EP-RTD50 & EP-RTS50 Rotary Disc Mower Bearing Hub – Compact & Extended Shaft Variants

EP-RTD50 (top) · EP-RTS50 (extended shaft) · bearing hub units

Bearing hub cross-section — shaft extension geometry and flange mounting face

GGG50 Nodular Iron — Impact Rated

The bearing hub housing must absorb the shock loads of blade-to-ground contact and foreign object strikes without fracturing. GGG50 nodular cast iron's elongation-at-break property (18% for GGG50 vs. <1% for grey iron) gives the housing the capacity to deform micro-elastically under shock rather than crack — protecting the bearings and shaft from the catastrophic misalignment that would result from a fractured housing half.

Heavy-Duty Tapered Roller Bearings

The EP-RTD50 and EP-RTS50 use tapered roller bearings rather than ball bearings at both the upper and lower shaft positions. Tapered rollers handle the combination of radial load (blade centrifugal force) and axial load (blade weight and vertical shock) more effectively than ball bearings at the blade disc loads typical of compact and mid-size mower decks. The tapered design also allows the bearing pre-load to be adjusted at assembly — a precision step that determines the shaft's running clearance and, consequently, blade carrier runout.

Multi-Layer Lower Seal

The lower shaft exit — where the blade carrier attaches — is the highest contamination-risk zone on the bearing hub. Grass fibres wrapping the rotating shaft at speed are the primary seal destroyer in disc mower bearing hubs. The EP-RTD50 and EP-RTS50 use a multi-layer sealing arrangement: a primary lip seal, a secondary dust exclusion ring, and a scraper profile at the shaft exit that deflects grass fibre wrap before it reaches the seal lips. This three-layer approach is standard on heavy-duty European disc mower bearing hubs and is reflected in the EP-RTD50/RTS50 design.

Shared Bolt Circle — Same Deck Template

Both EP-RTD50 and EP-RTS50 use the same Φ143.3mm bolt circle with 4-Φ13.5mm mounting bolts. This shared bolt pattern allows a mower deck manufacturer to drill one template for both models — using EP-RTD50 on positions where a compact shaft is required and EP-RTS50 on positions where extended reach is needed, without any deck plate modification. It also allows one model to replace the other in field repair situations where only the shaft length differs from the original specification.

Surface-Hardened Blade Carrier Shaft

The blade carrier shaft is surface-hardened at the blade disc mounting seat, the lock ring groove, and the lower bearing contact surface — the three zones of highest fretting wear in bearing hub service. The hardening is induction-targeted rather than through-hardened, preserving the core toughness needed to withstand impact loading while providing the surface hardness to resist fretting and abrasive wear from the fit between the blade carrier bore and shaft surface.

Runout-Verified Before Dispatch

As with the EP-MDH spindle series, every EP-RTD50 and EP-RTS50 unit is checked for blade carrier shaft runout using a dial indicator before packaging. Maximum allowable runout is 0.05mm TIR at the blade carrier seat location. Units outside this limit are rebuilt before dispatch — no exceptions, regardless of production pressure. Shaft runout above this limit is directly perceptible as disc vibration at blade speeds and creates cyclic bearing loading that shortens bearing life.

📋 Grease Schedule — Every 50 Hours

Use NLGI No.2 lithium complex grease, two pump strokes per 50 operating hours at the Zerk fitting. Over-greasing is counterproductive — excess grease in the bearing cavity heats and breaks down, creating a semi-solid plug that displaces fresh grease and prevents proper bearing lubrication. Two strokes at the correct 50-hour interval is more effective than four strokes at 100 hours.

⚠️ Shaft Play — The Primary Warning Sign

Grasping the stationary blade carrier and rocking it laterally: more than 1–2mm of movement indicates bearing play requiring replacement. Unlike spindle gearboxes where gear noise often precedes bearing failure, bearing hubs fail more quietly — the first audible sign is often a low, cyclic rumble at slow PTO speed that disappears at operating speed. Do not wait for the audible signal; rely on the physical play check at each 50-hour service.

⚠️ Grass Wrap on Lower Shaft

Accumulated grass fibre wrap on the lower shaft — visible as a tight, layered ring of compacted fibres around the shaft just above the blade carrier — is the warning sign of seal damage in progress. The fibre wrap accelerates by forcing itself into the seal gap on each revolution. Remove grass wrap at every 50-hour inspection, never cut it with a blade (risk of shaft scoring) — pull it off by hand with the machine fully stopped.

📋 EP-RTS50 Extended Shaft — Additional Check

The EP-RTS50's extended shaft is more susceptible to bending deflection from lateral ground contact than the compact EP-RTD50. At each seasonal inspection, sight along the shaft from above with the blade carrier removed — visible curvature of more than 1mm over the shaft length indicates a bending event that may have damaged the lower bearing. Bent shafts must be replaced — do not attempt to straighten a bearing hub shaft in the field.

Precision shaft turning and bearing seat machining — same facility as EP series gearboxes

Lee Sang-ho Disc Mower OEM Manufacturer · Changwon, South Gyeongsang, South Korea · 2024

We build both 3-point hitch and trailed disc mowers. The EP-RTD50 is our standard bearing hub for the compact 1.2–1.5m hitch-mount models, and the EP-RTS50 for the 1.8–2.2m trailed models where the blade needs to clear the frame structure. The fact that both use the same Φ143.3mm bolt circle was a key reason we adopted the EP series — one drill jig across the entire product range. We've been ordering for 10 months. Dimensional consistency has been very good — I've checked three random units from each shipment and they've all been within spec. Korea Ever-Power's OEM response time is usually same-day or next-day for technical questions.

