882,252. Vehicle couplings; road/rail vehicle undercarriages. CHESAPEAKE & OHIO RAILWAY CO. Dec. 31, 1958 [March 27, 1958], No. 42232/58. Classes 103(5) and 108(2). A vehicle having road and rail wheels selectively moveable by means of a reversible air motor 27, Figs. 2, 6, to a load carrying position also comprises a releasable coupler 17, 18, Figs. 8, 9, and 12, an air supply train pine 83 extending to each member of the coupler, a conduit 150 connecting the motor with the train pipe, a shut off valve 90 associated with the coupler for controlling the air pipe, and manually operable linkages for releasing the coupling and causing a sequential actuation of the shut off valve and the control valve. The vehicle has a longitudinal tubular centre sill 13, Fig. 3, and a pivotable wheel suspension unit 14 as disclosed in Specification 814,997, the unit being connected by torsion springs 21 to a lever 31 which may be swung by movement of a nut 30 trunnioned thereon along a transversely pivoted screw 29 rotated by the motor 27. The socket coupler, 17, which is preferably quadrilateral in cross-section, is provided with two pairs of spring pressed plungers 40 normally projecting part way into the socket. The male coupler 18, Fig. 12, comprises a ball 45 having a stem attached to a sill 13 and an outer frusto pyramidal shell 48 mounted to swivel on the ball and provided with a chamfer 53 which may be engaged by the plungers 40. The plungers are moved by U-shaped swing links 57 actuated by pin and slot connected links 66, 67 and arm 76 operated by a push-pull rod 78 extending to the side of the vehicle. The air train pipe 83 is provided with seals in the coupler members which define an air passage through the coupling when the members are connected. A valve 90 in the pipe includes a member 91 rotatable with respect to a seat 89 of a sealing bush 87 and is actuable by a pivot stem 92 rotatable in a bore 93 in the coupler body 32. Flats 96 on the stem 92 extend across an axial guide passage 97 and cooperate in the uncoupled position with a slot in a plunger 106 which constitutes a first locking device and is spring pressed outwardly when the male coupling part is removed to engage the flats and retain the valve 90 in the closed position. In the coupled position the plunger 106 is pressed inwardly to disengage the flats from the slot and the stem 92 is then free to be rotated and close the valve 90. The valve is operated by linkage 110 extending to the side of the vehicle and may be rotated against its seating by a lever 114 connected to the stem 92. The lever 114 carries a pin 115 which is extended to provide a portion 116 co-operating with a cam edge 70 on the lever 66. The other end of the pin has a projection 117 which anchors one end of a spring 120 adapted to pass over-centre and hold the valve 90 either open or closed when the lever 114 is pivoted. A pin 119 anchoring the other end of the spring 120 co-operates with projections 122 and 123 on the lever 114 to provide limit stops. The pin 115 when it engages a recess 125 in the lever 66, Fig. 8, constitutes a second locking device, in which position of the pin the valve 90 is open and the levers 66, 76, 67 prevented from moving to open the coupling. If a fully coupled position is not achieved when coupling, then the follower element 116 of the pin 115 cannot be moved around the corner 72 on the lever 66 to the Fig. 8 position so that the valve 90 may not be opened. To release the coupling it is first necessary to rotate the valve 90 to its closed position by pivoting the lever 114, this causes the second lock constituted by the follower 116 and the cam 70 to be broken by movement of 116 around the corner 72. In this position the levers 66, 76, 67, and 57 may be moved to retract the retaining members 40. The plunger 106 or first lock then moves outwardly as the coupling members separate, to lock the stem 92 and the valve 90 in a closed position. The air motor 27 operating the wheel unit 14 comprises a reversing valve 128, Fig. 6, and a reciprocable throttle 130 which may be operated by rotating a shaft 133. A flexible or telescopic lever 142 on the shaft is connected with the tiltable stem 129 of the valve 128 so that as the stem is tilted to its limit the lever 142 is merely extended by further rotation of the shaft. The throttle 130 is spring actuated to its closed position and has a lost motion connection between its stem 131 and the link 145. After initial rotation of the shaft 133 to operate the valve 128 one way or another, succeeding movement of the shaft will swing a lever 143 mounted thereon away from its dead centre position shown in Fig. 6 to transmit a pull-' ing force on the link 145 and produce movement of the throttle and operation of the motor 27. A third lock is provided between the linkage operating the coupling levers 57 and the linkage operating the valve 128 of the motor 27 and prevents operation of the motor when the coupling is made. Fig. 13 (not shown) illustrates a modification in the coupler release mechanism which allows the retaining members 40 to be held in a partially retracted position after uncoupling.