US2188364A - Load lifter and balancer - Google Patents

Description

Jan. 30, 1940. J, P. LANNEN LUAD LIFTEB AND BALAN'CER Filed Jan. 7, 193.8

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Zmventor Josep/L P dnnen Lr w1 Patented Jan. 30, 1940 y UNITED STATES PATENT y OFFICE 9 Claims.

' This invention relates to load lifting and bal- `ancing devices, and particularly to pneumatic liftersv and balancers.

-An object of the invention is to provide a pneumatic device for holding a load suspended while permitting it to be readily manipulated to a considerable extent in any direction.

Another object is to provide a device adapted l to be energized by compressed air to effect lift- 'lO ing of a load to a desired working level and adapted to be supported by compressed air at such level and manipulated freely in any direction, the arrangement being such as to derive y support from a very large volume of air such I5 as will yield quite freely to allow a considerable upward or downward manipulation of the load, without valving air. I

A further object is to provide a load lifter and balancer a-dapted to sustain a load upon an air cushion, lowering of the load from its working position being eiected by displacing air from the cushioning space, and its admission to such space being regulated solely by restricting the inlet to such space. A further object is to employ the load-engaging hook of a pneumatic load lifter and balancer 'as a mounting for a valve regulating the ex haust of air from said device, thus affording a maximum convenience in exercising control.

A further object is to form a load-carrying air cushion between a piston and cylinder of a pneumatic lifter and balancer and to augment said cushion by all air in the feed line leading to said cylinder and in the tank supplying such B5 line. y

These and various other objects are attained by the construction hereinafter described and illustrated in the accompanying drawing, wherev10 Fig. l is a side elevational view of the lifter and balancer, showing its supply tank and feed line.

Fig. 2 is an axial sectional view of the appliance showing the load-carrying cylinder partiall5 ly raised or in working position.

Fig. 3 is a similar view showing the lowermost position of the load-carrying cylinder.

Fig. 4 is an enlarged view of a portion of Fig. 3, showing the illustrated parts in greater detail.

"50 In these views, the reference character I designates a piston mounted fast on the lower end of a vertically elongated pipe 2 and working in a vertically elongated cylinder 3, of greater diameter than said pipe. The upper end of such cyl- 155 inder rigidly carries an elongated head 4 having a sliding t upon the pipe 2, and packing 5, retained in the upper portion of said head, is cornpressed around the pipe, establishing a seal against the escape of air from the cylinder.` Inserted in the lower end of the cylinder and rigid- 5" livered from a tank or reservoir 9 or directly from a compressor through a hose 9a to a fitting I0 adapted to admit such air to the upper end of the pipe 2 through a cap Il rigidly engaging and u u closing said end. Said fitting preferably carries a Valve Illa controlling such air admission. From the lower end of said pipe, such air may laterally discharge into the cylinder, through a highly restricted passage I2. Thus air may be accumulated between the piston I and head 4 to lift thel cylinder to a desired extent. Downward escape of air from the pipe 2 is prevented by a plug I 3- tightly pressed into the lower end of the pipe. Y u

For venting air from the cylinder to eiect its lowering, the head 4 carries a pipe tting I4 communicating with the chamber I3 and having a pipe I5 leading therefrom exteriorly down the cylinder, such pipe bein-g connected to any suito ablelexhaust valve I6 clamped upon the shank of the hook 8, as indicated at II. Preferably such connection is established through a length of flexible hose I8, joined to the pipe I5 at the lower end of the cylinder, thus affording such swinging movement of the hook as may be necessary in its functioning. At suitable vertical intervals the pipe I5 is engaged by keepers I9 welded or otherwise xed on the cylinder, and is thus heldgin close proximity to the cylinder. The valve I6 is of any ordinary normally closed type and is preferably equipped with a lever 2U facilitating manual opening of such valve.

Forreasons which will presently appear, it may be desirable to permit a more free iiow of air into' the pipe 2 from the cylinder 3 than the restricted passage I2 permits.

As a provision for such flow, a passage 2I considerably larger than the passage I2, is jointly formed in the lower portion of the pipe 2 and 50 the upper portion of the plug I 3, and communicates with the bottom of a valve chamber opening downwardly in the plug. Within such chamber a ball check valve 22 is normally seated to prevent outow from the pipe 2 through the 55 passage 2| but may freely unseat to afford infiow.

When the cylinder is fullylowered the head 4 seats on the piston I, in a surrounding relation to the passages l2 and 2l, as illustrated in Fig. 3. To avoid obstruction of such passages, when the cylin-der is thus lowered, a restricted chamber 23 is formed in the head 4, just above the cylinder, such chamber having an adequate upward extent to maintaincommunication of said passages with the cylinder v,when the head 4 is seated on the piston, as in Fig. 3.

The described machine is suspended at any convenient elevation, its point of support being preferably at the upper end of the pipe 2.' As illustrated, the machine is suspended from` a trolley 24 mounted to travel on an overhead I beam 25, a swinging link `rod26 or the like establishing the 'suspension and engaging an eyelet 2l rigidly surmounting the cap H.

