US3329403A - Combination hydraulic and pneumatic jacks - Google Patents

Description

July 4, 1967 D. H. JUDS COMBINATION HYDRAULIC AND PNEUMATIC JACKS Filed May 4, 1966 INVENTOR DONALD H. JUDS ATTORNEYS July 4, 1967 D. H. JUDS 3,329,403

COMBINATION HYDRAULIC AND PNEUMATIC JACKS Filed May 4, 1966 3 Sheets-Sheet V F 5s /3 5 INVENTOR DONALD H. JUDS ATTORNEYS July 4, 1967 JUDS 3,329,403

COMBINATION HYDRAULIC AND PNEUMATIC JACKS Filed May 4, 1966 3 Sheets-Sheet 5 INVENTOR DONALD H- JUDS ATTORNEYS KQHWZK United States Patent Hydraulic Products Corporation, Milwaukee, Wis., a

corporation of Wisconsin Filed May 4, 1966, Ser. No. 547,533 Claims. (Cl. 254-93) This invention relates to improvements in combination hydraulic and pneumatic jacks.

In Edward H. Schultz Patent No. 2,926, dated Mar. 1, 1960, there is disclosed a hydraulic service jack in which there is an hydraulic pump operable by a handle to raise the jack. In certain situations the pumping of the handle which is required becomes tedious. There are also jacks on the market which are adapted to be operated pneumatically by use of the air hose which is available in most garages and service stations. These pneumatic jacks have been popular because they are speedy and eliminate the tedious pumping. In places where air equipment is available, however, it is not always available in all locations where it might be necesssary to use a jack. This, therefore, has heretofore made it necessary to either move the work to a position close to the air hose, or else buy and maintain both types of jack.

While pneumatic jacks have substantial advantages in speed of operation, as above outlined, there are cetrain dangers connected with the use thereof. For example, if the air supply is suddenly cut oif, the column of air may not always support the load in such an emergency. In addition, should the load slip off of the jack, with an all air jack the air pressure may cause the head to spring up too fast and tear the jack apart.

It has heretofore been proposed to furnish a pneumatic jack having a locked in hydraulic system for the purpose of safety and smooth operation. With this type of prior construction it was not possible to operate the jack hydraulically either alone or as a supplement to the pneumatic operation. In addition, it is not possible in this prior arrangement to lock the jack hydraulically in a selected position during pneumatic operation.

It is a general object of the present invention to provide an improved combination pneumatic and hydraulic jack which has the pneumatic and hydraulic systems completely separated and arranged so that it is possible to switch from one to the other at will. Thus the jack can be operated with either method, or the major portion of the elevation of the jack can he done pneumatically 'for fast action, with the final adjustments in height being effected hydraulically.

A further object of the invention is to provide a device as above described wherein the arrangement issuch that the jack can be hydraulically locked in a selected position regardless of whether it is being operated pneumatically or hydraulically.

A further object of the invention is to provide an improved combination jack wherein a column of oil cushions the movement of the jack in either direction regardless of whether the jack is being operated pneumatically or hydraulically.

A further object is to provide a construction as above described where, if there is a loss of load as the jack is being raised pneumatically, the hydraulic circuit automatically prevents the jack from bouncing up at a dangerous speed.

A further object of the invention is to provide an improvided combination jack where, when it is being operated pneumatically, the hydraulic arrangement automatically follows the neumatic operation to maintain a cushion of oil effective to check too fast a movement in either direc- 3,329,403 Patented July 4, 1967 ice tion, Thus, if there was a sudden failure in the source of compressed air the jack would still stand on a column of oil, if the hydraulic return valve is closed, or allow descent at slow speed if the latter valve is open.

