EP-SE406BT3 Triple-Stage Track Drive Planetary Gearbox

The EP-SE406BT3 is a triple-stage track drive planetary gearbox for super-heavy crawler undercarriages in the 100–200 tonne machine class: large-capacity mining excavators, heavy foundation piling machines, super-heavy crawler cranes, and large tunnelling support platforms. At 250 kg, the nodular iron housing's greater thermal mass supports a +90°C operating temperature limit — higher than the 185 kg EP-SE406AT's +85°C limit, despite delivering 41% more torque. The 430 N·m spring brake acting through i=136 produces 58,480 N·m effective hold per drive — adequate parking security for machines up to approximately 115 tonnes on 15° slopes.

A two-stage unit reaching i=63–136 would require individual stage ratios of approximately i^(1/2) = 8–12 per stage. At these higher per-stage ratios, planetary gear efficiency begins to decline and planet gear tooth load increases. Three stages at i^(1/3) = 4–5 per stage keep each stage in the high-efficiency planetary operating zone — which is why SE406BT3 achieves >94% despite three stages of reduction. The three-stage architecture is not less efficient — under the right conditions, it is more efficient than two large stages.

At the end of stage 1, the output element (the stage 1 planet carrier, rotating at reduced speed with amplified torque) drives the stage 2 sun gear. Stage 2's carrier then drives stage 3's sun gear in the same manner. The final stage 3 planet carrier is the fixed element (connected to the machine spindle), and the stage 3 ring gear — integral to the rotating outer housing drum — is the output. Three carriers act as torque bridges, each handing an amplified, slowed output to the next stage's centre.

Three stages in this housing naturally produce ratios in the 63–136 range from the optimal 4–5× per stage configuration. Extending to i=220 would require a fourth stage or significantly higher per-stage ratios — neither of which fits this housing design without a complete redesign. More practically, the 100–200 tonne machines SE406BT3 targets do not need i=23: their maximum travel speed at i=63 is already in the 1.5–2.5 km/h range at 350 mm sprocket radius, which is appropriate for machines in this weight class.

The Speed Reality of 100–200 t Machines

A 150-tonne mining excavator's maximum productive travel speed is approximately 1.2–2.0 km/h on flat prepared ground — limited not by gearbox ratio but by machine stability, ground pressure, and hydraulic circuit capacity. At i=63 with a 3,500 rpm motor input and 400 mm sprocket radius, EP-SE406BT3 delivers approximately 2.3 km/h at the track — right at this machine class's practical limit. There is no engineering requirement to travel faster. The additional ratio range of i=23 in EP-SE406AT serves the lower-weight machines in its class, not the 100–200 t class. For this weight class, i=63 is already the fast end of the useful range.

24,000 N·m Within i=63–136 — Margin vs Requirement

A 150-tonne mining excavator on a 20° gradient requires approximately 2 × T_required = 2 × W × sin20° × r to move, where T per drive is approximately 150,000 × sin20° × 0.4 ÷ 2 = 10,260 N·m per drive before shock factor. Apply a 1.8× dynamic shock factor (typical for rocky terrain with sudden hard-ground engagement during bucket crowd cycles): 18,468 N·m per drive — within EP-SE406BT3's 24,000 N·m rated capacity with a 30% safety margin. That margin is important: it means the machine can work into gradient conditions slightly steeper than the design case, or with soil rolling resistance higher than the baseline calculation assumed, without the drive operating at its torque limit. The spring brake at i=100 provides 43,000 N·m per drive parking hold — more than twice the machine's tractive requirement on the same gradient, providing a parking safety factor well above the minimum regulatory requirement in most markets for this machine weight class. The i=63–136 range covers the 100–200 tonne machine class across its entire practical operating speed and load range with appropriate margins throughout the ratio band.

