EP-SE406AT Multi-Stage Track Drive Planetary Gearbox

The EP-SE406AT is a multi-stage track drive planetary gearbox producing 17,000 N·m at selectable ratios from i=23 to i=220. Its rotating outer housing serves directly as the track sprocket hub — the same inverted epicyclic architecture used throughout the SE series, now in a 185 kg nodular iron package for the 60–100 tonne machine class and specialised ultra-slow platforms. The 430 N·m spring-applied, hydraulically-released multi-disc brake engages automatically on pilot pressure loss at any selected ratio.

Fast repositioning class. Large tracked cranes and mobile crushers covering significant site distances between work positions. At i=23 and 3,500 rpm motor input, the machine can travel at approximately 3–4 km/h on a 350 mm sprocket radius — relatively fast for a 17,000 N·m class drive. OEMs requiring a high-speed travel option within the same housing envelope as ultra-slow configurations use this ratio band when building machines needing both sprint and load-bearing capability.

Standard heavy excavator and crane class. 60–100 tonne crawler excavators and large crawler cranes use this ratio range for normal travel speed of 1.5–3 km/h on typical site ground. At i=60, the spring brake provides 430 × 60 = 25,800 N·m effective hold per drive — sufficient for machines up to 59 tonnes on a 15° slope at 350 mm sprocket radius. This is the most common specification range for mainline large excavator OEM applications of EP-SE406AT.

Ultra-slow high-load class. Tunnel segment handlers, large slipform movers, heavy underwater or permafrost platforms where travel is measured in metres per minute rather than km/h. At i=100, the 430 N·m brake provides 43,000 N·m per drive output-side hold — far exceeding the machine's parking requirement at this weight class. Hydraulic motors at 3,500 rpm input through i=100 deliver approximately 35 rpm output — the precise slow-speed range required for controlled segment placement or continuous auger advance in geotechnical drilling.

Extreme slow precision class. Specialised platforms where travel speed requirements approach the structural movement rate rather than transportation speed — continuous crawler systems on large industrial presses, heavy-load skidding systems, seabed crawler vehicles, arctic ice-breaking platforms. At i=220, the output is approximately 16 rpm from a 3,500 rpm axial piston motor — enabling millimetric positioning accuracy via hydraulic motor flow control without additional throttling or pressure-compensated variable displacement.

Large Crawler Excavators — 60–100 Tonne

The 60–100 tonne crawler excavator class — representing machines in the range of 70-tonne standard excavators and 90-tonne heavy-duty class — is the primary mainstream application for EP-SE406AT. These machines require individual track drives capable of 14,000–17,000 N·m with adequate safety margin on hard rock and compacted aggregate work. At i=60–80, EP-SE406AT provides the required tractive force at 44–58 rpm output speed, corresponding to 2–3 km/h travel speed on a 350 mm sprocket radius. The spring brake at this ratio band provides 25,800–34,400 N·m per drive — the positive mechanical hold required by safety regulations for excavators above 50 tonnes in many markets. The +95% efficiency at this torque class means measurably lower hydraulic fluid temperature in the travel circuit compared to alternative drives at equivalent torque ratings — a directly observable operational benefit in hot climates and sustained heavy-duty travel cycles. Korea Ever-Power has confirmed field-measured hydraulic return circuit temperature reductions of 4–8°C when fleets have switched from lower-efficiency legacy drives to EP-SE406AT in comparable applications.

Large Rotary Drilling Rigs — 80–150 Tonne Chassis

Large bored pile rigs and diaphragm wall grab rigs in the 80–150 tonne chassis class require EP-SE406AT at i=80–120 for the travel undercarriage. These machines position between bore locations at less than 1 km/h, requiring high ratio for maximum tractive force under the full weight of the mast, kelly bar, and counterweight. The spring brake holds the machine stationary during crew operations between pile positions, with the kelly bar down and engine at idle. Korea Ever-Power provides dimensional confirmation against your incumbent drive model on the same day as enquiry.

