EP-SE401T1 Single-Stage Track Drive Planetary Gearbox

The EP-SE401T1 is a single-stage track drive planetary gearbox for mid-class crawler undercarriages, compact to medium excavators, rotary drilling rigs, mobile crushing and screening plants, and tracked crawler cranes. Its 2,000 N·m rated output torque, delivered at a fixed ratio of i=6.2 from a hydraulic motor input of up to 1,000 rpm, covers the torque requirement for machine operating weights of 6–12 tonnes on gradients up to 25°. Two drives are used per machine — one per track — with differential motor flow providing steering. The 270 N·m spring-applied brake automatically engages within one second of hydraulic pressure loss.

The EP-SE401T1 achieves 2,000 N·m from a single planetary stage at i=6.2 rather than using a two-stage design at higher ratio to reach the same output torque. In a single-stage track drive, the planet carrier is fixed and the ring gear rotates — the entire gear set operates in pure epicyclic mode with load shared across all planet gears simultaneously. This load-sharing is what allows a compact single-stage unit to handle torques that would require a larger two-stage parallel-shaft gearbox. The result is a shorter overall length than a two-stage unit at the same torque class, which fits the tight axial depth constraints of compact to mid-size crawler undercarriage frames.

The EP-SE401T1 spring brake delivers 270 N·m — exactly double the 130 N·m of the EP-SE400T1. This increase is not an arbitrary margin; it reflects the heavier machine class the SE401T1 targets. A 10-tonne crawler excavator parked on a 15° slope requires approximately 2 × 270 N·m × i × sprocket radius of holding force from the two track drives to remain stationary. The wet multi-disc configuration — oil-cooled friction discs clamped by Belleville springs — maintains consistent holding torque without thermal fade even during repeated engage-disengage cycles during grading and trench excavation work.

The taper roller bearings in the EP-SE401T1 are physically larger than those in the EP-SE400T1, sized for the higher combined radial and axial load that a 6–12 tonne machine imposes on the drum-spindle interface. When a mid-size excavator travels on a slope and the machine's weight acts laterally on the track frame, the bearing system must simultaneously absorb the full static machine weight as axial load and the track tension as radial load. The taper roller configuration — as opposed to cylindrical or ball bearings — is the only commercially viable bearing type for this combined load condition in a compact track drive housing.

The EP-SE401T1 is rated to −25°C versus −20°C for the EP-SE400T1 — a 5°C extension that reflects the larger internal oil volume and the spring brake design in this unit. At −25°C with ISO VG 150 oil, the oil viscosity rises but remains pumpable through the gear train under self-splash lubrication. The spring brake Belleville stack maintains adequate spring force at −25°C without becoming brittle. For deployments in northern Canada, Scandinavia, or high-altitude applications where overnight temperatures regularly reach −20 to −25°C, the EP-SE401T1 provides the margin the EP-SE400T1 does not. Note that the maximum operating temperature of +85°C is 5°C lower than the EP-SE400T1's +90°C — in sustained high-ambient-temperature applications, verify oil change intervals accordingly.

The floating mechanical face seals (duo-cone type) on the EP-SE401T1 are the same seal concept used on all Korea Ever-Power track drive units. At the 6–12 tonne machine class, the track drive regularly operates partially submerged in rock slurry from trenching, canal digging, and quarry floor operations. The lapped-flat metal face pairs maintain positive sealing pressure regardless of submersion depth during normal operation — the internal oil pressure generated by gear rotation exceeds the external hydrostatic pressure in typical applications. In applications where the machine is operated deeply submerged for extended periods, consult Korea Ever-Power for enhanced sealing specifications.

The EP-SE401T1 mounting flange bolt circle, spindle bore, drum OD, and hydraulic port locations match the equivalent torque class models in the Rexroth GFT track drive series and the Bonfiglioli 700C crawler drive series (cited for dimensional reference only — Korea Ever-Power claims no trademark affiliation). An excavator currently running a legacy drive in the 2,000 N·m class can be re-fitted with EP-SE401T1 without modifying the chassis, hydraulic lines, or sprocket hardware. Korea Ever-Power provides a cross-reference dimensional drawing confirming the specific legacy model match before order placement, at no charge. Brand disclaimer: Rexroth and Bonfiglioli are trademarks of their respective owners.

The EP-SE401T1 converts high-speed, low-torque hydraulic motor output into low-speed, high-torque sprocket rotation through the following four-stage sequence.

Remove all burrs, corrosion, and old sealant from the chassis bore. Measure the bore diameter with a telescoping gauge and confirm it matches the EP-SE401T1 spindle OD on the Korea Ever-Power dimensional drawing. Tolerance mismatch at this interface allows spindle micro-movement under load — the primary cause of early mechanical face seal failure in track drives.

