Custom Nitrile Mechanical Seal for a Washing Machine Tub

Amsted Seals was contacted by the largest manufacturer of commercial laundry equipment with a problem they were having with seals leaking in sandy environments. Sand was getting between the sealing surfaces of the mechanical seal, grooving the face and causing leakage.

To solve the problem, we designed a custom two-piece integrated sealing solution that sealed against the top and bottom of the tub. The top seal was designed to press-fit around the tub bearing to improve alignment between the transmission, tub and agitator and a triple sealing lip to prevent water, sand and debris from entering the bearing cavity. The bottom seal was designed with a locking pin to resist torque and press-fit into the top seal during installation. To further reduce sand and other contaminants, our engineers developed and patented a unique negative “R”; sealing lip geometry that allowed the sprung lip to perform as an excluder lip and keep all sand out of the sealing environment.

The end result was a patented sealing solution that eliminated warranty claims, cost 80% less and lasted more than 700% longer than the mechanical seal it replaced.

Custom Shaft Seal Specifications

Product Name: Washing Machine Tub Seal

Industry for Use: Laundry Equipment

Product Description: Custom two-piece integrated washing machine tub seal.

Capabilities/Processes Applied:

  • Problem Seal Analysis
  • Custom Seal Design
  • Application Engineering
  • Precision Manufacturing

Manufacturing Equipment Used: 
Commercial Vertical Washing Machine

Overall Dimensions of the Seal: Ö3.630×1.150 (OD xH assembled dimension)

Tightest Tolerances Met: RMA standards, .001″

Material Used:

  • Elastomer: Nitrile
  • Shroud: Stainless Steel
  • Metal Case: Carbon Steel
  • Grease: Mobilith SHC 100 Red grease
  • Spring: Stainless Steel


  • Bottom Seal:
    • Designed w/ Locking Pin to Resists Force from Torque
    • Two Sealing Areas Molded to the Metal Case
      • One Sealing Against the Bottom of the Tub
      • One Oval Hard Rubber Seal, Sealing Against the Opening of the Tub
    • Designed to Press Fit Into Top Tub Seal to a Specific Depth During Semi-Automated Assembly
    • Designed to drain water
  • Top Seal:
    • ThreeS ealing Lips Prevents Water, Sand & other Debris from Entering Bearing Cavity
    • Pre Greased Prior to Shipping
    • Face:.35 Grams of
    • Between Spring Lip & Un-Sprung Lip: .20 Grams
    • Between 2 Unsprung Lips: .45 Grams
    • Rough seal OD to improved adhesive bounding
  • Designed & Patented Negative “R” Lip Geometry:
    • Allows Sprung Lip to Act as an Excluder Lip
    • Extends Life of the Seals
  • Custom Designed Grease Dispensing Head:
    • Accurately Dispenses Correct Amount of Grease Between Each Sealing Lips


  • Eliminated warranty claims
  • Lasts 700% longer than the seal it replaced
  • 80% cost savings

In Process Testing Performed:

  • Inspected Each Assembly
    • After Insertion of the Bearing into the Bottom Seal for Rotation and Assembled Dimensions
  • Customer Life-Tested

Estimated Part Weight: 
0.8935 lbs

Standards Met:

  • Elastomer specification: SAE J200, JMLU2 and UL157
  • Metal case material specification: SAE 1008
  • Spring material specification: SAE 30304

Delivery Location: 
Ripon, Wisconsin