Case Studies

Custom Viton Shaft Seal for a Snow Blower

A leading manufacturer of snow blowers relied on Amsted Seals to solve a leaking seal problem.

After extensive review of their equipment and thorough analysis of the application, it was determined that the cause of leakage was a fairly common problem found in seasonal equipment. Mowers, agriculture equipment, watercraft and motorized vehicles all go through periods of heavy use and long storage, causing some rubber compounds to compress and relax for extended periods of time and loosen their dimensions and compression properties.This problem is further enhanced in seasonal equipment where run-out and shaft/housing misalignment is common.

The solution, as with most seasonal equipment, was to design a seal with extreme follow ability to resist compression set and stress relaxation at low temperatures, improve reaction ratio and increase lip force contribution from the garter spring since stainless steel springs are not subject to stress relaxation.

This custom sealing solution took one week to develop, was less expensive than their previous seal and ultimately reduced warranty claims by 94%.

Custom Shaft Seal Specifications

Product Name: Snow Blower Seal

Industry for Use: Outdoor Power Equipment

Product Description: Shaft Seal used in snow blower motor to prevent leakage caused from rubber stress relaxation of seasonal equipment

Capabilities/Processes Applied:

  • Problem Seal Analysis
  • Custom Seal Design
  • Precision Manufacturing

Overall Dimensions of the Seal
: Ö1.580x 0.197 ( OD x H )

Tightest Tolerances Met: RMA standards, .001″

Material Used:

  • Elastomer: Viton
  • Spring: Stainless Steel
  • Metal Case: Carbon Steel


  • Resists compression set and stress relaxation at low  temperatures
  • Remains more flexible during long periods of idleness
  • Design a bumper ring to prevent spring to be displaced with a narrow seal
  • Elastomer with low friction coefficient ingredients

In process testing performed: 
Customer Life-Test

Estimated Part Weight:  0.022 lbs

Standards Met:

  • RMA Standards
  • Elastomer specification: SAE J200 M4HK 814
  • Metal case material specification: SAE 1008
  • Spring material specification: SAE 30304

Delivery Location: 
Kohler, Wisconsin