Large Crawler Cranes — 60–200 Tonne Gross Weight

Crawler cranes from 60 tonne to 200 tonne gross vehicle weight use EP-SE406AT for the travel undercarriage. Large crane undercarriages require high ratio for slow, precise positioning under full counterweight and boom configuration — i=80–150 at less than 0.5 km/h travel speed. The spring brake is essential during lift cycles: the chassis must remain absolutely stationary with the hook loaded. At i=100, the 43,000 N·m per drive brake equivalent provides mechanical hold far beyond any crane in this weight class on any gradient within the standard working envelope.

Tunnel Segment Handlers and Slipform Systems

Tracked tunnel segment handling machines, heavy invert formwork movers, and large slipform concrete pavers require EP-SE406AT at i=150–220 for the extreme slow-travel capability. These machines advance at metres per hour — a continuous concrete slip mover may travel at 0.2–0.5 m/h during continuous pour — requiring a track drive capable of precise, steady low-speed output from a conventional high-speed axial piston motor input. At i=220, the 16 rpm output from a 3,500 rpm motor input enables fine speed control via hydraulic motor displacement or flow control without requiring special low-speed motors.

Heavy Agricultural and Forestry Platforms

Large-frame tracked forestry machines and heavy tracked agricultural platforms at 60+ tonnes operating weight require EP-SE406AT for travel final drives. In large-scale forestry, machines dragging heavy log bundles across uneven terrain face sustained high tractive force requirements that exceed EP-SE405.4T's 11,000 N·m capacity. The downstream agricultural multi-output gearboxes serving the cutting heads and conveyor systems operate independently on PTO circuits from the EP-SE406AT travel drives.

Specialised Industrial Tracked Systems

Nuclear plant refuelling machines, large precast concrete element movers, heavy seabed crawlers, and high-payload industrial logistics platforms use EP-SE406AT at high ratios (i=100–220) for ultra-slow precision crawling. On these platforms, a separate auxiliary winch or tensioning drive — commonly a worm gear reducer for its self-locking load hold on the cable drum — operates on a completely separate circuit from the EP-SE406AT travel drives. The spring brake provides chassis position hold when the travel motor is stopped and the auxiliary mechanism is active.

Rather than asking why EP-SE406AT weighs 185 kg, the more useful framing is: what does the 185 kg deliver that a lighter unit cannot? Three capabilities are directly funded by the additional mass compared to EP-SE405.4T (140 kg):

Ratio + Dimensional Confirmation Same Day

Provide target travel speed (or required output RPM), hydraulic motor specification (model or displacement), machine gross operating weight, maximum parking gradient, and incumbent drive model number. Korea Ever-Power returns same business day: the specific ratio from i=23–220 that meets your kinematic requirement; confirmation that 430 N·m × selected ratio exceeds your parking hold requirement at the specified gradient and machine weight; and explicit dimensional match — spindle bore diameter and fit class, drum outer diameter, sprocket bolt circle diameter, motor interface spigot, brake pilot port thread and position — against the Korea Ever-Power dimensional drawing for your ordered ratio. No charge, no order commitment. If the same chassis needs to be built in multiple travel speed variants (a common requirement for OEMs building a product range from the same platform), Korea Ever-Power can provide ratio selection recommendations for each speed variant in one same-day response.

Pre-Assembled Package with Brake Verified

EP-SE406AT is available pre-assembled with a matched high-speed axial piston motor, integrated overcenter valve, and pressure relief valve, tested as a complete unit. Brake function verified before shipping — pilot pressure applied, drum confirmed free, pressure released, drum confirmed locked within one second. Oil filled. Arrives ready for chassis mounting and hydraulic line connection only, eliminating motor-gearbox interface and brake function errors at machine assembly.

−25°C to +85°C — Thermal Boundary

The +85°C upper limit for EP-SE406AT reflects the higher thermal mass of the 185 kg housing. At sustained high-power-density cycles in ambient above +35°C, the housing temperature must not exceed +85°C. Korea Ever-Power can advise on duty cycle limits for specific ambient and power conditions. At −25°C, cold-start behaviour with GL-5 VG 150 oil and spring brake function are maintained without preheating procedures — the metal face seals and Belleville spring stack perform at this lower limit without cold-weather modification.

