OOSC, Part II, Item 12. Wheels, Rims and Hubs, i. Hubs (1) and (2) - Wheel Seal Leaks
| Entry Date | April 10, 2007 |
|---|---|
| Issue Number | 07-022-VEH |
| Name | Timothy P. Davis |
| Agency | Massachusetts Dept. of Telecommunications and Energy - Transportation Division |
| Address | 1 South Station - 2nd FloorBoston, MA, 02110United StatesMap It (opens in a new tab) |
| Phone | (617) 305-3773 |
| Fax | (617) 478-2598 |
| [email protected] | |
| Committee | Vehicle Committee |
| Status | Closed |
| Summary of Issue | Section 12., i. Hubs, (1) and (2) of the April 1, 2007 edition of the North American Standard Out-of-Service Criteria (OOSC), open view into the hub assembly due to a missing hub cap and smoking wheel due to bearing failure are addressed. However, there is no mention of a wheel seal. Although the wheel seal is the primary cause of loss of oil, the hub cap seal can also be a cause of failure. |
| Justification or Need | During the past 5 or more years, there has been at least 20 wheel bearing bus fires where it was reasonable determined that a failure occurred in the tag axle wheel bearing, ultimately heating the tire and causing a fire. Although formal research has not been done, it stands to reason that oil leaking from a wheel, whether it is from the wheel seal, hub cap, or missing fill plug, will ultimately result in a loss of oil in the hub. This is true for all types of highway commercial vehicles. The loss of oil in the wheel hub, if not corrected, will eventually lead to a bearing failure. If the failure goes undetected by the driver, it will ultimately lead to a wheel/tire lock, the total loss of a wheel(s), or a fire. The failure resulting in a fire seems to be more prevalent in 45-foot motorcoaches with tag axles, but it will ultimately lead to a bearing failure, with or without a fire, in other heavy commercial vehicles. |
| Request for Action | Change the OOSC to the following: (1) When any bearing (hub) cap plug or filler plug is missing, leaking or broken allowing an open view into hub assembly. (396.3(a)(1) or 396.7); (2) Smoking from wheel hub assembly due to bearing failure (396.3(a)(1) or 396.7); (3) When any wheel seal is leaking. This must include evidence of wet contamination and accompanied by evidence of further leaking will occur. (396.5); (4) No visible or measurable amount of lubricant showing in hub (396.3(a)(1) or 396.7); and, NOTE: Grease/oil on the brake lining edge, back of shoe, or drum edge and oil stains with no evidence of fresh oil leakage are not conditions for Out-of-Service. |