49 C.F.R. § 236.729 Cock, double heading.
Title 49 - Transportation
A manually operated valve by means of which the control of brake operation is transferred to the leading locomotive.
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 G—Definitions
§ 236.729 Cock, double heading.