EP-HRDR50 Harvester Rear-Drive Rear Box — 50 KW, 1:1 Direct-Drive Axle Interface
EP-HRDR50 Harvester Rear Box — Product Overview
Direct Drive — Power Through, No Speed Change
The EP-HRDR50 is deliberately designed to do one thing: pass power through at exactly the speed it receives, while turning the shaft axis 90 degrees to align with the rear axle. Its 1.0 : 1 ratio means that whatever speed the front-mounted EP-HRDF50 selects (from 259 to 536 rpm across its eleven gears) arrives at the rear axle unchanged. There is no additional speed modification, no torque multiplication, and minimal power loss — just a clean right-angle power transfer with the structural rigidity needed to carry the harvester’s rear-axle loads.
The Rear Half of a Two-Box System
In Korea Ever-Power’s tandem harvester driveline, the EP-HRDF50 front box handles all speed selection (eleven ratios), while the EP-HRDR50 rear box handles the mechanical interface between the propeller shaft and the rear axle. This division of labor keeps each unit compact and purpose-focused: the front box is optimized for ratio selection with multiple gear trains, while the rear box is optimized for structural load-bearing and right-angle power transfer with a single spiral bevel gear pair running at 1 : 1.
50 KW Continuous Rating
The EP-HRDR50 is rated at 50 KW continuous — matched to the EP-HRDF50 front box capacity. The 540 rpm nominal input rating represents the maximum expected shaft speed from the front box (the EP-HRDF50’s highest output is 536 rpm in Gear 11). Because the 1 : 1 ratio does not multiply torque, the spiral bevel gear pair operates at relatively low tooth loads, contributing to exceptionally long service life even under sustained full-power harvesting conditions.
Full Technical Specifications
| Paramètre | Spécification |
|---|---|
| Rapport de transmission | 1.0 : 1 (direct drive — no speed change) |
| Vitesse d'entrée nominale | 540 rpm (actual speed varies with front-box gear selection) |
| Vitesse de sortie | Equal to input — 259–536 rpm (from EP-HRDF50 front box) |
| Puissance nominale | 50 KW (approx. 68 HP) |
| Configuration de l'arbre | Right-angle 90° (propeller shaft to axle) |
| Driveline Position | Rear-mounted (axle interface after propeller shaft) |
| Type d'engrenage | Spiral bevel gear pair, matched and lapped |
| Matériel d'équipement | 20CrMnTi alloy steel, case-hardened 58–62 HRC |
| Matériau du boîtier | HT250 cast iron, CNC finish-machined |
| Structural Function | Load-bearing axle mount — carries rear-axle weight and drive reactions |
| Lubrification | Sealed oil bath — SAE 80W-90 GL-5 |
| Application | Combine harvester rear-axle interface in tandem driveline systems |
Why 1 : 1 Direct Drive — The Engineering Rationale
A gearbox that does not change speed might seem unnecessary. But the EP-HRDR50 performs three critical functions that justify its existence in the driveline:
90° Shaft Redirection
The propeller shaft from the front box runs longitudinally along the harvester chassis. The rear axle requires power delivered perpendicular to this axis. The EP-HRDR50’s spiral bevel gear pair performs this right-angle turn with 98%+ mechanical efficiency — far superior to universal-joint-based angle drives that lose efficiency and generate vibration at high angles.
Structural Axle Mount
The EP-HRDR50’s HT250 cast-iron housing serves as the primary structural connection between the harvester chassis and the rear axle assembly. It carries the axle’s weight, absorbs drive-reaction torque, and maintains axle alignment under field loads — functions no simple coupling can provide.
Driveline Modularity
By keeping the rear box at 1 : 1, all speed selection is consolidated in the front box. This means upgrading from five to eleven speeds requires changing only the front unit — the rear box, propeller shaft, and axle assembly remain untouched. Clean separation of functions enables independent service and upgrade paths.
Rear Box in the Tandem System — Complete Power Path
Where the EP-HRDR50 Sits
The complete tandem driveline runs: harvester engine (500 rpm) → EP-HRDF50 front box (11-ratio selector) → propeller arbre de transmission → EP-HRDR50 rear box (1 : 1 right-angle turn) → rear-axle differential → wheels. The EP-HRDR50 occupies the final transmission position immediately before the differential, serving as the structural and mechanical junction between the longitudinal driveline and the transverse rear axle.
