Most guides about Korean highland stone management focus on the concasseur de roches — the machine that fragments granite to sub-5 cm size. Fewer discuss what comes next. The ramasse-roches CT-2100 is the machine that completes the process: it collects the fragmented stone from the soil surface and deposits it away from the field, making the cleared surface permanent rather than temporary.
Without the CT-2100 collection step, fragmented granite sits in the top 10–15 cm of the soil profile. The Korean highland freeze-thaw cycle — which operates at 600 m altitude from November through March — progressively elevates subsurface stones back to the surface each winter. By the following spring, a field that was cleared in October will have recovered 40–70% of its surface stone cover from sub-surface material returning to the surface layer. The THOR 2.4 pass must then be repeated, and the clearing investment is essentially renewed every season rather than compounding across years.
The CT-2100 rock picker for tractor removes the fragmented stone from the clearing zone — permanently. With the collection step completed, the sub-surface material that returns each frost cycle is progressively smaller and sparser, until the field reaches the stable maintenance standard where only the EP-EW-4000 surface rake is needed each year.
Why Stone Collection Is as Important as Fragmentation — The Frost-Heave Cycle Explained
Korean highland granite fragments produced by the THOR 2.4 range from dust particles to 4–5 cm pieces — all small enough to pass below the surface during PSW-3200 tillage. However, “below the surface” in Korean highland context means within the frost-active zone, which extends to 30–50 cm at 600 m altitude. The physics of frost heave applies to stones regardless of their size: any particle with a density significantly different from the surrounding soil matrix will be displaced toward the surface during freeze-thaw cycling.
Without CT-2100 collection (fragment left in soil)
- Fragments remain in frost-active zone (0–30 cm)
- November–March frost cycles push 40–70% back to surface
- Spring requires full THOR 2.4 re-pass
- Clearing investment renewed every season, not compounding
- Sub-surface stone density never permanently reduces
With CT-2100 collection (fragment removed from field)
- Fragmented stone removed from frost-active zone entirely
- Only stones still below the CT-2100’s collection depth return
- Year 2: 60–70% less surface stone than Year 1 (sub-surface depleted)
- Year 5+: EP-EW-4000 surface maintenance sufficient most blocks
- Permanent soil improvement compounds across years
The long-term stone management curve is fundamentally different between the two approaches. Without collection, the farm is on a treadmill — clearing the same stones every season. With the CT-2100 collection step, each season’s clearing draws down the sub-surface stone reserve until the field reaches the stable low-maintenance equilibrium that makes Korean highland farming commercially viable for the long term.
CT-2100 Confirmed Specifications — What the Official Brochure States
All CT-2100 specifications are from the official Watanabe product brochure. No estimates — confirmed values only.
Three additional confirmed specifications complete the picture: working width of 1,95 m, machine weight of 3,400 Kg, and Cat. 2 rear three-point hitch. These numbers are the operational foundation for every calculation and routing decision in this guide.
Why 60 L/min Hydraulic Flow Is the Critical Tractor-Side Requirement
The CT-2100’s picking head mechanism — the hydraulically driven system that lifts stones off the field surface and transfers them into the bunker — requires a sustained 60 litres per minute of hydraulic flow from the tractor. This figure is higher than the rear hydraulic output of many Korean domestic tractors in the 110–130 HP range, which may provide only 40–50 L/min on the rear remotes when the transmission and other auxiliary circuits are also active.
Before pairing a CT-2100 with an existing tractor, confirm the tractor’s rear remote hydraulic output specification — specifically the maximum continuous flow rate available at the rear remote couplers under normal operating conditions, not the system pump capacity. If the tractor provides less than 60 L/min to the CT-2100, the picking head cycle rate slows and stones that should be collected are left behind, reducing the collection pass’s effectiveness. Korea Watanabe confirms hydraulic flow compatibility for any specific tractor model during the pre-purchase assessment.
