Patent GB-580823-A (GB)
Title: Door latch mechanism for dumping cars
IPC: B61D7/16
Filed: 1944-04-14
Abstract: 580,823. Releasable fastenings. SANFORD, H. W. April 14, 1944, No. 6924. [Class 44] [Also in Group XXXII] Door latch mechanism for securing the bottom discharge door of a hopper wagon is opened automatically by the passage of the wagon over a tripping mechanism on the track which actuates wedging means to dislodge the latch. The hopper wagon comprises side and end walls 1, 2, Fig. 1, and side sills 3 connected by combined end sills and bumpers 4, mounted on wheels 5. The bottom comprises three doors 10,11,12 mounted on shafts 13, 14, 14, the doors 11, 12 having longitudinal movement on the shafts 14 such that in the closed position the hinged end of the door 12 supports the free end of the door 11 and the hinged end of the door 11 supports the free end of the door 10 whereby release of the latch 18 allows the doors to open in succession. The latch 18, Fig. 2, is pivoted at 19 and is spring-pressed to engage the hook 21 of the door 12, a spigot 22 projecting through the end wall 2 for manual operation of the latch. The trip gear on the track comprises a lever 28 fixed to a shaft 29 and limited in downward movement by a bracket 40. A toggle 30 is pivoted at the free end of the lever and is maintained against a stop 32 by a spring 34. A two-armed lever 41, 42 is journalled on the shaft 29, the arm 42 being provided with an adjustable shoe for contact with a cam 47 on the underside of the hopper and the arm 41 bears against adjustable stops 51 mounted in a bracket 52 on an arm 53 journalled on a shaft 29 and provided with a seat for a spring 55, the opposite end of which bears on a seat on the lever 28, a bolt 57 passing through the spring and limiting the separation of the arm 53 and lever 28 but allowing the movement of the shoe 42 to be transmitted to the lever 28 through the medium of the spring. An arm 59 fixed to the lever 41 carries a counterweight. When the hopper wagon moves to the left the shoe 42 is moved counterclockwise by the cam 47 to raise the lever 28 and thereby the toggle 30 into contact with a lip 37 on the door to raise the door, and with further movement, the nose of the toggle uses this point as fulcrum to wedge the latch away from the hook 21. When the shoe leaves the cam 47 the toggle 30 is bent backwardly against the tension of the spring 34 and clears the bottom of the end sill 4. In a modification, the shoe operates a longitudinal rod connected to a wheeled carriage provided with a wedge which contacts a wedge on a pivoted arm to raise the latter and thereby strike the latch away from the hooked end of the door. In a further modification movement of the shoe closes electric contacts to energise a solenoid, the armature of which is connected to the wheeled carrier, or the contacts may comprise a mercury switch and the armature comprise a vertical rod adapted to strike the latch. The cam 47 may operate a valve admitting pneumatic pressure to a piston connected to the trip lever and when the shoe returns to the vertical position the pneumatic cylinder would be exhausted and the piston returned to its normal position by a spring. Specification 568,791 and U.S.A. Specification 2,001,471 are referred to.