With the above and other objects in view, the invention consists of the improved combination hydraulic and pneumatic jack and all of its parts and combinations as set forth in the claims and all equivalents thereof. In the accompanying drawings ilustrating one complete embodiments of the preferred form of the invention, in which the same reference numerals designate the same part in all of the views:

FIG. 1 is a vertical sectional view through the jack showing the parts in lowered position, parts of the base and lifting arms being broken away;

FIG. 2 is a sectional view taken approximately on the line 2-2 of FIG. 1, .parts being broken away;

FIG. 3 is a sectional view taken approximately on the line 3-3 of FIG. 2;

FIG. 4 is a sectional view taken approximately on the line 4-4 of FIG. 2;

FIG. 5 is a sectional view taken approximately on the line 5-5 of FIG. 2;

FIG. 6 is a sectional view taken approximately on the line 6-6 of FIG. 2;

FIG. 7 is a sectional View taken approximately on the line 7-7 of FIG. 2;

FIG. 8 is a sectional view taken approximately on the line 8-8 of FIG. 2; and

FIG. 9 is a sectional view taken approximately on the line 9-9 of FIG. 2.

Referring more particularly to the drawings, there is a suitable wheeled base rigidly supporting the lower end of an upright fixed guiding tube 16 having a disc 17 secured within its interior a short distance unpwardly from its lower end. Within the tube 1-6 and bolted by a bolt 18 to the disc 17 is an upright cylinder 19 performing the function of an hydraulic cylinder. Telescopically as-' sociated with the cylinder 19 is a tubular piston .rod 20 having an open lower end. Surrounding the lower end and suitably engaging the inner wall portion of the cylinder 19 is a piston 21. It is to 'be noted that there is a bleed hole 22 in the tubular piston rod 20 a short distance above the piston 21, which bleed hole communicates with an annular chamber 23 located betweenthe tubular piston 20 and its cylinder 19.

The upper end of the fixed tube 16 carries a packing assembly 24 which comprises a lower annular flanged packing member 25 threaded on the upper end of the tube 16, an upper annular packing member 26, and a piece of flanged packing material 27 disposed between the members 25 and 26. The member 26 has a depending ring 28 which has threaded engagement with the threading on the upper end of the fixed tube 16.

The upper packing member 26 has an upstanding cylindrical central portion 29 and suitable ears for rotatably supporting rollers 30 which rollably engage the interior of an extensible air cylinder 31. Threaded into the upper end of the hydraulic cylinder 19 is a fitting 32 serving as a guide for the upper end of the tubular piston rod 20 during telescoping movement of the latter, there being suitable seals carried by the member 32, and there being a slidable engagement between the interior of the annular member 29 and the exterior of the fitting 32, with a suitable annular sealing member 33 therebetween.

Secured to a reduced upper end of the outer cylinder 31 and to the upper end of the tubular piston rod 20 is a pump head 34. Projecting upwardly from the top of the head is a reservoir 35 having its top 36 suitably arranged to act as a lifting surface when required. A bolt 37 detachably connects the reservoir to the top of the head 34.

Hydraulic operation As in Patent No. 2,926,888, when the pivoted operating handle 38 of the oil pump is raised and operated to pull the plunger 39 in an outward direction ('FIG. 1), hydraulic fluid such as oil from within the reservoir 35 is sucked down through the duct 40 (FIG. 7) of the pump head 34 and upwardly into duct portion 41, and then past a non-return ball check 42 into the :bore for the plunger 39, the latter communicating with the duct 41 through the passageway 39 (see FIGS. 3 and 7 On the return stroke of the plunger 39 the ball 42 closes (see FIG. 1) and the fluid is forced past ball 43 into a duct 44 and down through duct 45 into the interior of the tubular piston rod 20 (see FIG. This oil under pressure reacts with the lower end of the piston 21 as well as with the portion of the pump head.34 which surrounds the oil inlet 45 to cause raising of the head, outer cylinder '31, and tubular piston rod 20. It is to be noted that the lower end of the outer cylinder 31 has a wheeled assembly 46 bolted thereto by bolts 47, which wheeled assembly carries wheels 48 which ride on the outside of the tube "16 during operation of the jack.

To lower the jack hydraulically, the lever 49 is turned to a position to open the check valve 50. This allows oil from the hydraulic cylinder 19 to flow out through passageway 45 and duct 44 (FIG. 5) into an outlet line 51 (FIG. 6) which connects with lateral outlet ports 52. This oil then must pass slowly through a screen 53 before it can enter the reservoir 35.

