EP-SE403T2 Double-Stage Track Drive Planetary Gearbox

Ο EP-SE403T2 is a double-stage track drive planetary gearbox for heavy crawler excavators, large drilling rigs, and tracked construction crane undercarriages in the 25–40 tonne operating class. It delivers 7,000 N·m at ratios from i=15.4 to i=40.0, with max 3,500 rpm input from high-speed axial piston hydraulic motors. The rotating outer housing drives the sprocket directly — same inverted epicyclic architecture as all SE series units. What distinguishes it from the EP-SE402T2 above is not just 40% more torque, but the integration of a spring brake that provides independent mechanical parking hold regardless of hydraulic system state.

At the 12–25 tonne machine class, the travel circuit's overcenter (counterbalance) valves provide adequate parking hold in standard operating conditions. These valves create a back-pressure that prevents motor rotation — and therefore chassis movement — even when the pump is in neutral. The hydraulic circuit provides the holding function, and the circuit is sized appropriately for this machine weight. An integral spring brake would add cost, weight, and a pilot circuit requirement to a unit where the hydraulic hold is sufficient. Korea Ever-Power offers the spring brake as a custom option on EP-SE402T2 for applications where a mechanical backup is specifically required by safety standards or machine design.

At the 25–40 tonne class, the situation changes. Heavier machines parked on steeper slopes impose larger static loads on the travel circuit. More importantly, many international machine safety regulations for excavators and cranes above certain weights mandate a positive mechanical parking hold independent of the hydraulic system — a requirement an overcenter valve cannot fulfil, because it is a hydraulic device. The spring brake satisfies this regulatory requirement directly. At ratio i=40, the 270 N·m spring force produces 10,800 N·m effective braking at the sprocket — a mathematically verified hold for a 34-tonne machine on a 15° gradient. This is why the spring brake is standard on EP-SE403T2: the machines it serves require it by application and often by regulation.

At maximum ratio i=40: 270 × 40 = 10,800 N·m per drive
Two drives combined: 21,600 N·m total sprocket-level braking

At minimum ratio i=15.4: 270 × 15.4 = 4,158 N·m per drive

Machine parking hold requirement per drive:
T = W × sinθ × r ÷ 2

Example: 30-tonne machine (294,300 N), 15° slope, 250 mm sprocket radius:
T = 294,300 × sin15° × 0.25 ÷ 2 = 9,507 N·m per drive

Spring-applied / hydraulically released. Heavy Belleville springs permanently clamp the multi-disc friction pack — brake is ON by default. Travel requires deliberate pilot pressure (15–30 bar) to compress the spring stack and release the discs. Releasing the travel control drops pilot pressure; springs re-engage within approximately one second.

Heavy Crawler Excavators — 20–40 Tonne Class

Standard 20–30 tonne excavators represent the largest and highest-volume application for EP-SE403T2. Machines in this class working on 25° gradient slopes in road construction and hillside development require the spring brake as a safety requirement independent of the hydraulic system state. Many markets and machine safety standards for excavators above 20 tonnes mandate an independent mechanical hold independent of hydraulic circuit integrity — a requirement that overcenter valves, which are hydraulic devices, cannot fulfil. The EP-SE403T2 satisfies this at i values from 25–35, giving the machine a mechanical parking hold that engages automatically within one second of losing pilot pressure, regardless of whether the hydraulic pump is running. This means the machine holds its position on a steep embankment even if the engine is shut down mid-cycle, a scenario common during operator shift changes and refuelling stops on hillside construction sites. The EP-SE403T2 simultaneously delivers the 7,000 N·m tractive capacity the heavier 25-tonne machine demands during travel — a capacity the EP-SE402T2's 5,000 N·m ceiling cannot cover with adequate safety margin on hard clay or compacted gravel slopes.

Large Tracked Drilling Rigs

Drilling rigs in the 25–50 tonne chassis class — carrying the full weight of the mast, rotary head, kelly bar, and drill pipe — are parked on sloped terrain between bore locations for extended periods, often with the engine shut down. The spring brake ensures the machine cannot roll during these idle periods even with zero hydraulic pressure. At i=40.0 (slowest ratio, highest brake effectiveness), the spring brake holds a 34-tonne rig on a 15° slope — providing the safety margin required when crew work is being performed near a stationary machine on a gradient.

