US2432076A

US2432076A - Hydraulic ram

Info

Publication number: US2432076A
Application number: US472643A
Authority: US
Inventors: Rothery James Stewart
Original assignee: Individual
Current assignee: Individual
Priority date: 1941-10-28
Filing date: 1943-01-16
Publication date: 1947-12-02
Anticipated expiration: 1964-12-02

Description

' Dec. 2, 1947.

.Z/ zziel I I7 @2656: Kai calf [We iZZy Filed Jan. 16, 1.943

Patented Dec. 2, 1947 UNITED STATES PATENT OFFICE HYDRAULIC RAM James Stewart Itothery, llford, England Britain June 24, 1941 4 Claims.

This invention relates to improvements in the packing of hydraulic rams and the application is divided out of my U. S. A. patent application No. 416,881, new Patent No. 2,330,518 issued Sept. 28, 1943.

The invention is applicable to hydraulic rams or pistons generally, hereinafter called rams. One object of the invention is to prevent the escape of working fluid from the ram cylinder at that end of the latter, herein referred to as the top, through which the ram extends, without the necessity of a packing gland at this end. The present invention, therefore, is particularly useful in conjunction with the hydraulic jacks according to my said patent application in that the diametral boring of the rams thereof precludes the satisfactory provision of a packing gland at the tons of the rams.

The above and other objects of my invention will be clear from the following description taken in conjunction with the accompanying drawings, the invention being shown applied to a jack according to my Patent No. 2,330,518.

In these drawings:

Fig. 1 is a perspective view of the jack, the ram being lowered;

Fig. 2 is a side elevation, partly in section, showing the top of the jack cylinder and the lower part of the ram with the present packing or safety seal.

Fig. 2 is a detail of a modified form of safety seal packing.

The jack shown in Fig. 1 comprises the tubular tripod i from the peak of which the. ram cylinder 2 depends, the legs being braced together by hollow members 3 and being braced to the cylinder 2 by hollow members 4. A pump 5 is fixed to the base of the ram. The pump draws liquid from the reservoir formed by the hollows of the legs of the tripod and of the members 3 and 4 and delivers it to the bottom of the cylinder to raise the jack; and a release valve 6 allows liquid to flow from the cylinder and into the reservoir to allow the ram to sink. The jack as described so far is substantially as described in my U, S. A. patent specilication No. 2,214,440.

The ram 1, Fig. 2 is provided with a number of pairs of vertically superposed holes 8, the holes of each pair being diametrically opposite to each other, and around the ram and resting on a guide collar 9 for the ram is a sustaining element comprising a rotatable sleeve ID in which are a number of pairs of holes H. The centres of the holes I lie on a double helix so that each hole has another diametrically opposite to it and each pair of holes is at a different height from the others. The guide collar 9 is flanged at 12 and the flange rests on the top of the cylinder 2.

In use, the jack is raised, 1. e., the ram is lifted, to bring the crutch [3 (Fig. 1) into engagement with the article to be sustained, the sleeve in is turned to bring two of its holes into register with a pair of holes 8 and a pin I4 is thrust into the four aligned holes and locks the ram in the raised position, the ram thrusting downwardly on the pin if able to overcome the pressure of the working fluid. the pin thrusting on the collar and the collar thrusting on the cylinder through the flange l2 of the guide collar.

The collar 9 is provided in lieu of a packing gland. To overcome the disadvantage arising from the absence of a gland at the top of the cylinder the ram is provided with the packing or safety seal l5. This seal is located at the reduced bottom of the ram above the usual cup leather l6, said cup leather being secured to the ram by means of a washer I1 and a bolt l8 which enters a plug 19 forced into the bottom of the ram.