Ratio Selection Within i=63–136

Specify ratio at order using three inputs: (1) required maximum travel speed in km/h, (2) sprocket pitch radius in mm, and (3) maximum motor input speed at maximum pump flow. Formula: i = (n_motor × 2π × r) ÷ (v_machine × 1000/60). Example: 3,200 rpm motor, 400 mm sprocket, 1.8 km/h target → i = (3200 × 2π × 0.4) ÷ (1.8 × 1000/60) = 8,042 ÷ 30 = 268 — too high, indicating the motor displacement needs to increase or the travel speed target revised downward to match the i=63–136 available range. Korea Ever-Power assists with this calculation at no charge, same day as enquiry, and can also confirm whether any available standard ratio within i=63–136 exactly matches or closely approximates the calculated requirement — with the deviation in travel speed expressed as a percentage for engineering sign-off.

Super-Heavy Mining Excavators — 100–250 Tonnes

Large-capacity mining excavators in the 100–250 tonne class — operating in open-pit iron ore, copper, and gold mines — require track drives that the 17,000 N·m SE406AT cannot cover with adequate safety margin. At operating weights of 130–200 tonnes on iron ore mine floor gradients up to 15°, required tractive force per drive (including dynamic shock factor) approaches or exceeds the SE406AT's limit. EP-SE406BT3 at 24,000 N·m covers this class with the margin required for sustained operation. These machines travel slowly and rarely require the fast repositioning ratios of SE406AT — i=90–120 is the typical operating ratio for this weight class.

Super-Heavy Crawler Cranes — 100–500 Tonne Class

Super-heavy crawler cranes in the 100–500 tonne gross vehicle weight class use EP-SE406BT3 for the undercarriage travel drives. These machines position at very low speeds (under 0.3 km/h during crane work) and require maximum tractive force to move the crane when fully counterweighted across compacted but uneven site surfaces. The spring brake provides the mechanical chassis hold during lift cycles — with 430 N·m × i=110 = 47,300 N·m per drive at the sprocket, the hold capacity substantially exceeds any positioning requirement for even the heaviest machine in this class.

Heavy Rotary Drilling Rigs and Foundation Machines

Super-heavy rotary drilling rigs and diaphragm wall crane systems in the 100–200 tonne chassis class require EP-SE406BT3 for travel drives. These machines carry the full weight of the mast, rotary head, kelly bar (which can extend to 100 m depth), and counterweight system during repositioning between bore locations. The spring brake provides position hold with the kelly bar suspended mid-depth — a condition where any chassis movement would be hazardous to both the hole and the machine structure.

Large Mobile Crushing Plants

Tracked primary gyratory and jaw crushers above 100 tonnes operating weight require EP-SE406BT3 for the travel drives. The nodular iron housing sustains the sustained high-amplitude vibration from the crusher mechanism without micro-fracturing — the failure mode of grey iron housing alternatives. The floating mechanical face seals withstand the fine iron ore, limestone, and granite dust that abrades rubber seals within hundreds of operating hours in hard-rock quarry environments.

Heavy Forestry — Large-Frame Feller Bunchers

Large-frame tracked feller bunchers and heavy timber haulers exceeding 100 tonnes operating weight require EP-SE406BT3 when terrain gradients and machine weight exceed the SE406AT's capacity. In commercial logging operations in British Columbia, Scandinavia, and Siberia, machines drag multi-tonne timber bundles across slopes with frozen or saturated ground conditions that impose sustained maximum tractive effort. The downstream agricultural and forestry multi-output gearboxes serving the harvester head and conveyor systems operate on separate PTO circuits from the EP-SE406BT3 travel drives.

Tunnelling and Underground Heavy Transport

Large tracked back-hoe muckers, heavy invert segment transporters, and super-heavy maintenance platforms in metro and road tunnelling operations require EP-SE406BT3 for the travel drives. These platforms move at very low speed — typically 0.5–1.5 km/h — and must sustain full load during continuous operation in high-humidity, 100% enclosed tunnel environments. The floating metal face seals maintain oil containment under the constant water spray from tunnel ventilation and groundwater infiltration. Auxiliary winch drives on the same platforms use worm gear reducers for cable drum self-locking hold independent of the EP-SE406BT3 travel drive spring brake.

