EP-CWB-2L Potato Harvester – Big Bag, 2-Row, On-Field Sorting

① Drawbar

The tractor connection point. The CWB-2L trails behind the tractor on a drawbar coupling — pulling the full 4,500 Kg machine on its own ground wheels through the potato field.

② Share Blade

The flat blade that slides under the potato ridge at the set working depth, lifting the entire ridge soil mass — tubers and soil together — onto the primary web. Correct depth setting is critical for zero blade-cut damage.

③ Limiting Wheel

Rides on the un-dug soil beside the ridge to limit maximum blade depth. Prevents the blade from running too deep in soft soil or on downhill sections, maintaining consistent lift depth across variable terrain.

④ 24" Disc Guide

A 24-inch disc that runs in the inter-row space to guide the machine's tracking along the planted rows. Keeps the share blades centered on the ridges throughout the pass, compensating for any tractor steering drift.

⑤ 1st Main Web

The primary separation conveyor — a wide steel bar chain that carries the lifted ridge material and allows soil to fall through the bar gaps while tubers travel rearward. This is where the bulk of soil separation occurs.

⑥ 2nd Web

A secondary conveyor stage that continues soil separation from the primary web, handling the material that did not fully separate in the first pass. The dual-web arrangement provides more separation time and distance than single-web machines.

⑦ Deviner Web

The haulm (vine) separation stage — a specialized screen that pulls potato vine material away from the tubers. Essential for spring harvests where vine cover is significant. Keeps vine out of the big bags, which would otherwise require manual removal at the receiving facility.

⑧ Steering Wheels

The machine's own ground wheels that carry its weight and allow directional control as it follows the tractor. The hydraulic drive controls these wheels to keep the machine aligned with the row direction independently of terrain variation.

⑨ 3rd Web — Lifting

A third conveyor stage that elevates the cleaned tubers from the lower separation level to the upper section of the machine where sorting, picking, and bag-filling take place. The gentle incline design minimises impact as potatoes are elevated.

⑩ Pintle Web

A specialized chain web with pintle-type links — metal pins extending from the chain links — that provide additional clinging surface for potatoes during the lifting stage, preventing tumbling and rolling on the inclined section. This gentling effect contributes directly to the machine's low tuber damage profile.

⑪ Separator

The size sorting stage — separates small potatoes from large potatoes by allowing smaller tubers to pass through a graded gap or screen while larger ones continue on the main conveyor path. This is the on-field grading function that distinguishes the CWB-2L from all other Watanabe potato diggers.

⑫ Picking Web

A slow-moving conveyor where human operators stationed on the machine remove damaged, diseased, or visually unsuitable tubers before they reach the big bags. This is the quality control stage — the operator inspection pass that no mechanical screen can replicate. The picking web is why the EP-CWB-2L can fill bags at processor-ready quality standards.

⑬ Bag's Web Feeder

The final conveyor stage that directs the quality-controlled, separated potatoes into the big bag frames. Flow rate is controlled to fill bags smoothly without the drop-impact that direct chuting would cause, protecting tuber skin integrity at the final stage.

⑭ Double Bags (700 Kg each)

Two big bag frames positioned at the rear of the machine, each holding a 700 Kg FIBC bag. One bag receives large-grade tubers; the other receives small-grade tubers — simultaneously filling two different size grades as the machine harvests. When a bag is full, it is lowered to the ground and a new bag placed in the frame without stopping the harvest operation.

⑮ Operators Protection Canvas

A canopy or shade structure over the operator picking station that protects the staff manning the picking web from direct sun, rain, and flying soil during the harvest operation. Korea's summer harvest conditions — June-July heat in Gangwon-do, April-May sun on Jeju — make this protection practically necessary for extended daily shifts.

⑯ Complete Hydraulic Drive

All conveyors, the separator, the bag feeder, and the steering mechanism are driven by the machine's integrated hydraulic system, powered by the tractor's PTO via the Cardan shaft at 540 RPM. Hydraulic drive allows smooth, variable-speed control of each conveyor stage independently — a capability that rigid mechanical chain drive cannot provide — and is why 2 hydraulic control valves on the tractor are required.

