US2691503A - Mine prop - Google Patents

Description

Oct. 12, 1954 BIGELQW I 2,691,503

MINE PROP Filed March 18. 1950 00571.9 94 Dl-FLECTOI? FLA "GE INVENTOR. flog f fliyelow.

A TT'O/QNEY Patented Oct. 12, 1954 MINE PROP Roy S. Bigelow, Chicago, Ill., assignor to Goodman Manufacturing Company, Chicago, 111., a 'corporationof Illinois Application'March 18, 1950, Serial No. 150,878

1 Claim. 1

This invention relates to props and particularly to props of the type employed in mines to span the space between the ground and roof for holding up the roof and for holding down various kinds of equipment, for-example shaker conveyor.

This application is a continuation-in-part of applicants prior application, Serial No. 552,243, filed September 1, 1944, Patent No. 2,630,902, .and relates to the prop disclosed but not claimed in that prior application.

A principal object of this invention is to provide a prop which can be put up and taken down by a single man with a minimum of time and effort.

An important feature of the improved prop is that it comprises a doubly expandable structure having manually extensible screw means for quick initial adjustment of the prop to the height of the roof, and extensible hydraulic means for applying a subsequent holding load between the ground and roof.

Another, ancillary, object is the provision of a screw-hydraulic prop of the above-mentioned character which will operate without jamming or clogging by dust normally encountered in mines.

Other objects and advantages will be-apparent from the following description taken in connection with the figures of the drawing in which:

Figure 1 is a perspective view of a prop illustrating one embodiment of the present invention, and

Fig. 2 is an enlarged fragmentary cross sectional view of the hydraulic portion of the prop shown in Fig. 1.

Referring now in more detail to the drawing, the embodiment illustrated comprises a doubly expandable structure I8 having manually operable screw means 2l carried atop hydraulic means 8|.

The screw means comprises, in this instance, a rod or ram screw 83 having external threads 24 formed thereon and engaged with internal threads 26 formed in wing nut member 86. The latter carries an upstanding tubular extension 84 and an upper roof-engaging shoe 85. Thus, it will be apparent that, by grasping one of the wing nut handles 3|, and spinning the wing nut rapidly, the upper portion of the prop (including also parts 84 and 85) may be spun rapidly into engagement or proximity with the roof.

The upper, internally threaded element 86 is provided at its bottom end with a continuous annular radially extending flange l9 having a downwardly facing surface I911. The flange l9 forms a dust deflecting ledge, note Fig. 2', having a greater diameter than the outside diameter of the adjacent portion of the internally threaded wing nut member 86 and extending radially a substantial width overhanging the external threads 24 to act as a dust deflector to prevent clogging or jamming of the threaded parts under dirty service conditions. Furthermore, by this construction, in which the inner threaded member is open at the bottom, any dust which may collect within the threads is enabled to work downwardly and to drop out of the threads when the parts are rotated relative to one another. This construction also permits the internal threads 26 of the element 86 toact as wipers to clean off any dust or grime collecting on the external threads 24. The threads are, to a substantial extent, self-cleaning, and will operate for long periods under extremely dirty conditions without accumulating enough foreign matter to jam the threads.

Referring now to the hydraulic means, generally designated 8|, attention is directed first toFig. 2. A base l6 carries upstanding inner and outer cylinders 34 and 68, respectively. At its bottom end, the inner cylinder is threadedly engaged with the base, as indicated at 37, and at its upper end is threadedly engaged with a cover 38, the latter having a flange 39 overlapping and abutting the upper edge of cylinder $8. The upper end portion of the cover member 38 is formed to receive packing 4i and threaded packing nut 42 for maintaining a liquid-tight seal about the ram screw 83. On the inner end of the latter is a follower or piston 82 carrying a resilient, rubberlike or leather, cup member 44 held in place by washer 46 and nut 47. A hand pump 81 having operating handle 49, and piston and cylinder 5| and 52 respectively, is provided for applying pressure beneath the ram follower to lift the ram screw 83 and apply the final holding load to the ground and roof through shoes 53 and 85, respectively. For tilting adjustment of the prop, with respect to the vertical, the ground shoe 53 may be attached to the base I6 by pivot pin 54 as shown.