Thermal Mass — What 250 kg of Nodular Iron Provides

The specific heat capacity of nodular cast iron is approximately 500 J/(kg·K). At 250 kg, the EP-SE406BT3 housing can absorb approximately 125,000 J of heat per degree Kelvin of temperature rise. For a drive generating 5 kW of heat from gear mesh losses (at >94% efficiency, 100 kW input), the housing heats at approximately 5,000/125,000 = 0.04°C per second. This means the housing takes approximately 37 minutes to heat from +25°C ambient to +90°C limit under continuous maximum load — providing substantial thermal inertia for intermittent and semi-continuous duty cycles typical of mining and construction travel operations.

Surface Area — Larger Housing Dissipates More Heat

Natural convection heat transfer is proportional to exposed surface area. The 250 kg EP-SE406BT3 housing has approximately 35% more outer surface area than the 185 kg SE406AT housing. At +50°C temperature differential to ambient (+25°C ambient, housing at +75°C), the larger housing dissipates correspondingly more heat per unit time by natural convection than the smaller unit — which is part of why it can sustain +90°C versus SE406AT's +85°C ceiling under similar duty conditions. In applications where the undercarriage frame encloses the drive partially, this self-cooling advantage is reduced — confirm thermal management with Korea Ever-Power for specific confined installations above +40°C ambient.

Practical Implication for Hot-Climate Deployment

For a 150-tonne mining excavator operating in the Pilbara or Arabian Peninsula at +45°C ambient, the EP-SE406BT3's +90°C housing limit provides 45°C of thermal headroom — adequate for typical travel duty cycles in mining operations, which involve travel intermittently between dig positions rather than sustained maximum-power travel. The SE406AT's +85°C limit provides only 40°C of headroom at the same ambient. For machines with very intensive travel duty cycles at high ambient temperature, confirm the specific duty cycle thermal model with Korea Ever-Power's application engineering team before specifying either unit.

Ratio + Brake + Dimensional Confirmation Same Day

Provide target travel speed (km/h or output RPM), motor specification, machine gross weight, steepest parking gradient, and incumbent drive model. Korea Ever-Power returns the appropriate ratio from i=63–136; brake adequacy confirmation (430 N·m × selected ratio vs your parking requirement); and explicit dimensional cross-reference against your current drive (spindle bore, drum OD, sprocket bolt circle, motor interface, brake pilot port). Same business day, no charge, no order commitment required.

Pre-Assembled and Tested — 250 kg, Ready to Mount

EP-SE406BT3 is available as a pre-assembled, function-tested package: gearbox + matched high-speed axial piston motor + overcenter valve + pressure relief valve. Before shipping, Korea Ever-Power verifies brake engagement (spring applied → drum locked) and brake release (15–30 bar pilot → drum free) and fills to the correct oil level. The assembly arrives at machine assembly ready for chassis mounting and hydraulic line connection only — eliminating all interface and brake function errors at the OEM assembly stage.

Installation at 250 kg — What This Requires

EP-SE406BT3 requires a rated lifting device capable of ≥350 kg (with appropriate safety factor) for installation — a standard construction site crane, a tracked machine auxiliary lift line with a certified chain sling, or a purpose-built installation hoist mounted above the track frame. Korea Ever-Power's dimensional drawing specifies the chain wrap attachment points on the housing drum and the angle of lift required for safe spindle entry into the chassis bore. At 250 kg, the unit requires controlled lowering into the spindle bore with precise angular alignment to avoid cross-threading the retaining bolts — a process that is significantly more sensitive to alignment than lighter single-stage units. Typical installation time is 5–7 hours per side by two qualified technicians with appropriate hoisting equipment: one operating the hoist, one guiding the unit into position. Never attempt manual lifting of EP-SE406BT3. Confirm the lifting attachment method, hoisting capacity, and guide procedure with Korea Ever-Power installation documentation before scheduling the installation shift.