■ Harvest to Bag in One Pass

Eliminates windrow formation, collection, transport, packhouse sorting, and bagging as separate operations. What used to require four to six post-harvest steps — each adding time, fuel, labour, and cumulative tuber handling damage — is consolidated into one continuous field operation.

■ On-Field Size Grading

Small and large potatoes are separated automatically in the field, filling separate bags by grade. For commercial supply to chip processors or export buyers who specify minimum tuber diameter, on-field grading eliminates the rejection risk from out-of-spec tubers mixed through an unsorted bag — improving delivery quality and the farm's reliability as a supplier.

■ Operator Picking Station

The picking web gives the harvest crew the ability to remove damaged, diseased, or visually non-conforming tubers before they reach the bag. No mechanical sorter can match human visual quality detection — this operator station is what makes it possible to fill processor-grade or export-grade bags directly in the field without a subsequent packhouse inspection step.

■ Minimum Handling, Lower Damage

Every additional handling step — transferring potatoes from windrow to trailer, trailer to grader, grader to bagging conveyor — adds cumulative bruising. The CWB-2L's single continuous field-to-bag path reduces total handling contacts from six or more (in a typical windrow → packhouse workflow) to the controlled web-conveyor sequence of the machine itself.

■ Standard Commercial Packaging

700 Kg FIBC big bags are the standard bulk potato packaging format for chip processors, large distributors, and export operations. Filling this format directly in the field means the product moves from harvest to delivery without repackaging — eliminating a further handling step and the capital cost of packhouse bagging equipment.

The EP-CWB-2L is the most complex implement in the Watanabe potato machinery lineup — 16 interacting mechanical and hydraulic components operating continuously across a full harvest day. Watanabe's 50+ years of manufacturing experience in Paraná, Brazil produced a design that has been validated across Brazilian commercial potato operations with similar scale and supply chain requirements to Korean commercial production.

The hydraulic drive system — which powers all conveyors independently — is particularly important for quality maintenance: hydraulic speed control allows each web stage to be tuned to the optimal conveying velocity for the current crop density and soil conditions. A fully mechanical fixed-ratio drive cannot provide this operational flexibility. The 2 control valve requirement on the tractor reflects this full hydraulic drive scope.

✓ Pre-Sale Tractor Compatibility

We verify both PTO output (540 RPM) and 2 hydraulic control valve availability on your tractor before the order is placed. The separator grade threshold — small vs large potato division — is also confirmed at the pre-sale stage to match your buyer's specification.

✓ Web Components in Local Stock

Primary web bars, pintle web components, and share blade wear parts for the CWB-2L are stocked locally in Ansan-si. The machine's complexity makes pre-season inspection and parts pre-ordering particularly important — a mid-harvest breakdown on a 4,500 Kg multi-stage machine has a longer resolution time than a simpler digger.

✓ Crew Setup Guidance

The picking web crew size and positioning, bag change procedure, and separator grade adjustment are all covered in our pre-season setup support. Getting these operational parameters right before the first harvest day has a direct impact on daily output quality and crew efficiency.

What exactly is a "big bag" and what is the 700 Kg specification?

A big bag — formally called a Flexible Intermediate Bulk Container (FIBC) or jumbo bag — is a large industrial fabric sack designed for bulk dry goods. Standard sizes commonly used in Korean commercial potato distribution hold 500–1,000 Kg. The EP-CWB-2L is designed to fill bags of 700 Kg capacity. FIBC bags are standard receiving format at chip processing plants and large distribution centres — they stack efficiently on pallets, handle by forklift, and can be discharged directly into processing lines. Bags must be sourced separately by the operator; we can advise on appropriate FIBC specifications for potato harvest use.

How does the on-field size separation work?

