PTO Stone Crusher vs. Stone Picker vs. Rock Rake: Which Machine Fits Your Land Clearing Job?

Land Clearing Equipment Guide

PTO Stone Crusher vs. Stone Picker vs. Rock Rake: Which Machine Fits Your Land Clearing Job?

A practical, side-by-side breakdown of three fundamentally different approaches to removing rocks from agricultural land — so you can invest with confidence.

Ask a Korean farmer in Gangwon-do what the biggest obstacle to expanding a vegetable plot is, and the answer comes up quickly: rocks. Surface stones, buried boulders, fist-sized gravel scattered through clay — each presents its own challenge and demands a distinct mechanical answer. Walk into any agricultural machinery dealership in South Korea today and you will find at least three categories of equipment lined up to solve these problems: the PTO stone crusher (sometimes called a tractor stone crusher or agricultural stone crusher), the stone picker, and the penggaruk batu. All three attach to the rear of a tractor via the three-point hitch, and all three deal with stone in some way. The similarities, however, end there.

Choosing the wrong machine means paying twice — once for the wrong piece of equipment and once for the rental or purchase of the right one. This guide breaks down how each machine actually works, what it is built from, where each earns its keep, and which scenarios genuinely call for one over the others. Real technical specifications from the product range are included where relevant, along with notes on relevant regulations across key agricultural markets.

1. Action Method: How Each Machine Actually Handles Stone

PTO Stone Crusher — Impact and In-Situ Reduction

A PTO stone crusher converts mechanical power from the tractor’s Power Take-Off shaft directly into high-velocity rotor rotation. Inside a heavy-duty steel housing, a rotor fitted with rows of hardened-steel hammers or fixed teeth spins at speeds typically between 540 and 1,000 RPM. When the machine passes over a stone, the hammers strike it with tremendous kinetic force, shattering it against a set of adjustable counter-blades. The resulting fragments — graded by a rear hood — fall back into the seedbed as fine aggregate. Nothing is collected and nothing needs to be hauled away. The crushed material stays in the field and actually improves the soil’s drainage and texture. This is what makes the PTO stone crusher fundamentally different from every alternative: it eliminates stones rather than relocating them.

Direct PTO transmission is central to the performance advantage. By driving the rotor without intermediate belt slippage, the machine maintains consistent crushing force across variable stone densities. Models in the PSC series, for example, operate at 1,000 RPM PTO speed and can process stones up to 300 mm in diameter at working depths up to 200 mm — performance figures that a rock rake or stone picker cannot begin to replicate.

Stone Picker — Mechanical Collection and Bunker Storage

A stone picker uses a rotating tine or paddle mechanism to scoop stones off the surface or shallow subsurface, elevating them onto a conveyor that deposits them into an on-board bunker. Once the bunker is full, the operator drives to a designated collection point and empties it. The stones remain whole — they are not crushed or reduced in any way. The CT-2100 Rock Picker, for instance, features a working width of 1.95 m and a bunker capacity of 2.5 m³, requiring a minimum of 110 cv of tractor power and a hydraulic oil flow of at least 60 L/min. This is an effective solution where you want to physically relocate stones — for instance, to build field-edge windbreaks, fill access roads, or simply dump the material off-field.

Stone pickers are hydraulically driven in most modern configurations, requiring 2 control valves. Working speed is typically 3–5 km/h. The key limitation is the bunker: once full, fieldwork stops. On heavily stone-laden ground, operators may empty the bunker multiple times per hour, which adds up to significant time overhead across large parcels.

Rock Rake — Passive Windrow Formation

A rock rake is a passive, unpowered (or lightly powered) implement that consists of a set of curved or straight tines arranged in a row. As the tractor pulls the rake across the field, the tines catch and drag surface stones into rows or windrows. The stones accumulate in a concentrated line that can later be collected with a loader bucket, stone picker, or by hand. The EW-4000 Rock Rake operates with a 3.6 m working width at 3–5 km/h, requiring either 100 cv (hydraulic version) or as little as 75 cv (tractor-powered variant). It weighs 1,800–1,900 kg and mounts on a Category 2 three-point hitch. There is no crushing, no bunker, and no hydraulic drive system involved in most configurations — making it the lowest-cost option by a considerable margin.

The rock rake is most appropriate as a surface-preparation tool on fields where stones are large, numerous, and concentrated near the surface. It does not deal with buried stones and does not reduce the stone to a smaller size. After raking, a secondary operation (loader, picker) is still required to actually remove the material from the field.

2. Quick-Reference: Action Method Comparison

3. Manufacturing Structure: What Goes Into Each Machine

Understanding the structural architecture of each implement helps explain both the price differential and the durability differences you will encounter in daily use.

