Descrição
EPK-791A Rotary Rake Gearbox – Replacement of Comer Code
Spiral Bevel 7.2:1 Agricultural Transmission · Direct Cross-Reference to Comer K-791A · Engineered for Brazilian Haymaking and Latin American Forage Operations
1. Technical Specifications
The parameter set below consolidates the mechanical, lubrication, and dimensional data required by engineers evaluating this Rotary Rake Gearbox for new implement designs or as a direct spare. All values are verified on the production floor and documented on each unit datasheet. Overall dimensions follow length × width × height convention.
| Parameter | Value |
|---|---|
| Modelo | EPK-791A |
| Relação de Engrenagem | 7.2 : 1 |
| Max. Output Torque | 190 Nm |
| Rated Input Speed | 540 rpm |
| Input Shaft | 1 3/8″ Z6 |
| Shaft Type | 1 × 1.3/8 (Z6) |
| Number of Rake Arms Supported | 9 |
| Material de Construção | Grey Cast Iron GG25 |
| Material da Engrenagem | Aço Temperado 20CrMnTi |
| Dureza da engrenagem | HRC 58-62 |
| Tipo de Rolamento | Tapered Roller, Anti-Friction |
| Sealing | Double-Lip NBR Oil Seals |
| Mounting Style | Flange Mounted |
| Oil SAE Viscosity Grade | 90EP / API GL-5 |
| Oil Supply Condition | Supplied Without Oil |
| Oil Capacity | 0.35 L |
| First Oil Change | After 50-70 Operating Hours |
| Subsequent Oil Change Interval | Every 500-700 Hours or Annually |
| Faixa de temperatura operacional | -20°C to +80°C |
| Overall Dimensions (L × W × H) | 180 × 150 × 220 mm |
| Net Weight | Approx. 8.5 kg |
| External Finish | Anti-Corrosive Epoxy Powder Coating |
| Garantia | 12 Months From Shipment |
2. Rotary Rake Gearbox Working Principle
Power flows from the tractor Power Take-Off at 540 rpm down the driveline and into the input shaft of the Rotary Rake Gearbox, where a spiral bevel pinion meshes with a larger bevel crown wheel. This first stage redirects the axis of rotation through ninety degrees so that the nearly horizontal input is converted into the sweeping rotation required to spin the tine carousel around the central pivot. The 7.2:1 reduction softens the fast PTO speed into a gentler, more controlled cadence that lifts grass without tearing individual leaves from the stem.
Inside the tractor pto driven rotary rake gearbox, tapered roller bearings carry both radial and axial loads while machined oil galleries splash a semi-synthetic gear lubricant across every mesh point. Precision lip seals keep soil, dust, and silage juice on the outside of the housing, a crucial detail during humid Amazonian harvests. As the output shaft rotates, it drives the cam track that raises and lowers each tine arm along its path, forming a clean, uniform windrow behind the machine. This coordinated sequence is the heart of reliable rotary rake gearbox operation and it explains why the 7.2:1 Rotary Rake Gearbox has become a workshop favourite across Brazil, Argentina, and Paraguay.
3. Five Key Advantages of the EPK-791A Rotary Rake Gearbox
1. Heavy-Duty Hardened Gear Set
Spiral bevel gears are forged from 20CrMnTi alloy, carburised and quench-hardened to HRC 58-62. This extends rotary rake gearbox quality and service life, even under continuous silage cutting shifts in heavy Brazilian pasture.
2. Bolt-for-Bolt Comer Replacement
Input spline, flange pattern, and output geometry exactly match the Comer K-791A reference, so this Rotary Rake Gearbox Replacement of Comer Code drops into the existing implement without chassis modifications or special tooling.
3. Wide Cross-Brand Compatibility
Confirmed fitment across Pronar, Jar-Met, Mesko-Rol, Talex, Armasz, Euro-Masz and further Eastern European rakes commonly operating on Brazilian and Argentine fields helps buyers standardise spare parts across mixed fleets.
4. Tropical-Climate Sealing
Double-lip NBR oil seals and long-life O-rings resist silage acids, high humidity, and fine dust blown in from unpaved farm roads, directly contributing to the rotary rake gearbox benefits experienced by contractors in Mato Grosso.
5. Balanced 7.2:1 Reduction
The conservative ratio protects the entire driveline, extends tine bearing life, and produces neat windrows at reasonable tractor engine speeds, supporting predictable rotary rake gearbox functions season after season.
4. Material Construction and Build Quality
Material selection for the EPK-791A Rotary Rake Gearbox reflects more than two decades of learning about what actually fails in the field. The main housing is cast from GG25 grey iron, a grade prized for its vibration-damping character, which quietens gear mesh noise during long afternoons of raking. Internal bevel gears are forged from 20CrMnTi alloy, then carburised and quenched to achieve a tough, fatigue-resistant core beneath a hardened running surface. This duplex structure resists pitting even when the Rotary Rake Gearbox operates near its torque ceiling, a common condition during second-cut alfalfa in Rio Grande do Sul.
