# NHTSA Preliminary Evaluation PE88068
> **VARIOUS BRAKE PROBLEMS** · Opened 1988-06-28 · Closed 1988-11-07
## Investigation
- **Action number:** PE88068
- **Type:** Preliminary Evaluation
- **Open date:** 1988-06-28
- **Close date:** 1988-11-07
- **Manufacturer:** E-One Incorporated
- **Affected makes:** EMERGENCY ONE; FEDERAL MOTORS
- **Affected components:** SERVICE BRAKES, HYDRAULIC
- **Affected model years:** 1978, 1979, 1980, 1981, 1982, 1983, 1984, 1985, 1986
- **Affected (make, year) variants:** 10
## Summary

SUMMARY: RECENT ROCKWELL REPORTS IDENTIFIED THE FOLLOWING ADDITIONAL CONCERNS: A: INSUFFICIENT AIR PRESSURE DUE TO INADEQUATE AIR COMPRESSORCAPACITY; B: AIR HORN PLUMBED INTO AIR SYSTEM WITHOUT PRESSURE PROTECTIONVALVE; C: BRAKE IMBALANCE CAUSED BY BRAKE PROPORTIONING VALVES WHICHREDUCE THE FRONT BRAKE PRESSURE. THE ABOVE PROBLEMS MAY RESULT IN HEAT CHECKING AND CRACKING OF THE REAR BRAKE DRUMS.

## Source
- [NHTSA ODI investigation page](https://www-odi.nhtsa.dot.gov/owners/SearchResults?searchType=ID&targetCategory=I&searchCriteria.nhtsa_ids=PE88068)
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