Component Parts — Three Stages Supported Independently

Korea Ever-Power stocks all internal components for EP-SE406BT3 by stage: Stage 1 sun gear + planet set, Stage 2 sun gear + planet set, Stage 3 sun gear + planet set, complete 430 N·m brake disc pack, floating mechanical face seal kits, taper bearing sets for each bearing position, and housing O-ring sets. A failure in Stage 2 gearing does not require Stage 1 and Stage 3 components — parts are quoted and supplied per the failed stage, not as a complete internal kit.

Warranty — 12 Months Commissioning / 18 Months Ship

12 months from commissioning or 18 months from shipment (whichever occurs first), covering all three planetary stages, the brake assembly, and the floating face seals. For OEMs building machines from stocked gearboxes, the 12-month in-service period begins at commissioning — not at shipping date. Warranty component replacement dispatched from Korea Ever-Power stock independently — a brake pack failure under warranty is resolved with a brake pack kit, not a complete 250 kg unit return.

7–14 Day Stock · 30–45 Day Custom

Standard ratio configurations available from Korea Ever-Power stock in 7–14 days. Pre-assembled motor packages and custom ratios: 30–45 days production. For major mining OEMs with recurring fleet requirements, Korea Ever-Power can discuss framework agreements and consignment stocking arrangements to reduce lead times on emergency machine-down replacements. Contact Korea Ever-Power with fleet size, machine model, and annual volume for framework pricing.

Our 160-tonne electric rope shovel conversion project required replacement track drives that could handle 22,000–24,000 N·m rated torque with an appropriate safety margin on 15° iron ore mine floor gradients. EP-SE406BT3 at i=100 was the specification Korea Ever-Power recommended. The dimensional cross-reference to our legacy Rexroth drives was confirmed within a business day. Field swap at Pilbara site: 6 hours per side with our 50-tonne crane — the 250 kg unit required careful positioning during final spindle engagement, but the process was straightforward with the installation guide Korea Ever-Power provided. At 2,400 hours of iron ore mining operation with 45°C+ summer ambient, no seal, bearing, or gear failures across both drives. Oil samples at 1,000 h showing clean baseline — no metallic particle elevation or water ingress.

We manufacture 250-tonne crawler cranes for bridge and industrial plant construction. At this gross vehicle weight, EP-SE406BT3 at i=120 is the specification for our undercarriage travel drives. The spring brake at i=120 provides 430 × 120 = 51,600 N·m per drive, which our calculations confirm holds the fully counterweighted crane stationary on our acceptance test slope of 12° with a 2.1× safety margin. Korea Ever-Power pre-assembled the gearbox with our specified axial piston motor and set the overcenter valve to our circuit's back-pressure requirement before shipping — the complete drive assembly arrived ready for chassis mounting. At 1,800 hours of crane operation across four production units, all drives are performing within specification. The 250 kg unit weight requires dedicated lifting tooling during erection, but this is standard practice for equipment at this crane scale.

We operate a rental fleet of 120-tonne tracked excavators used in oilsands pipeline and infrastructure work across Alberta and British Columbia. Operating conditions include −30°C winter starts, deeply saturated organic ground, and frequent track immersion in water-saturated clay. EP-SE406BT3 cold-start at −30°C with GL-5 VG 150 oil: no resistance on first travel movement, spring brake releases cleanly at 19 bar pilot pressure (within the 15–30 bar specification). The floating metal face seals have withstood continuous mud submersion — the oilsands clay is particularly abrasive, and previous rubber-sealed drives from another supplier were leaking within 300–400 hours. At 3,200 hours across our fleet, we have not had a single seal, bearing, or gear failure on any EP-SE406BT3 unit. 1:1 swap with the European drives we replaced — no chassis modifications required.

क्यूThe SE406BT3 has the same 430 N·m brake as SE406AT but delivers 24,000 vs 17,000 N·m. Does the same brake torque adequately protect a heavier-duty unit?