Input and output shafts are machined from 42CrMo4 tempered steel, selected for its excellent shock resistance during PTO engagement transients. Tapered roller bearings from recognised European or Japanese suppliers handle axial thrust from the bevel mesh while providing long service intervals. Lip seals use NBR elastomers compatible with mineral and semi-synthetic gear oils available in Brazil. On the exterior, an epoxy primer plus polyurethane topcoat shields the Rotary Rake Gearbox housing against UV exposure, morning dew, and the salty breeze encountered in coastal warehousing along the Atlantic seaboard.
5. Application Scenarios
The EPK-791A Rotary Rake Gearbox is used wherever plant material needs to be swept, collected, and windrowed efficiently. Below are the most common application scenarios on farms, ranches, and contracting operations, especially across Brazil and neighbouring MERCOSUR countries.
Haymaking
During the Brazilian winter dry window, contractors rake cured Tifton and Coast-cross hay into uniform windrows before baling. The Rotary Rake Gearbox keeps tine tip speed steady so dry leaves are not shattered, preserving nutritional value for cattle feed in São Paulo and Minas Gerais.
Silage Production
Before silage chopping, grass and corn stover are raked to a consistent windrow thickness. A robust Rotary Rake Gearbox drives the tine arms through heavy, wet material without stalling, a critical requirement for dairy herds in Paraná and Santa Catarina reliant on high-moisture silage.
Straw Collection
After wheat, rice, and soybean harvests in the southern states, straw must be raked for baling as bedding or boiler fuel. The Rotary Rake Gearbox handles abrasive residues with its sealed bearing design, giving long intervals between service visits from the mechanic.
Grass Windrowing for Pasture Renewal
Pasture renovation programmes in Goiás and Mato Grosso do Sul frequently involve mowing old grass, raking it aside, and reseeding. The Rotary Rake Gearbox enables fast, clean pickup without dragging soil into the windrow, preserving the regrowth bed for new germination.
Municipal and Landscape Use
Beyond farming, compact rakes equipped with the EPK-791A Rotary Rake Gearbox are used by municipal teams to gather grass clippings, fallen leaves, and light debris along urban parks, airstrips, and roadside verges, extending useful life into mixed-application fleets.
6. PTO Shaft and the Rotary Rake Gearbox Relationship
The Power Take-Off shaft is the mechanical bridge that carries engine torque from the tractor rear output into the input spline of the Rotary Rake Gearbox. A correctly matched PTO shaft must respect the 540 rpm nominal speed, provide enough telescopic travel for headland turns, and incorporate the guard system required by ISO 5674. When these conditions are satisfied, the rotary rake gearbox how does it work narrative becomes predictable: power is transferred without wind-up, the spiral bevels mesh without impulse loading, and the tine arms sweep the swath in a smooth arc.
Mismatched shaft length or an over-angled universal joint, by contrast, introduces vibration that loosens flange bolts and accelerates seal wear. For this reason our technical team recommends ordering a PTO driveline matched to the implement and tractor whenever a new Rotary Rake Gearbox is installed. Careful maintenance of shielding, lubrication of cross joints every 8-10 operating hours, and periodic inspection of telescopic profile overlap all contribute to extended service life.
7. Compliance With National and Regional Regulations
Brazil. Agricultural machinery gearboxes operating in Brazil fall within the framework of NR-12, the Regulatory Standard on Safety of Machinery and Equipment issued by the Ministry of Labour. NR-12 dictates guarding, labelling, and documentation obligations that apply to any implement using a Rotary Rake Gearbox driven by a tractor PTO. ABNT NBR ISO 4254-10 further specifies safety requirements for rotary rakes and tedders, and units supplied for the Brazilian market should carry readable instructions in Portuguese, together with pictograms identifying rotating parts and shear points.
European Union. Rakes equipped with a Rotary Rake Gearbox must comply with Machinery Directive 2006/42/EC and harmonised standards such as EN ISO 4254-10 and EN ISO 5674 for driveline guarding. A signed EU Declaration of Conformity is required before CE marking.
United States. ASABE/ANSI S318.18 covers rotary rake safety, while OSHA 1928.57 applies to guarding of power take-offs on farms. California buyers should also review CAL-OSHA requirements for agricultural drivelines.
Australia and MERCOSUR. Australian purchasers should consult AS 2153 for agricultural driveline safety. Argentine and Paraguayan contractors generally align with IRAM and MERCOSUR technical regulations. Our EPK-791A Rotary Rake Gearbox is built to support compliance with all of these frameworks through proper driveline shielding, durable warning decals, and owner manuals issued in the buyer’s preferred language.
8. About Us
As a specialised manufacturer of agricultural transmission components for more than two decades, our engineering team designs, casts, machines, and assembles every Rotary Rake Gearbox under one roof. Our in-house foundry melts ductile and grey iron in induction furnaces, our gear shop runs modern CNC hobbing and grinding centres, and our assembly line follows ISO 9001:2015 procedures that include torque testing of every unit and selective noise sampling. Keeping the entire workflow integrated lets our metallurgists and agronomy-minded product managers iterate quickly when a new rake brand enters the Latin American market.