The 3–5 km/h Optimum — Why Speed Determines Collection Quality
The CT-2100’s operating speed range of 3–5 km/h is not a manufacturer recommendation — it is the engineered design range at which the picking mechanism’s cycle time is correctly matched to the tractor’s ground speed. Operating outside this range produces measurable collection quality degradation in both directions:
The practical operating approach for Korean highland CT-2100 operators: set ground speed to 3–4 km/h for the first collection pass on a newly cleared field (higher stone density from the THOR 2.4 output), and increase to 4–5 km/h for the second collection pass or for established fields in their annual maintenance cycle (lower residual stone density). The speed increase for the lighter-load pass maintains good collection completeness while reducing the time per hectare.
Bunker Capacity and Dump Cycle Planning — How Many Times Per Hectare?
The 2.5 m³ bunker is the CT-2100’s production-limiting parameter. When it fills, the machine must travel to the dump location, unload, and return to the collection route — time during which no stone is being collected. Planning the collection route to minimise dump cycle interruptions is one of the most practical productivity improvements available to CT-2100 operators.
Bunker Fills Per Hectare — Reference Calculation
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On established fields in their third year and beyond, where the residual stone density is significantly lower (1–2 Kg/m²), the CT-2100 covers 2.5–4 ha between dumps — transforming the machine’s daily productivity from approximately 2.5–3.5 ha/day on first-year cleared fields to 5–8 ha/day on maintained fields at the same 3–5 km/h operating speed.
The 1.95m Width and THOR 2.4 Routing — Planning the Two-Machine Passes Together
The CT-2100’s working width of 1.95 m is narrower than the Concasseur de pierres THOR 2.4‘s 2.4 m. This 450 mm difference means that for every THOR 2.4 pass, the CT-2100 must make approximately 1.25 passes at the same track spacing to cover the same ground completely. In practice, the CT-2100 collection plan should be laid out with a track spacing of 1.7–1.8 m to ensure full coverage of the THOR 2.4’s cleared strip with slight overlap between CT-2100 passes.
Strategy 1 — Sequential: THOR 2.4 completes field, CT-2100 follows
Idéal pour : Single-tractor operations or farms where the same tractor powers both machines. THOR 2.4 completes the full field clearance pass (1–3 days depending on field size). CT-2100 then begins the collection pass on the fully cleared field, starting from the end where the THOR 2.4 finished.
Avantage: The CT-2100 operator can see the complete fragmented stone distribution and optimise the collection route for dump cycle efficiency. The field is in a consistent cleared state throughout the collection pass.
Disadvantage: The THOR 2.4’s fragmented output sits on the surface for several days before collection — on windy Korean highland conditions in spring, fine material may redistribute. Not the optimal approach if the field needs to be sown promptly.
Strategy 2 — Zone clearing: THOR 2.4 clears one block, CT-2100 follows immediately
Idéal pour : Two-tractor operations or farms with an available contractor for one of the two machines. The field is divided into zones (typically strips of 0.5–1.0 ha). The THOR 2.4 clears Zone 1; the CT-2100 begins collecting Zone 1 while the THOR 2.4 moves to Zone 2.
Avantage: Cleared ground is collected within 24 hours of fragmentation, before any significant re-distribution. The sowing window opens progressively — cleared and collected zones can receive PSW-3200 preparation and seeding while the THOR 2.4 is still working on later zones. Total field-to-seed timeline is significantly shorter.
Disadvantage: Requires coordinating two machines and two tractor operators simultaneously. Higher daily management complexity but faster overall completion.
Pre-Season Service Checklist — 10 Checks Before the First Collection Pass
The CT-2100 pre-season service should be completed in February — before the THOR 2.4 preparation work begins in March. A CT-2100 breakdown during the collection phase is operationally worse than a THOR 2.4 breakdown because the fragmented stone left on the surface will be redistributed by the next tillage pass, requiring re-collection when the machine is repaired. The service takes approximately 3–4 hours and requires no special tools beyond standard workshop equipment.
Foire aux questions
What is the difference between a rock picker and a stone crusher for a tractor?