PTO Stone Crusher Build Architecture

A well-engineered tractor stone crusher is essentially a rotating impact mill inside a torsionally rigid steel shell. The main housing is fabricated from thick-gauge structural steel, often reinforced with bolt-on Hardox wear plates at high-impact zones inside the crushing chamber. The rotor — the most mechanically demanding component — is typically machined from heat-treated alloy steel and carries interchangeable tool holders. These holders accept different tooth profiles: standard fixed teeth for general fieldwork, heavy-duty HD teeth for abrasive granite-heavy soils, and flat-profile FP teeth for fine finishing work. The adjustable Hardox counter-blade is hydraulically operated on mid-range and larger models, allowing the operator to tune the aggregate output size without stopping the tractor.

The gearbox or belt-drive transmission sits at the top of the housing, protected by its own sealed casing. On the THOR 2.4 model, the entire unit weighs 2,300 kg, spans 2,481 mm in width, and requires a minimum tractor output of 180 cv. The THOR 3.0 steps up to 2,800 kg and 3,000 mm wide, needing at least 230 cv. Both mount on a Category 2 three-point hitch and operate at a working speed of 3 km/h. On PSC-series (STCM-type) machines, the rotor diameter reaches 550 mm with working widths from 1,340 mm to 2,304 mm depending on model — covering everything from a compact orchard tractor to a 280-cv high-horsepower unit. The entire machine body is dust-sealed on these larger units, protecting internal bearings from the significant amounts of fine stone dust generated during operation.

Stone Picker Build Architecture

The stone picker (CT-2100) has an entirely different structural logic. Its frame spans 6,000 mm in length and 3,050 mm in width, standing 2,340 mm tall at an operating weight of 3,400 kg. The working mechanism is a rotating tine drum or cam-driven pickup system at the front, feeding onto a cleaning web that separates soil from stone before depositing the material into the hopper. A hydraulic tipping system empties the 2.5 m³ bunker. Because no crushing takes place, the internal components — tines, webs, drive sprockets — face lower peak forces than a stone crusher rotor, but face higher cycle fatigue from continuous rotation. Tine replacement is the most common maintenance task on these machines.

Rock Rake Build Architecture

The EW-4000 Rock Rake is the structural simplest of the three. At 4,550 mm long and 2,400 mm wide, it weighs 1,800–1,900 kg (slightly more in the tandem EW-4000 T configuration). The core of the implement is a set of spring-steel or hardened-steel tines mounted in a staggered pattern across the working width. Ground-following wheels and adjustable depth skids allow the tines to track surface contours without digging into soft soil. Two hydraulic control valves manage the tine angle and implement lift. There is no drive shaft, no rotor, and no gearbox — which is precisely why maintenance costs are low and reliability is high. The structural weak point is tine fatigue: on heavily-stoned ground, bent or broken tines are a regular service item.

4. Material System: Steels, Alloys, and Wear Components

The stone crushing industry relies on a specific vocabulary of specialty materials, and understanding these choices matters when comparing long-term operating costs across machine types.

Hardox wear steel (produced by SSAB) is the dominant choice for internal liner plates and counter-blades on professional-grade stone crushers. With a Brinell hardness rating typically between 400 and 600 HBW depending on grade, Hardox plates absorb impact energy without shattering, extending service intervals dramatically compared to standard structural steel. The PSC-series machines use interchangeable Hardox liner plates bolted inside the crushing chamber — when worn, they are replaced individually rather than requiring the entire housing to be rebuilt.

Rotor teeth on stone crushers are typically manufactured from tungsten-carbide-tipped alloy steel or forged heat-treated tool steel. The STC/3 tooth profile used on STCM-family crushers features a wide cutting edge that distributes impact load over a larger surface area, reducing fracture risk. STC/3/HD teeth offer additional mass for harder granitic material. The STC/3/FP flat-profile tooth is designed for secondary passes where granulometry control is the priority. Tooth-holder blocks are bolt-on and individually replaceable — an important design choice that reduces both downtime and spare parts cost in the field.

Stone picker tines are commonly produced from medium-carbon spring steel that can deform slightly on impact (absorbing energy) before returning to shape. After repeated flexing cycles, they develop fatigue cracks and must be replaced. Higher-end picker models use solid hardened tines that are more brittle but last longer on moderate-stone-density soils.

Rock rake tines face bending loads rather than impact, so spring-tempered flat-bar steel is the common material. Tines are bolted on, and replacement sets are typically available from dealers in-country. Because the tines do not contact stone at high velocity, wear rates are substantially lower than on any active crushing machine — a meaningful consideration for operations evaluating long-term parts cost.