Across the last decade we have shipped Rotary Rake Gearbox units to family farms in Rio Grande do Sul, custom silage crews in Mato Grosso, and co-operative workshops in Eastern Europe. Every order leaves our warehouse with export-grade VCI packaging, fumigation certificates when required, and certificates of origin to simplify customs clearance at Santos, Paranaguá, or Rio Grande. A dedicated Portuguese-speaking technical desk supports Brazilian customers with installation questions, oil recommendations, and post-commissioning checklists so your first harvest with a new rotary rake gearbox replacement goes smoothly.
Workshop
9. Related Products and System Compatibility
Beyond the Rotary Rake Gearbox itself, we manufacture a full range of agricultural driveline components. Ordering matched sets from a single supplier shortens lead times, simplifies customs paperwork, and keeps performance within the design envelope of every part in the system. Two of our most commonly paired products are listed below.
Eixo de Tomada de Força
A properly matched PTO Shaft is the component that transmits engine torque from the tractor flywheel into the input spline of the Rotary Rake Gearbox. We produce a complete range of CV joint and cross joint driveshafts with protective shielding that aligns with ISO 5674. Pairing a fresh Rotary Rake Gearbox with a correctly sized PTO Shaft extends the life of both components, because worn telescopic tubes otherwise introduce angular misalignment that stresses bevel gears. Brazilian customers can source matched sets from a single supplier, consolidate shipping, and reduce the risk of mismatched specifications between shaft and gearbox.
Sprockets and Chain
Larger single-rotor and twin-rotor rakes often use chain-driven height adjustment and drop-down systems for transport. We manufacture hardened steel chain sprockets and roller chain assemblies in ISO and ANSI pitches, tooth-hardened for abrasion resistance in dusty silage environments. When a Rotary Rake Gearbox is replaced as part of a mid-life overhaul, farm mechanics commonly refresh the associated sprockets at the same time to restore timing precision across the full implement. Combining sprocket and gearbox orders under a single purchase order shortens downtime during the critical haymaking window in Rio Grande do Sul and neighbouring states.
Frequently Asked Questions
Q1. Which tractor PTO speeds are safe for continuous operation of the EPK-791A Rotary Rake Gearbox during forage season?
The EPK-791A Rotary Rake Gearbox is designed for continuous operation at 540 rpm PTO input speed, the global reference for Category 1 and Category 2 tractors. Short excursions up to 600 rpm are tolerated during headland turns, but sustained operation above that limit increases gear tooth sliding velocity and oil temperature. If your tractor offers 1000 rpm PTO output, either select a gearbox rated for the higher speed or use a proper step-down adapter hub. Running outside design limits voids warranty and shortens rotary rake gearbox service life.
Q2. How do I identify the correct rotary rake gearbox parts for Jar-Met and Mesko-Rol rakes used on Argentine farms?
Jar-Met and Mesko-Rol rakes common on Argentine farms share mounting geometry with the Comer K-791A family, so the EPK-791A Rotary Rake Gearbox is an appropriate replacement part. Confirm the input spline (1 3/8″ Z6), the flange bolt pattern, and the arm count on your specific implement before ordering. Our parts catalogue lists full compatibility tables, and our technical staff will validate fitment against the implement serial number supplied by the buyer. Accurate identification prevents wasted shipping time and keeps a pampas hay crew productive during short harvest windows.
Q3. What are the long-term benefits of choosing a spiral bevel Rotary Rake Gearbox over a straight bevel equivalent?
Spiral bevel Rotary Rake Gearbox designs offer several long-term advantages over straight bevel equivalents. The curved tooth profile distributes load across several teeth simultaneously, lowering contact stress and reducing perceived noise at the operator seat. This translates into longer service life, cooler running during sustained silage shifts, and quieter working conditions, which matter most on cab-less tractors common in smaller Brazilian operations. Straight bevel units are cheaper to produce but transmit impact loads less gracefully. For professional haymaking businesses, the spiral configuration usually pays for itself in lower downtime.
Q4. Which oil grade should I use when commissioning the EPK-791A Rotary Rake Gearbox on a Pronar rake in Rio Grande do Sul?
Use SAE 90EP mineral gear oil or an equivalent API GL-5 product for the EPK-791A Rotary Rake Gearbox on any Pronar rake. The housing capacity is approximately 0.35 litres. Fill through the designated port with the unit level, confirm at the sight plug, and torque the plug to specification. Brazilian distributors commonly stock compatible grades under Ipiranga, Petrobras, and Shell labels at farm supply outlets. Keep temperature and moisture records in your maintenance log so subsequent changes line up with the recommended 500-700 hour interval or annual service.
Q5. When should hay contractors in Paraná schedule the first oil change on a newly installed Rotary Rake Gearbox?
Paraná hay contractors should schedule the first oil change on a newly installed Rotary Rake Gearbox after the initial 50 to 70 operating hours. That early change flushes microscopic run-in debris created as the hardened bevel teeth bed in against each other. After that, plan every 500 to 700 hours or annually, whichever comes first. Many farms service their rakes before the spring cut as a practical milestone. Good record-keeping extends component life and protects the resale value of the implement when the time comes to upgrade.
Editor: PXY
