment in the same pass.
What CVT tractor models are compatible?
The THOR ST requires a CVT tractor at 250 CV minimum with 1.3/8" - 21 spline 1000 RPM rear PTO. Compatible CVT tractors in the 250 CV+ range: Fendt 700 Vario (720–724), Fendt 800 Vario; CLAAS AXION 800 series; Case IH Optum CVX; New Holland T7 AutoCommand; John Deere 6R/7R with DirectDrive or IVT. Most Korean domestic tractor brands do not currently offer CVT in the 250 CV class — most Korean THOR ST operators use European CVT tractors. Confirm CVT specification and PTO spline count before ordering.
Does the THOR ST work alone or only with the DCW 2.2?
The THOR ST operates as a standalone milling and mixing unit when binder has been distributed by another method (separate pass, broadcast truck), or for road pulverization projects without chemical stabilization. The full efficiency of the system is achieved when the DCW 2.2 binder spreader is front-mounted on the same CVT tractor — enabling single-pass combined binder distribution and soil milling. Whether to use both together or the THOR ST alone depends on the project method specification and available equipment configuration.
What is the realistic daily project coverage?
At 1.0 km/h working speed and a rotor drum width of 2,200 mm, productive coverage is approximately 2,200 m² per hour of active rotor engagement. Accounting for water truck fill stops, bit inspections, and daily equipment checks, a realistic productive day covers 400–700 linear meters of road (at standard Korean rural road width of 3–4 m effective treatment width per pass). Water truck logistics — fill interval, travel distance to water source — is often the practical constraint on daily coverage rather than the THOR ST's milling capacity.
How long before the stabilized road can carry traffic?
After the THOR ST milling pass, the road section is graded and compacted on the same day. Light traffic (passenger cars, light trucks) can typically use a lime-stabilized road section within 24–48 hours of compaction. Cement-stabilized sections develop higher early strength and can typically carry light traffic within 24 hours. Full structural strength (used for pavement design) develops over 7–28 days depending on binder type, application rate, and curing conditions. Heavy agricultural truck traffic should be deferred for a minimum of 7 days on cement-stabilized sections and longer on lime-stabilized sections — the engineer supervising the project specifies the traffic opening criteria.
Are Korean government 농어촌도로 program contracts suitable for this method?
In-place soil stabilization is a recognized road rehabilitation method in Korean engineering practice and is eligible for consideration in rural road improvement programs (농어촌도로 정비사업, 농촌마을 기반시설 개선사업). Whether a specific project contract permits in-place stabilization as an alternative to conventional reconstruction depends on the contract specification and the supervising structural engineer's assessment of the site soil conditions. We recommend consulting with the regional county road bureau or provincial road engineer before committing to stabilization on government-funded contracts. We provide technical specification documentation and project reference materials to support the approval process.
Customer Reviews
Yoo Sung-jin — Rural Road Contractor, Jecheon, North Chungcheong (2025)
★★★★★
"THOR ST + DCW 2.2 on a 4.2 km county agricultural road rehabilitation project in North Chungcheong. The Cover Adjustment Cylinder depth system is genuinely simple to use — one adjustment before the pass and the depth holds perfectly throughout. Completed the project in 9 working days. The county road office accepted the work on first inspection and has requested a quote for two additional sections. The CVT tractor requirement was explained clearly by Korea Watanabe before we committed — no surprises."
Kim Hyeon-taek — Road Contractor, Wonju, Gangwon-do (2024–2025)
★★★★★
"Mountain access road rehabilitation in Gangwon-do — decomposed granite base, cement stabilization at 160 mm depth. The 92 Kennametal RK4 bits have held up well in the granite conditions. I carry 20 spare bits on site at all times, and have used maybe 8 over two seasons of work — very manageable. The 0.5–1.5 km/h speed range with the CVT tractor is the right speed for thorough mixing in this material. Three projects accepted on first inspection."
Choi Wan-su — Civil Engineering Contractor, Naju, South Jeolla (2025)
★★★★★
"Lime stabilization on South Jeolla heavy clay roads using the THOR ST + DCW 2.2 system. Korea Watanabe confirmed lime was the right binder for the clay soil type here before we ordered, and the soil test results from the completed sections confirm the stabilization worked as designed. The cost versus conventional aggregate overlay was 47% lower on one of our project sections — a significant saving for the county client."
Park Dong-su — Forestry Road Contractor, Hamyang-gun, South Gyeongsang (2025)
★★★★★
"Forestry bureau contract for timber transport roads in Hamyang — the THOR ST at 180 mm depth with cement stabilization produced a road that has now survived two full heavy-timber seasons without any surface maintenance. The water truck connection works well and the water injection uniformity across the full 2,200 mm rotor width is visibly consistent in the mixed material. The seven-component layout of the machine makes field servicing straightforward — everything is accessible."
Lee Sang-bum — Plantation Manager, Yeongam-gun, South Jeolla (2024)
★★★★★
"Plantation internal road stabilization — 11 km of farm road network. The THOR ST stabilized sections have been maintenance-free for 14 months. Before stabilization, we were grading these roads three times per year and dust was a constant complaint from the neighboring citrus operation. Both problems eliminated. The operational cost reduction from eliminating annual grading on the stabilized sections has been material."
Jeong Hyun-jo — County Road Bureau Engineer, Boryeong-si, South Chungcheong (2025)
★★★★★
"From a supervising engineer's perspective: the THOR ST's 7-component system is well-thought-out from a maintenance and field operation standpoint. The RK4 fixation block + bit system with no rotor removal for bit replacement is the right design for rural road site conditions where a workshop is not available. The depth adjustment system is simple and reliable. Project accepted by our quality review on first submission of documentation."
Discuss Your Rural Road Rehabilitation Project
Tell us your road length, width, soil type, existing surface condition, and available CVT tractor model — we provide technical guidance on stabilization suitability and complete system configuration. THOR ST and DCW 2.2 binder spreader available from steenbreker-tractor.com, Ansan-si, Gyeonggi-do.
Aanvullende informatie
| Editor | Cxm |
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