The separator stage passes the tuber stream across a graded gap or screen: smaller tubers fall through to a separate path leading to the small-grade bag, while larger tubers continue to the large-grade bag. The effective separator threshold — the dividing size between small and large — is adjustable and should be set to match your buyer's specification before the harvest season starts. We provide guidance on the separator adjustment procedure at the pre-sale and pre-season setup stages. The adjustment should be confirmed with a calibration pass before beginning commercial harvest to ensure the separation threshold matches the target grade split.

How many operators are needed on the picking web?

Typically 2–4 operators on the picking web, depending on tuber density, working speed, and quality control standards. At 2 km/h through a dense crop at high harvest quality standards, 3–4 operators can inspect the full stream. At 4–5 km/h with a cleaner crop, 2 operators may be sufficient. In commercial Korean harvest operations, the picking crew often consists of seasonal agricultural workers or cooperative member households — establishing the right crew size for your crop before the harvest season reduces bottlenecks during the actual harvest window.

What happens when a big bag is full?

When a bag reaches the 700 Kg fill weight, the tractor driver stops briefly while the harvest crew lowers the full bag to the ground using the bag frame mechanism and places an empty bag in the frame. This bag change typically takes 2–3 minutes. Full bags are left standing in the field in a line at the rear of the machine's path — they are collected by a front loader or telehandler at the end of the day's run, or by a following collection vehicle. The bag change stop is the only scheduled operational pause in the harvest day — unlike windrow-based harvesters where collection is a completely separate subsequent operation.

Why is the working speed 2–5 km/h — slower than the AWB digger series?

The lower working speed is a necessary feature of the CWB-2L's design, not a limitation. Two factors require the reduced speed: (1) the multi-stage separation chain — six web conveyor stages need sufficient time to separate soil, vines, and debris thoroughly before tubers reach the operator station; (2) the picking web quality control — at higher speeds, tubers pass the operators too fast for effective visual inspection. The 2–5 km/h range represents the balance between acceptable harvest throughput and the quality of separation and inspection that makes field-to-big-bag viable. Daily harvest area is lower than the AWB series, but post-harvest handling labour is eliminated — the net operational efficiency depends on your specific supply chain.

Is the EP-CWB-2L suitable for hillside or terraced fields?

The EP-CWB-2L is a large machine — 8.8 meters long, 3.9 meters tall, 4,500 Kg empty weight. It is designed for open, relatively flat to gently sloped commercial potato fields with adequate field access for a machine of this size. Tight terraced plots, steep hillsides, and narrow farm tracks are not appropriate operating environments for the CWB-2L. For hillside and terraced Korean potato production, the compact EP-AWB-1600 mounted digger series is the more practical choice. If you are uncertain whether your fields are suitable for the CWB-2L, discuss your field dimensions, access routes, and slope profiles with us before ordering.

What preparation does the field need before the CWB-2L harvest pass?

The same seven-step sequence applies as for any Watanabe harvest machine: stone clearance, primary tillage, furrowing, fertilization, planting, mid-season cultivation — all performed correctly across the season. The share blade depth setting before harvest is particularly critical for the CWB-2L because cut tubers reaching the picking web increase operator workload and reduce the percentage of the batch that passes quality control. Allow adequate vine death or vine kill time before harvest to reduce the deviner web load and minimize vine in the bags.

How does the complete hydraulic drive affect maintenance requirements?

The hydraulic drive system requires checking hydraulic oil level and condition, inspecting all hose connections for leaks or wear, and confirming hydraulic cylinder and motor operation before each season start. Hydraulic oil should be changed per the manufacturer's schedule — contaminated hydraulic oil is the leading cause of premature hydraulic component failure on complex agricultural machines. We provide the Watanabe maintenance schedule and specification documentation at delivery. Given the machine's complexity, we recommend a thorough pre-season inspection by a competent hydraulic machinery mechanic for the first two seasons of operation.

How many hectares per day can the EP-CWB-2L harvest?

