US2431382A - Rail sander sand trap - Google Patents

Description

1947. J. VAN v. ELSWORTH 2,431,382

RAIL SANDER SAND- TRAP Filed July 13, 1945 9 m w 5L 1:: J 4. & 8 L A Fis. 3

Smaentor Patented Nov. 25, 1947 RAIL SANDER SAND TRAP John Van Varick Elsworth, Watertown, N. Y.,- assignor to The New York Air Brake Company, a corporation of New Jersey Application July 13, 1945, Serial No. 604,879

1 Claim. 1

This invention relates to sand traps and particularly to traps of the type in which sand is fed by gravity to a pocket in the trap and is withdrawn by an air operated ejector which draws atmospheric air into the pocket through a stirring nozzle.

In prior art sanders of this general type, the stirring nozzle was at least partially, and in some cases completely, submerged in sand in the pocket, the idea being to ensure active agitation by air entering under a low pressure differential. Such traps have good operating characteristics. They are, however, subject to the objection that if the sand discharge line becomes clogged, sand will be blown out through the stirring nozzle. Such discharge of sand rarely occurs but cannot be tolerated where the discharged sand may reach cross-head guides, reverse gear and similar mechanism.

The present invention is based on the results of a series of tests directed to the discovery of some arrangement of the pocket and the stirring nozzle, such that inflow through the nozzle will cause adequate stirring of the sand; whereas outflow to and through the stirring nozzle will not entrain any sand. The problem is difiicult because the pressure diiierential causing normal inflow is small, whereas a, completely clogged discharge lin: may require discharge of air at quite a rapid ra e.

The successful solution involves the use of a sand pocket so contrived that the sand level is well below the crest over which the ejector draws air and sand, and the stirring nozzle is of large area, directs air downward against the surface of the sand, and is so related to the crest that flow from the ejector nozzle to the stirring nozzle will by-pass the pocket and produce no eddies therein.

A commercial embodiment of the invention is illustrated in the accompanying drawing, in which:

Fig. 1 is a vertical axial section of the complete trap. The plane of section is parallel with the longitudinal axis of an ordinary steam locomotive boiler on which the trap would customarily be mounted.

Fig. 2 is a section on the line 2-2 of Fig. 1.

Fig. 3 is a plan View.

The main components of the trap are a suitably chambered body 4 and a removable cover plate 5 which is sealed by a gasket 6 and retained by units 1 on 'studs as shown. Removal of the 2. to the entrance to the Venturi throat, both hereinafter described.

The body 4 has a sand retaining pocket 8 from which sand may be drawn over a horizontal straight crest or dam 9 (see Fig. 2) and to which sand flows by gravity beneath .a pendant baiile it from an entrance chamber IZhaving a sloping bottom l3. Sand. enters chamber l 2 from the sand box (not shown) through apipe (not shown) connected to the threaded inlet M,

A. partition l5 defines within body 4' an air passage ta Whichh'as an inlet IT: at the back. of the trap; When the trap is mounted on a locomotive boiler the inlet i1 is presented toward the boiler and thus is protected in some degree against the entrance of rain water;

Mounted in a horizontal portion of partition l 5 is a ported bushing I 8 which is the stirring nozzle. This is simply pressed to place beneath a threaded plug l9. This nozzle has a notably large port. Actually it is larger than the constricted portion of the Venturi throat hereinafter described. It discharges atmospheric air, entering through port H and passage l6; substantially vertically downward on sand in pocket 8.

Since the lower edge of baflie II is below crest 9, the surface of sand flowing into pocket 8 is well below the crest 9 and something over twice as far below nozzle I8. Nevertheless, the entrance of air through the large nozzle l8 under a low pressure difierential causes sufiicient turbulence in pocket 8 to stir up sand and cause it to be entrained by the ejector mechanism now about to be described, and for which no novelty is here claimed.