Structural Load Bearing
Unlike the front box which sits in the relatively protected engine bay, the rear box must withstand the full spectrum of rear-axle loads: the static weight of the axle and wheels, the dynamic drive-reaction torque during acceleration and braking, the lateral forces during turning, and the vertical impacts from rough field terrain. The CNC-machined HT250 cast-iron housing is designed with generous wall thickness and reinforced mounting bosses to handle these combined loading scenarios throughout the harvester’s service life.
Efficiency at 1 : 1
A 1 : 1 spiral bevel gear pair is the most efficient configuration possible for a right-angle drive. Both the pinion and ring gear are the same size, producing balanced tooth loading and symmetrical wear patterns. Korea Ever-Power grinds and laps each 1 : 1 gear pair as a matched set, achieving a contact pattern that covers over 85% of the tooth face. The result is mechanical efficiency exceeding 98% — meaning less than 2% of input power is lost as heat in the rear box, keeping oil temperatures low and extending both gear and bearing service life.
EP-HRDR50 vs. EP-HRDR60 — Choosing the Right Rear Box
Korea Ever-Power offers two rear-box models for the tandem driveline system. Both share the 1.0 : 1 ratio and right-angle architecture — the difference is power capacity:
| Spécification | EP-HRDR50 | EP-HRDR60 |
|---|---|---|
| Puissance nominale | 50 KW (68 HP) | 60 KW (80 HP) |
| Rapport de transmission | 1.0 : 1 | 1.0 : 1 |
| Nominal Input | 540 tr/min | 540 tr/min |
| Gear Set Size | Standard | Enlarged (wider tooth face) |
| Logement | Standard | Reinforced (larger bearings) |
| Idéal pour | Standard combines, 50–68 HP rear drive | Heavy-duty combines, 60–80 HP rear drive |
Scénarios d'application sur le terrain
Standard Tandem Driveline Harvesters
The EP-HRDR50 is the standard rear box for Korean combine harvesters using the tandem driveline architecture. It pairs with the EP-HRDF50 front box in new-build combines and as a matched replacement set for existing tandem systems. The 50 KW rating covers the rear-drive power requirements of the most common Korean combine models operating in the 68–100 HP range, where the front box absorbs the engine output and the rear box simply redirects it to the axle.
Aftermarket Rear-Box Replacement
When a harvester’s existing rear box develops bearing wear, gear noise, or oil leakage, the EP-HRDR50 provides a drop-in replacement. Because the 1 : 1 ratio is universal and does not affect speed selection (which is entirely controlled by the front box), the EP-HRDR50 is compatible with any tandem system that uses a 1 : 1 right-angle rear box with matching mounting dimensions. CNC machining to ±0.02 mm ensures exact fitment without shimming or adaptation.
OEM Harvester Manufacturing
Combine harvester manufacturers specify the EP-HRDR50 as a standard component in their rear-axle assemblies. The CNC-machined housing integrates directly into the harvester frame design as a load-bearing structural element, reducing the number of separate brackets and mounting plates required in the rear-axle architecture. The consistent dimensional accuracy across production batches eliminates assembly-line fitment variation.
Why Choose the EP-HRDR50
98%+ Mechanical Efficiency
The matched 1 : 1 spiral bevel pair delivers over 98% power transfer efficiency. Less than 2% of input power is lost as heat, keeping the rear box cool and extending gear and bearing life well beyond typical agricultural duty cycles.
Structural Load-Bearing Housing
The HT250 cast-iron housing is more than a gear enclosure — it structurally connects the harvester chassis to the rear axle. Reinforced wall sections and mounting bosses absorb axle weight, drive reactions, and terrain impacts.
Independent Serviceability
The rear box can be removed and replaced without disturbing the front-mounted speed selector. A rear-box swap takes approximately three hours with standard tools — far less than an integrated rear-axle gearbox requiring full axle disassembly.
Garantie de 12 mois / 1 000 heures
Full manufacturer warranty with Korean service center support. Korea Ever-Power stocks replacement units for rapid dispatch to minimize harvester downtime during the critical harvest window.
