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C.F.R.
»
Title 49
» CHAPTER II—FEDERAL RAILROAD ADMINISTRATION, DEPARTMENT OF TRANSPORTATION › PART 230—STEAM LOCOMOTIVE INSPECTION AND MAINTENANCE STANDARDS › Subpart C—Steam Locomotives and Tenders
Crossheads shall be maintained in a safe and suitable condition for service, with not more than
1/4 inch vertical or
5/16 inch lateral clearance between crossheads and guides.