EP20100.131.00 Agricultural Drive Gearbox – 100HP, 13:1 Reduction, 600RPM, 8-Bolt Flange

EP20100.131.00 · 100HP · 13:1 · 58kg · 8-bolt Φ48X flange

Why 8 Bolts Rather Than 4

At 15,500 Nm reaction torque, a 4-bolt flange on a Φ48mm bolt circle would require each bolt to carry approximately 3,875 Nm of shear force — approaching the fatigue limit of M12 grade 10.9 bolts at the bolt circle diameter. Eight bolts halve the per-bolt load to approximately 1,937 Nm, providing the fatigue safety margin needed for the cyclic torque loading of harvesting and tillage applications where the output shaft load is not constant but varies with crop density and soil resistance. The 8-bolt arrangement also produces a smaller angular spacing between bolts (45° rather than 90°), which reduces the torsional compliance of the flange connection under alternating torque direction changes — important in reversible or intermittent drive systems.

Φ42×8mm Key Slot — Torque Path

The Φ42mm output shaft with 8mm wide keyway transmits the 15,500 Nm output torque to the driven component via a standard parallel key. The bearing pressure at the key-to-shaft interface at 15,500 Nm and Φ42mm shaft diameter is calculated for the key length and key material (hardened steel) to remain within the allowable bearing pressure for continuous duty. If the driven component hub is shorter than the calculated minimum key engagement length, the key becomes the limiting factor — contact Korea Ever-Power for the minimum hub engagement length specification before designing the output shaft coupling.

600RPM Input — Not 540RPM

The EP20100.131.00 is rated for 600RPM input — not the 540RPM standard used by all other EP gearboxes. This reflects the drive source: the 600RPM standard corresponds to the second-stage output speed of a multi-stage agricultural machine primary drive train, or the output of an engine-driven hydraulic motor calibrated for 600RPM. Connecting a 540RPM PTO directly would produce approximately 41.5RPM output rather than the design 46RPM — a 9.6% speed reduction from design specification. For PTO-driven applications where 540RPM is the only available input, confirm with Korea Ever-Power whether the 540RPM input is within the rated operating range or whether a speed-increase stage between the PTO and the EP20100.131.00 input is required.

M7.0 at Maximum Torque Output

Module 7.0 appears in the EP-RC81 (80HP, 1:1.93 ratio) and the EP-RC61 (60HP) — in those gearboxes it handles high rotational speed at moderate output torque. In the EP20100.131.00, M7.0 handles the opposite condition: low output speed but the highest output torque in the EP range. The tooth root bending stress at 15,500 Nm and 46RPM is dominated by the large static torque moment rather than the moderate fatigue cycling that governs mower gearbox design. M7.0 provides the large tooth cross-section needed to maintain bending stress below the yield limit under this quasi-static high-torque loading condition.

58kg GGG50 Housing — Reaction Torque Mass

The 58kg housing mass — the heaviest single-path EP gearbox — provides the structural rigidity needed to transfer 15,500 Nm reaction torque from the gear mesh to the 8-bolt flange without housing deflection. Housing deflection under reaction torque produces gear mesh misalignment — the most common cause of premature tooth wear in high-torque low-speed gearboxes. At 58kg, the EP20100.131.00's housing wall cross-sections are calculated for the housing to remain within the allowable deflection limits at full rated torque, maintaining gear mesh alignment throughout the service life.

Bearing Selection for Low-Speed High-Load

At 46RPM output, the output shaft bearings operate at very low rotational speed but carry the radial and axial loads from the 15,500 Nm torque transmitted through the bevel gear mesh. Low speed combined with high load is the condition where bearing contact fatigue is less of a concern than bearing static capacity — the bearing's static load rating (C₀) rather than dynamic rating (C) governs the specification. The EP20100.131.00's output shaft bearings are selected for their C₀ static rating appropriate for the gear mesh reaction forces at maximum rated output torque.

100% Load Test at 100HP Full Torque

Every EP20100.131.00 is bench-tested at full 100HP input and 600RPM, with the output shaft loaded to the corresponding 15,500 Nm torque, before dispatch. At this output torque level, the test bench must provide a reaction torque of 15,500 Nm at 46RPM — a demanding test bench requirement that Korea Ever-Power's production equipment is designed to handle for this unit. The test confirms gear mesh contact pattern, housing surface temperature, output shaft bearing temperature, and all six seal positions (input shaft, output shaft, and the four housing face seals at the flange interface).

⚠Input speed: 600RPM — not 540RPM: The EP20100.131.00 is specifically rated for 600RPM input. Operating at 540RPM standard PTO speed produces a 9.6% under-speed at the output (approximately 41.5RPM rather than 46RPM). If 540RPM is the only available input and the output design speed is critical, a 1.11:1 speed-increase stage between the PTO and the EP20100.131.00 input will restore the designed output speed. Contact Korea Ever-Power for a compatible speed-increase stage specification if required.