The nozzle of the ejector is threaded into a boss 2i and comprises a shouldered tube 22. Threaded into the end of the tube 22 is the nozzle tip 23. The nozzle orifice is formed in a bushing 2:3 pressed into the end of the tip 23. The holes 25 are provided merely as a, means for engaging the tip 23 when it is screwed into the tube 22.

At the upper end of the tip 23 is a sleeve-like extension 26, smaller than the bore of the tube 22 and cross-drilled at 21 to serve as a strainer to protect the nozzle orifice. The upper end of the extension 26 is closed by a threaded plug 28,

Compressed air to operate the sander is furnished through a pipe (not shown) connected by a union 29 with the upper end of the tube 22. Upon disconnection of the union 29 it is possible to unscrew the tube 22, thus removing the entire nozzle structure so that it can be cleaned, re-

cover plate gives access to the sand pocket, and paired or replaced.

The body 4 of the trap is preferably mounted as indicated so that the stirring nozzle I8 directs its jet vertically downward and so that the ejector nozzle also discharges vertically downward. Below the ejector nozzle is a Venturi throat formed in a metal bushing 3| with the throat proper 32 composed of rubber or rubber-like synthetic material. The tube 3| has a flange 33 at its lower end so as to be retained by the union nut 34 and the flanged upper end of the discharge pipe 35.

Sand is always present in the pocket 8 to which it flows by gravity from the sand box, passing beneath the bafile ll. Consequently it fills the pocket 8 to a limited level which is below the crest 9. When air under pressure is supplied to the nozzle the jet and throat operate as an ejector and reduce the pressure within the chamber 8. Consequently air under atmospheric pressure enters through port I! and passage l6, and flows downward through the nozzle I 8 producing turbulence at the surface of the sand in the pocket 8. The off-flowing air entrains parts of this sand, carrying it to and through the throat 32.

If the throat 32 should become clogged, or if the sand pipe 35 is stopped up, as sometimes happens in winter, delivery of air under high pressure through the nozzle 24 tends to develop pressure in the pocket 8. However, the nozzle I8 is so large that the pressure is dissipated and since the path from the crest 9 to the nozzle I8 is considerably above the surface of the sand in the pocket 8, no sand whatever will be entrained.

Thus, low pressure downward flow through the nozzle I8 produces an adequate stirring turbulence at the surface of the sand, whereas a more violent outflow in the reverse direction produces no turbulence which can afiect the sand. The invention for the first time provides a trap, having an atmospheric stirring inlet, and in which even a completely clogged sand pipe cannot cause the discharge of sand through the stirring passage.

While the best position of the trap is one in which the stirring nozzle directs the stirring air vertically downward, minor departures from this position are possible without destroying the operative characteristics of the trap. It is not always practicable to mount the trap in the precise attitude desired, and vertical mounting though preferred is not critical as to operativenes The stated position should, however, be approximated.

What is claimed is:

A track sander comprising in combination a body having a sand retaining pocket and a suction chamber separated by a crest, the suction chamber being at a higher elevation, and closed against entrance of atmospheric air, other than air flowing through said pocket and thence over said crest; a gravity sand-supply connection to the pocket; means serving to limit to a level below said crest the surface of sand maintained in said pocket by gravity flow thereto; a stirring nozzle of large cross-sectional area arranged to be fed by atmospheric air and to direct said air downward against the surface of sand maintained in said pocket; a discharge connection for sand-charged air having at its entrance end a Venturi throat whose entrance aperture is in said suction chamber adjacent said crest; and a nozzle having a fiat end opposed to the entrance aperture of the throat, and arranged to direct a propelling jet of air into said throat.

JOHN VAN VARICK ELSWORTH.

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

UNITED STATES PATENTS Number Name Date 409,578 Gresham Aug. 20, 1889 381,837 Gresham Apr. 24, 1888 2,376,463 Vroman May 22, 1945 FOREIGN PATENTS Number Country Date 11,487 Great Britain 1907 6,072 Great Britain 1887

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