Descripción
Agricultural Power Transmission
EP-Rotary Mower Gearbox – Replacement of Comer Code T-305J
Direct Drop-In Replacement | 540 & 1000 RPM Compatible | CE / ISO 9001:2015 Certified
Trusted by Agricultural Operations in Brazil, Argentina, and Markets Worldwide
1. Rotary Mower Gearbox T-305J — Configuration Specifications
The following table lists the three rated operating configurations for the EP T-305J replacement rotary mower gearbox. Each configuration defines the gear ratio, PTO input speed, input power, and resulting output torque for the corresponding shaft arrangement (X, Y, or Z input).
| Ratio (i) | Input Speed N1 (rpm) | Input Power P1 (kW) | Output Torque M2 (Nm) | Shaft X | Shaft Y | Shaft Z | Active Input |
|---|---|---|---|---|---|---|---|
| 1.35 | 540 | 183.8 | 2,335 | 1″ 3/4 Z20 | 1″ 3/4 Z20 | 1″ 3/4 Z20 | X |
| 1.20 | 1000 | 183.8 | 2,043 | 1″ 3/4 Z20 | 1″ 3/4 Z20 | 1″ 3/4 Z20 | X |
| 1.35 | 1000 | 183.8 | 2,298 | 1″ 3/4 Z20 | 1″ 3/4 Z20 | 1″ 3/4 Z20 | X |
2. Five Key Product Advantages
When selecting a rotary mower gearbox for sale to replace an existing Comer T-305J unit, these five engineering advantages distinguish the EP replacement from generic aftermarket options.
1 — True Drop-In Compatibility
Exact mounting dimensions, housing envelope, and 1-3/4″ Z20 spline shaft geometry match the original Comer T-305J specification precisely. No adapter plates, custom machining, or deck modification is needed. The gearbox installs using existing hardware and coupling components, keeping changeover time to an absolute minimum — critical during peak Brazilian mowing season when every hour of downtime has a direct production cost.
2 — Carburized Alloy Steel Gear Set
All gears are machined from 20CrMnTi chromium-manganese-titanium alloy steel, carburized to achieve a case hardness of 58–62 HRC while retaining a tough 30–38 HRC core. Gear flanks are precision-ground to AGMA quality class 10, providing tight backlash control and consistent load-sharing across the full tooth profile. This metallurgical specification directly extends service intervals in high-duty-cycle agricultural applications such as sugarcane inter-row management and pasture maintenance across Brazil’s extensive cattle farming regions.
3 — Multi-Ratio PTO Flexibility
Available in both 1.20:1 and 1.35:1 gear ratios, the EP rotary gearbox supports tractor PTO outputs at 540 rpm and 1000 rpm — the two universal PTO speed standards used throughout Brazil and the rest of the world. This flexibility means the same replacement gearbox model can be matched to lower-horsepower compact tractors commonly used in municipal and orchard mowing applications, as well as high-power row-crop tractors operating on large agricultural estates in the Cerrado.
4 — IP65-Rated Sealed Housing
Double-lip NBR oil seals at all shaft exits and a phosphate-treated cast-iron housing provide protection rated at IP65 against dust ingress and water jet exposure. This level of sealing is particularly relevant in Brazilian tropical conditions where high-humidity air, heavy rain, and fine crop-debris dust are regular operating realities. The IP65 classification ensures the internal gear oil remains uncontaminated and the gear surfaces retain their lubrication film throughout the rated service life.
5 — Field-Serviceable Design
All serviceable components — bearing cartridges, oil seals, breather plugs, and drain plugs — are accessible using standard agricultural workshop tools. A magnetic drain plug captures metallic wear particles during oil changes, providing early-warning maintenance intelligence. This design philosophy reduces dependence on specialist service centers and supports the practical reality of rural field maintenance across Brazil’s interior farming regions, where proximity to specialized workshops may be limited.
3. Working Principle of the Rotary Mower Gearbox
At the input stage, the 1-3/4″ Z20 spline shaft interface couples directly to the tractor PTO stub shaft. The PTO delivers rotational torque at either 540 rpm (standard for lower-horsepower tractors) or 1000 rpm (standard on high-power agricultural tractors). This input torque passes into the gearbox housing, where it engages the first stage of precision-cut helical and bevel gears. The gear mesh applies the selected ratio reduction — either 1.20:1 or 1.35:1 — before the torque exits through the output shaft(s). The ratio reduction means the output shaft turns slightly faster than the input, delivering increased torque to the blade carrier. At the rated 183.8 kW input power, the output torque reaches a maximum of 2,335 Nm in the 1.35:1 / 540 rpm configuration — sufficient to drive multiple cutting blades through dense vegetation without stalling.
