EP-SE402T2 Double-Stage Track Drive Planetary Gearbox

Ang EP-SE402T2 is a double-stage track drive planetary gearbox delivering 5,000 N·m through two successive planetary stages to cover machine classes from 12 to 25 tonnes — compact crawler cranes, larger mini-excavators, tracked pile drivers, and tracked aggregate screeners that exceed the single-stage SE401T1's 2,000 N·m capacity. The standard unit does not include an integral spring brake; parking safety at this torque class is typically managed through overcenter (counterbalance) valves in the travel circuit, or a motor-integrated brake on custom order. As a double-stage planetary gearbox for tracked machine final drives, it applies the same inverted epicyclic architecture — fixed spindle, rotating outer drum housing — across the full ratio range. Specify your ratio, motor interface, and braking requirement at enquiry.

Understanding why double-stage matters — and why single-stage units cannot simply be made larger to reach 5,000 N·m in the same form factor.

Required machine travel speed in km/h (or output RPM at full pump flow). Combined with sprocket pitch radius, this defines the required output RPM: i = n_motor ÷ n_output. Example: 3,000 rpm motor, 160 rpm required output → i = 18.75, select i≈18–20 from available range.

Calculate: T = W × (sinθ + f·cosθ) × r ÷ 2 where W = gross weight (N), θ = max gradient, f = rolling resistance (0.10–0.30), r = sprocket radius (m). Apply shock factor 1.5–2.0 for rock/abrupt terrain. Must be ≤ 5,000 N·m per drive.

Verify: n = Q × 1000 ÷ (V × η_v). Must stay ≤ 3,500 rpm. For most axial piston motors paired with EP-SE402T2, motor displacement of 45–90 cc/rev at pump flows of 80–200 L/min will be within this limit. Confirm your specific motor and pump combination.

Specify how parking hold will be achieved: (a) overcenter valve in travel circuit (most common at this class), (b) motor case drain check valve, or (c) integrated spring brake on custom order. Provide the machine's maximum parking gradient and gross weight — Korea Ever-Power can specify the correct overcenter valve setting or optional brake torque.

Compact Crawler Excavators — 12–20 Tonne Class

This is the primary market for EP-SE402T2 globally. A 15-tonne excavator working on a 25° gradient requires approximately 3,200–4,000 N·m per track drive after applying shock load factors for hard ground and loaded bucket positioning — within EP-SE402T2's 5,000 N·m rated capacity. The selectable ratio allows OEMs to configure the same drive for two-speed variants (high-speed tramming ratio vs high-torque digging travel ratio) by specifying different i values in the same housing.

Rotary Drilling and Pile Drivers

Tracked rotary drilling rigs in the 15–30 tonne class require the higher ratios in the EP-SE402T2 range (i=30–37.1) for slow, precise repositioning between bore locations — typically 2–5 metre moves at less than 0.8 km/h, carrying the full weight of the mast, rotary head, kelly bar, and drill string suspended in the derrick. At i=37.1 and a 3,500 rpm maximum motor speed, the output speed is approximately 94 rpm — and with a 220 mm sprocket radius, travel speed is approximately 0.7 km/h at full motor flow. This is precisely the slow-positioning speed class this ratio is designed for. The 3,500 rpm input rating allows the rig's high-flow hydraulic pump to serve the travel circuit with a high-speed, small-displacement axial piston motor — eliminating the need for a separate low-flow motor circuit for travel positioning that older rig designs required.

Mobile Crushing Plants and Aggregate Screeners

Tracked impact crushers and jaw crushers above 15 tonnes operating weight require EP-SE402T2 for the travel drive. The nodular cast iron housing handles the continuous high-amplitude vibration from the crushing mechanism — vibration levels that fracture grey iron housings in lighter-duty drives. The floating mechanical face seals prevent the fine silica and limestone dust generated by crushing from penetrating the gear oil.