The seal comprises a packing ring 20 in the lower annular Surface of which isaV -groove; and an expander ring 2| of triangular cross section but less in height as regards the V-section than the groove is deep lies in the groove so as to expand the lips of the groove first. The expander rests on the upper portion of that part of the surface of a flange 22 on the plug [9 which projects beyond the sides of. the ram whilst a movable collar 23 with an external flange 24 at its bottom end rests on the top of the ring 20. Above the collar 23 and bearing against the shoulder 25 on the ram by the flange 22 the lips of the groove in the ring 7 are splayed and make close contact with the cylinder and the outer surface of the ram, respectively. Liquid which leaks past the leather I6 is able to raise the seal l5 until the collar 23 butts against the collar 26. Thereafter the liquid is trapped until pressure on the leather is released whereupon the spring is able to expand to the position shown and the seal l5 drives the liquid back into the cylinder past the said leather. Either collar (23, 26) may be considerably shorter than shown and the other as shown or longer. Spring means of known type may be employed to expand the cup leather in order to ensure that the seal l5 does not do all the work of the said leather. An important feature of the present invention is the provision of means indicated in the

collars

23 and 26 which serves to limit the degree of compression of the packing by the spring 28. If this limiting means were not provided, compression of the packing would take place to the limit of the spring, and having regard to the hydraulic pressure the compression might well be such as to damage the packing 2| or cause it to bind.

A seal comprising a groove and expander hav-' ing sections differing from a V may be used. Fig. 2 shows one alternative form. In this case the underside of the ring 20 has a groove 20 of half round section and the expander ring 2| is of corresponding shape, the radius of curvature, however, of the top of the expander being greater than that of the groove to ensure outward movement of the groove lips by the expander.

If the jack be laid on its side or inverted the seal l5 will prevent the flow of liquid to that end of the cylinder at which the collar 9 is located.

Although the drawings show the invention applied to a jack the invention is applicable to rams generally.

What I claim is:

1. A seal for hydraulic rams of the type in cluding a cylinder, a ram operative in the cylinder and a main packing at the lower end, of said ram, said seal comprising an annular packing ring between the ram and the cylinder immediately above the main packing, an annular expander ring underlying and contacting the packing ring, the meeting faces of the packing ring and the expander ring being formed to compel the sealing spread of the packing ring between the ram and cylinder on pressure on the expander ring, and a spring assembly between the ram and cylinder including a spring, a lower collar slidable on the ram and supporting the lower end of the spring, and an upper collar fixed against upward movement with respect to the ram and overlying the spring, the seal and lower collar moving upwardly under leakage past the main packing and beneath the expander ring to compress the spring and maintain the contact between the expander ring and packing ring to provide the seal between the ram and cylinder, the upward movement of the lower collar being limited to limit the degree of spring compression, the spring maintaining effective cooperation of the seal in all positions of such seal.

2. A construction as defined in claim 1, wherein the face of the packing ring contacting with the expanding ring is formed with a V-shaped depression and the meeting face of the expanding ring is formed with a similarly shaped projection, the vertical dimension of which is less than the similar dimension of the depression on the packing ring.

3. A hydraulic ram including a cylinder, a ram movable in the cylinder, the ram having an annular flange at its lower end to substantially contact the cylinder, a main packing secured to the ram and having sealing cooperation with the cylinder beneath said flange, an expanding ring resting on said flange and fitting between the ram and cylinder, an annular packing ring in the space between the ram and cylinder and overlying and contacting the expanding ring, collars slidable on the ram and having terminal shoulders at opposite ends respectively, and a spring surrounding the collars and bearing between the shoulders thereof, said spring holding the shoulder of the lowermost collar in pressure contact with the annular packing ring, the meeting faces of the annular packing ring and expanding ring having complementary formations operating to spread th annular packing ring under upward pressure on the expanding ring.

4. A seal for hydraulic rams including a cylinder and a ram slidable therein, a main packing on said ram sealing same against the cylinder, a freely disposed expander ring seating against a wall of the ram, a subsidiary packing expandable by pressing on said expander ring, a pair of flanged collars slidabie on the ram, one of said collars seating against the subsidiary packing ring and the other seating against an abutment on the ram and a compression spring embracing said collars to force the one collar against the subsidiary packing ring to expand same against the expander ring into sealing contact with the cylinder while permitting said packing ring to yield under the influence of leakage fluid, the limit of said yield being determined by the engagement of the two collars.

JAlVIES STEWART RO'I'HERY.

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

UNITED STATES PATENTS Number Name Date 1,974,362 Marsh Sept. 18, 1934 2,188,957 Pfauser Feb. 6, 1940 2,209,032 Mott July 23, 1940