The screen disperses the oil slowly into a lowermost portion of the reservoir where it is always below the level 'of the oil. If no screen were employed the oil discharging violently from the exhaust port '51 would pass violently upward into the top, air-filled portion of the reservoir to splash around and mix with the air. This would in time result in air accumulating in the lower portion of the hydraulic cylinder 19 which air might enter said portion each time the jack is raised pneumatically, creating a void in the hydraulic cylinder which sucks in oil from the reservoir. If this were air-mixed oil, air would naturally be entrained with the oil. With the present invention the oil in the reservoir is prevented from mixing with the air .which is always in the upper portion thereof.

The pneumatic mechanism- Referring to FIGS. 2 and 4, there is an air inlet port 54 to which the end of an air hose 55 may be readily coupled in any convenient manner. This is a standard air hose which is usually present in all filling stations and garages. Air admitted into the port 54 is adapted to travel through a duct 56 (FIG. 4) to an annular chamber 57 (FIG. 8) surrounding a tubular fitting 58. S-lidable within the fitting 58 is the reduced portion of a plunger 59 having an externally-projecting enlarged end 60. The end 60 is pivotally connected at 61 to a lever 62 as shown in FIG. 2. The lever 62 has its inner end suitably pivoted to the head 34.

Compressed air entering the chamber 63 (FIG. 8) through radial ducts 63' is normally confined between sealing rings 64 and 65 which are located on the longitudinally spaced enlarged portions of the plunger. The plunger 59 has an inner extension portion 59a movable in a chamber 66. The extreme inner end of the plunger portion 59a is enlarged and carries a sealing ring 67. The spring 68 within the chamber 66 normally acts between washers 69 and 70, which are slidable on the plunger portion 590, to normally hold the plunger in the position of FIG. 8.

Pneumatic operation With an air hose coupled to the head as in FIGS. 2 and 4, if the lever 62 is manipulated to push the plunger "59 inwardly, the seal 64 will be moved sufiiciently far to the left in FIG. 8 to allow compressed air to enter the chamber 66. This air will then flow by way of the duct 71 into the chamber portion 72 beneath the head 31. The

compressed air in the chamber 72 reacts on the underside of the head 34 to cause lifting of the jack. When this is occurring the piston tube 20 is moving upwardly, allowing more space for oil within the center of the jack. This creates a void which sucks oil from the reservoir past the non-return check valve (FIG. 5) into the interior of the tube 20 and into the other spaces within the cylinder 19. Thus this oil follows the air operation to act as a constant check in case something goes Wrong with the air sup ly. This sucking of the oil into the system during pneumatic operation also makes hydraulic operation immediately available for further lifting whenever it might be needed, should it be desired to change from air operation to a hand pumping hydraulic operation.

To lower the jack, when operating with air, the lever 62 of FIG. 2 is pulled outwardly. This unseats O-ring 67 from its valve seat and allows all of the air from within the space 72 of the jack to pass out through the port 71, and exhaust duct 73 (FIG. 8) to the atmosphere. During such lowering, the hydraulic exhaust valve 50 of FIG. 6 must also be in open condition.

Overload safety feature When operating hydraulically, if it is attempted to lift more than a rated load (for example, more than 4000 lbs.) the normally spring closed relief valve 74 will open under the excess pressure and oil will bypass into the reservoir 35 to prevent hydraulic actuation of the jack.

When operating the jack pneumatically, if it is attempted to lift too large a load the air pressure reacts on a slidably mounted piston 75 (FIGS. 8 and 9), there being a plate 76 carried by the upper end of the piston which is connected to the upper end of the rod 77 for the valve 74. This is normally set at 4000 lbs. The average garage load is in the neighborhood of 2500 lbs. This therefore unseats the valve 74 to bypass oil into the reservoir and prevents supplemental use of the hydraulic system. Therefore, if the air capacity is not sufiicient to lift the excessive load, the operator is automatically prevented from trying to supplement the pneumatic pressure by a hydraulic pumping operation beyond rated capacity. While there is no direct provision for release of air under these circumstances, this is unnecessary, because the jack can be built to stand all of the air pressure which is normally available. It is only when there is an attempt to combine the maximum available air pressure with additional hydraulic lift capacity that there is danger of overloading the jack.