Foundation Crawler Cranes — Undercarriage Travel

Compact crawler cranes in the 15–40 tonne lifting class use EP-SE402T2 for the travel undercarriage drives. Travel speed requirements are slow (typically 0.5–1.5 km/h), which directs selection toward the higher ratio end (i=30–37.1) to maximise available tractive force at the track. Parking hold is managed by the crane's travel spool centre position and overcenter valves — no integral spring brake is required.

Heavy Tracked Agricultural Equipment

Large-frame tracked sugar cane harvesters and tracked tractors above 14 tonnes operating weight exceed the EP-SE401T1's 2,000 N·m capacity and require EP-SE402T2 for the track final drives. The wider ratio range suits agricultural harvest cycles where tramming speed between field sections differs significantly from working speed through the crop rows. The downstream agricultural multi-output gearboxes for the cutting platform and elevator operate on a separate PTO circuit from the EP-SE402T2 travel drives.

Tunnelling and Tracked Segment Handlers

Tracked segment handling machines in tunnel boring operations and underground construction require precise low-speed positioning of heavy concrete ring segments — exactly the application profile suited to EP-SE402T2 at i=30–37.1. The high-speed input capability allows the machine's main hydraulic pump to serve both travel and handling functions without a separate low-flow circuit for the travel motor. Auxiliary winch drives on the same machine typically use a worm gear reducer for the self-locking load hold function.

At 5,000 N·m output, the reaction torque on the spindle-chassis interface is substantially higher than in single-stage units. Measure the chassis spindle bore with a telescoping gauge and confirm it matches the EP-SE402T2 spindle OD within the tolerance stated on the Korea Ever-Power dimensional drawing. Any clearance fit that would be acceptable in a lighter unit may result in fretting and micro-movement at the spindle-bore interface under the higher torque reaction forces of the double-stage drive. Clean all burrs, rust, and paint from the bore contact surface before fitting.

The EP-SE402T2 double-stage housing contains a significantly larger oil volume than the single-stage SE400T1 or SE401T1 — approximately 2.5–3.5 litres depending on ratio configuration and motor adapter. Fill through the highest port in the operating orientation using filtered API GL-5 gear oil. The oil must submerge the lower gear mesh of the second stage for splash lubrication to reach both stages effectively. Confirm the exact fill volume and fill/level/drain port positions on the Korea Ever-Power dimensional drawing for your specific ratio variant before filling.

Because the EP-SE402T2 standard configuration has no integral spring brake, parking hold is the responsibility of the hydraulic circuit. If overcenter (counterbalance) valves are specified for the travel circuit — the most common approach for this machine class — they must be set to the correct back-pressure before initial machine travel. The setting should be high enough to prevent motor rotation (and thus chassis movement) under machine weight on the steepest parking slope, but not so high that it prevents smooth motor acceleration during initial travel engagement. Korea Ever-Power's application engineering team can calculate the recommended overcenter valve setting based on your machine weight, gradient, and motor displacement.

High-speed axial piston motors (rated to 3,500 rpm) typically have smaller shaft diameters and finer spline specifications than the low-speed orbit motors used with single-stage drives. Confirm the motor spline specification — tooth count, module, and fit class — against the EP-SE402T2 input bore specification. Insert the motor output shaft into the sun gear bore until full spline engagement depth is achieved and confirmed by visual reference or depth measurement. Torque the motor-to-gearbox fasteners in a cross pattern to the motor manufacturer's torque specification.

The double-stage design has two sets of gear tooth surfaces that require micro-seating during run-in: the first stage planet set and the second stage planet set. Operate at approximately 50% maximum load for the first 10 hours. Both stages generate fine metal wear particles during run-in — the larger the gear set, the more particles are generated. The first oil change at 150 hours is particularly important for the EP-SE402T2's larger oil volume, as the particle concentration at 150 hours reflects two stages of run-in wear rather than one. Drain while warm; refill with fresh GL-5 oil.

Because the EP-SE402T2 does not have an integral spring brake, the machine operator must understand the parking procedure specific to this configuration. On machines using overcenter valves for parking hold — the standard approach for this planetary gearbox class — verify that the travel spool returns to centre position when the control is released, and that the overcenter valves lock before the machine is left unattended on a slope. If the machine application requires a spring-applied fail-safe brake independent of the hydraulic circuit — for instance, in unmanned autonomous operation or in applications where the hydraulic system could be inadvertently vented — specify this requirement at order time so Korea Ever-Power can include the optional integrated brake.