Inside the housing, gear pairs are designed to distribute contact load across multiple teeth simultaneously, reducing peak stress at any single contact point. This is especially critical in rotary mowing where sudden blade strikes on embedded rocks or tree roots can generate impact loads several times the nominal rated torque. The 20CrMnTi carburized gear case withstands these shock events without pitting or spalling, while the tough core absorbs the energy without fracturing.
Output torque is transmitted to the blade carrier via the output shaft, also featuring the 1-3/4″ Z20 spline interface for secure coupling. Tapered roller bearings at each shaft journal simultaneously handle radial loads from blade centrifugal forces and axial thrust forces arising from blade angle variations. The SAE 90 hypoid gear oil filling provides continuous splash lubrication to all gear and bearing contact surfaces, while the sealed breather plug prevents internal pressure buildup during the thermal cycling common to full-day mowing operations in Brazil’s warm agricultural climate.
4. Technical Specifications — 20 Key Parameters
The following comprehensive technical specification table covers all primary parameters of the EP rotary mower gearbox T-305J replacement model. These parameters are representative of the product’s engineering design and have been verified against accepted performance benchmarks for this category of agricultural PTO gearbox.
| # | Parameter | Value / Specification |
|---|---|---|
| 1 | Gear Ratio (i) | 1.20 / 1.35 |
| 2 | Input Speed (N1) | 540 rpm / 1000 rpm |
| 3 | Rated Input Power (P1) | 183.8 kW |
| 4 | Output Torque M2 (i=1.35, N1=540 rpm) | 2,335 Nm |
| 5 | Output Torque M2 (i=1.20, N1=1000 rpm) | 2,043 Nm |
| 6 | Output Torque M2 (i=1.35, N1=1000 rpm) | 2,298 Nm |
| 7 | Input / Output Shaft Type | 1″ 3/4 Z20 Spline (all positions) |
| 8 | Material de vivienda | GG25 Gray Cast Iron |
| 9 | Gear Material | 20CrMnTi Alloy Steel (carburized) |
| 10 | Dureza de la superficie del engranaje | 58–62 HRC (case); 30–38 HRC (core) |
| 11 | Tipo de rodamiento | Tapered Roller Bearings (DIN/ISO) |
| 12 | Seal Type | Double-Lip NBR Oil Seal |
| 13 | Lubricación | SAE 90 Hypoid Gear Oil (splash) |
| 14 | Oil Capacity | 0.8 L |
| 15 | Operating Temperature Range | -20°C to +80°C |
| 16 | Overall Dimensions (L × W × H) | 320 × 210 × 185 mm |
| 17 | Unit Weight | Approx. 14 kg |
| 18 | Protection Level | IP65 |
| 19 | Noise Level (at rated load) | ≤72 dB(A) |
| 20 | Quality Certification | ISO 9001:2015 / CE |
5. Materials & Construction
Every material selection in the EP rotary mower gearbox reflects an engineering decision made with longevity and field reliability as the primary criteria — not minimum cost. The combination of materials outlined below is the result of accumulated production experience across thousands of agricultural gearbox units deployed in diverse climate conditions worldwide.
The main housing is precision-cast from GG25 gray cast iron, a material chosen for its excellent combination of compressive strength, vibration-damping capacity, and machinability. The graphite microstructure inherent to gray cast iron absorbs and dissipates oscillation energy, which meaningfully reduces the noise and vibration transmitted to the tractor operator cab during continuous mowing cycles. After casting, every housing undergoes shot-blast cleaning to remove surface scale, followed by a phosphate conversion coating and a two-coat exterior paint system. This surface treatment sequence provides effective rust protection against the humid, rain-exposed field conditions common throughout Brazil’s agricultural regions — including the tropical north, the sub-tropical south, and the semi-arid northeastern crop-growing zones. The housing bolt-face surfaces are finish-machined to maintain flatness within 0.05 mm, ensuring a reliable seal against the mower deck mounting plate.
The complete gear set — input pinion, intermediate gears, and output gear — is machined from 20CrMnTi chromium-manganese-titanium alloy steel billets. This steel grade is the recognized standard for carburized agricultural gearbox gears because of its favorable hardenability profile, toughness retention after heat treatment, and consistent case depth response during carburizing. Finished gears are precision-ground on flanks and tooth profiles, achieving AGMA quality class 10 tolerances that deliver low backlash and smooth load transition between meshing teeth. The dual hardness profile — 58–62 HRC at the surface, 30–38 HRC at the core — provides both the wear resistance needed to survive continuous grass and crop stalk cutting cycles and the impact toughness needed to absorb shock loads from occasional debris strikes without catastrophic tooth fracture.
