US1792875A - Packing - Google Patents

Description

Feb. 17, 1931. w, STEVENS 1,792,875

PACKING Filed March 17, 1925 I N VEN TOR Edward W Sfevens BY Al's ATTORNEY Patented Feb. 17, 1931 UNITED STATES PATENT OFFICE- nnwann w. srnvnns, or person, MICHIGAN, nssreno'n 'ro cmcaeo immune 'roor. comrnnv, or new YORK, 1v. Y., A conronnrron or NEW- messy Application-filed new; 11.1925. Serial 80.18995.

The present invention relates to packings generally as for reciprocating rods with particular reference to fluid pressure tools such as pneumatic sand rammers'.

In order that a pneumatic sand rammer may operate efiiciently it is essential that the packing for the rammer rod maintain a ti ht seal for the outer end of the piston cham er since motive fluid is admitted thereto at the end of each forward movement of the piston to effect its return stroke. The usual practice has been to have the packing glands make a loose fit in the forward end of the cylinder with the packing compressed therebetween and with the cylinder bore serving as a wall for the packing. Not only is this loose fitting not conducive to a tight sealing of the iston chamber but it also leaves the piston co to exert a force against the packin at every tends to, estroy the packing.

Among the objectsvof the invention are to avoid relative movement of the packing mem bers which results in the destruction of the seal and of the packing material, to reduce the amount of packing material required with a reduction in the pressure necessary to maintain the seal, to provide for manual adjustment of the packing without the use of tools, to facilitate the handling and inserting of, new packings, to provide a newform of mold ed packing and protective container therefor. and in general to improve prior structure in the interests of more efficient and satisfactory service.

In order to illustrate the invention and the manner of its use one concrete embodiment thereof is shown in the accompanying draw ings in which: v l Fig. 1 is a longitudinal sectional view through the forward end of the cylinder of a pneumatic sand rammer; I

Fig. 2 is a right end elevation of the part shown in Fig. 1; I 1

Fig. 3 is a view similar to Fig. 1 on a reduced scale showing the manner of insert-" in a new packing, and

iig. 4 is aperspective view of the molded packing in its container.

The embodiment of the invention chosen for the purpose of illustration is shown in I the drawings as sealing the forwardend of the piston chamber of a rammer comprising the cy inder or barrel 5 in which piston 6 reciprocates, the latter having attached thereto or integral therewith a stem'fia which projects beyond the-cylnder 5 and carries the butt or pein (not shown). The motive fluidadmitted to the front end of the piston chamber through passage 7 to drive piston 6 on its backstroke 1s sealed against escape through the forward open end of the cyhnder by the following construction. A packin gland member 8 in the form of a hollow cylinder or sleeve is rigidly secured within the open end of the cylneumatic sandinder as shown. One method of rigidly se- I curing member 8 in the cylinder is to provide'the latter'with internal screwthreads 5a and: the member with external screw threads 8a. Opposite slots as'8b permit the use of aspanner wrench for inserting member 8a and a shoulder 80 cooperating with a similar shoulder within cylinder 5 serves as a stop. The cylinder bore 9 of member 8 receives stem 6a with a slidin fit and serves as a bearing for'thelatter. videdwith a counter bore 9a in which packing material 10 is seated'surrounding stem (iaand a second gland member 11 in the form ofa cylinder sleevedover stem 6a-makes a close sliding fit with counterbore 9a and telescopes within member 8 toplace packing 10 under compression. Member 11 is of substantiallength as indicated and projects beyond cylinder 5. A gland nut 12 having a head 12a with a bore 126 loosely receiving stem 6a is provided with a cylindrical extension 12c arranged loosely to telescope over the projecting portion of member 11 and is ember 8 is pro- 1 exteriorly threaded for engagement with the interior threads 5a of cylinder 5. Head 12a is formed with a rim extending beyond cylinder portion 120 and interposed between this rim and the end of the cylinder 5 and surrounding projection 120 is a coiled spring 13 whose ends 13a and 136 are removably seated in sockets 5b and 12d respectively in cylinder 5 and nut head 12a to hold the manually adjustable nut 12 in adjusted position.

0 shown the mol ed packing in its container as a unit is sleeved over the piston stem 6a until the container 14 abuts the outer end of member 8. Gland member 11 is then sleeved over the stem 6a and is telescope'd within the container 14 forcing the molded packing 10 into the counterbore 9a of gland member 8, the member 11 being forced through packing 10 and into telescopic engagement with member 8 until the parts reach the position shown in Fig. 1, t e packing then being seated in its recess. The container or envelope 14 is now removed from the stem 6a and the gland nut '12 with its locking spring is a plied and set up to put packing 10 under tlib desired compression. The tool is then ready for use.

From the above it will be apparent that the rigid securing of gland member 8 within the cylinder end prevents relative movement of the parts and provides a good bearing for the stem 6a, that the packing material is contained wholly within the gland member 8 and protected from wear through 'relative movement of the adjacent parts, that the other gland member 11 telescoping within member 8' and closely fitting the same provides additional bearin surface for stem 6a and closely confines t e packing material within rigid walls, that by this gland construction only a small amount of packing material and a relative low pressure of the same are required to seal the cylinder, that the telescoping engagement of member 11 and gland nut 12 serve as an additional support for the latter, that the low pressure required on packing 10 permits manual adjustment of nut 12, tains the nut 12 in its adjusted position.

While but one embodiment of the invention has been herein shown and described it is to be understood that the invention is not limited to the specific details thereof but covers all changes, modifications and adaptations within the scope of the appended claim.

The packing herein disclosed is claimed per se and as to the method of applyi the same in my copending application, erial No.

95,842, filed March 19th, 1926, as a division of this application.

I claim as my invention:

In a fluid pressure tool having a cylinder with an open end and a piston reciprocable in the cylinder with a stem projecting therefrom, the cylinder having a long counterbore threaded substantially throughout its length 7 and that the locking spring '13 re- Y meaaaa and forming an internal shoulder, packing means for said piston stem comprising an elongate gland member sleeved over said stem and threaded into said counterbore to provide a rigid bearing for said stem, said member having a shoulder to engage the internal shoulder of said cylinder, packing material surrounding said stem within said member, a second gland member sleeved over said stem and telescoping within said first member with a sliding fit, said second member being of substantial length and projecting well beyond said cylinder, a nut sleeved over said stem and having a cylindrical extension telescoping over the projecting portion of said second gland member, said extension being exteriorly threaded to screw into said counterbore of said cylinder in spaced relation to said first gland member, said gland members and nut cooperating to permit tightening of said packing material y the operator of the tool by grasping the nut with his hand and turning Signed by me at Detroit,

12th day of March, 1925.

EDWARD W. STEVENS.

it. Michigan, this

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