EP-225 Multi-Ratio Intermediate Gearbox — 5 Selectable Speeds

EP-225 Multi-Ratio Intermediate Gearbox — Product Overview

Five Ratios, One Gearbox — The Versatility Advantage

Not every field demands the same rotor speed. Heavy clay in a Korean rice paddy after monsoon season calls for a slow, high-torque pass, while a dry autumn corn-stubble field responds better to a faster blade. The EP-225 multi-ratio intermediate gearbox solves this by offering five distinct gear ratios (2.416, 1.846, 1.692, 1.467, and 1.333) that you can select by swapping the internal gear set — all within the same external housing and the same mounting interface. This means one rotary cultivator gearbox can optimally drive every tillage implement in your shed.

Power Rating & PTO Compatibility

Rated at 75 KW (approximately 100 HP), the EP-225 is designed for mid-power tractors widely used across Korea, Japan, and Southeast Asia. The input accepts a standard 540 rpm PTO connection through a 6×28×34.93×8.69 involute spline — the same profile used by many Korean-made rotary tillers and beaters, ensuring direct compatibility without adapters.

Two Housing Variants for Maximum Flexibility

Korea Ever-Power manufactures the EP-225 in two housing variants to accommodate different implement mounting geometries. Both variants share identical gear internals, power ratings, and five-ratio capability, but differ in output interface and envelope dimensions — giving implement builders and end users full integration flexibility without compromising on drivetrain performance.

Complete Specification Matrix — All Five Ratios

All specifications verified against Korea Ever-Power engineering drawings (catalog reference P02/P03). Output speeds calculated at the standard 540 rpm PTO input.

Ratio Selection Guide — Match Output Speed to Your Soil

How to Choose the Right Ratio

Selecting the correct ratio is not guesswork — it follows a practical decision path based on your soil conditions and the type of implement you are running. Korean agricultural extension services generally recommend 280–350 rpm for rice-paddy rotary tillers and 350–420 rpm for dry-field straw choppers. The EP-225 covers this entire range from a single gearbox.

Heavy Soil — Ratio 2.416 (219 rpm)

Use the highest reduction ratio when working waterlogged paddy clay in early spring or compacted subsoil during deep-plowing operations. The 219 rpm output delivers maximum torque multiplication (2.416× the PTO input torque), preventing stall even in the heaviest conditions. Best suited for 80–100 HP tractors running wide rotary tillers at full depth.

General Purpose — Ratio 1.692 (319 rpm)

The 1.692 ratio is the all-rounder — balanced speed and torque that works for most Korean farms operating in medium loam. Agricultural extension advisors consider this the default starting point. If you only plan to stock one gear set, choose 1.692 and adjust your tractor ground speed to fine-tune the tillage result.

Light Soil & Finishing — Ratio 1.333 (405 rpm)

The fastest output setting is ideal for sandy or volcanic ash soils (common in Jeju and Hokkaido) and for surface finishing passes where fine tilth matters more than cutting force. Also use 1.333 for high-speed straw mulching on harvested fields before winter cover crop seeding.

Variant A vs. Variant B — Choosing Your Output Interface

The EP-225 ships in two distinct housing configurations. The internal gears, input spline, power rating, and all five ratios are identical between variants — the only difference is the output connection and overall envelope. This table helps you select the correct variant for your implement.

Involute Spline Engineering & Gear Material

6×28×34.93×8.69 Involute Spline Input

The EP-225’s input connection uses a six-tooth involute spline profile rather than a simple keyway. The involute tooth form — the same geometry used in automotive transmission gears — self-centers under load and distributes torque across all six teeth simultaneously. Each tooth carries approximately 16.7% of total torque instead of 100% at a single key. This even load distribution reduces peak contact stress by roughly 40% compared to a keyway connection, directly extending spline service life under the cyclic shock loads typical of rocky Korean hillside fields.