5. PTO Stone Crusher Model Range: Specifications at a Glance

The Mulchers / Stone Crushers product line covers a wide horsepower range. Below are the core models currently available, each suited to different tractor classes and field conditions.

THOR 2.4 + Kit Drawbar

Working Width	2,4 m
Berat	2,300 kg
Min. Tractor HP	180 tenaga kuda
Working Speed	3 km/h

View Product

Penghancur Batu Pertanian RockMaster

Designed for heavy-duty agricultural stone clearing. Ideal for fields with high stone density and varied rock sizes. Compatible with mid-to-high horsepower tractors used in Korean upland farming zones.

PSC Models (STCM Series)

HP Range	80–280 cv
Max Stone Dia.	300 mm
Max Work Depth	200 mm
Rotor Dia.	550 mm

Agricultural Rock Crusher (Korea)

Specifically configured for Korean agricultural field conditions. Suited to the stone-dense volcanic and alluvial soils found across the Korean peninsula, including highland fields in Gangwon and Gyeongbuk provinces.

6. Depth Capability and Application Fit

Depth capability is probably the single most decisive factor when choosing between these three machine categories. The rock rake operates purely on the surface — it cannot address anything below soil level. The stone picker can typically retrieve stones sitting within 50–100 mm of the surface, depending on tine geometry and soil hardness. The PTO stone crusher, by contrast, is the only one of the three that actively works below the plough layer. PSC-series (STCM) machines work to 200 mm depth; the larger RSM and RSH machines penetrate to 400–500 mm. This means a stone crusher can address subsurface stones that would cause plough or subsoiler damage in the next season — a capability that neither the picker nor the rake can touch.

For Korean agricultural operations dealing with the coarse granite soils common in the mountainous interior regions, subsurface stone management is not optional — it is a prerequisite for sustainable tillage. Fields that have been surface-raked or picked will still break cultivation implements on buried rock heads. Fields that have been processed with a small pto stone crusher or a full-size agricultural stone crusher reach a genuinely stone-clear profile that persists across multiple crop cycles.

The stone picker earns its keep in a different scenario: pasture renovation and sports turf projects where stones are on or just below the surface and the client specifically requires the stones to be removed from the site — perhaps to satisfy a landscape specification or environmental requirement. It is also the right choice on sandy or light soils where stones are abundant but the ground is soft enough that tines can penetrate freely without excessive resistance.

The rock rake is best deployed as the first pass on heavily-stoned ground before another operation. Raking concentrates the stone load, dramatically reducing the number of passes required by the picker. Some operators combine all three: rake first to gather large surface stones, pick them up, then run the PTO stone crusher to address the remaining embedded material. This multi-pass approach is common on severe land reclamation projects in the Jeju Island volcanic soil belt.

7. Tractor Requirements and PTO Compatibility

Matching the implement to the available tractor is not optional — it is a safety and performance requirement. Here is what each machine category demands.

Note: The small PTO stone crusher (PSC/STCM 125) starts at just 80 cv, making it the most accessible entry point for compact or sub-100 hp tractors. Farmers operating Korean-market sub-compact units should confirm their PTO spline configuration (6-spline or 21-spline) and output speed before purchase.

8. Regulatory Considerations: Gearboxes, PTO Safety, and Agricultural Machinery Standards

Agricultural machinery operating in any jurisdiction is subject to safety standards that affect the design of PTO-driven implements. Understanding the applicable framework protects both the operator and the equipment supplier.

South Korea

In South Korea, agricultural machinery is regulated under the Agricultural Mechanization Promotion Act (농업기계화 촉진법), administered by the Ministry of Agriculture, Food and Rural Affairs (MAFRA). Tractor-mounted implements must comply with Korean Industrial Standards (KS) where applicable, and importers are required to obtain certification from the Korea Agricultural Machinery Industry Association (KAMIA) for safety-critical components. PTO-driven implements specifically must have an appropriate PTO shaft guard covering at minimum the rotating shaft between the tractor output flange and the implement gearbox input — a requirement derived from both the Occupational Safety and Health Act (산업안전보건법) and internationally harmonized EN ISO 11684 guarding standards. Stone crushers that incorporate exposed drive shafts without full-length guarding are not compliant with Korean workplace safety law, and operators face liability risk in the event of an incident.

