The NATIONAL Oil Seal 4.250x5.381x0.500 Design 41 NBR is intended for industrial rotary shaft applications requiring reliable lubricant retention around a large inch-size shaft.

Installed between the rotating shaft and stationary housing, the seal creates controlled radial contact with the shaft surface. This helps retain oil or compatible grease within the bearing or transmission assembly while reducing contamination that could accelerate bearing wear and equipment deterioration.

The product is identified by the manufacturer’s Design 41 designation. Because seal design codes are manufacturer-specific, the actual lip geometry, outside-diameter construction, spring arrangement, and installation direction should be compared with the original seal or technical drawing before replacement.

Manufactured from NBR, the sealing element is generally suitable for compatible applications involving:

Mineral oils

Gear oils

Hydraulic oils

Bearing grease

Petroleum-based lubricants

General industrial lubricating fluids

NBR is widely used for conventional industrial shaft seals because of its oil resistance, flexibility, and wear resistance. Actual suitability depends on lubricant formulation, temperature, shaft speed, pressure, and environmental exposure.

The inch dimensions correspond approximately to:

Shaft diameter: 4.250 inches or 107.95 mm

Housing diameter: 5.381 inches or 136.68 mm

Seal width: 0.500 inch or 12.70 mm

The non-standard metric-equivalent dimensions suggest that this seal may be intended for a specific inch-size bearing housing, transmission, or OEM machine assembly. Accurate dimensional measurement and Design 41 profile verification are therefore essential before installation.

⚙️ Applications

Industrial gearboxes

Bearing housings

Industrial pumps

Mechanical transmissions

Power transmission equipment

Agricultural machinery

Construction equipment

Conveyor drive assemblies

Legacy industrial equipment

OEM rotating machinery

🎯 Benefits

✔ Helps retain oil or compatible grease

✔ Protects bearings and rotating components

✔ Oil-resistant NBR sealing material

✔ Suitable for large inch-size shaft assemblies

✔ Designed for industrial rotary applications

✔ Good wear and abrasion resistance

✔ Suitable for maintenance and overhaul work

✔ Helps extend bearing and equipment service life

✔ OEM replacement ready when profile and dimensions match

🧠 Technical Insight

NATIONAL Design 41 Seal Reference

Inch-Size Rotary Shaft Seal

NBR Sealing Material

Radial Shaft-Sealing Function

Lubricant Retention Design

Large Shaft Application

Approximately 107.95 mm Shaft Diameter

Design 41 Profile Verification Required

✅ Key Features

NATIONAL Industrial Seal

Design 41 Reference

Industrial Rotary Shaft Construction

Oil-Resistant NBR Material

Large Inch-Size Dimensions

Suitable for Compatible Oil and Grease

Industrial Replacement Seal

OEM Cross-Reference Ready

📊 Specifications

Brand: NATIONAL

Model: Design 41

Size: 4.250 × 5.381 × 0.500 inch

Metric Equivalent: Approximately 107.95 × 136.68 × 12.70 mm

Type: Industrial Rotary Shaft Oil Seal

Material: NBR (Nitrile Butadiene Rubber)

Profile: Design 41

Construction: Manufacturer-Specific Industrial Shaft-Seal Construction

Lip Design: Design 41 profile; verify against the original seal

Dust Lip: Verify from the actual Design 41 cross-section

Spring Type: Verify from the actual seal construction

Shaft Diameter (ID): 4.250 inches / approximately 107.95 mm

Housing Diameter (OD): 5.381 inches / approximately 136.68 mm

Width: 0.500 inch / approximately 12.70 mm

Pressure Capability: Low-pressure rotary shaft-sealing service unless otherwise specified by the equipment manufacturer

Lubrication: Oil and compatible grease

Temperature Range: Compound and application dependent; verify before installation

Application Class: Industrial Bearing and Rotating Equipment

Standard: Inch-Size Industrial Seal

🔁 Equivalent

Suitable replacement for compatible:

NATIONAL Design 41 Rotary Shaft Seal

4.250x5.381x0.500 Oil Seal

107.95x136.68x12.70 Rotary Seal

Inch-Size NBR Oil Seal

Industrial Bearing Housing Seal

Industrial Gearbox Shaft Seal

Pump Shaft Oil Seal

Transmission Shaft Seal

OEM Design 41 Seal

OEM Industrial Rotary Shaft Seal

The same dimensions alone do not guarantee interchangeability. The replacement must match the original Design 41 cross-section, lip orientation, outside-diameter construction, spring arrangement, and material compound.

(Always verify dimensions, Design 41 profile geometry, lip direction, spring construction, shaft condition, lubricant compatibility, rotational speed, temperature, and operating conditions before ordering.)

📦 Availability

✅ In Stock

🚚 Fast Delivery Available

🌎 Worldwide Shipping Available

📦 MOQ: 1 Piece

🏭 Suitable for gearbox overhaul, bearing-housing maintenance, pump repair, transmission servicing, agricultural equipment maintenance, legacy machinery restoration, and compatible OEM replacement applications.

📲 Contact via LINE ID: dusitrea

📧 Email: sales@seal4go.com

💬 Technical support available before ordering.

🔍 Assistance available for cross-reference and equivalent part identification.