High pressure valve for railway car brake control valve device
AssigneeWestinghouse Air Brake Company
InventorsJames E. Hart, John B. Carroll
Life of this patent
Estimating the term…
Abstract
A spool type valve arrangement in which a booster spring is employed to overcome static friction of the spool valve O-rings and thereby assure prompt actuation of the spool valve member. The arrangement is such that the booster spring is only active through a limited distance of travel from release position toward application position, this limited distance of spool valve travel being selected so as to occur prior to any transition of the port connections controlled by the spool valve. In this manner, the spool valve return spring force need not be increased in order to reset the spool valve sufficiently to reestablish the original spool valve port connections.
Claims17
Spool valve means for a railway car brake control valve device comprising:
- (a) spool member having its opposite ends subject to fluid under pressure and having at least one annular elastomeric pressure seal surrounding the periphery thereof;
- (b) a bore in which said spool member is reciprocally disposed for axial movement in opposite directions between a release position and an application position;
- (c) at least two axially spaced ports opening into said bore and connected to each other by said spool member in said release position;
- (d) said spool member in a position intermediate said release and application positions locating said elastomeric seal between said spaced ports to effect transition from said connected condition thereof to a disconnected condition thereof in said application position, thereby providing a brake control function;
- (e) a first spring acting on said spool member in the direction of said release position through the full range of travel of said spool member between said release and application positions;
- and
- (f) a second spring acting on said spool member in the opposing direction of said first spring, but through only a limited distance from said release position of said spool member and without extending said spool member to said intermediate position, whereby said second spring acts on said spool member only prior to said transition between said connected and disconnected conditions.
For a railway car having a brake pipe, a brake cylinder, and an emergency reservoir charged to the pressure carried in said brake pipe, a brake control valve device comprising:
- (a) a quick action chamber charged to the pressure carried in said brake pipe;
- (b) high pressure valve means for effecting an emergency brake control function;
- (c) means operative responsive to an emergency rate of reduction of said brake pipe fluid under pressure for piloting said high pressure valve means, said high pressure valve means comprising:
- (i) a spool member subject on one end thereof to fluid under pressure in said brake pipe and on the opposite end to fluid under pressure in said quick action chamber, said spool member having a first pressure seal surrounding the periphery thereof;
- (ii) a bushing in which said spool member is reciprocally disposed for axial movement between a release position and an application position, said bushing including first and second ports to which said emergency reservoir and said brake cylinder are connected respectively, said first pressure seal being located intermediate said first and second ports in said release position of said spool member to interrupt fluid pressure communication therebetween and displaced therefrom in said application position of said spool member to establish fluid pressure communication therebetween thereby providing a first aspect of said emergency brake control function;
- (iii) a first spring acting on said spool member in the direction of said release position;
- and
- (iv) a second spring acting on said spool member in the direction of said application position only during said movement of said spool member from said release position toward said application position prior to said first pressure seal being displaced from between said first and second ports, and during said movement of said spool member from said application position toward said release position only after said first pressure seal is aligned between said first and second ports.
Dependencies are inferred from the claim text.