All rolling elements use DIN/ISO-dimensioned tapered roller bearings with a calculated L10 service life exceeding 5,000 operating hours at rated load conditions. Bearing bores are machined to H7 fit tolerances, and all shaft journals meet h6 tolerances, ensuring reliable bearing seating without fretting or micro-movement. The double-lip NBR oil seals are formulated for full chemical compatibility with SAE 90 hypoid gear oil and maintain their sealing integrity across the -20°C to +80°C operating temperature envelope — spanning cold mornings in Brazil’s highland regions and the peak afternoon temperatures of the Cerrado summer months.
6. Application Scenarios
The EP rotary mower gearbox replacement serves a wide range of tractor-mounted mowing applications across agriculture, infrastructure, and municipal operations. The following scenarios represent the most common deployment contexts encountered globally and specifically within Brazil.
Large-Scale Crop Field Maintenance — Brazilian Cerrado
Soybean and corn farms across Mato Grosso, Goiás, and Mato Grosso do Sul states operate tractor-mounted rotary mowers to manage cover crops, headland vegetation, and terracing bands between planting and harvest seasons. These operations typically run 8–10 hour daily mowing shifts across thousands of hectares, placing sustained demand on the gearbox drivetrain. The EP rotary mower gearbox is engineered for continuous-duty operation at this scale, with its sealed bearing assemblies and carburized gear set providing the consistent torque delivery needed to maintain uniform cutting width and speed across undulating Cerrado terrain without overheating or premature wear.
Sugarcane Plantation Vegetation Management
Brazil is the world’s leading sugarcane producer, and between planting cycles, inter-row vegetation must be controlled regularly to prevent weed competition and reduce pest habitat. Rotary mowing with reliable PTO gearboxes is the preferred mechanical solution because it avoids the soil compaction and chemical residue concerns associated with herbicide alternatives. The EP rotary mower gearbox handles the high side-load moments generated when cutting dense regrowth between narrow-spaced sugarcane rows, maintaining consistent blade speed even when the cutting load fluctuates rapidly between open-row sections and dense vegetation patches.
Highway and Road Right-of-Way Maintenance
Federal and state road agencies — including DNIT and DER regional offices — maintain roadside vegetation along thousands of kilometers of Brazilian highways using tractor-mounted rotary mowers. This application subjects the gearbox to frequent shock loads from road debris such as stones, discarded materials, and embedded roots at road verge edges. The IP65 sealing and impact-resistant cast-iron housing of the EP T-305J replacement rotary mower gearbox provide the durability profile required for high-frequency, high-shock infrastructure maintenance cycles in both urban periphery and rural highway corridors.
Cattle Farm Pasture Management
Brazil’s extensive beef cattle industry maintains vast pasture areas across Mato Grosso do Sul, Goiás, and Minas Gerais. Regular rotary mowing of pasture promotes uniform grass regrowth by removing stemmy, unpalatable top growth and controlling invasive shrubs and broadleaf weeds. The gearbox must perform reliably across entire dry seasons — often months of continuous seasonal use — before any scheduled maintenance can be performed. The serviceable design and extended oil change intervals of this rotary gearbox make it a practical choice for remote farm operations where workshop access is limited.
Municipal Parks and Urban Green Space
Urban and suburban municipalities across Brazil operate fleets of compact tractors with rotary mower attachments for the regular maintenance of parks, sports grounds, embankments, and public rights-of-way. These applications typically use the 540 rpm PTO configuration matched to lower-horsepower compact tractors. The EP replacement gearbox’s 1.20:1 and 1.35:1 ratio options provide the correct blade tip speed for quality finish cutting on established turf areas while maintaining operator safety through reliable, predictable gearbox behavior.
Orchard and Vineyard Inter-Row Management
In the southern Brazilian states of Rio Grande do Sul, Santa Catarina, and parts of São Paulo, fruit orchards and wine grape vineyards require regular mowing of inter-row cover crops throughout the growing season. Narrow-track tractors suited to orchard alleyway conditions need compact, lightweight gearbox assemblies that still deliver adequate torque for dense cover crop management. The EP rotary mower gearbox’s dimensional profile is compatible with narrow-deck mower configurations, and its sealed construction handles the wet, chemical-laden environments common in intensive orchard production systems.