At a working speed of 3 km/h and 60 cm row spacing, the productive field throughput is approximately 0.36 hectares per hour of actual travel time. Accounting for bag changes, headland turns, and typical operational pauses, a realistic daily harvest area is 2–3 hectares in a full working day. This is lower than the AWB digger series, but the CWB-2L replaces multiple post-harvest operations that the AWB windrow approach still requires. The net daily throughput comparison should include all steps from field to delivered bag, not just the harvest machine travel time.

Ha Seong-tae — Atlantic Contract Potato Farm (22 ha), Pyeongchang-gun, Gangwon-do (summer 2024)

★★★★★

"We supply Atlantic to one of the major chip manufacturers under a multi-year contract with strict size grade and defect limits. Before the CWB-2L we sorted at a rented packhouse facility — the added cost and two extra handling steps were eroding the contract margin. Two seasons with the CWB-2L and we now deliver direct from the field. Rejection rate at the processor gate dropped from about 8% to under 2% — the on-field picking web makes all the difference for catching the damaged ones before they reach the bag. Machine runs well on our 115 HP John Deere with 2 remote valves."

Yim Jae-hyeon — Export Potato Operation (Haryoung for Japan market), Seogwipo, Jeju Island (spring 2025)

★★★★★

"Supplying to a Japanese importer who specifies 60+ mm diameter in one grade and 40–60 mm in another, both in 700 Kg big bags. Before CWB-2L we had two separate sorting sessions — harvest to windrow, collect, sort at a facility, bag. The machine now does all of that in the field. Japanese buyer's inspection team was impressed with the grade consistency in the bags. Slower than a standard digger at 2–3 km/h on the Jeju basalt fields, but for export-grade supply the extra on-field time is more than recovered by eliminating the packhouse step entirely."

Lim Bo-young — Agricultural Cooperative Manager, Hoengseong-gun, Gangwon-do (2024 harvest)

★★★★★

"Our cooperative of six member farms holds a direct supply contract with a large retail distributor who receives in big bags. We run the CWB-2L as cooperative-shared equipment across all six farms during the harvest window — 3–4 days per farm at 2–3 hectares per day. The bags go directly from the field to our cold storage and then to the distributor's facility. We have a three-person picking crew that rotates across member farms. The Korea service team helped us plan the crew rotation and bag collection logistics before first use — that operational planning support was valuable."

Ko Dong-jin — Contract Harvest Service, Wonju, Gangwon-do (2025)

★★★★★

"Running CWB-2L as a contract service for three farms that all supply to chip processors. The daily area is lower than with a high-speed trailed digger, but the contract pricing reflects the full-service — harvest, grade, bag — rather than just digging. The farms I service save the packhouse step entirely, which is worth more to them than having a slightly larger windrow at the end of the day. Machine has been reliable through two seasons. Pre-season setup support from the Korea team covered separator adjustment and picking web crew positioning, which was helpful for the first season."

Bang Hyun-soo — Large Commercial Potato Farm (Atlantic, 35 ha), Jeongseon-gun, Gangwon-do (2024 and 2025)

★★★★★

"We run both a CWB-2L and an AWB-1600 CAR trailed digger — CWB-2L for the Atlantic supply contract sections where bag grade matters, AWB-1600 CAR for the fresh market sections where we sell through a local auction. Two seasons with this split approach and it works well. The CWB-2L section's contract retention and price premium have more than justified the machine's cost compared to sending everything through the packhouse. One comment: have a well-organized bag change and collection logistics plan ready before harvest starts — it's the CWB-2L's operational complexity that requires the most preparation."

Ji Young-hee — Organic Premium Potato Farm (Dejima, direct sales), Inje-gun, Gangwon-do (spring 2025)

★★★★★

"We supply organic Dejima to a premium online grocery platform that requires 60+ mm grade in 700 Kg FIBC, zero diseased or visually defective tubers. No packhouse would take on grading at our volumes with those standards — we had to do it manually after harvest before CWB-2L. Now the picking web handles most of the selection in field and we do a quick bag inspection before dispatch. The grade rejection rate from the online platform dropped significantly in the first season. Working at 2–3 km/h on our highland fields is fine for the area we work."