The oil fill, level check, and drain ports are positioned for standard horizontal-spindle-axis installation. If the machine places the spindle at a non-horizontal angle, confirm port orientation with Korea Ever-Power before installation. Operating with fill and drain ports reversed results in the gear set running partially unlubricated from day one.

Fill the gearbox through the fill port with ISO VG 150 (below +15°C ambient) or ISO VG 220 (above +15°C). Typical fill volume for EP-SE401T1 is approximately 1.2–1.8 litres — confirm the exact figure on the Korea Ever-Power drawing for your configuration. Check level at the side port: oil should reach the bottom of the side port opening. Do not overfill — foaming from excess oil can push past the mechanical face seals.

Insert the hydraulic motor output shaft spline into the sun gear bore until full engagement depth is reached — do not force. Partial spline engagement concentrates torque transmission over a reduced tooth area, causing spline tooth shear at peak travel torque. Bolt the motor face to the gearbox input flange and torque to the motor manufacturer's specification in a cross (star) pattern.

Connect only the brake pilot line. Apply 15–30 bar pilot pressure and confirm the drum rotates freely by hand. Release pressure and confirm the drum locks immediately. This two-state test verifies brake function before the machine is under load. A brake that does not release prevents travel; a brake that does not engage on pressure loss is a safety failure. Do not connect the motor work ports until this test passes.

Operate at approximately 50% maximum torque for the first 10 hours. Run-in allows gear tooth surfaces to micro-seat; fine metal particles enter the oil. At 150 operating hours, drain the oil while warm (particles remain suspended for complete removal), then refill with fresh GL-5 oil of the same grade. This first oil change is not optional — it removes the fine abrasive particles that would otherwise circulate through bearings and gear flanks. Subsequent changes every 1,000 hours or annually.

① Compact to Mid-Size Crawler Excavators (6–12 Tonnes)

The 6–12 tonne crawler excavator class is the most common excavator category globally and the primary target application for EP-SE401T1. Machines in this class — used for trenching, foundation digging, and general site preparation — require a track drive capable of propelling the machine on 25° gradients under full bucket load and holding position on those gradients when the operator releases the travel pedal. At 2,000 N·m per drive and 270 N·m spring brake, EP-SE401T1 covers this requirement with an appropriate safety margin.

② Rotary Drilling Rigs — Across Unstable Construction Terrain

Tracked rotary drilling rigs in the 8–15 tonne chassis class require higher travel drive torque than the EP-SE400T1 provides, due to the additional weight of the mast, rotary head, and kelly bar. EP-SE401T1 at 2,000 N·m handles this weight class across typical site surfaces — compacted fill, stabilised sand, and clay. The slow repositioning speed requirement (typically 0.5–2 km/h between bore locations) suits the EP-SE401T1's output speed range, and the spring brake provides the automatic position hold between repositioning moves.

③ Mobile Crushing and Screening Plants

Tracked impact crushers and jaw crushers in the 8–20 tonne class reposition frequently within quarries — moving across fragmented rock, aggregate stockpiles, and wet clay between processing stations. The EP-SE401T1's spring brake engages automatically between moves, preventing the machine from sliding on aggregate slopes during the brief pauses between repositioning. The floating mechanical face seals handle the fine silica and limestone dust that rapidly destroys rubber lip seals on lighter-duty track drives.

④ Foundation Piling and Crane Machines

Compact crawler cranes (10–20 tonne lifting class) and piling rigs use the EP-SE401T1 for the undercarriage travel drive. These machines require precise positioning accuracy — often moving 1–5 metres per repositioning cycle to a specific pile location — and must hold position precisely while the pile or crane load is applied. The EP-SE401T1 proportional response to motor flow allows controlled slow-speed positioning, and the spring brake provides the stationary hold required during pile driving or crane pick events.

⑤ Tracked Agricultural Machinery — Large-Frame Harvesters

Large-frame tracked combine harvesters and sugar cane harvesters in the 8–14 tonne operating weight class exceed the torque capacity of EP-SE400T1 and require EP-SE401T1 for the track final drive. Operating in wet, yielding soil — paddy fields, clay-heavy cane fields — the track drive must generate sufficient tractive force to propel the fully loaded machine without track slippage. The downstream agricultural multi-output gearboxes for the cutting platform and threshing drum operate on entirely separate hydraulic circuits from the EP-SE401T1 travel drives.

⑥ Tracked Pipe-Laying Equipment and Winch-Fitted Platforms

Pipe-laying machines in the 8–15 tonne class use EP-SE401T1 for the travel drive while advancing at controlled low speed (0.1–1 km/h) during continuous trenching operations. The winch drum on the same machine — handling the pipe tensioner or cable pull function — is independently served by a worm gear reducer on a separate hydraulic circuit, providing self-locking load hold on the drum independently of the travel drive's spring brake function on the chassis.