7. Regulatory Compliance & Safety Standards
Agricultural machinery components — including PTO-driven gearboxes — are regulated under multiple overlapping frameworks across different markets. Buyers and procurement managers in Brazil and other markets should be aware of the following applicable standards and requirements when sourcing a rotary mower gearbox replacement.
Brazil — MAPA, ABNT, INMETRO & NR-31
In Brazil, agricultural machinery safety falls under the jurisdiction of the Ministério da Agricultura, Pecuária e Abastecimento (MAPA). Relevant ABNT (Associação Brasileira de Normas Técnicas) standards address agricultural machinery hazard assessment. PTO-driven equipment operators must comply with NR-31 (Norma Regulamentadora de Segurança e Saúde no Trabalho na Agricultura), which mandates proper guarding and safety protocols for power take-off driven machinery. INMETRO certification may be applicable for specific product categories entering the Brazilian market. Importers and distributors should consult with MAPA-registered technical advisors for category-specific guidance.
European Union — CE Marking & Machinery Directive
Rotary mower gearboxes and mowing machinery sold within the EU must comply with the EU Machinery Directive 2006/42/EC. CE marking is mandatory, and manufacturers must compile a Technical File including a Declaration of Conformity and risk assessment documentation. EN ISO 4254-7 covers specific safety requirements for rotary mowers and flail mowers. Products may also need to meet PREN 12999 (sound level standards) and EN 13683 (thrown object risk assessment) requirements depending on the end-use application category.
United States — ASABE & OSHA
In the U.S. market, ASABE (American Society of Agricultural and Biological Engineers) standards S318, S203, and related documents govern PTO shaft safety and rotary mowing equipment design. OSHA 29 CFR Part 1928 covers occupational safety requirements for agricultural operations. ANSI/OPEI B71.8 applies to PTO-driven outdoor power equipment. While ASABE standards are voluntary, they are widely referenced by equipment manufacturers and liability attorneys and serve as the de facto engineering benchmark in North American agricultural machinery procurement.
Australia / New Zealand — AS/NZS & Safe Work Australia
Agricultural machinery operated in Australia and New Zealand falls under AS/NZS 4600 structural steel and related standards. Safe Work Australia’s national guidance on PTO-driven equipment and rotary mowing machinery sets workplace health and safety expectations. State-level WHS (Work Health and Safety) legislation mandates risk management procedures for all mechanical hazards on agricultural worksites. AS 2726 covers safety of agricultural machinery in the Australian/New Zealand context.
International — ISO Standards
ISO 11684 (series) covers safety signs and pictogram requirements for agricultural machinery on a global basis. ISO 4254-7 establishes specific test methods and safety requirements for rotary mowers and flail mowers internationally. ISO 9001:2015 quality management system certification — held by the EP gearbox production facility — ensures that production processes and quality controls are independently audited to international standards, providing a documented quality assurance baseline for global procurement programs.
8. About Us
Our manufacturing facility specializes in agricultural power transmission components, with engineering and production focused on gearboxes serving the global agricultural machinery market. Decades of accumulated expertise in gear design, metallurgical heat treatment, and precision machining have shaped a product range covering rotary mowing, baling, tillage, harvesting, and specialty crop gearbox applications.
For customers in Brazil and throughout South America, we provide dedicated application engineering support from professionals who understand the specific demands of tropical agricultural environments — high ambient operating temperatures, aggressive crop debris, seasonal humidity extremes, and the practical maintenance realities of large-scale rural operations far from urban service centers. We recognize that downtime for agricultural equipment during planting or harvesting windows carries direct economic consequences measured in lost production area, and this reality shapes every engineering decision we make on behalf of operators in these markets.
Our quality management system is certified to ISO 9001:2015. CE marking is maintained for gearbox product lines entering European markets. We participate in regular product line audits and pursue continuous improvement in dimensional consistency, surface finish, and assembly process control to ensure that the EP T-305J replacement unit you receive today performs at least as well as the unit we shipped last season.
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9. Related Products & System Compatibility
A complete PTO-driven mowing system requires more than a high-quality rotary mower gearbox. The following components are produced and supplied within the same agricultural drivetrain product range, ensuring full system compatibility and the convenience of single-source procurement for your entire drivetrain assembly.
PTO Shaft (Power Take-Off Drive Shaft)
The rotary mower gearbox requires a compatible PTO shaft to transmit torque between the tractor output and the gearbox input. Our PTO shaft range is engineered to match the 1-3/4″ Z20 spline interface used across the T-305J gearbox series, available in a range of telescoping lengths to accommodate different hitch-to-deck distances. Overrunning clutch and shear-bolt torque limiter options are available to provide drivetrain protection against sudden blade stall events. For full compatibility information and to view available configurations, visit our PTO shaft.