Crawler Cranes — Undercarriage Travel

Compact crawler cranes in the 30–60 tonne lifting class use EP-SE403T2 for travel undercarriage drives. Travel between lift positions is slow — typically under 1 km/h — requiring high ratios in the i=35–40 range to generate sufficient tractive force to move the machine under partial counterweight configuration across compacted site ground. The spring brake is critical during stationary crane operations: when the crane is mid-lift with a suspended load, the tracks must remain absolutely stationary. Any chassis travel — even a few millimetres — repositions the crane's center of gravity relative to the load radius and can exceed the rated capacity margin. The spring brake prevents this movement entirely and independently of whether the travel hydraulic circuit is pressurised, closed, or in any other state. Crane operators performing a long lift sequence with the boom at full radius rely on the EP-SE403T2's spring brake to hold the undercarriage position throughout the lift cycle without needing to maintain any hydraulic circuit condition in the travel system.

Heavy Foundation Piling Equipment

Tracked piling rigs positioning large-diameter cast-in-place piles require precise slow-speed travel on stabilised ground with significant superstructure weight. The combination of high ratio (max torque at slow output speed) and spring brake (hold position while the pile is being driven, between moves) matches exactly the EP-SE403T2's design intent. The high-speed axial piston motor input (3,500 rpm rated) allows the rig's high-flow pump to serve both travel and rotary head functions without separate low-flow circuit design.

Large Tracked Agricultural Machinery

Large-frame tracked combines, high-capacity tracked sugarcane harvesters, and orchard tractors exceeding 25 tonnes operating weight require EP-SE403T2 when the EP-SE402T2's 5,000 N·m capacity is exceeded. In paddy field and wetland harvest conditions, the floating mechanical face seals withstand continuous mud submersion. The downstream agricultural multi-output gearboxes for cutting platforms and grain elevators operate independently on PTO circuits separate from the EP-SE403T2 travel drives.

Tracked Utility Platforms — Arctic and Desert

The EP-SE403T2 track drive planetary gearbox operating range from −25°C to +90°C covers arctic construction and middle-eastern desert grading simultaneously. At −25°C, the ISO VG 150 oil remains pumpable under splash lubrication, and the spring brake Belleville stack retains adequate force without becoming brittle. In desert environments, the nodular iron housing and 94%+ efficiency limit heat build-up compared to less efficient drives. Separate winch and tensioner drives on the same platforms — for pipeline tensioning or cable pulling work — use worm gear reducers for their self-locking holding function alongside the EP-SE403T2 travel drives.

The EP-SE403T2 is engineered to match the mounting flange bolt circle, spindle bore, drum OD, motor interface, and hydraulic port positions of equivalent Rexroth GFT and Bonfiglioli 700C models in the 7,000 N·m double-stage class. This enables field replacement of a legacy track drive without chassis modification, welding, or hydraulic rerouting — a critical consideration when a drive fails on a live construction site and machine downtime directly costs project revenue. Korea Ever-Power confirms the specific dimensional match against the incumbent model number before order placement — same-day cross-reference at no charge. When the spring brake configuration of the legacy drive differs from the EP-SE403T2 standard (for example, if the incumbent uses a different pilot pressure range), Korea Ever-Power flags this in the cross-reference document and advises on any pilot circuit adjustment required. Rexroth and Bonfiglioli are trademarks of their respective owners, cited for dimensional reference only.

Ratio + Brake Specification Same Day

Provide target travel speed, motor displacement, pump flow rate, machine gross weight, and steepest parking gradient. Korea Ever-Power returns: the ratio selection from the i=15.4–40.0 range based on your kinematic requirement; a brake adequacy calculation confirming that 270 N·m × selected ratio exceeds your required output-side holding torque at the specified parking condition; and an explicit dimensional match against your incumbent drive model — spindle bore, drum OD, sprocket bolt circle, motor interface, and brake pilot port. All of this is provided same business day. No order commitment, no fee, and no obligation to purchase. If any standard ratio does not match your requirement precisely, Korea Ever-Power will advise on alternative configurations or custom options at the same time.

Pre-Assembled Drive + Valves, Ready to Mount

EP-SE403T2 is available as a pre-assembled, tested package: gearbox + high-speed axial piston motor + overcenter valve + pressure relief valve, brake function verified. All fasteners torqued, oil filled, brake release confirmed at 15–30 bar. Arrives at machine assembly ready for chassis mounting and hydraulic connection.