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EP-SE401T1 on our 8-tonne compact excavator platform — replaced failing European track drives that we were sourcing at 3× the cost. Dimensional match to the legacy drive was confirmed by Korea Ever-Power same-day: spindle bore, drum OD, motor SAE flange, and brake pilot port — all matched without any chassis modification. Field installation at a construction site took one technician, two hours per side. At 3,000 hours of mixed trenching and rock-breaking cycles, both drives are running cleanly — oil samples show zero metal particle elevation and no water ingress. The 270 N·m spring brake holds the machine solidly on our standard 20° test slope.

We run a fleet of 12-tonne tracked jaw crushers across granite quarry sites in central Nigeria — ambient temperature peaks at 42°C, the ground is pulverised granite dust and coarse aggregate. Previous track drives — European brand, rubber lip seals — needed seal replacement every 800–1,000 hours because the granite dust abrades the lip seal contact point. EP-SE401T1 mechanical face seals have now run 2,200 hours across four units without a single seal replacement. The 96%+ efficiency has also reduced hydraulic fluid temperature on the crusher's circuit, which was running hot with the old drives. The cost saving over 2,200 hours per unit is significant.

Our tracked excavators work Finnish construction sites where winter temperatures regularly hit −22°C to −25°C. We specifically chose the EP-SE401T1 over the EP-SE400T1 because of the lower −25°C cold-start rating. With ISO VG 150 GL-5 oil, cold-start behavior on the first travel movement of the morning at −24°C was normal — no sluggish initial rotation, no excessive brake drag from stiff oil. After two Finnish winters of continuous use, the spring brakes function identically to commissioning; we've measured brake pilot release pressure at 18 bar, well within the specified range. Korea Ever-Power's technical response time on cold-weather questions was same-day.

क्यूCan EP-SE401T1 replace a Rexroth GFT or Bonfiglioli 700C drive without chassis modification?

For units in the equivalent 2,000 N·m torque class, the EP-SE401T1 mounting flange bolt circle, spindle bore diameter, drum OD, hydraulic port locations, and motor interface geometry match those of the corresponding Rexroth GFT and Bonfiglioli 700C models. Korea Ever-Power verifies this match explicitly against the specific legacy model number before order, supplying a cross-reference dimensional comparison document. If any dimension differs from the chassis requirements, it is identified before the machine comes off line. Rexroth and Bonfiglioli are trademarks of their respective owners, cited solely for dimensional reference.

क्यूThe source page lists brake release pressure as 15–30 bar. Why is this lower than typical track drive brakes?

Brake release pressure is determined by the spring stack design and piston area in the specific unit — not by a universal track drive standard. The 15–30 bar range cited in the SE401T1 source page reflects the spring and piston configuration of this specific model. A lower release pressure reduces the pilot circuit flow requirement for brake release, which can be beneficial when the pilot circuit is shared with other valve functions. The exact release pressure for a specific installation should be confirmed with Korea Ever-Power before hydraulic circuit design, as the range (15–30 bar) is relatively wide and the actual value depends on the specific spring specification used in the batch.

क्यूWhy does EP-SE401T1 have a lower maximum temperature (+85°C) than EP-SE400T1 (+90°C)?

The maximum housing surface temperature specification reflects the thermal limit of the spring brake disc materials and the oil viscosity floor at the operating temperature. The EP-SE401T1 carries a larger internal oil volume and a heavier spring brake pack — these components have a different thermal equilibrium point than the smaller EP-SE400T1. In practice, a correctly installed EP-SE401T1 on a 6–10 tonne machine in ambient temperatures up to +40°C will not approach the +85°C housing temperature limit under normal operating duty cycles. In sustained high-duty or high-ambient applications, contact Korea Ever-Power for thermal analysis based on your specific cycle and ambient conditions.

क्यूWhat oil grade, volume, and change interval applies to EP-SE401T1?

Use API GL-5 gear oil: ISO VG 150 for ambient temperatures consistently below +15°C; ISO VG 220 for ambient above +15°C. Do not mix grades. Approximate fill volume is 1.2–1.8 litres depending on motor adapter configuration — the Korea Ever-Power dimensional drawing specifies the exact volume. Fill through the topmost port in the operating orientation; check level at the side port. First oil change at 150 operating hours to clear run-in particles; thereafter every 1,000 hours or annually, whichever is sooner.

क्यूCan EP-SE401T1 be supplied pre-assembled with a hydraulic motor?

Yes. Korea Ever-Power supplies EP-SE401T1 as a pre-assembled, test-run drive package including a compatible axial piston or orbit hydraulic motor, integrated pressure relief valve, and overcenter (counterbalance) valve — as a single part number. The assembly is function-tested before shipment: brake release verified, spline engagement confirmed, oil level set. Specify your hydraulic motor model (or provide flow rate, pressure, and displacement requirements) and the required valve options at time of enquiry.