Component-Level Spare Parts — 185 kg Serviced Not Replaced

At 185 kg and corresponding unit cost, Korea Ever-Power maintains independent stock of all internal components for EP-SE406AT: 430 N·m brake disc packs, floating mechanical face seal kits, taper bearing sets for each internal bearing position, sun gear and planet gear assemblies, housing O-ring kits. A failed brake disc pack is a brake pack kit replacement — not a complete unit order. Korea Ever-Power provides service documentation with each unit covering brake pack and seal replacement procedures.

12-Month / 18-Month Warranty — All Stages and Brake

Manufacturing and material defects covered for 12 months from commissioning or 18 months from shipment. Warranty covers all internal planetary stages, the brake assembly, and the floating mechanical face seals. For OEMs stocking before machine assembly, the 12-month in-service period begins at commissioning. Warranty component replacement shipped from stock — no requirement to return the complete 185 kg unit for a warranty claim on a seal kit or brake pack.

7–14 Days Stock · 30–45 Days Custom

Standard ratio configurations from Korea Ever-Power stock in 7–14 days. Custom ratio or pre-assembled motor package: 30–45 days. For large OEM batch orders where production scheduling matters, Korea Ever-Power can confirm batch allocation timelines at enquiry stage. Machine-down emergencies: contact with the incumbent drive model, required ratio, and ship-to location for same-day lead time confirmation.

Our 85-tonne excavator range was running Rexroth GFT units at three times the cost and 8–10 week lead times. Korea Ever-Power dimensional cross-reference to our specific GFT model was returned same day — spindle bore, drum OD, sprocket bolt circle, motor face, and brake pilot port all confirmed. Field swap on an operational unit by our service team in West Africa: 4.5 hours per side. At i=65, the 430 N·m × 65 = 27,950 N·m per drive spring brake holds the machine solidly on our standard 18° acceptance slope. Seal performance through two Lagos wet seasons — operating in laterite clay that destroys rubber seals in weeks — has been flawless at 2,900 hours across six units. Oil samples at 1,000-hour changes show no contamination. We have also confirmed that the spring brake holds to specification at our annual maintenance check — brake pack condition assessed visually at each 500-hour service without requiring removal from the chassis, which Korea Ever-Power confirmed is feasible through the motor interface access port with standard service tools.

We manufacture heavy tunnel segment handling machines for major tunnelling projects in Scandinavia and Central Europe. Our machines travel at approximately 0.5–2 m/min during segment placement — a requirement that placed us in the i=150–180 range of EP-SE406AT. At i=160, the 430 N·m × 160 = 68,800 N·m per drive spring brake provides an extraordinary position hold during segment installation cycles — well beyond anything our previous drives could offer. Korea Ever-Power confirmed the ratio selection and dimensional match within 24 hours of our initial enquiry. The 30-day production lead time for our specific ratio fitted our project schedule. Operating in tunnel environments at constant +20°C and 90–95% relative humidity, the metal face seals have shown zero oil leakage or water ingress across our first two project deployments (total 3,500 hours across four units).

Our open-cast iron ore mining fleet runs 75-tonne excavators across abrasive laterite and magnetite ore floor surfaces, ambient temperature up to +42°C. We specified EP-SE406AT at i=55 after Korea Ever-Power confirmed the ratio selection and brake adequacy (430 × 55 = 23,650 N·m per drive vs our 19-t@15° parking requirement). Housing temperature under sustained travel duty at +42°C ambient has peaked at 78°C in our worst-case measurements — within the +85°C specification. The >95% efficiency has measurably reduced hydraulic return circuit temperature: travel circuit return oil is 5°C cooler than with our previous drives, extending the charge circuit filter service intervals. At 4,100 hours across eight units, all are operating without bearing, seal, or brake failure. The cost per operating hour including maintenance is substantially below our previous European drive supplier.