Ratio Confirmation Before Commitment

Korea Ever-Power reviews your motor speed, target travel speed, sprocket pitch radius, and required machine travel speed — and returns the specific ratio selection from the i=12.4–37.1 range, same business day. The selection process confirms output RPM at your operating motor speed, verifies the selected ratio is within the available double-stage configurations, and checks that the resulting output speed meets your machine's travel cycle requirements for both fast tramming and working travel. If no standard ratio precisely matches your kinematic requirement, custom ratio configurations are available — discuss at the enquiry stage before any order commitment.

Pre-Assembled Drive Package Available

EP-SE402T2 is available pre-assembled with a matched high-speed axial piston motor, integrated overcenter (counterbalance) valve, and pressure relief valve as a single tested and function-verified assembly. Korea Ever-Power sets the overcenter valve to the back-pressure calculated for your machine weight and maximum parking gradient before shipping — so the assembly arrives with the parking hold function verified, not requiring field setting by the machine assembler. This eliminates the motor-gearbox interface fit risk and the overcenter valve calibration step from your machine assembly process. Specify machine gross weight, steepest parking gradient, and sprocket pitch radius when ordering the pre-assembled package.

Long-Term Spare Parts Support

Korea Ever-Power maintains dedicated stock of EP-SE402T2 internal components, covering both planetary stages: first-stage sun gear, first-stage planet set and carrier, second-stage sun gear, second-stage planet set and carrier, complete mechanical face seal kits, taper roller bearing sets for both the first and second stage output bearings, housing O-ring kits, and motor adapter fastener sets. Because the EP-SE402T2 is a double-stage unit with two independent gear sets that can wear or fail separately, parts are catalogued and stocked per-stage — a first-stage gear replacement does not require purchasing second-stage components. Parts can be dispatched from stock with a 24–48 hour lead time for standard seal and bearing items.

12-Month Commissioning Warranty

12 months from commissioning or 18 months from shipment, covering manufacturing and material defects. Warranty begins at commissioning — giving OEMs who stock before assembly a full 12-month in-service protection period. Warranty coverage includes both planetary stages and housing.

7–14 Day Stock / 30–45 Days Custom

Standard ratio configurations ship in 7–14 days from Korea Ever-Power stock. Custom ratio specifications and motor package assemblies: 30–45 days. For emergency machine-down situations, contact Korea Ever-Power with the machine model and required ratio for same-day lead time confirmation.

−25°C to +90°C — Widest Temp Range in SE Series

EP-SE402T2 shares the −25°C cold-start capability of EP-SE401T1 but extends the upper limit to +90°C — matching the EP-SE400T1 and exceeding the EP-SE401T1's +85°C. The nodular iron housing's superior thermal mass helps dissipate heat from two stages of gear mesh friction, which contributes to the higher upper temperature tolerance at this torque class.

EP-SE402T2 at i=21 on our 16-tonne crawler excavator platform. We were previously using a European double-stage drive at 3× the cost with a 12-week lead time. Korea Ever-Power dimensional cross-reference confirmed the match to our spindle bore and sprocket bolt circle same day. Field swap by two technicians in four hours per side — no chassis modification. At 2,500 hours of clay trenching and rock excavation, both drives are running cleanly. The nodular iron housing shows no cracking or deformation despite the repeated hard-ground impacts we inflicted during acceptance testing.

We build 18-tonne tracked jaw crushers for Japanese quarry and demolition contractors. The key challenge is continuous vibration from the crusher jaw mechanism — previous drives using grey iron housings were developing micro-cracks at the housing flange after 1,200–1,500 hours. Switched to EP-SE402T2 with nodular cast iron housing 18 months ago. Zero housing cracks across six units at 1,800–2,100 hours. The seal durability in granite fines is excellent — oil samples at each 1,000-hour change show no silica ingress. The 94%+ efficiency has also reduced hydraulic fluid temperature in the travel circuit by approximately 6°C.