A stone crusher (like the THOR 2.4) fragments large stones embedded in the soil into smaller pieces using a high-speed rotor — it does not remove stone from the field, it changes stone size. A rock picker for tractor (like the CT-2100) collects stones already on or near the surface and deposits them in a bunker for removal from the field — it does not fragment, it relocates. The two machines serve different functions and are not alternatives to each other. For Korean highland farms pursuing permanent stone management, both are needed: the stone crusher reduces large stones to a collectible size; the rock picker removes the fragmented material from the field permanently. A rock picker alone cannot process stones above approximately 80 Kg or fragments more than 20–25 cm on the surface — it requires the THOR 2.4 to pre-fragment large stones into the collectible range first.
Can the CT-2100 be used without the THOR 2.4 on fields that have never been cleared?
On un-cleared Korean highland fields where stones range from 5 cm surface fragments to 30+ cm embedded boulders, the CT-2100 alone can collect only the stones that are already on or near the surface and below the 80 Kg single-stone limit. It cannot process stones that are embedded in the soil or stones larger than 80 Kg. Attempting to use the CT-2100 on a field with significant 20–30 cm stones at the surface will result in machine overloading, potential picking head damage, and incomplete collection. For first-time clearance of un-cleared Korean highland fields, the THOR 2.4 primary fragmentation pass is the mandatory first step. The CT-2100 is the second step. The ramasseur de pierres is designed for fields where the fragmentation work is already done.
How many daily hours can the CT-2100 operate before operator fatigue or machine heat becomes a concern?
The CT-2100’s hydraulic system generates heat during sustained operation — at 60 L/min continuous flow, hydraulic oil temperature rises progressively throughout the day. After 5–6 continuous operating hours, the hydraulic oil in a standard 110–130 HP Korean tractor may reach temperatures above the recommended 70–80°C operating limit, particularly on warm Korean spring days (above 20°C). A 20–30 minute rest period with engine idling to allow the hydraulic system to cool is recommended after every 3–4 hours of continuous CT-2100 operation. This cooling break also coincides naturally with fuelling, operator break, and the mid-day bunker dump cycle — it does not necessarily reduce productive operating hours if planned into the daily schedule. Total productive operating time: approximately 7–8 hours on a standard Korean spring day with two cooling breaks.
What is the best rock picker for a 10 ha Korean highland farm — is the CT-2100 the right choice at this scale?
The CT-2100 is Korea Watanabe’s standard rock picker recommendation for farms in the 5–20 ha range. Its 2.5 m³ bunker capacity, 80 Kg maximum stone weight, and 3–5 km/h optimum speed are specifically matched to the stone density and field scale typical of Korean highland terrace farms. For a 10 ha farm with moderate stone density after THOR 2.4 clearance, the CT-2100 completes the full-field collection in approximately 3–5 operating days in the first year (higher stone density) and 1–2 days in Years 3–5 as the sub-surface stone reserve depletes. This timeline fits comfortably within the Korean highland preparation window between the last frost and optimal planting date. For operations below 3 ha, the CT-2100 may be oversized — Korea Watanabe advises on lighter collection machines appropriate for very small operations. For operations above 30 ha per season, a second CT-2100 or a transition to the higher-capacity CT range may be worth evaluating. Contact Korea Watanabe for a scale-matched recommendation.
Where should the collected stone be deposited on a Korean highland farm?
Collected stone from the CT-2100 has significant value on a Korean highland farm and should not be wasted as spoil. The most productive uses for THOR 2.4-fragmented, CT-2100-collected stone are: (1) farm road aggregate — the sub-5 cm fragmented granite is an excellent base material for highland farm access roads, providing stable, draining aggregate that bonds under tractor wheel compaction; (2) terrace wall reinforcement — larger collected fragments (5–80 Kg) are valuable for rebuilding and reinforcing the terrace walls and drainage channels that define Korean highland field boundaries; (3) foundation material for farm building pads. Deposit collected stone in designated stock zones at the field boundary, sorted roughly by size during the dumping cycle — this sorting is easily done by dump direction and adds no operating time. Korea Watanabe’s farm road construction guide describes how collected stone integrates with the full road building programme using the THOR 3.0 and BlackBird combination.
CT-2100 System Planning — Pair It Correctly With Your THOR 2.4
Farm area + tractor hydraulic flow output + current stone density + field routing constraints → CT-2100 recommendation with bunker planning, dump cycle schedule, and pre-season service timing.
Éditeur : Cxm
