US2588798A - Buffer means - Google Patents

Description

March 11, 1952 BONE ETAL 2,588,798

BUFFER MEANS Original Filed Nov. 27, 1948 III 14 595055 140 55 2/ 25 24 L IN VEN TOR).

' g4 mpbept L. 5012a and 18 IIZ II JJA WGauan Fly 2 %J\ THEIR ATTORNEY Patented Mar. 11, 1952 i if 2,588,798

BUFFER MEANS Herbert L. Bone, Forest Hills, and Kenneth J. J. McGowan, Pittsburgh, Pa., assignors to Westinghouse Air Brake Company, a corporation of Pennsylvania Original application November 27, 1948, Serial Divided and this application August 16, 1949, Serial No. 110,506

2 Claims. (Cl. 267-1) The present invention relates to a retarding mechanism, and more particularly to a hydraulic bufier for a treadle operated circuit controller.

This is a division of our copendin application bearing Serial No. 62,328, filed on November 27, 1948, now abandoned, for Control Apparatus.

Treadle operated circuit controllers for railway operation to initiate or control signal equipment are usually provided with retarding or bufier means to prevent successive operation of the controller bythe train'wheels after the first actuation thereof by the initiating train wheels. While such controllers have been provided with resiliently mounted treadles, or with resilient treadles, the shock of impact of the train wheels as the treadle is depressed is transmitted to the buffer mechanism of the controller, particularly in instances of fast moving trains. The piston of the buifer is thereby subjected to quick movement, the movement being abruptly halted by the abutment of the piston with the piston stop within the cylinder. The shock of piston impact and the excessive pressures developed by the sharp movement of the piston will cause damage to the buffer mechanism.

An object of our invention is to provide a hydraulic buffer in which the shock of the sudden stop of the piston by the cylinder is absorbed.

Another object of the present invention is to provide a hydraulic buffer in which the maintenance of the oil level in the bufier housing is not dependent upon the integrity of any seals between the moving parts.

Still another object of our invention is to provide a hydraulic bufier in which an expansion chamber is formed above the level of the hy-- draulic fluid to provide a cushionin effect should excessive pressures be developed due to a sharp piston movement.

Yet another object of this invention is to provide a hydraulic bufier of the character indicated which shall consist of few and simple parts, relatively inexpensive to manufacture, which shall be positive in its operation, have a large variety of application and yet be practical and efiicient to a high degree in use.

Other objects of the invention will in part be obvious and in part hereinafter pointed out.

The foregoing objects of the invention are accomplished by providing a two-part housing for the buffer mechanism, one part at a slightly higher level than the other. The lower part or section of the housing forms the cylinder of the buifer, the piston being movable therein. A spring is provided for biasing the piston to a normal or inactive position against a stop.

A check valve on the piston permits longitudinal movement of the piston within the cylinder against the action of the spring. The piston is pivoted to an arm passing from the lower section into the upper section, the arm being fixed to a shaft journaled through the upper section of the housing. A frusto-conical spring disc is provided for one end of the piston to absorb the shock of sudden stopping of the piston by the cylinder stops.

The housing of our buifer mechanism is provided with a filler plug well below the level of the buffer actuating shaft. The level of the hydraulic fluid will be determined by the level of the filler plug. This fluid level will be above the cylinder but below the level of the actuating shaft. Theair space in the housing above the fluid level forms an expansion chamber for the fluid and the air trapped therein will provide a cushioning effect for any quick movement of the piston.

In the accompanying drawings forming a part of this specification in which one of the various possible illustrative embodiments of our invention i shown, and wherein the same refer- .ence characters designate corresponding parts throughout the two views.

Fig. 1 is a vertical cross-sectional view of our bufier mechanism forming a part of a treadle operated circuit controller, while Fig. 2 is a fragmentary sectional view of the treadle and operating shaft.

Referring now in detail to the drawings, the numeral Ill designates a bufier embodying our invention. The bufier Ill as herein illustrated is incorporated into a track circuit controller II more fully detailed in the aforesaid parent application. The track controller H is enclosedin a housing l2 adapted for mounting on the gauge side of a track rail [3 by means of clip bolts l4, clips l.5, and nuts Hi.

The housing H is divided into two compartments l1 and I8, compartment I! enclosing an electric circuit controller (not shown) and compartment 18 housing the buffer Ill. The buffer compartment [8 is divided into two interconnecting sections 20 and 2|, the horizontal section 20 enclosing the bufier mechanism to be described, and the vertical section enclosing the buffer actuating mechanism; the two sections beinginterconnected by an opening 22. I

A splined shaft 23 is journaled in suitable bearings 24 (Fig. 2) in the housing IL, Fixed to the ends of the splined shaft are treadle supporting ams 26 having fixed thereto, as by bolts 21 and reenforcing clamps 28, an elongated flexible treadle 29 paralleling the track rail l3. The splined shaft 23 passing through the compartment l8 has fixed thereto a depending buffer operating arm l9, the bifurcated lower end of which passes through the opening 22 into the horizontal section 2|).