Installation & Maintenance
Procédure de montage
❶ Support the rear axle with a jack or axle stand. Position the EP-HRDR50 housing on the rear-axle mounting frame and align the bolt holes with the chassis mounting points.
❷ Insert all mounting bolts finger-tight. Verify the output shaft aligns concentrically with the differential input. Torque all bolts in a star pattern to specification.
❸ Connect the propeller shaft from the front box (EP-HRDF50) to the EP-HRDR50’s input flange. Verify alignment and secure the coupling bolts.
❹ Fill gear oil (SAE 80W-90 GL-5) and run a low-speed test with the front box in Gear 9 (1 : 1 direct). Verify smooth, quiet operation and zero oil leakage before field use.
Maintenance Schedule
◆ Before every harvest day — Check oil level; visually inspect housing for cracks; check propeller shaft coupling bolts.
◆ Après les 100 premières heures — First oil change; re-torque all mounting bolts.
◆ Toutes les 500 heures / annuellement — Full oil change; inspect magnetic drain plug; check propeller shaft alignment.
◆ Every 1,500 hours — Inspect spiral bevel gear contact pattern; check bearing play. The 1 : 1 ratio produces very low tooth loads, so gear inspection intervals are longer than multi-ratio units.
◆ End of harvest season — Top off oil; inspect housing mounting bolts for fatigue; apply corrosion inhibitor to exposed shaft surfaces.
Companion Products & Tandem Driveline Components
Front-Box Pairing
The EP-HRDR50 works in tandem with the EP-HRDF50 front box (11 ratios, 50 KW). Together they form a complete tandem driveline: the front box handles all speed selection, the rear box provides the right-angle axle interface. Contact Korea Ever-Power engineering for a matched front-rear specification for your harvester model.
Off-Season Equipment
Between harvest seasons, farms equip tractors with boîte de vitesses pour cultivateur rotatif assemblies for tillage and boîte de vitesses pour presse à balles rondes units for straw management. Korea Ever-Power supplies the complete seasonal equipment range.
Foire aux questions
Avis clients et rapports de terrain
★★★★★
“We pair the EP-HRDR50 with the EP-HRDF50 front box in our tandem-driveline combine harvesters. The 1 : 1 rear box is the most reliable component in our entire driveline — zero warranty claims across 200+ units over four production years. The cast-iron housing also serves as a structural frame member, which simplified our rear-axle design and reduced the number of separate brackets we need to manufacture.”
OEM Buyer · 200+ units · Tandem driveline harvester manufacturing
★★★★★
“Replaced the worn rear box on my 10-year-old combine with the EP-HRDR50. The old unit had developed bearing noise and a persistent oil leak. The new EP-HRDR50 dropped into the same mounting points with zero modification. It runs quieter than the original ever did — the 1 : 1 matched gear pair is noticeably smoother. Oil consumption went from visible leakage to zero.”
Verified Purchase · Aftermarket replacement · 10-year-old combine restoration
★★★★☆
“We stock the EP-HRDR50 for Korean-brand combine harvesters operating in Thailand. The 1 : 1 design is simple and reliable — our technicians appreciate the ease of service compared to multi-ratio rear boxes. Only 4 stars because we occasionally need the EP-HRDR60 for heavier Thai soil conditions, and that model is stocked less frequently.”
Wholesale Buyer · 10+ units/year · Thai harvester aftermarket
★★★★★
“Our cooperative replaced rear boxes on 15 combines over three seasons as part of a fleet refurbishment program. The EP-HRDR50 is the easiest gearbox in the driveline to swap — three hours per machine with two mechanics, no special tools, no axle removal. The 1 : 1 ratio means there is essentially nothing to go wrong internally. These are set-and-forget components.”
Group Purchase · 15 units · Fleet refurbishment program
★★★★★
“We service Korean-brand harvesters operating on Hokkaido’s large grain farms. The EP-HRDR50’s 1 : 1 efficiency means the rear box generates almost no heat — after an 8-hour harvest day, the housing is barely warm to the touch. This thermal efficiency extends oil life significantly. Our customers report the EP-HRDR50 as the lowest-maintenance component in their entire harvester driveline.”
Wholesale Buyer · 8 units/year · Japanese grain harvester service
Informations complémentaires
| Éditeur | Cxm |
|---|
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