EP-SE400T1 Track Drive Planetary Gearbox

De EP-SE400T1 is a single-stage track drive planetary gearbox for crawler undercarriages, rotary drilling rigs, mobile crushing plants, and tracked agricultural machinery. At a fixed ratio of i=6.09, it accepts up to 1,000 rpm from an axial-piston or orbit hydraulic motor and delivers 1,300 N·m of output torque through the rotating outer housing directly to the sprocket — sufficient to propel a 3–5 tonne crawler on a 20° gradient using two drives, one per track. The integrated multi-disc spring brake holds 130 N·m without any hydraulic pressure, locking the machine automatically the instant the operator releases the travel control.

In every EP precision series (TM, TNF, TEG), the ring gear is bolted stationary to the housing and the planet carrier rotates as the output shaft. EP-SE400T1 reverses this: the hollow central spindle (planet carrier) bolts to the machine chassis and remains fixed; the ring gear, cast as an integral part of the outer rotating drum, spins as the output. This lets the gearbox body itself become the sprocket hub. The track chain sprocket bolts to the outer drum face, and the entire assembly sits within the track frame width with no shaft protruding beyond the sprocket plane — a package geometry impossible to achieve with a conventional shaft-output gearbox.

The integrated brake operates on a fail-safe principle that is the opposite of every friction brake in common use: heavy internal Belleville springs permanently clamp a stack of alternating steel and friction discs against the rotating drum, holding 130 N·m of braking torque without any hydraulic pressure. Travel requires the operator to deliberately apply pilot pressure to a dedicated brake port — this hydraulic pressure compresses the spring stack and lifts the disc pack, allowing the drum to rotate. The moment the machine shuts down, hydraulic pressure drops to zero and the spring brake re-engages automatically. A machine parked on a slope cannot roll even on total hydraulic system failure.

The sealing system at the rotating drum–spindle interface uses floating mechanical face seals (sometimes called duo-cone seals or rotating lip metal seals in industry literature). Each seal pair consists of two hardened and lapped-flat metal toric rings pressed together by toroidal elastomer O-rings acting as springs. The sealing action is metal-to-metal contact across lapped surfaces, not elastomer-to-shaft sliding contact. Lapped metal faces do not wear or stiffen with temperature. Abrasive soil particles that cut through rubber lip seals in days cannot penetrate the pressurised metal interface. This is the standard sealing system on excavator final drives worldwide because it is the only design that survives continuous immersion in rock-mud slurry.

The EP precision series uses sealed-for-life synthetic grease lubrication inside a closed housing — no oil fill or drain ports. EP-SE400T1 uses oil bath splash lubrication: a fill of API GL-5 rated gear oil (ISO VG 150–220 depending on ambient temperature) partially submerges the gear train. As the planet gears orbit, they pick up oil and distribute it across all tooth surfaces and bearings. The first oil change is at 150 operating hours (run-in metal particle clearance), then every 1,000 hours. Oil fill, level check, and drain ports are positioned to be accessible without removing the gearbox from the machine — a maintenance design priority absent from sealed-for-life precision gearboxes.

The EP-SE400T1 input is designed for splined shaft plug-in connection to axial piston hydraulic motors (such as the A2FE63 series) or hydraulic orbit motors (gerotors). The motor's output shaft inserts directly into the sun gear bore; the motor face bolts to the gearbox input flange. There is no coupling, no adapter sleeve, and no key — the spline transmits torque over full tooth length contact area. Optional integrated pressure relief valves and overcenter valves (specified at order) simplify the hydraulic circuit by eliminating external cartridge valves that would otherwise sit in the motor case drain line. The 1,000 rpm max input limit applies to the rated continuous duty; the motor displacement should be selected to reach max travel speed within this limit at the system's maximum pump flow rate.

The EP-SE400T1 mounting flange bolt circle, spigot diameters, center bore dimensions, and hydraulic port locations match the equivalent size 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). This dimensional parity means a machine currently running a legacy drive in this torque class can be re-fitted with EP-SE400T1 without modifying the chassis, hydraulic lines, brake pilot circuit, or sprocket hub hardware. Field replacement requires only a drain of the old oil and a refill with GL-5 grade oil before commissioning. Brand disclaimer: Rexroth and Bonfiglioli are trademarks of their respective owners, cited solely for dimensional reference.

The EP-SE400T1 track drive planetary gearbox operates through a four-stage power chain, each stage a distinct form of energy conversion. Understanding the sequence clarifies why each design feature exists.

Measure the chassis spindle bore diameter and check it against the EP-SE400T1 spindle OD on the Korea Ever-Power dimensional drawing. Tolerance mismatch here causes fretting and spindle micro-movement under load, which rapidly destroys the mechanical face seal at the drum-spindle interface. Clean all burrs, rust, and paint from the bore mating surfaces.

The oil fill and level ports are orientation-specific — they are positioned for the gearbox's operating attitude (typically spindle axis horizontal). If your machine installation places the spindle at a non-standard angle (e.g. tilted on a slope-walking machine), confirm the oil port orientation with Korea Ever-Power before installation. Installing with ports in the wrong position can result in operating under- or over-oiled from day one.