A cylinder 30 is formed in the right-hand end of the horizontal section 20. A piston 3| is slidably received within the cylinder 30 and is connected to the bifurcated end of dependent arm 29 by way of a pin 32 extending transversely of the piston 3|. The left-hand end of the piston is formed with an arcuate shoulder 33, for purposes hereinafter appearing, while the right-hand end is provided with a check valve 34 in the longitudinal passage of the piston. The check valve is biased'to a closed position by a coil spring 36, the outer end of which is held by a spring retainer 31 fixed to the piston.

The right-hand end of the cylinder 38 is formed with a shoulder 38 serving as a limit stop for the piston 3|, while the left-hand end of the cylinder is similarly provided with the shoulder 39. Drain plugs 40 are provided for opposite ends of the cylinder 30, while a filler plug 4| is provided for the right-hand end of the cylinder. The filler plug is formed with a restricted orifice 42 interconnecting the right-hand end of cylinder 30 with the upper section 2|. It will be appreciated that the level of the filler plug 4| is below the splined shaft. When a suitable hydraulic fluid is supplied for. the buifer mechanism thus far described the horizontal section 23 will be filled and the vertical section 2! only partly filled, the oil level remaining below the splined shaft 23.

Maintenance of the oil level in the buffer mechanism is therefore not dependent on seals for the shaft, or any other seals between moving parts. The construction of the vertical section is such that an expansion chamber is formed above the oil level to take care of any expansion of the oil due to temperature changes. The volume of air therein also provides a cushioning effect in the event excessive pressures are developed on the left side of the piston 3|.

The shoulder 33 on the left-hand end of the piston 3| supports a frustc-conical spring disc 43 which is adapted to engage the left-hand shoulder 39 of the cylinder. The left-hand end of the horizontal section 20 is closed by a plug 44, the plug acting as a spring retainer for a coil spring 45. The coil spring is compressed within the section 28 between the plug 44 and the piston 3|, to bias the piston to the position shown against the right-hand stop 38 of the cylinder.

As more appropriately detailed in the aforesaid parent application, the depression of the treadle 29 will rotate the splined shaft 23 in a clockwise direction. The piston 3| will thus be moved to the left against the bias of the spring. The movement of the piston 3| by the swing of arm |9 will create a difference in pressure between the left-hand end and right-hand end of the cylinder. Due to the high pressure on the left-hand end of the cylinder, the check valve I! 34 will open against the bias of the spring 36. The difference in pressure is thereby relieved permitting the piston to move to the left and be brought to a sudden stop by the abutment of the piston 3| and the cylinder shoulder 35. The frusto-conical spring 43 will cushion the shock of impact, thereby preventing any damage to the bufier mechanism.

Upon release of ,the treadle 29; the coil spring 45 will tend to return the piston 3| to its initial position against the stop 38. The increased pressure on the right hand side of the piston due to the return movement will close the check valve 34. The only fluid connection between the two sides of the piston is by way of the restricted passage 42 of plug 4|. The return of the piston 3| to its initial position by the spring will thus be retarded'for the time interval required for the hydraulic fluid on the right of the piston to pass through the orifice 42.

It will thus be seen that there is provided a novel bufier mechanism in which the several objects of this invention are achieved, and which is well adapted to meet the conditions of practical use.

As various embodiments of the above invention may be made, and as various changes may be made in the embodiment set forth above, it will be understood that all matter herein set forth, or shown in the accompanying drawings, is to be interpreted as illustrative and not in a limiting sense.

Having thus described our invention, what'weclaim is: v f

1. In a buffer mechanismfia cylinder, a piston movable within said cylinder, a passage con-v necting the ends of the cylinder to permit free movement of the piston toward one end. of the cylinder, a return spring, for said piston, a stop in said cylinder for limiting the free movement of said piston, and a frusto-conical spring disc located on said piston having its periphery projecting toward said stop to absorb shocks due to sudden stopping of the piston by said stop.

2. In a buffer mechanism, a cylinder, a piston movable within said cylinder, a passage connecting the ends of the cylinder to permit free movement of the piston toward one end of the cylinder,

said cylinder having an annular shoulder, a circular projection on the end of the piston nearest said one end of the cylinder, an annular frustoconical spring disc received on said projection and having its periphery projecting toward said shoulder to absorb shocks due to sudden stopping of the piston, and a coil spring having one end abutting said one cylinder end and having its other endencircling said projection and en gaging said projection and engaging said springdisc soas to bias the piston for movement toward the other end of the cylinder and to hold the disc in place.

HERBERT L. BONE. KENNETH J. J. MCGOWAN.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Italy Oct. 1, 1928

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