European Union (CE Marking)

All agricultural machinery sold within the EU must carry a CE mark, affirming conformity with the Machinery Directive 2006/42/EC (to be replaced by the EU Machinery Regulation 2023/1230 from January 2027). PTO-driven stone crushers fall under Annex IV as high-risk machinery, requiring third-party conformity assessment. Gearboxes specifically must meet EN 13736 (safety requirements for gearboxes for agricultural tractors and self-propelled machinery), which governs housing integrity, shaft sealing, lubrication intervals, and overload protection. Torque limiters and shear-bolt couplings are generally mandatory on PTO inputs above a specified torque threshold to prevent drivetrain shock loading. The THOR and PSC-series machines include a central PTO shaft with integrated torque limiter for exactly this reason.

United States

The US does not mandate CE marking, but OSHA 29 CFR Part 1928 (agricultural operations) requires that all power-driven farm equipment be equipped with adequate guarding on rotating components, including PTO shafts. The ASABE (American Society of Agricultural and Biological Engineers) Standard ASAE S203.12 covers agricultural tractor PTO shaft speed and spline dimensions, while ASAE S318 addresses safety requirements for implement PTO systems. Stone crushers marketed in the US should carry documentation confirming compliance with these standards, and dealers offering a tractor stone crusher for sale in the US market should verify applicable state-level agricultural equipment registration requirements.

Australia and New Zealand

In Australia, AS 4024.3610 and the relevant Safe Work Australia Codes of Practice govern PTO implement guarding. New Zealand’s Health and Safety at Work (General Risk and Workplace Management) Regulations 2016 impose similar guarding requirements for rotating PTO-driven machinery. Importers of stone crushing equipment must ensure that PTO shaft guards are included and documented in the supplied machinery manual.

9. Maintenance and Operational Cost Factors

Total cost of ownership extends well beyond the purchase invoice. For stone management equipment specifically, wear-part replacement and downtime are the dominant cost drivers after the initial acquisition.

PTO stone crusher maintenance centers on rotor teeth and internal liner plates. On a machine working in abrasive granitic soil at full capacity, rotor teeth may need inspection every 50–80 hours of operation. Replaceable bolt-on tooth holders allow individual teeth to be swapped without workshop facilities — a straightforward 30-minute job for a single operator. Liner plates inside the crushing chamber are more durable and typically require replacement after 200–400 hours. The sealed gearbox or belt drive system requires periodic oil or belt inspection per the manufacturer’s schedule, with belt-drive units on smaller models checked more frequently. Overall, a well-maintained agricultural stone crusher operating in Korean agricultural conditions should deliver multiple seasons of productive work before requiring any major component overhaul.

Stone picker maintenance centers on tine replacement, web chain or belt servicing, and hydraulic system upkeep. Tine cost per unit is relatively modest, but frequency of replacement on stony ground adds up. Hydraulic hose condition should be checked regularly given the dusty environment. The emptying mechanism — usually a hydraulic tilting bunker — places repetitive load on the hydraulic cylinder seals and pivot points.

Rock rake maintenance is the simplest and least expensive of the three. Spring tines are the only regular consumable, and they are available as standard replacement sets from any dealer stocking the EW-4000 range. The hydraulic cylinders controlling tine angle and implement lift should be inspected for seal weeping during routine service. Because there is no high-speed rotating mechanism, bearing replacement and rotor balancing — two of the costlier stone crusher maintenance items — simply do not apply.

10. Which Machine for Which Job? A Decision Matrix

11. Return on Investment and Long-Term Land Value

Investing in stone clearing equipment is ultimately a land-improvement decision. In Korea, where arable land is scarce and farmland transactions occur at a premium per pyeong, the ability to reclaim rock-strewn hillside fields and convert them into productive cultivated land represents a tangible increase in asset value. An agricultural stone crusher working a previously uncultivable rocky plot can transform it within one to three passes into land capable of supporting vegetable crops, orchards, or pasture — uses that generate ongoing revenue rather than remaining idle.

Beyond land conversion, the operational savings from in-situ crushing are frequently underestimated. Farms that previously hired excavators and dump trucks to periodically clear rocks from active fields — a common practice in Jeju, North Chungcheong, and Gyeonggi provinces — find that a tractor-mounted rock crusher eliminates this recurring cost entirely after the first season. The machine pays for itself not just in improved yields from cleared land but in the elimination of third-party hauling contracts and the reduction of implement damage caused by undetected subsurface stones.

Stone pickers and rock rakes, while less capable in isolation, can meaningfully reduce the number of passes required by a crusher on ground that carries a very heavy surface stone load. A strategic combination of implements — rake to gather, crush what remains, and periodically pick up oversized material after initial clearing — is the approach favored by professional land reclamation contractors operating across mountainous Korean agricultural zones.

Frequently Asked Questions