EP-HRD75A Harvester Rear-Drive Gearbox Type A — 75 KW, Five-Ratio Transmission with Brake Drum

EP-HRD75A Harvester Rear-Drive Gearbox — Product Overview

Purpose-Built for Harvester Ground Propulsion

The EP-HRD75A is fundamentally different from Korea Ever-Power’s tillage and baler gearboxes. While those products drive implements from the tractor PTO, the EP-HRD75A drives the harvester itself — it is a multi-speed rear-axle transmission that converts engine power into ground propulsion at five selectable speeds. Rated at 75 KW with a 500 rpm input (from the harvester’s engine output shaft, not the standard 540 rpm PTO), the EP-HRD75A provides the speed flexibility that combine operators need when transitioning between heavy grain harvesting, light straw conditions, field-edge maneuvering, and road transport.

Five Ratios — Both Increase and Reduction

Unlike implement gearboxes that only reduce or only increase speed, the EP-HRD75A offers ratios on both sides of 1.0 — from the 0.84 : 1 speed-increase ratio (producing 595 rpm output for high-speed transport) through the 2.02 : 1 deep reduction (producing 248 rpm for maximum traction in wet or soft ground). This bidirectional ratio range gives the harvester operator complete control over ground speed and wheel torque across every field condition encountered during the harvest season.

Integrated Brake Drum

The EP-HRD75A includes an integrated brake drum on the input shaft that provides both parking and service braking functions. Braking through the gearbox input side means the brake acts on the high-speed, low-torque side of the gear train — requiring less braking force to achieve the same deceleration than a wheel-side brake would need. This reduces brake component wear and provides more consistent stopping performance across all five gear ratios.

Complete Specification — All Five Gear Ratios

Five-Ratio Ground Speed Guide — Matching Gear to Harvest Conditions

The EP-HRD75A’s five ratios are not arbitrary — each corresponds to a specific harvesting condition that Korean and Asian combine operators encounter across the season. Selecting the correct gear maximizes harvesting efficiency, grain quality, and machine longevity:

Integrated Brake Drum Engineering

Input-Side Braking Advantage

Positioning the brake drum on the input (high-speed) side of the gear train is a deliberate engineering choice. Because the input shaft rotates faster than the output, the brake needs to absorb less torque to achieve the same deceleration at the wheels. At the maximum 2.02 : 1 reduction, the brake only needs to generate half the torque that a wheel-side brake would require for the same stopping force. This reduces brake pad wear, lowers operating temperatures, and provides more consistent braking performance throughout the service interval.

Parking & Service Dual Function

The drum brake serves both as a service brake (applied during field operation and road transport to control speed and stop the machine) and as a parking brake (mechanically locked when the harvester is stationary on slopes). The dual-function design eliminates the need for a separate parking brake mechanism on the rear axle, simplifying the harvester’s brake system architecture and reducing maintenance complexity for operators.

Brake-Through-Gearbox Safety

Because the brake acts through the gear train, it retains full braking authority in all five gear ratios. The operator does not need to remember which gear provides the most effective braking — the input-side drum provides consistent pedal feel and stopping distance regardless of the selected ratio. This is a critical safety feature for Korean hillside harvesting operations where combine harvesters frequently operate on slopes exceeding 10 degrees.

Type A vs. Type B Housing — Selecting the Correct Variant

Korea Ever-Power manufactures the harvester rear-drive gearbox in two housing configurations. Both Type A (EP-HRD75A) and Type B (EP-HRD75B) share identical internal gear sets, all five ratios, the same 75 KW power rating, and the same integrated brake drum. The difference is exclusively in the external housing geometry and mounting interface:

Field Application Scenarios

Korean Rice Combine Harvesters

Korean rice harvesting presents extreme variability: the same combine may operate in firm, dry paddy soil one day and waterlogged clay the next. The EP-HRD75A’s five ratios let the operator adapt instantly — shifting to Gear 1 (2.02 : 1) when the paddy is saturated and traction is critical, then moving to Gear 3 or 4 as conditions firm up. This adaptability prevents the bogging, wheel spin, and crop damage that occur when a fixed-ratio drive cannot match ground conditions.

Multi-Crop Harvesting Operations

Combines harvesting rice, wheat, barley, and soybeans across different seasons and field conditions benefit from the full 248–595 rpm output range. Dense, high-moisture rice requires slow, steady advance (Gear 1 or 2), while dry wheat on firm ground permits faster travel (Gear 4). Road transport between distant fields uses Gear 5 for maximum ground speed, reducing non-productive transit time during the narrow harvest window.

Hillside Harvesting with Integrated Braking

Korean geography includes extensive hillside terrace farming where combines must operate on slopes exceeding 10 degrees. The EP-HRD75A’s integrated brake drum provides consistent stopping authority on these gradients, and the low-gear traction (Gear 1) prevents uncontrolled acceleration on downhill passes. The input-side brake design maintains identical pedal feel in all five gears, giving the operator predictable speed control regardless of terrain.

Why Choose the EP-HRD75A for Your Harvester

Installazione e manutenzione

Mounting Procedure

❶ Lift the EP-HRD75A into position on the harvester’s rear-axle mounting frame. Align the Type A housing bolt pattern with the existing mounting holes. Insert bolts finger-tight.

❷ Connect the input shaft to the harvester’s engine-output drive coupling. Verify the brake drum sits correctly within the brake caliper or shoe assembly.

❸ Connect the output shaft to the rear-axle differential or final drive. Torque all mounting bolts to specification in a star pattern.

❹ Connect the gear selection linkage and verify all five ratios engage cleanly with positive detent feel. Test the brake mechanism for full engagement and release.

❺ Fill gear oil (SAE 80W-90 GL-5) and perform a low-speed field test in each gear before commencing harvest operation.

Maintenance Schedule

◆ Before every harvest day — Check oil level; test brake engagement; verify gear selection linkage.

◆ After first 100 hours — First oil change; inspect brake drum lining thickness.

◆ Every 500 hours / annually — Full oil change; inspect brake components; check gear selector detents.

◆ Every 1,000 hours — Inspect all gear meshes; check bearing play; measure brake drum for wear limits.

◆ End of harvest season — Top off oil; release parking brake to prevent drum-to-shoe bonding during storage; apply corrosion inhibitor.

Companion Products & Seasonal Equipment

Harvester Front-Drive & Rear-Drive Gearboxes

Korea Ever-Power manufactures a complete family of harvester drive gearboxes including the EP-HRD75B (Type B housing), EP-HRDF50 (front-drive, 11 ratios), and EP-HRDR50/EP-HRDR60 (rear-drive, direct-ratio). Matched albero motore assemblies for the engine-to-gearbox connection are also available. Contact our engineering team for a full harvester driveline specification matched to your combine model.

Off-Season Tillage & Baling Equipment

Between harvest seasons, many Korean farms equip their tractors with rotary cultivator gearbox assemblies for spring tillage and cambio per pressa per balle rotonde units for autumn straw management. Korea Ever-Power supplies the complete seasonal equipment range to keep your machinery productive year-round.

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