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Industry Oil Seal

Mack Truck Wheel Oil Seal Manufacturer | OEM Part Supplier
Industry Oil Seal

Mack Truck Wheel Oil Seal Manufacturer | OEM Part Supplier

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  • Mack Truck Wheel Oil Seal Manufacturer | OEM Part Supplier
  • Mack Truck Wheel Oil Seal Manufacturer | OEM Part Supplier
  • Mack Truck Wheel Oil Seal Manufacturer | OEM Part Supplier

Description


1. Primary Purpose and Function

A MACK wheel oil seal, more accurately called a wheel end seal or hub seal, is a critical component designed to perform two main functions:

  • Retain Lubricant: It seals the inside of the wheel hub, preventing the gear oil or grease from leaking out onto the brakes and wheel.

  • Exclude Contaminants: It acts as a barrier, keeping dirt, dust, water, road salt, and other abrasive contaminants from entering the wheel bearing assembly.

A properly functioning seal is essential for the longevity and safe operation of the wheel end components.

2. Location

The seal is pressed into the center of the wheel hub, creating a dynamic seal against the axle spindle (a stationary shaft). It sits inboard of the wheel bearings, separating the lubricated bearing cavity from the outside environment.

3. Design and Construction (The "Twin-Piston" Seal)

MACK Trucks are renowned for their proprietary and robust engineering, and their wheel seals are a prime example. The most famous and widely used type is the MACK "Twin-Piston" or "Duo-Cone" Seal.

Key Components and How It Works:

  • Two Synthetic Rubber Sealing Lips: This is the "twin" part. It has a primary and a secondary lip.

    • Primary Lip: Faces the inside of the hub, responsible for retaining the bulk of the lubricant.

    • Secondary Lip: Faces the outside, acting as the first line of defense against contaminants. The space between the two lips is typically packed with a special grease to provide an extra barrier.

  • Garter Springs: Each sealing lip is held in tight contact with the spindle by a small, circular spring. This spring ensures constant pressure and compensates for minor spindle wear or run-out.

  • Rigid Metal Case: The rubber seal is bonded to a sturdy metal outer case. This case is pressed firmly into the hub bore, providing a secure, static seal and preventing the seal from moving.

  • Special Coating on the Spindle: For the seal to work correctly, the MACK axle spindle has a precisely machined and hardened seal wear sleeve surface. The seal lips ride on this specific area. If this surface becomes scored or worn, a replacement speedi-sleeve is often installed to restore a perfect sealing surface.




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What factors influence the performance of industry rubber seals

The sealing effect of the sealing ring is related to the material characteristics of the sealing ring. There is also a close influence on other factors. For example, the speed of rotation, working temperature, working pressure, working medium, etc., today I will tell you about the four factors that affect the sealing performance of the sealing ring.

First, the speed of rotation

  When the rotation speed is very low (< 0.03m/s), it is necessary to consider the smoothness of the operation of the equipment and whether the operational appears "crawling" phenomenon. When the movement speed is very high (> 0.8m/s), the lubricating oil film may be destroyed, and the oil seal is not well lubricated and frictions heat, resulting in greatly reduced life. It is recommended that polyurethane or rubber and plastic oil seal work in the speed range of 0.03m/s ~ 0.8m/s. High-speed oil seals need to put forward higher requirements for structure and material, and the speed of household appliances oil seals can reach 20000rpm. Both wear and temperature resistance need to be met, and the concentricity requirements of dynamic sealing on the installation are relatively high.  

Second, the temperature of the working environment

  Low temperature will reduce the elasticity of rubber and plastic oil seals, resulting in leakage, and even the entire oil seal becomes hard and brittle. High temperature will make the oil seal volume expansion, soft, resulting in the oil seal friction resistance increases rapidly and the pressure resistance decreases. It is recommended that the continuous operating temperature range of ordinary polyurethane or rubber and plastic oil seals be -10 ° C to +80 ° C. For the high temperature and high speed requirements of the working environment, we need to choose to use fluorine rubber and PTFE, high temperature resistance and wear resistance is better, the low temperature environment is generally to -40 degrees, and the rubber performance is tested at high and low temperatures to ensure that the product quality meets the requirements.  

Third, the working pressure of machinery

  The oil seal has a minimum service pressure requirement. Oil seals with low friction and low starting resistance should be selected for low pressure work. Below 2.5MPa, polyurethane oil seal is not suitable; High pressure to consider the oil seal pressure deformation, need to use anti-extrusion stop ring, grooving processing also has special requirements.

Fourth, the working medium

  General sealing media are gasoline, oil, diesel, grease, and some static sealing dust. In addition to selecting the working medium strictly according to the manufacturer's recommendations, it is important to keep the working medium clean. Aging or contamination of the oil will not only cause the components in the system to fail, accelerate the aging and friction of the oil seal, but also the dirt in it may scratch or embed the oil seal, making the seal fail. Therefore, it is necessary to regularly check the quality of the oil and its cleanliness, and replace the oil filter or oil according to the maintenance specifications of the equipment. The air remaining in the oil in the cylinder will be compressed by high pressure, which will cause the oil seal to burn out or even carbonize. In order to avoid this situation, exhaust treatment should be carried out at the initial operation of the hydraulic system. The hydraulic cylinder should also run at low pressure and slow speed for a few minutes to confirm that the residual air in the oil has been drained before it can work normally.