PHow does i=23–220 in a single housing work — can any ratio between 23 and 220 be specified?

The i=23–220 range represents the outer boundary of available configurations within the EP-SE406AT housing class. Not every integer ratio between 23 and 220 is independently available — the available ratios are a discrete set determined by the planet gear count and stage configurations used in this housing size. Korea Ever-Power's selection guide covers the available standard ratios within the range. When you provide your required output RPM or target travel speed, Korea Ever-Power selects the nearest available standard ratio and confirms whether it meets your kinematic requirement exactly or within acceptable tolerance. Custom ratios outside the standard set can be manufactured but require a longer lead time (typically 45–60 days vs 30–45 for standard). Contact Korea Ever-Power with your exact output RPM requirement for same-day ratio availability confirmation.

PWhy is the temperature limit +85°C when EP-SE405.4T is rated to +90°C?

The +85°C upper limit for EP-SE406AT is a consequence of the higher thermal mass and internal heat generation profile of the 185 kg housing at 17,000 N·m operation. The larger gear mass and additional stages generate proportionally more internal friction heat per unit time at maximum load, and the housing mass — while larger — takes longer to reach thermal equilibrium. The +85°C figure is the maximum steady-state housing surface temperature under continuous rated-load operation within the specified ambient range. In practice, most EP-SE406AT installations in ambient temperatures below +30°C will not approach this limit. In +40°C+ ambient combined with sustained maximum travel duty cycles, the housing should be thermally assessed for specific duty cycle conditions. Korea Ever-Power can provide a thermal calculation for your specific application power and ambient on request. The +5°C difference from EP-SE405.4T is not a quality deficit — it reflects a different thermal equilibrium point at the larger unit scale.

PAt i=220, can the spring brake still release cleanly? Does the extreme ratio affect brake function?

The spring brake operates at the input side of the multi-stage gear train — not at the output. The pilot pressure acts on the annular brake piston, compressing the Belleville spring stack and separating the disc pack, regardless of the downstream gear ratio selected. From the brake's perspective, i=220 and i=23 are identical: the same spring force, same piston area, same pilot pressure requirement (15–30 bar), same engagement and release behaviour, same engagement time of approximately one second after pilot pressure drops. The ratio amplification that makes 430 N·m become 94,600 N·m effective output-side hold at i=220 is a one-way mechanical advantage in the output direction — the gear train amplifies the brake spring force as it transmits it to the sprocket, but does not impose any additional load on the brake release mechanism in return. Releasing the brake (applying pilot pressure) requires the same hydraulic effort regardless of whether i=23 or i=220 is fitted. This is an important operational consideration for machine designers: the pilot circuit sizing for brake release does not need to be changed when a different ratio is specified within the i=23–220 range.

POil volume, first-change interval, and maintenance for a unit at i=220 vs i=23 — any differences?

The oil volume varies slightly by ratio configuration (typically 6.0–9.0 litres for EP-SE406AT depending on specific stage arrangement) — confirm exact fill volume on the Korea Ever-Power dimensional drawing for your ordered ratio. The maintenance schedule is the same regardless of ratio: first oil change at 150 operating hours to clear run-in particles, then every 1,000 hours or annually. At high ratios (i=150–220), the gear tooth speed at the final output stage is very low, but the intermediate stages still operate at intermediate speeds and generate normal wear particle levels during run-in. The 150-hour first change removes particles from all stages. API GL-5 ISO VG 150 (below +15°C ambient) or VG 220 (above +15°C) applies regardless of ratio. Do not mix oil grades. API GL-5 extreme pressure gear oil is mandatory for the multi-stage gear sets in EP-SE406AT — standard API GL-4 oil is not approved for this unit at any ratio or temperature condition.

EP-SE405.4T — 11,000 N·m Multi-Stage

Multi-stage, i=26–57, 280 N·m spring brake, ~140 kg, +90°C, 40–70 t. One step below EP-SE406AT — appropriate when machine weight and torque fall below EP-SE406AT's range, or when the wider i=23–220 range is not required.

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