General operation In general, when operating the jack hydraulically it will be operated in the same manner as fully described in prior Patent No. 2,926,888, dated Mar. 1, 1960, the load being supported on spaced arms 78, as shown more clearly in the prior patent, or in any other suitable manner. Or, of course, the load may be supported on the top of the reservoir 35. With the present combination jack, where air is conveniently available it is the usual practice to couple the air hose 55 with the air port 54 and then push the handle 62 inwardly to cause flow of air into the air chamber 72 within the top of the air cylinder 31. This will cause rapid lifting of the jack into contact with the load and rapid lifting of the load to final position, or in certain cases, close to final position. In the latter situation, if an accurate final position is desired the air valve lever 62 may be released to the position of FIG. 2 and the handle 38 may be manipulated to cause a few strokes of the pump plunger 39 until the load is in the final desired position.

As heretofore described, during pneumatic operation oil free of air is sucked into the interior of the tubular piston rod 20 and then into the lower end of the hydraulic cylinder 19. This supply of oil follows the pneumatic operation to act as a constant check in case something goes wrong with the air supply. Also, by thus maintaining the hydraulic system full of oil during air operation, oil in the system is immediately available for lifting whenever it is desired to shift from pneumatic operation to hydraulic operation.

To lower the jack, when operating with air, the lever 62 of FIG. 2 is pulled outwardly, which allows exhaust of air through the exhaust port 73 of FIG. 8, as heretofore explained. During such lowering it is also necessary to have the hydraulic control lever 49 for the hydraulic valve 50 (FIG. 6) in open condition to allow oil to return to the reservoir 35. This requirement that both valves must be open for lowering is also a safety feature. At any time during lowering, if air is lost through some emergency condition or through leakage in the pneumatic system, the lowering of the jack and load will always be controlled on a column of oil. Whenever the lever 49 for the hydraulic valve 50 is in the closed position, the jack will support the load in fixed position, regardless of the condition of the pneumatic system such as leaks from long use.

Safety feature when load is lost During pneumatic raising, if the load should suddenly slip off of the jack, the compressed air cannot act to cause the jack to spring violently upwardly to tear itself apart, as is possible with the conventional pneumatic jack. With the present invention, when such an emergency occurs, the oil within the annular chamber 23 which surrounds the tubular piston rod must be bled out of the hole 22 in order to permit the jack to rise. This hole is of such size that such bleeding can only take place at a selected rate. Thus it eliminates the possibility of the jack springing up violently, even if the handle 49 for the valve 50 should be left in open condition. Normally the leaving of the valve 50 closed acts as a safety factor in itself.

From the above it is apparent that a very eflicient jack has been provided, wherein the air and hydraulic systems are completely separated so that it is possible to use them independently, as well as to switch from one to the other at will. It is also apparent that the arrangement is such as to provide safety in all emergencies which might be encountered.

Various changes and modifications may be made without departing from the spirit of the invention, and all of such changes are contemplated as may come within the scope of the claims.

What I claim is:

1. A hydraulic and pneumatic jack comprising a base, a lifting element, means between said base and lifting element supporting the latter for extensible movement and including a pneumatic chamber located to react on said lifting element, means for directing compressed air from an external source into said pneumatic chamber to cause such extensible movement, an optionally selectable hydraulic ram between said base and lifting element. for causing such extensible movement, an hydraulic circuit for said ram including a reservoir, and means including an externally operable hydraulic pump in said hydraulic circuit for controlling the operation of said hydraulic ram in causing such extensible movement of said lifting element.

2. A ja-ck as set forth in claim 1 in which there is means in the hydraulic circuit between the reservoir and the hydraulic ram for causing the drawing of oil from the reservoir into the hydraulic ram whenever the jack is pneumatically raised so that the hydraulic ram and its circuit are always immediately available for hydraulic operation.