Transmission Chain & Sprockets
For mower deck configurations that distribute power from the central rotary gearbox to satellite blade carriers via chain drives, our agricultural transmission chains and sprockets are sized and rated to match the torque outputs of the T-305J gearbox range. Available in ANSI/ISO standard pitches with hardened link plates and sealed or unsealed roller options, these drivetrain components are engineered to the same service life standards as the gearbox units they complement. One-stop supply of gearbox, chain, and sprocket components simplifies procurement logistics for fleet maintenance programs operating across multiple properties or regional maintenance depots.
Frequently Asked Questions
Common questions from agricultural machinery engineers, fleet procurement managers, and dealers sourcing rotary mower gearbox parts and replacement units for markets including Brazil and South America.
Q1. How long should a well-maintained rotary mower gearbox last when operating continuously in sugarcane field conditions in Brazil?
Under well-maintained conditions in sugarcane inter-row mowing applications in Brazil — including correct oil fill levels, timely oil changes, properly adjusted PTO shaft angles, and blade balance within manufacturer tolerances — a quality rotary mower gearbox should achieve a minimum service life of 2,000 operating hours. In practice, many well-managed units in sugarcane operations running 540 rpm PTO configurations exceed 3,000 hours before requiring internal overhaul. The most common premature failure modes in sugarcane environments are oil contamination from seal damage caused by sugar crop juice contact, and input shaft spline wear from misaligned PTO angles exceeding the recommended 15° maximum joint angle.
Q2. What PTO speed and gear ratio combination is recommended for this rotary mower gearbox when operating in dense tropical vegetation in humid climate conditions?
For dense tropical vegetation conditions — thick native grasses, heavy cover crop regrowth, or mixed woody-stemmy vegetation typical of Brazilian Cerrado margins and coastal agricultural zones — the recommended combination is 1000 rpm PTO input with the 1.35:1 gear ratio. This delivers 2,298 Nm of output torque at a higher blade peripheral speed than the 540 rpm / 1.35:1 combination, which improves cutting efficiency through thick-stemmed material while maintaining adequate torque reserve to absorb root and debris impacts without blade stall. For lighter finishing work on established lawns or established pastures with fine-leafed grasses, the 1000 rpm / 1.20:1 combination with its 2,043 Nm output torque is the more appropriate selection.
Q3. Which gear ratio should I select for a heavy-duty rotary mower gearbox running at 540 rpm PTO in the Brazilian Cerrado farming region?
For a 540 rpm PTO application in the Cerrado, the 1.35:1 gear ratio is the appropriate selection. This configuration delivers 2,335 Nm of output torque at 183.8 kW input power, which provides the highest torque margin of the three available configurations and is best suited to dense cover crop management, thick grass mowing, and vegetation conditions with variable crop density — all common scenarios in Cerrado agricultural operations. The 1.20:1 ratio is more appropriate for 1000 rpm PTO tractors where a higher blade speed is needed for turf finishing quality in light vegetation conditions.
Q4. How often should the gear oil in a heavy-duty rotary mower gearbox be changed during continuous agricultural operations in tropical climates?
For heavy-duty continuous agricultural applications in tropical climates such as Brazil’s Cerrado and coastal zones, the initial gear oil change should be completed after the first 50 operating hours to flush any metallic break-in particles. Subsequent oil changes are recommended every 250–300 operating hours for season-long field operations, or at least once annually at the start of the main mowing season. In extremely high-ambient-temperature conditions (consistently above 38°C), reducing the interval to 200 hours is advisable. Always use SAE 90 hypoid gear oil as specified; substituting a different viscosity grade affects bearing film thickness and gear lubrication coverage under the rated load conditions.
Q5. What are the key warning signs that indicate a rotary mower gearbox needs full replacement rather than repair?
Replace rather than repair the rotary mower gearbox when any of the following conditions are confirmed: housing fracture or crack at any bearing bore or mounting pad location; splined shaft scoring or tooth shear on either input or output shafts; gear tooth pitting extending across more than 25% of the tooth flank area; bearing bore-to-outer-race clearance exceeding 0.1 mm (indicating housing bore erosion from bearing spin-out); or a history of overheating events that have caused visible oil carbonization inside the housing. In all of these cases, the structural integrity or precision geometry of the housing or gear set has been compromised beyond cost-effective repair, and a new replacement rotary mower gearbox is the appropriate remedy.
Editor: PXY