20CrMnTi Spiral Bevel Gears

All five interchangeable gear sets are forged from 20CrMnTi alloy steel — carburized at 920°C and oil quenched to achieve 58–62 HRC surface hardness while maintaining a tough, ductile core at approximately 35 HRC. The spiral bevel tooth profile provides smooth, quiet engagement with full-face contact, and each gear pair is lapped together as a matched set to optimize the tooth contact pattern. These matched sets are serialized, so replacement gear sets install with the same quiet, precise mesh as the factory originals.

Sealed HT250 Housing with Oil Monitoring

The CNC-machined HT250 cast-iron housing encloses the gear set in a sealed oil bath (SAE 80W-90 GL-5, approximately 1.8 liters). An oil-level sight glass on the side and a magnetic drain plug at the base are standard, allowing operators to monitor fluid condition and capture metallic wear debris before it circulates through the gear mesh. For farms connecting the gearbox to a PTO drive shaft, the involute spline input provides centering accuracy that eliminates vibration at operating speed.

Why Upgrade from a Single-Ratio Intermediate Gearbox

Many farms start with a fixed-ratio gearbox like the EP-BJ60 beater intermediate gearbox and upgrade to the EP-225 as their operation grows. Here is what the multi-ratio design gives you:

Field Application Scenarios

Multi-Crop Korean Farms

Korean farms operating across multiple crop types — rice in flooded paddies, corn or soybeans on dry upland fields, and vegetables in polytunnels — benefit most from the EP-225. A single tractor fitted with one EP-225 can run a heavy paddy tiller at 219 rpm in spring, switch to general-purpose cultivation at 319 rpm for summer vegetables, and finish the year chopping corn stubble at 405 rpm in autumn. No gearbox changes, no extra equipment purchases, no storage headaches.

Contract Tillage Services

Contract tillers working on different customers’ fields encounter unpredictable soil conditions daily. The EP-225 lets the operator select the optimal ratio before entering each field rather than compromising with a fixed speed across all jobs. This flexibility directly improves tillage quality and customer satisfaction while reducing fuel consumption by 10–15% compared to running an oversized single ratio in light soil.

Implement Manufacturers & OEM Integrators

Tillage implement builders can specify the EP-225 as a standard intermediate gearbox across their entire product line. Since the external housing and mounting interface remain constant regardless of which internal ratio is installed, manufacturers simplify their bill-of-materials while offering end users speed customization as a factory option or aftermarket upgrade.

Gear Ratio Swap Procedure

Changing the gear ratio requires removing the housing cover and swapping the internal spiral bevel gear pair. The job takes roughly 45 minutes with standard hand tools and is best done in a workshop, though field-side changes are possible on a clean, flat surface.

❶ Drain gear oil completely through the bottom plug into a clean container. Inspect for metallic particles.

❷ Remove the housing cover bolts (17 mm and 19 mm sockets). Lift off the cover carefully to avoid damaging the gasket surface.

❸ Extract the existing gear pair using a standard gear puller. Keep the removed pair clean and oiled for future re-use.

❹ Install the new matched gear pair, verifying the serial numbers match (gear and pinion must be a lapped set). Torque the retaining nut to specification.

❺ Apply a thin bead of silicone gasket sealant to the housing face, re-install the cover, and torque cover bolts in a star pattern.

❻ Refill with fresh SAE 80W-90 GL-5 gear oil (approximately 1.8 liters) and run a 5-minute no-load test before field use.

Companion Products & Driveline Components

The EP-225 anchors a flexible tillage driveline. Korea Ever-Power also supplies the companion components that complete the power path from tractor to implement:

PTO Drive Shafts

A properly matched cardan shaft with the correct involute spline profile connects the tractor PTO to the EP-225 input boss. Korea Ever-Power supplies matched drive shafts from our drive shaft division, pre-configured for the 6×28×34.93×8.69 input spline and including full-length safety guards.

Seasonal Gearbox Pairings

If your tractor also runs a round baler gearbox or harvester equipment during off-season, Korea Ever-Power manufactures dedicated speed-increaser and rear-drive gearboxes rated from 30 to 100 KW. For ancillary equipment such as fertilizer spreaders or seed metering units, a self-locking worm gear reducer provides holding torque without a separate brake mechanism.

Preventive Maintenance Schedule

Frequently Asked Questions

Customer Reviews & Field Reports