3. A jack as set forth in claim 1 in which the lifting element includes a head and in which the hydraulic ram is located between the head and base and in which the hydraulic pump is carried by said head.

4. A jack as set forth in claim 1 in which there is means releasably locking the hydraulic circuit to maintain the jack in a selected position against descent regardless of whether the jack is being operated pneumatically or hydraulically.

5. A jack as set forth in claim 1 in which there is a submerged oil exhaust port connected with the reservoir and in which there is a screen element covering said exhaust port and having mesh of a size to cause the oil exhausted therethroug-h, during lowering of the jack, to be dispersed slowly into the lower portion of the reservoir.

6. A jack as set forth in claim 1 in which there is relief means in the hydraulic circuit responsive to air pressure, when the jack is being operated pneumatically with an overload, to prevent supplemental hydraulic operation while said overload continues.

7. A jack as set forth in claim 1 in which the lifting element includes an extensibly supported outer pneumatic cylinder having the pneumatic chamber in an upper portion thereof, and in which the hydraulic ram includes a stationary ram cylinder within said pneumatic cylinder and also includes a tubular piston rod depending from the lifting element for telescopic movement in said hydraulic cylinder.

'8. A jack as set forth in claim 7 in which the hydraulic reservoir is carried by the lifting element and in which there is means for releasably locking the hydraulic circuit to prevent return of hydraulic fluid from the ram to the reservoir and thereby prevent descent of the jack whether it is being operated pneumatically or hydraulically.

9. A jack as set forth in claim 3 in which the head carries the hydraulic pump and also accommodates the air directing means leading to the pneumatic chamber, and in which there is valve means associated with said air directing means in the head for controlling the admission and exhaust of compressed air to and from said pneumatic chamber.

10. A jack as set forth in claim 1 in which the base has an upright guiding tube provided with packing means at its upper end; in which the hydraulic ram includes an upright elongated hydraulic cylinder projecting upwardly from the base within said guiding tube and surrounded thereby; in which the lifting element includes an outer pneumatic cylinder telescopically supported on the packing member of said guiding tube and having a head; in which the hydraulic ram also includes a tubular piston rod projecting downwardly from said head within said hydraulic cylinder and movable with said head; in which the pneumatic chamber is located within said pneumatic cylinder between said packing member of the guiding tube and the head; and in which the hydraulic pump is located in said head and is arranged to introduce oil under pressure into said hydraulic cylinder through said tubular piston rod.

References Cited UNITED STATES PATENTS 1,465,278 8/1923 Melchior 2s4 93 X 2,926,888 3/1960 Schultz 2s4 2 FOREIGN PATENTS 86,494 6/1936 Sweden.

OTHELL M. SIMPSON, Primary Examiner.

Claims (1)

1. A HYDRAULIC AND PNEUMATIC JACK COMPRISING A BASE, A LIFTING ELEMENT, MEANS BETWEEN SAID BASE AND LIFTING ELEMENT SUPPORTING THE LATTER FOR EXTENSIBLE MOVEMENT AND INCLUDING A PNEUMATIC CHAMBER LOCATED TO REACT ON SAID LIFTING ELEMENT, MEANS FOR DIRECTING COMPRESSED AIR FROM AN INTERNAL SOURCE INTO SAID PNEUMATIC CHAMBER TO CAUSE SUCH EXTENSIBLE MOVEMENT, AN OPTIONALLY SELECTABLE HYDRAULIC RAM BETWEEN SAID BASE AND LIFTING ELEMENTS FOR CAUSING SUCH EXTENSIBLE MOVEMENT, AN HYDRAULIC CIRCUIT FOR SAID RAM INCLUDING A RESERVOIR, AND MEANS INCLUDING AN EXTERNALLY OPERABLE HYDRAULIC PUMP IN SAID HYDRAULIC CIRCUIT FOR CONTROLLING THE OPERATION OF SAID HYDRAULIC RAM IN CAUSING SUCH EXTENSIBLE MOVEMENT OF SAID LIFTING ELEMENT.

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