The TROSTEL Oil Seal 3.125x8.125x0.500 M/L LEATHER is designed for rotary shaft applications requiring lubricant retention around a 3.125-inch shaft within a very large 8.125-inch housing bore.

This unusual dimensional relationship gives the seal a relatively large radial section between the shaft and housing. For that reason, exact construction must be verified carefully before replacement, including the metal support geometry, leather-lip position, internal carrier structure, outside-case configuration, and installation direction.

The sealing element uses industrial leather supported by a metal case or structural carrier. When correctly conditioned and lubricated, leather can conform to the shaft surface and tolerate minor surface irregularities, making it especially useful in older gearboxes, transmissions, agricultural machines, and legacy heavy equipment.

The M/L profile is manufacturer-specific. The exact leather-lip geometry, metal support arrangement, outside-case construction, lip orientation, and installation direction should be verified against the original TROSTEL seal, technical drawing, or equipment specification.

Leather seals should generally not operate dry. Adequate lubrication at the sealing interface is important to reduce friction, heat generation, hardening, and premature wear.

Typical compatible lubricant/service environments include:

• Mineral oils
• Gear oils
• Bearing oils
• Bearing grease
• Petroleum-based lubricants
• General industrial lubricated shaft service

The usable temperature and shaft-speed range depend on leather grade, lubricant type, shaft surface finish, alignment, and actual operating conditions.

The inch dimensions convert approximately to:

Shaft diameter: 3.125 inches or approximately 79.38 mm

Housing diameter: 8.125 inches or approximately 206.38 mm

Seal width: 0.500 inch or 12.70 mm

The 3.125 × 8.125 × 0.500-inch configuration is a highly specialized dimensional arrangement and should be cross-checked carefully against the original seal and housing before installation.

⚙️ Applications

• Heavy industrial gearboxes
• Large bearing housings
• Mechanical transmissions
• Agricultural machinery
• Construction equipment
• Conveyor drive assemblies
• Industrial shaft systems
• Older heavy mechanical equipment
• Legacy rotating machinery
• OEM restoration applications

🎯 Benefits

✔ Genuine industrial leather sealing element

✔ Suitable for lubricated rotary shaft applications

✔ Can conform to minor shaft-surface irregularities

✔ Suitable for 3.125-inch shaft assemblies

✔ Metal-supported M/L construction

✔ Suitable for unusually large housing-bore applications

✔ Well suited to legacy machinery restoration

✔ Suitable for slow-to-moderate shaft speeds when properly lubricated

✔ Replacement ready when dimensions and M/L construction match

🧠 Technical Insight

• TROSTEL M/L Leather Seal Reference
• Specialized Inch-Size Rotary Shaft Seal
• Oil-Treated Industrial Leather
• Metal-Supported Seal Construction
• Large 8.125-Inch Housing Diameter
• Lubrication Is Essential
• Approximately 79.38 mm Shaft Diameter
• Exact M/L Cross-Section Must Be Verified

✅ Key Features

• TROSTEL Industrial Seal
• M/L Profile Reference
• Genuine Leather Sealing Element
• Metal-Supported Construction
• Large Outside-Diameter Configuration
• 3.125x8.125x0.500 Dimensions
• Legacy Equipment Replacement
• Cross-Reference Support Available

📊 Specifications

Brand: TROSTEL

Model / Profile: M/L

Size: 3.125 × 8.125 × 0.500 inch

Metric Equivalent: Approximately 79.38 × 206.38 × 12.70 mm

Type: Specialized Large-Diameter Industrial Leather Rotary Shaft Oil Seal

Material: Genuine Oil-Treated Industrial Leather

Profile: M/L

Construction: Manufacturer-Specific Metal-Supported Leather Shaft-Seal Construction

Lip Design: Leather sealing lip; verify exact M/L lip geometry and orientation against the original seal or technical drawing

Dust Lip: Not assumed; verify from the actual M/L construction

Spring Type: No spring unless the original seal specifically indicates one

Shaft Diameter (ID): 3.125 inches / approximately 79.38 mm

Housing Diameter (OD): 8.125 inches / approximately 206.38 mm

Width: 0.500 inch / 12.70 mm

Radial Section: Approximately 2.500 inches / 63.50 mm per side based on nominal dimensions

Pressure Capability: Primarily low-pressure rotary shaft-sealing service unless otherwise specified

Lubrication: Oil or grease lubrication is generally required; leather should not normally operate dry

Temperature Range: Depends on leather grade, lubricant, shaft speed, and actual operating conditions; verify application-specific limits

Speed Consideration: Generally best suited to slow-to-moderate shaft speeds with adequate lubrication

Installation Consideration: Due to the unusually large housing-to-shaft diameter ratio, confirm the original cross-section, metal carrier geometry, shaft finish, housing-bore condition, installation depth, lip orientation, concentricity, and axial positioning before fitting

Application Class: Heavy Industrial, Legacy, and Specialized Rotating Equipment

Standard: Inch-Size Specialized Leather Shaft Seal

🔁 Equivalent

Suitable replacement or cross-reference candidate for compatible:

• TROSTEL M/L Leather Shaft Seal
• TROSTEL 3.125x8.125x0.500 Oil Seal
• 79.38x206.38x12.70 Leather Seal
• 3.125-Inch Shaft Leather Oil Seal
• Large-Diameter Leather Shaft Seal
• Metal-Supported Leather Shaft Seal
• Heavy Gearbox Leather Oil Seal
• Large Bearing Housing Leather Seal
• Legacy Equipment Oil Seal
• OEM M/L Leather Seal

The same dimensions alone do not guarantee interchangeability. This is particularly important for the unusually large 8.125-inch outside diameter. The replacement must match the original M/L cross-section, leather-lip geometry, metal carrier/support structure, lip orientation, outside-case construction, installation direction, leather grade, lubricant requirements, and operating conditions.

(Always verify the 3.125 × 8.125 × 0.500-inch dimensions, M/L construction, metal support geometry, leather-lip orientation, shaft finish, housing condition, installation depth, axial position, lubricant compatibility, shaft speed, temperature, runout, and operating conditions before ordering.)

📦 Availability

✅ In Stock

🚚 Fast Delivery Available

🌎 Worldwide Shipping Available

📦 MOQ: 1 Piece

🏭 Suitable for heavy gearbox overhaul, large bearing-housing maintenance, transmission repair, agricultural-machinery servicing, construction-equipment maintenance, conveyor-drive repair, legacy-equipment restoration, and specialized 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