Tanaka Yoshiko Agricultural Equipment Workshop · Nagano Prefecture, Japan · 2024

I service European trailed disc mowers for dairy farms in Nagano. Finding replacement bearing hubs for the non-gearbox disc positions has always been difficult — the parts come from Europe and take 6–8 weeks. The EP-RTD50 fits the bearing hub positions on a Krone model I service regularly — same bolt circle, same shaft diameter at the blade carrier seat. I confirmed the fit by measuring the original before ordering. Three units fitted and running for about 5 months now with no issues. Korea Ever-Power delivered to Nagano in 5 days. This has solved a parts availability problem I've had for years.

Park Ji-hoon Forage Farm Operator · Pyeongchang, Gangwon Province, South Korea · 2024

I run a 6-disc trailed mower on 180 hectares of ryegrass. Two bearing hub failures in one season prompted me to replace all six preventively rather than wait for the others to fail mid-season. I ordered six EP-RTS50 units. Korea Ever-Power delivered in 4 days. The shaft runout on all six was within tolerance when I checked them before fitting. That matters — I had one aftermarket unit from a different supplier last year that was 0.2mm out and I had to return it. The EP-RTS50 units have now completed a full forage season with no bearing failures and no abnormal vibration at any of the six disc positions.

Wirote Phusangthong Agricultural Machinery Parts Importer · Chiang Mai, Thailand · early 2025

I supply parts to mower operators in northern Thailand who run both Korean and European disc mowers. The EP-RTD50 has become my standard stock item for compact bearing hub positions. Customers initially were sceptical about a non-European replacement for European mower hubs, but the dimensional fit is correct and the quality has held up in the field. I've had no returns on EP-RTD50 units in six months of stocking them. Price is about 40% below the OEM equivalent. Lead time from Korea Ever-Power to Chiang Mai: 6 days. That's the kind of supply situation that makes stocking viable.

How do I tell whether my disc mower uses bearing hubs (EP-RTD50/RTS50) or spindle gearboxes (EP-MDH)?

The fastest check: look for an oil filler plug on the side of each disc position housing. A plug means it is a spindle gearbox (EP-MDH type) that contains bevel gears requiring oil lubrication. No plug, only a grease nipple, means it is a bearing hub (EP-RTD50 or EP-RTS50) with no internal gearing. If you cannot identify the component clearly from external inspection, send Korea Ever-Power a photograph of the disc position housing from the side — we will identify the component type before you order.

Can I use the EP-RTS50 on a mower that currently uses EP-RTD50, or vice versa?

The mounting bolt circle is identical (Φ143.3mm, 4-Φ13.5mm bolts), so either model will bolt to the same deck plate holes. However, swapping models changes the blade carrier position height — the EP-RTS50 positions the blade approximately 200mm lower than the EP-RTD50. This will change the effective cutting height of the mower by approximately 200mm and may also change the geometry of the belt or chain drive to the blade position. Substitution should only be done with engineering assessment of the resulting geometry and cutting height change for your specific mower design.

What lubricant and interval does the EP-RTD50/RTS50 require?

NLGI No.2 lithium complex grease, two pump strokes every 50 operating hours at the Zerk fitting. No gear oil — these units contain no gears. There is no oil drain or fill procedure. The only lubricant maintenance is the grease nipple. In extended-shaft EP-RTS50 units, confirm the Zerk fitting location before greasing — on some installations the fitting may face toward the deck structure and require a flexible grease extension to access.

Will the EP-RTD50 or EP-RTS50 fit Krone, Claas, or Kuhn disc mower positions?

Many European disc mowers use bearing hubs with Φ143.3mm bolt circles at their non-gearbox disc positions — the same dimension as the EP-RTD50 and EP-RTS50. Compatibility also requires matching the blade carrier shaft diameter and length, and confirming the outer flange diameter (Φ180mm for RTD50, Φ190mm for RTS50) fits the mower's housing recess or mounting configuration. Send Korea Ever-Power your mower make, model, and a photo or drawing of the existing bearing hub — we will confirm dimensional compatibility. Korea Ever-Power is not affiliated with Krone, Claas, or Kuhn.

The EP-RTS50 extended shaft seems very long — is bending deflection a concern during normal mowing?

At approximately 357mm of shaft below the mounting flange, the EP-RTS50 shaft does experience greater bending deflection under blade centrifugal load than the compact EP-RTD50. The shaft diameter and material specification of the EP-RTS50 are calculated to keep this deflection within acceptable limits for normal mowing conditions — the blade carrier runout from shaft deflection at operating speed is within the ≤0.05mm TIR standard checked before dispatch. The deflection becomes a concern in two specific scenarios: if the shaft receives a lateral impact (ground contact) that exceeds the elastic limit, causing a permanent bend; or if the bearing pre-load is insufficient, allowing the shaft to run with more dynamic play than designed. Both are checked before dispatch and are covered by the warranty.

What warranty and shipping options apply?

12-month warranty from dispatch against manufacturing defects — covering housing integrity, bearing failure not caused by grease neglect or contamination, shaft runout above the 0.05mm TIR limit, and seal defects present at delivery. Not covered: bearing failure from insufficient greasing, shaft bending from ground contact impact, or seal damage from grass wrap accumulation that was not cleared at the maintenance interval. Shipping: DHL or FedEx for 1–10 units (3–5 days Korea/Japan; 5–7 days SEA); sea freight for larger quantities (10–18 days). Full export documentation including Certificate of Origin prepared for every shipment for RCEP and ASEAN preferential tariff applications.