49 C.F.R. § 236.339 Mechanical locking, maintenance requirements.
Title 49 - Transportation
Locking and connections shall be maintained so that, when a lever or latch is mechanically locked the following will be prevented: (a) Mechanical machine. (1) Latch-operated locking. Raising lever latch block so that bottom thereof is within three-eighths inch of top of quadrant. (2) Lever-operated locking. Moving lever latch block more than three-eighths inch on top of quadrant. (b) Electromechanical machine. (1) Lever moving in horizontal plant. Moving lever more than five-sixteenths inch when in normal position or more than nine-sixteenths inch when in reverse position. (2) Lever moving in arc. Moving lever more than 5 degrees. (c) Power machine. (1) Latch-operated locking. Raising lever latch block to that bottom thereof is within seven thirty-seconds inch of top of quadrant. (2) Lever moving in horizontal plane. Moving lever more than five-sixteenths inch when in normal position or more than nine-sixteenths inch when in reverse position. (3) Lever moving in arc. Moving lever more than 5 degrees.
Title 49: Transportation
PART 236—RULES, STANDARDS, AND INSTRUCTIONS GOVERNING THE INSTALLATION, INSPECTION, MAINTENANCE, AND REPAIR OF SIGNAL AND TRAIN CONTROL SYSTEMS, DEVICES, AND APPLIANCES
Subpart C—Interlocking
Rules and Instructions
§ 236.339 Mechanical locking, maintenance requirements.