1.8-bolt flange torque specification: Bolt the 8-bolt Φ48X flange to the machine frame using M12 grade 10.9 bolts torqued to the manufacturer's specification for the flange material and surface condition. Under-torqued flange bolts allow micro-motion at the flange interface under the 15,500 Nm cyclic reaction torque — producing fretting corrosion at the mating faces within one season. Use thread-locking compound (medium strength) and torque to specification at installation and re-verify at the first 50-hour service interval.

2.Output shaft key engagement length: The Φ42×8mm keyed output shaft must engage the driven component hub over the full calculated minimum key engagement length for the 15,500 Nm torque. Do not shorten the hub or use a hub shorter than the minimum specified length — key bearing pressure failure at excessive short engagement is a non-recoverable damage mode for both the key and the shaft keyway. Request the minimum hub engagement length specification from Korea Ever-Power before designing the output coupling.

3.Oil specification and fill: SAE 140 GL-4 gear oil — higher viscosity than standard EP agricultural gearboxes — approximately 1,200–1,500ml. The higher viscosity is required for the low output shaft speed (46RPM) where hydrodynamic film formation is limited, and for the high output torque load where boundary lubrication conditions exist at the gear tooth contact zone. Fill to the level plug mark before first operation. The unit ships without oil. First change at 50 hours; subsequent changes every 200 hours.

4.Vibration monitoring at installation: At first commissioning, run the EP20100.131.00 at rated speed for 30 minutes and measure housing vibration at the flange face and at the output shaft bearing. Any vibration amplitude significantly above the pre-commissioning baseline indicates gear mesh misalignment, bearing pre-load error, or housing flange micro-motion. Investigate and resolve before full load commissioning.

M7.0 gear production and 58kg housing machining — same floor as EP-40002 and EP-RC81

How does a single bevel gear stage achieve 13:1 when standard bevel gearboxes typically achieve only 1:1 to 1:5?

Standard bevel gearboxes achieve their ratio through the tooth count difference between the input and output gears. The EP20100.131.00 uses a combination of the 18/21 tooth count offset plus a significant difference in the bevel gear cone angles between the input and output gears — the input gear has a much steeper cone angle than the output gear. This cone angle differential produces a much larger effective pitch radius ratio at the mesh contact point than the tooth count ratio alone would suggest, enabling the large 13:1 speed reduction within a single mesh stage. The precise cone angle parameters are proprietary engineering data — contact Korea Ever-Power for integration design purposes.

Can the EP20100.131.00 operate in reverse — using the 46RPM shaft as the input and the 600RPM shaft as the output (13:1 speed increase)?

Mechanically possible in principle, but the EP20100.131.00 is not rated for reverse operation as a speed increaser. At 46RPM input and 600RPM output, the input torque required to produce 100HP at the output would be approximately 15,500 Nm — the same value as the forward direction output torque. This torque must now be applied to the slow-speed shaft, which means the input coupling must handle 15,500 Nm rather than the standard application's 600RPM-side input torque of approximately 1,192 Nm. The input shaft, input shaft bearings, and input-side housing structure are not designed for this loading condition. Korea Ever-Power does not recommend or warranty reverse direction operation of the EP20100.131.00.

What is the efficiency of the EP20100.131.00 at rated conditions?

Bevel gearbox efficiency at M7.0 and appropriate lubrication is typically 96–98% at rated speed and load. For the EP20100.131.00, the unusual combination of very low output speed and very high gear mesh tooth loading means that the boundary lubrication regime at the tooth contact zone (where hydrodynamic film formation is limited at 46RPM) produces slightly higher tooth friction than in standard-ratio gearboxes at higher speeds. Estimated efficiency is approximately 94–96% at rated full-load conditions — slightly lower than a standard-ratio bevel gearbox at the same power level. The heat generated by this friction (4–6% of 100HP = 3.0–4.5kW thermal dissipation) requires adequate housing surface area and air circulation for heat rejection. Korea Ever-Power provides housing surface temperature data from load test results on request.

What warranty and shipping apply?

12-month warranty from dispatch against manufacturing defects. Not covered: operation above 100HP rated input, input speed above 600RPM, oil neglect or wrong viscosity specification (use SAE 140 GL-4, not SAE 90), dry running before initial fill, flange under-torque allowing micro-motion at the flange interface, or output shaft key engagement below the minimum specified length. Shipping: DHL or FedEx for 1–2 units (58kg — dimensional weight applies; Korea Ever-Power advises on shipping cost before order confirmation); sea freight for batch orders (10–18 days). Full export documentation including Certificate of Origin for RCEP and ASEAN tariff applications on every shipment.