−25°C to +90°C — Full Climate Coverage

Widest temperature range in the SE series. The nodular iron housing provides superior thermal mass, dissipating heat more effectively at high ambient than equivalent steel housings — this is one reason the EP-SE403T2 can operate to +90°C while the EP-SE401T1 (lighter housing, single stage) is rated to +85°C. At the low end, ISO VG 150 GL-5 oil maintains adequate viscosity at −25°C for splash lubrication to reach both gear stages without pump-driven pre-circulation. The spring brake Belleville spring stack retains its design clamping force at −25°C without any special preheating procedure — important for machines parked outdoors in arctic construction conditions where the hydraulic system is completely cold and unpressurised at start of day. The floating mechanical face seals maintain their spring-loaded face contact at −25°C and provide the same sealing behaviour as at ambient temperature, without any change in cold-start procedure.

12-Month Commissioning / 18-Month Ship Warranty

Manufacturing and material defects covered for 12 months from commissioning or 18 months from shipment. Warranty covers both planetary stages and the spring brake assembly. Warranty replacement parts can be dispatched independently — a brake disc pack failure, for example, is resolved with a brake pack kit, not a full unit replacement.

7–14 Day Stock / 30–45 Days Custom

Standard ratio configurations from Korea Ever-Power stock in 7–14 days. Custom ratio and pre-assembled motor packages: 30–45 days. For machine-down emergencies, contact Korea Ever-Power with the incumbent drive model, required ratio, and ship-to location — same-day lead time confirmation.

Dedicated Πλανητικό κιβώτιο ταχυτήτων Manufacturer

Korea Ever-Power manufactures exclusively planetary gearboxes — from compact EP-TM servo units to EP-SE track drives to large-capacity winch and slewing drives. Specialisation means the engineering team, tooling, quality control, and spare parts cataloguing are all focused on one product family rather than split across multiple gear types.

EP-SE403T2 at i=28 on our 25-tonne crawler excavator range. We specified this over EP-SE402T2 specifically because Greek construction regulations for excavators over 20 tonnes operating on public road embankments require a positive mechanical hold independent of the hydraulic circuit — the spring brake satisfies this. Korea Ever-Power confirmed dimensional fit to our existing legacy drives within the same day. At 2,800 hours of mixed rock and clay excavation, both drives are clean on oil samples. The brake releases without delay at our 22 bar pilot setting and engages immediately when the travel spool centres.

We run tracked utility machines at up to −25°C on Arctic Circle infrastructure projects. The spring brake was a non-negotiable specification — our machines park on 15° snow-covered slopes with the engine off overnight. At −25°C, hydraulic systems are cold and unpressurised; we cannot rely on overcenter valves for parking hold. The EP-SE403T2 spring brake holds without hydraulic support. GL-5 VG 150 oil cold-start behaviour at −25°C was excellent — no resistance on first travel engagement. We also replaced our old Rexroth GFT drives 1:1 without any chassis modification. Seal performance through two Norwegian winters has been flawless.

We operate a fleet of 22–28 tonne crawler excavators on highway cut and fill work in the Riyadh region — ambient temperature peaks at +48°C for 3–4 months per year. Our previous track drives ran housing temperatures exceeding +90°C in sustained travel on steep embankments and required forced air cooling shrouds as a workaround. The EP-SE403T2 housing temperature peaks at approximately 82°C in our worst-case duty cycle — comfortably within the +90°C specification — without any additional cooling. The >94% efficiency at this torque class means approximately 6% of the transmitted power becomes heat instead of the 8–10% typical of alternative drives in this class, which translates directly into lower housing and hydraulic oil temperature in sustained operation. The fine desert silica (sub-30 micron particles that penetrate standard rubber lip seals in hours) has made no impact whatsoever on the floating metal face seals after 3,500 hours across six units in our fleet. We sample oil at every 500-hour interval — silica particle count has remained at baseline since commissioning. ROI versus our previous European supplier across these six units: dramatic, and the procurement cycle time of 7–14 days from Korea Ever-Power stock (versus 8–12 weeks from our legacy supplier) has eliminated the spare unit inventory we previously had to carry.

QIs the spring brake adequate for all parking scenarios, or should overcenter valves be used alongside it?