Our tracked sugarcane harvesters run at 16–18 tonnes operating weight through acidic clay soils in the São Paulo state — working two-shift harvest cycles for 5–6 months per year. At this weight class, EP-SE401T1 was at its limit. We moved to EP-SE402T2 at i=18 for the travel final drives. After four harvest seasons — approximately 4,000 total operating hours per unit — the mechanical face seals remain intact with zero oil contamination in samples. The ratio i=18 gives us 2.8 km/h travel speed between rows with our 195 mm sprocket radius, which matches our harvest cycle timing perfectly. ROI versus the European drives we previously used is substantial.

QDoes the standard configuration truly have no parking brake? Is this a safety concern?

The standard EP-SE402T2 does not include an integrated spring-applied parking brake. This is not an oversight — it is a deliberate design for the 12–25 tonne machine class, where parking hold is typically managed by the hydraulic system. The most common method is an overcenter (counterbalance) valve in the travel motor circuit, which creates a back-pressure requirement before the motor can rotate in either direction, preventing free-wheeling under machine weight even with the pump in neutral. A motor case drain check valve provides additional security. For applications requiring positive mechanical parking hold independent of the hydraulic circuit — particularly on steep slopes in forestry or mining — Korea Ever-Power offers an integrated spring-applied brake on custom order. Provide machine gross weight and steepest parking angle for brake torque specification.

QWhy is the max input speed 3,500 rpm rather than 1,000 rpm like the single-stage models?

In a single-stage track drive (EP-SE400T1 / SE401T1), the motor input goes directly to the single planet set and then to the ring gear output — with only one reduction, the input speed limit is relatively low (1,000 rpm) to keep output speed in the correct range for machine travel. In the EP-SE402T2 two-stage design, the first stage performs an initial speed reduction before the power reaches the second stage. A 3,500 rpm motor input is reduced by the first stage ratio before it enters the second planet set — the second stage sees a much lower speed than 3,500 rpm. This allows the use of high-speed axial piston motors (typically 2,000–3,500 rpm rated) which have higher power density in a smaller displacement than the low-speed orbit motors used with single-stage drives.

QCan EP-SE402T2 directly replace existing Rexroth GFT or Bonfiglioli 700C drives?

For units in the 5,000 N·m double-stage torque class with matching ratio, the mounting flange bolt circle, spindle bore, drum OD, and hydraulic port positions match the equivalent Rexroth GFT and Bonfiglioli 700C models. Korea Ever-Power provides an explicit dimensional cross-reference against the specific legacy model number before order — if any dimension differs, it is identified before the machine comes off line. The ratio must also be confirmed to match, as both the legacy drive and EP-SE402T2 offer multiple ratio options within the same housing class. Rexroth and Bonfiglioli are trademarks of their respective owners, cited for dimensional reference only.

QWhy is efficiency rated at >94% rather than the >96% of the single-stage models?

Each planetary gear stage has a mesh efficiency of approximately 97% for helical and spur planetary gearing under rated load. With two stages in series, the combined efficiency is approximately 0.97 × 0.97 = 0.94 — hence >94%. This is not a quality deficiency; it is a fundamental result of having two gear mesh events in the power path versus one. The 3–4% efficiency difference between single and double stage corresponds to about 2–4 kW of heat generated per 100 kW transmitted — well within the thermal capacity of the nodular iron housing and oil bath lubrication system at rated duty.

QWhat oil volume and service schedule applies to EP-SE402T2?

Use API GL-5 gear oil: ISO VG 150 for ambient below +15°C; ISO VG 220 for ambient above +15°C. The double-stage housing contains a larger oil volume than single-stage models — typically 2.5–3.5 litres depending on configuration (confirm on Korea Ever-Power dimensional drawing). First oil change at 150 operating hours to remove run-in particles from two stages of gear mesh. Subsequent changes every 1,000 hours or annually, whichever is sooner. The larger oil volume provides better thermal buffer at this torque class.