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.

Полные технические характеристики

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:

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 карданный вал → 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:

Сценарии применения на практике

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

Монтаж и техническое обслуживание

Процедура монтажа

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.

График технического обслуживания

◆ Before every harvest day — Check oil level; visually inspect housing for cracks; check propeller shaft coupling bolts.

◆ После первых 100 часов — First oil change; re-torque all mounting bolts.

◆ Каждые 500 часов / ежегодно — 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 редуктор роторного культиватора assemblies for tillage and редуктор круглого пресс-подборщика units for straw management. Korea Ever-Power supplies the complete seasonal equipment range.

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