The 270 N·m spring brake, acting through the gear reduction ratio, provides substantial static parking hold — at i=40, approximately 10,800 N·m per drive, sufficient to hold approximately 34 tonnes stationary on a 15° slope (two drives combined). However, there are two important distinctions to understand. First, the spring brake is designed for static parking hold — it clamps the gear train stationary when pilot pressure drops to zero. It is not designed for dynamic braking during active travel (where motor inertia and load inertia act against the brake). For machines requiring controlled deceleration on downhill travel or on very steep grades during movement, overcenter (counterbalance) valves in the motor circuit are the engineering-correct solution for dynamic hold. Second, for steep gradients beyond the spring brake capacity at lower ratios (for example, at i=15.4, the effective output-side hold is only 4,158 N·m per drive — adequate for approximately 13 tonnes at 15°), additional overcenter valve back-pressure provides supplementary dynamic hold during active travel. Korea Ever-Power can specify both the overcenter valve setting and confirm spring brake adequacy for your specific machine weight, slope, and ratio combination — provide these parameters at enquiry.

QWhy does the EP-SE402T2 have no standard spring brake but the EP-SE403T2 does?

Both EP-SE402T2 and EP-SE403T2 are double-stage T2 units, but at different torque levels targeting different machine weight classes. At the EP-SE402T2 torque and weight class (5,000 N·m, 12–25 tonne machines), the industry standard is hydraulic parking hold via overcenter valves — adequate for this machine class. At the EP-SE403T2 torque and weight class (7,000 N·m, 25–40 tonne machines), the higher machine weight and steeper gradient requirements in many markets and machine safety standards require a positive mechanical brake independent of the hydraulic circuit. The spring brake is added at this model precisely because the application demands it — not as a differentiation feature, but as a functional engineering requirement for the heavier machine class. EP-SE402T2 can also be ordered with an optional integrated brake on custom order; EP-SE403T2 includes it as standard.

QCan EP-SE403T2 replace Rexroth GFT or Bonfiglioli 700C units at this torque class?

For units in the 7,000 N·m double-stage class with matching ratio, the EP-SE403T2 mounting flange bolt circle, spindle bore, drum OD, and motor interface dimensions match the equivalent Rexroth GFT and Bonfiglioli 700C models. Korea Ever-Power provides an explicit dimensional cross-reference document against the specific legacy model number before order placement. The ratio must also match — both the legacy drive and EP-SE403T2 offer multiple ratio options within the same housing class, so confirm the incumbent ratio before ordering. Rexroth and Bonfiglioli are trademarks of their respective owners, cited for dimensional reference only.

QWhat gear oil volume and service schedule applies?

API GL-5 gear oil: ISO VG 150 for ambient below +15°C, VG 220 above +15°C. The EP-SE403T2 double-stage housing contains approximately 3.0–4.5 litres depending on ratio and motor adapter — confirm exact fill volume on the Korea Ever-Power dimensional drawing for your specific configuration. Fill through the topmost port in operating orientation; check level at the side port. First oil change at 150 operating hours to flush run-in particles from both stages; every 1,000 hours or annually thereafter. The larger oil volume at this torque class provides better thermal buffering than smaller single-stage units.

QCan Korea Ever-Power supply the hydraulic motor with the gearbox?

Yes. EP-SE403T2 is available pre-assembled with a matched high-speed axial piston motor, integrated overcenter valve, and pressure relief valve as a single tested assembly. Specify your pump flow rate, system pressure, and required travel speed — Korea Ever-Power selects the motor displacement, sets the overcenter valve to the correct back-pressure for your machine and gradient, verifies brake function, and ships the assembly oil-filled and function-tested.

QWhat is the recommended oil fill procedure for a double-stage unit, and does the brake require separate lubrication?

For the EP-SE403T2, the entire internal housing — including both planetary stages and the brake disc pack — is filled from the same oil fill port. The multi-disc brake discs are oil-bathed (wet brake design), which provides the following advantages: the oil film prevents dry friction heat spikes that warp brake plates; the oil carries away any brake dust generated during engage/release cycles; and the brake engagement force remains consistent because the oil viscosity at operating temperature provides a predictable separation film between the discs when the brake releases. Fill through the topmost port in the operating orientation using API GL-5 ISO VG 150 (ambient below +15°C) or VG 220 (above +15°C). The combined fill volume for the double-stage housing with the brake pack is typically 3.0–4.5 litres — confirm the exact volume on the Korea Ever-Power dimensional drawing for your specific ratio and motor adapter configuration. Do not mix oil grades. Change at 150 hours (run-in) and every 1,000 hours or annually thereafter — the wet brake disc pack condition is assessed by monitoring oil colour and any metallic particle increase at each scheduled oil change.