Fill the gearbox to the correct level with API GL-5 gear oil (ISO VG 150 or VG 220) through the fill port before the hydraulic motor is attached. This is easier with clear access to the fill port. Use a filtered funnel. Volume: approximately 0.8–1.2 litres. Check level at the side port — oil should just reach the bottom of the opening with gearbox in operating position.

Insert the motor output shaft spline into the sun gear bore — do not force. Confirm full spline engagement before bolting the motor face. Torque all motor fasteners to the motor manufacturer's specification in a cross (star) pattern. A partially engaged spline transmits torque over a reduced tooth length, generating concentrated stress that shears spline teeth under load.

Before connecting the travel motor work ports, connect only the brake pilot line and apply pressure (25–35 bar). Confirm the drum rotates freely by hand — this verifies the brake has released. Release the pilot pressure and confirm the drum locks. A brake that does not fully release prevents travel; a brake that does not lock on pressure loss is a safety failure. Do not proceed to travel testing until this two-state test is passed.

Operate at 50% maximum load for the first 10 hours. During run-in, gear surfaces micro-seat and fine metal particles enter the oil. At 150 operating hours, drain the oil while warm (particles stay suspended), refill with fresh GL-5 oil of the same grade. This first oil change is not optional — it is the primary protection against abrasive particle recirculation through the bearing and gear train. Thereafter, drain and fill every 1,000 hours or annually.

① Crawler Undercarriage — Small to Mid-Size Excavators

This track drive planetary gearbox at 1,300 N·m rated output covers the travel drive requirement for mini and compact excavator classes (approximately 3–6 tonnes operating weight on 20° gradient). Each machine uses two EP-SE400T1 units, one per track, independently controlled by separate motor flow. Speed differential between the two drives steers the machine — forward flow to both drives for straight travel, differential flow for turning, reversed flow to one drive for pivot steering. The rotating outer housing design keeps the total drive assembly within the track frame width with no axial protrusion beyond the sprocket plane.

② Rotary Drilling Equipment — Site Positioning Drive

Tracked rotary drilling rigs position themselves slowly and precisely across construction sites between bore locations. The travel drive does not need high speed — drilling rigs rarely exceed 2 km/h repositioning speed — but must handle the full machine weight (often 8–12 tonnes for the rig chassis alone) on uneven surface. EP-SE400T1 at i=6.09 provides adequate torque for this weight class in the motor speed range achievable at low pump flow (200–400 rpm output), moving the rig at controlled walking pace without requiring separate travel speed control valves beyond motor displacement adjustment.

③ Mobile Crushing and Screening — On-Site Repositioning

Tracked mobile crushing and screening plants are among the harshest environments for track drives: the machines vibrate continuously at high amplitude from the crusher and screen, the ground surface is fragmented rock, and repositioning movements often cross deep piles of crushed aggregate. The spring-applied brake on EP-SE400T1 holds the machine stationary between movements — the brake engages as soon as the operator releases the travel control, preventing the machine from sliding on aggregate slopes during the frequent brief repositioning moves that characterise quarry operation.

④ Foundation Piling Machines — Precision Slow Travel

Piling rigs require precise positioning of the lead and pile guide at each bore location — travel moves of 1–3 metres, accurate to within ±20 mm. The EP-SE400T1's fixed ratio i=6.09 converts motor speed linearly to travel speed, making closed-loop positional control of machine travel straightforward with a standard electrohydraulic proportional valve in the motor circuit. The mechanical face seals handle the concrete dust and slurry that piling operations generate, which rapidly destroys the lip seals used in lighter-duty track drives.

⑤ Tracked Agricultural Machinery — Wet Field Operation

Tracked combine harvesters and large tracked tractors operating in wet rice paddies, saturated peat soils, and heavy clay fields use EP-SE400T1 or equivalent drives because the distributed track footprint minimises soil compaction compared to equivalent wheeled machines. The mechanical face seals operate indefinitely in the standing water and mud that characterise paddy field harvest conditions. Downstream agricultural multi-output gearboxes distribute the engine power to the cutting platform, threshing drum, grain elevator, and fan — entirely separate from the EP-SE400T1 track propulsion circuit — allowing the implement drive to be optimised independently of ground speed.

⑥ Tracked Pipe-Laying and Trenching Equipment

Pipe-laying machines and chain trenchers require the track drive to pull the machine forward at precisely controlled slow speed (0.1–1.5 km/h) while the trenching attachment excavates a continuous cut. The EP-SE400T1's efficiency of >96% is relevant here: the travel power is a significant continuous load component in addition to the trenching load on the hydraulic system. A snekkegearreduktion on the winch drum of a pipe-laying frame provides the self-locking load hold for the pipe tensioner and cable drum drives alongside the EP-SE400T1 travel system on the same machine platform.

