This invention relates to manually operable valves for use in railroad car air brake systems.
Air brake systems for railroad cars include a brake pipe running from one end of the car to the other end, with a branch pipe leading from the brake pipe to a control valve which is in turn connected to other brake components, such as for example the brake cylinders, a compressed air reservoir, etc. It has been conventional practice for many years to provide the brake pipe with manually operable shut off angle cocks at opposite ends of the car, along with a manually operable shut off cock in the branch pipe leading to the control valve. When operating the angle cocks, brakemen must lean over couplings and reach in between cars. This presents operating difficulties and sometimes exposes the brakemen to safety hazards.
In order to avoid these difficulties and hazards, a prior art valve has been proposed for connection at the junction of the branch pipe with the brake pipe. This prior art valve takes the place of the two angle cocks in the brake pipe and the shut off cock in the branch pipe, and it can be operated from opposite sides of the car to interconnect the branch pipe and the two brake pipe sections in various combinations, thereby eliminating the need for brakemen to position themselves in the coupling area between the cars when making such valve adjustments.
Although this prior art represents a step forward in operational safety, unfortunately it incorporate a number of design and mechanical drawbacks which are likely to create serious difficulties in both operation and maintenance. For example, the prior art valve has a single housing containing the valve components as well as the actuator components. This arrangement is prone to seal damage and resulting leakage, because at least some of the actuator components must undergo both rotational movement and axial movement into and out of the housing. The valve is also difficult to connect into standard brake systems, due in large part to its ports being arranged in vertically separated planes. Finally, the prior art valve is unnecessarily heavy, cumbersome and difficult to operate.
The general objective of the present invention is to provide an improved valve and actuator assembly which overcomes the above stated drawbacks.