The spring brake torque (430 N·m) is the same physical spring force applied to the same disc pack design — but the ratio through which it acts is different and higher in EP-SE406BT3 (i=63–136) than in SE406AT (i=23–220 at the low end). The effective output-side parking hold is 430 N·m × selected ratio. At i=63 (SE406BT3's lowest ratio), the parking hold is 27,090 N·m per drive — already higher than SE406AT at its lowest ratio i=23 (9,890 N·m per drive). At SE406BT3's highest ratio i=136, the hold is 58,480 N·m per drive — holding approximately 115 tonnes at 15° slope per drive pair. The brake is adequate because SE406BT3's ratio range starts higher than SE406AT's, so the same 430 N·m spring force provides proportionally greater output-side hold across the entire i=63–136 range.

क्यूWhy does EP-SE406BT3 (triple-stage, >94%) show lower efficiency than EP-SE406AT (multi-stage, >95%)?

The efficiency figures come from the Korea Ever-Power source specifications for each model and reflect tested performance at rated conditions: >95% for EP-SE406AT and >94% for EP-SE406BT3. The 1% difference is consistent with three stages of epicyclic reduction having marginally more cumulative mesh loss than the SE406AT's arrangement — even when each individual stage is optimised. In absolute terms, at 100 kW input: EP-SE406AT generates ≤5 kW heat, EP-SE406BT3 generates ≤6 kW heat — a difference of 1 kW, well within the thermal capacity of the 250 kg nodular iron housing. The >94% figure for EP-SE406BT3 is meaningfully higher than the theoretical 0.97³ ≈ 91% for three stages at standard efficiency — indicating the use of optimised helical or high-tooth-count gear geometry in the triple-stage configuration. Korea Ever-Power can provide factory acceptance test efficiency data for specific ratio configurations upon request.

क्यूWhat oil volume and maintenance schedule applies to the triple-stage housing?

The triple-stage EP-SE406BT3 housing contains a larger oil volume than any preceding SE model — typically 8.0–12.0 litres depending on ratio configuration and motor adapter. The exact fill volume is specified on the Korea Ever-Power dimensional drawing for your specific configuration. Fill through the highest port in operating orientation; check level at the side port. The three-stage gear train generates three sets of run-in wear particles during the initial 150-hour break-in period — the first oil change at 150 hours is critical to remove particles from all three stages simultaneously before they circulate through bearings and gear flanks. Drain while warm (metallic particles remain suspended in warm oil for complete removal), allow 15+ minutes of drain time before sealing, then refill with fresh API GL-5 oil of the same grade and viscosity. Subsequent changes at 1,000 hours or annually. Do not mix oil grades — adding VG 220 to a VG 150-filled unit, for instance, changes the combined viscosity-temperature profile and may affect lubrication adequacy at cold-start temperatures where the mixed oil is thicker than either grade alone would be at the same temperature. At 250 kg with 8–12 L oil volume, the larger oil volume provides significant additional thermal buffer compared to lighter SE units — a key contributor to the +90°C operating limit. Oil temperature at the fill port (not housing surface) should be monitored if any sustained high-duty-cycle travel is suspected of approaching the +90°C housing limit in hot ambient conditions. Korea Ever-Power recommends monitoring housing surface temperature with a contact thermometer at 250-hour intervals during the first year of operation on a new installation, to establish the unit's thermal baseline for the specific machine and duty cycle.

क्यूIs EP-SE406BT3 a direct dimensional replacement for Rexroth GFT or Bonfiglioli 700C triple-stage units?

For triple-stage units in the 24,000 N·m torque class with matching ratio range (i=63–136), EP-SE406BT3 is dimensionally matched to the equivalent Rexroth GFT and Bonfiglioli 700C high-torque models at this class. Korea Ever-Power provides an explicit dimensional cross-reference — spindle bore, drum OD, sprocket bolt circle, motor interface, brake pilot port — against the specific legacy model number before any order commitment. The ratio configuration of the legacy drive must also match: both the legacy drive and EP-SE406BT3 may offer different ratios within the i=63–136 range. Provide your incumbent model number and the current ratio for Korea Ever-Power to confirm dimensional and kinematic compatibility in the same-day response. Rexroth and Bonfiglioli are trademarks of their respective owners, cited for dimensional reference only.