📐

🔩

🛠️

🌡️

📋

⏱️

We build compact tracked impact crushers for quarry and demolition contractors. Replaced the travel drives on our 4-tonne model with EP-SE400T1 after chronic seal failures on the previous supplier's units working in high-silica aggregate dust. Korea Ever-Power's dimensional drawings matched our chassis to within 0.3 mm on the spindle bore. After 4,000 operating hours of abrasive dust exposure, zero seal leaks, brake holds perfectly on 20-degree rock stockpile climbs. The spring-applied brake also eliminated a runaway incident on a steep ramp — the machine stops the instant the operator releases the control.

We field these machines in the Alberta boreal forest — deep snow, frozen muskeg, and temperatures that regularly hit −30°C. The previous travel drive units had lip seals that hardened in cold and allowed oil ingestion from frozen mud during river crossing operations. Replaced 1:1 with EP-SE400T1 units. Field swap took under two hours per machine. Metal face seals have survived two full winters including frozen mud packing events that previously destroyed gearboxes within a season. Cold-start performance at −20°C with VG 150 oil is normal with no warm-up delay required.

Our tracked harvesters work wet clay sugarcane fields at +40°C ambient during harvest season. The EP-SE400T1 runs continuously for 12-hour shifts. We measured housing surface temperature at 74°C peak — well within the 90°C spec. Efficiency stays above 96%, confirmed by the fact that our hydraulic cooler temperature doesn't rise when we switched from the previous drives that were running at 92–93% efficiency. Full harvest season complete, zero breakdowns across a fleet of six machines. Cost-to-performance ratio versus the European brand we replaced is dramatically in our favour.

QIs the EP-SE400T1 truly a 1:1 drop-in replacement for Rexroth GFT and Bonfiglioli 700C equivalent models?

For this size class of track drive planetary gearbox, the mounting flange bolt circle, spigot diameters, spindle bore dimensions, motor interface geometry, brake port location, and gear ratio match the equivalent size models in the Rexroth GFT track drive range and the Bonfiglioli 700C crawler drive range. Korea Ever-Power provides a cross-reference dimensional comparison document — specifying the exact legacy model being replaced — before order placement. If any dimension differs from the chassis requirements, this is identified at the cross-reference stage before the machine comes off line, not after installation attempt. (Rexroth and Bonfiglioli are trademarks of their respective owners, cited for dimensional reference only.)

QThe hydraulic motor I'm using outputs up to 1,200 rpm at maximum pump flow. Does this damage the EP-SE400T1?

The 1,000 rpm rating is a continuous duty limit — the bearing fatigue life and oil film formation assumptions are based on 1,000 rpm rated speed. Brief exceedances (e.g. 1,200 rpm for less than 10% of operating time during downhill travel on no-load or overcenter valve release) will reduce bearing L10 life proportionally but typically do not cause immediate damage. For applications where the motor regularly exceeds 1,000 rpm at full pump flow, Korea Ever-Power recommends either selecting a smaller motor displacement (to cap motor output speed within 1,000 rpm at max pump flow) or specifying the next larger EP-SE series model with a higher rated input speed. Contact Korea Ever-Power application engineering with your pump flow and motor displacement data for a specific recommendation.

QWhat oil grade and quantity does EP-SE400T1 require, and how is the level checked in the field?

Use EP (Extreme Pressure) gear oil to API GL-5 specification: ISO VG 150 for ambient temperatures below +15°C, ISO VG 220 for ambient above +15°C. Oil volume varies slightly by motor adapter configuration — the Korea Ever-Power dimensional drawing includes the fill volume for each configuration, typically 0.8–1.2 litres for EP-SE400T1. Fill through the highest port on the housing with the gearbox in its operating orientation. Level check through the side port: oil should reach the bottom of the side port opening. Do not overfill — excess oil foams under gear churning and can push past the face seals. First drain and fill at 150 operating hours; subsequent change every 1,000 hours or annually, whichever is sooner.

QHow is the spring brake pilot pressure circuit connected, and what pressure is required to release the brake?

The brake release port accepts a dedicated pilot line, typically tapped from the machine pilot hydraulic circuit at 25–35 bar. This pressure must remain present continuously throughout travel — the moment it drops below the release threshold, the spring pack re-engages. Most machines connect the brake pilot line to the travel spool outlet so brake release and travel motion are always simultaneous. The brake port size, thread specification, and exact release pressure are in the Korea Ever-Power dimensional drawing supplied at quotation. An optional integrated overcenter (counterbalance) valve prevents free-wheeling on downhill grades by requiring back pressure before the motor can rotate freely.

QCan EP-SE400T1 operate submerged in water during river crossings or dredging work?

The standard floating mechanical face seals provide excellent protection against mud submersion and intermittent wading — typical of forestry, agricultural, and construction river crossing conditions. The metal-to-metal sealing face is a positive differential seal: internal oil pressure slightly exceeds external water pressure during normal operation, reinforcing seal integrity. For continuous deep submersion (dredging machines, underwater trenching) or applications where external water pressure exceeds internal oil pressure, Korea Ever-Power offers enhanced marine sealing options. Contact application engineering with the expected submersion depth and operating duration.