Any suitable arrangement of passages and valving inthe base may be employed for applying hydraulic pressure from the pump to the ram follower and releasing it when desired. In the present case passage 56 (in cylinder member 52) leads through passage 57 to the interior of cylinder 34 and branches through passage 58 to the annular cross-section reservoir 59. Bypass passage 6| connects 5! and 58 and flow therethrough is controlled by valve 62, diagrammatically illustrated. Handle 53 controls the opening and closing of valve 82. On the up-stroke of the pump piston 5| fluid is drawn from the reservoir 59 past check valve 64. On the downstroke it is forced past check valve 66 into cylinder 34 and displaces the ram follower and the parts carried thereby in an upward direction, any fluid on the top side of the ram follower being displaced to the reservoir through low pressure bypass 67. As an overload protection, to prevent damage at the upper end of the stroke, a capillary bypass is provided to short circuit high pressure fluid into the reservoir. When the upper shoe 85 is pressed into contact with the roof it will be so held by check valve 66, which prevents the back flow from cylinder 34. When it is desired to release the prop the release handle 53 is moved to open valve 52 permitting the fluid beneath the piston to be displaced into the reservoir as the ram screw moves downwardly under the weight of itself and of members 86, 84 and 85.

Thus, in operation, when a miner desires to set one of the improved props at a particular location, he simply moves valve 62 to closed position, spins the wing nut member 80, and moves the pump handle 49 up and down until, by its resistance, he knows that a sufficient load is applied against the ground and roof. To release the prop for removal at a subsequent time, he simply opens valve 62.

From the above it will be apparent that the improved prop constitutes a significant advance in a field where a single prop has often required the slow and laborious efforts of three or four men operating with long levers, often in restricted quarters, to emplace and remove it. A single operator can emplace and remove the improved prop in less time and do it more effectively than three men could do with a conventional prop. Furthermore, due to the self-cleaning arrangement of the threaded parts, it will operate for long periods without clogging or jamming, even in very dirty installations.

While but a single embodiment of the present invention has been shown and described it will be apparent to those skilled in the art that many specific structural variations may be employed 4 within the spirit of the invention. Accordingly the invention should not be understood as limited to the specific embodiment described, excepting in so far as limited by the appended claim.

I claim as my invention:

A doubly expandable mine prop comprising a manually extensible screw means for quick initial adjustment of the prop and an extensible hydraulic means for applying a subsequent and final holding load thereto, said hydraulic means comprising a base, vertically disposed inner and outer cylinders carried by said base in concentric relation defining a reservoir and a pressure chamber, a piston in said chamber, means for actuating said piston comprising, a pump, conduits and valve means connecting said reservoir and chamber in operative relation with each other, said manually extensible screw means comprising a rod secured to said piston and having an externally threaded portion extending beyond said chamber, and an internally threaded element interengaged with said externally threaded portion of said rod, said internally threaded portion having handle means thereon for applying said quick initial adjustment of the prop and a continuous annular radially extending flange adjacent the lower end of said internally threaded element, said flange providing a ledge having a greater diameter than the outside diameter of the adjacent portion of said internally threaded element and extending radially a substantial width and overhanging the external threads of said rod extension to act as a dust deflector therefor.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 637,945 Reed Nov. 28, '1899 1,877,364 Schoenburg Sept. 13, 1932 1,922,401 Scott Aug. 15, 1933 2,151,057 Suth Mar. 21, 1939 2,461,810 Curtis Feb. 15, 1949 2,465,653 Leterman Mar. 29, 1949 2,503,659 Curtis Apr. 11, 1950 2,520,686 Light et al Aug. 29, 1950 2,584,015 Hawes Jan. 29, 1952

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