In use of the'described appliance, thevalve Illa is normally open and consequently the cylinder 3 is normally upwardly urged by compressed air admitted tothe cylinder from the pipe 2 through the passage l2 and reacting between the piston l and head 4. It follows that the cylinder and its load-carrying hook 8 automatically assume their upper limiting position (not shown), when the machine is not loaded, such position being established by engagement ofthe head 6 with the piston l. To lower the cyl-inder for loading the hook S, the Voperator vents air by opening the exhaust valve I6, exerting at the same time a light downward pull on the hook or cylinder. During such venting ofI air, there is maintained an air delivery to the cylindery through the passage l2, but the volume ofA this delivery is too small to exercise material effect. After applying a load to the hook 8, the

' operator closes the exhaust valve, and air flowing through the passage l2 again accumulates above the piston and reacts against the head 4 toupwardly urge the cylinder and load. The latter is of a magnitude suited to the lifting capacity of the machine, which is designed to sustain a certain weight at any elevation permitted by its cylinder travel.. Hence lifting of theload maybe accomplished through application by the operator of a slight upward pull to overcome the balanced relation of air pressure and dead Weight. Proximity of the piston to the head 4 in the loading position of the machine is such that there is no material delay in upward travel after closing of the exhaust valve and application of a manual lifting force. When the load has reached a desired elevation, it will be automatically maintained at that elevation, since its weight is substantially counterbalanced by the applied air pressure. Without applying any further control, the operator may now move the load as his purpose may dictate, by manually applying a very moderate force. Thus for example pressure may be applied lengthwise of the beam 25 to induce travel of the trolley 24 and thus shift the load to any desired point beneath the beam. Or the load may be swung laterally about its pivotal 'connection with the trolley to dispose it above a desired support.. Upward manipulation of the load requires only slightly greater eiortthan horizontal shifting thereof since flow through the passage I2 increases the volume of air beneath the head 4 as the cylinder is raised. Lowering of the load involves a very slight effort, since displacement of air from beneath the head 4 may occur through both of the passages l2 and 2|, the latter having a much greater flow capacity than the former. Obviously the machine can be just as usefully employed in lowering loads as in raising the same.

A machine of the described character has many uses, among which may be mentioned the raising and manipulation of heavy parts for loading or storing purposes or to position them for assembly in a machine or. other structure, and the raising -or lowering of parts'requiring machining to mount them on or remove them from the Work holder of a machine tool.

If energized by air at a substantially constant-pressure, the described machine is suited only to handle loads of a fairly definite predetermined weight, and heavier or lighter loads will require larger or smaller machines. If, however, some provision is made for varying the pressure at which air is delivered to the machine, such pressure variation. will permit of a corresponding variation in the load capacity 0f the machine.

Av vitally important and unique feature of the described machine is the maintenance of constant communication between the air cushion chamber, underlying the head 4, and reservoir from which air is delivered to the machine. This permits utilization of theair in said reservoir, in the supply line leading therefrom, and in the pipe 2, as part of the load-sustaining air cushion, and the consequent large volume of such cushion facilitates manipulation, sinceit assures that only slight resistance will be encountered in displacing air from beneath the head.4 through the passages I2 and 2L As compared to an air hoist, the described machine is much less expensive, more easily installed, more-readily portable, and allows a freer and more extensive manipulation of the load.

The invention is presented as including all such modifications and changes as come within the scope of the following. claims.V

What I claim is:

1. A pneumatic lifter and balancer comprising an upper member, a lower member carried by and movable 4upwardly and downwardly on the upper member, one of said members being a cylinder closed at one end, and the other including a piston fitted in the cylinder and a rod attached to the piston and having a sliding t in said cylinder end, a pressure chamber being formed between the piston and said cylinder end, a support from which the upper member is suspended, a load-receiving element attached to the lower member, the pressure chamber having a restricted inlet port in open communication therewith and an exhaust port of relatively large capacity opening therefrom, means for continuously delivering compressed air to the inlet port, and a manually operable valve controlling the exhaust port.

2. In a pneumatic lifter and balancer as set forth in claim 1, a valve controlling venting of the pressure chamber, secured to the load-receiving element. k

3. In a pneumatic lifter and balancer as set forth in claim l, al check valve carried by one of said members, such member having a passage affording a free flow from the pressure chamber to said air delivery means, and said check valve resisting reverse flow through such passage.

4. In a pneumatic lifter and balancer as set forth in claim 1, a compressed air tank normally in communication with the pressure chamber through said delivery means, whereby the volume of air in the tank and delivery means supplements that in the pressure chamber in forming an air cushion.

5. A pneumatic lifter and balancer as set forth in claim 1, said rod being tubular and having constant communication with the pressure chamber,

and hence adding to the volume of air effective in the pressure chamber to form an air cushion. 6. A pneumatic lifter and balancer comprising a substantially vertical rod, a support pivotally lengaged by the upper end of the rod, a piston on the lower end of the rod, a cylinder operatively receiving the piston, the cylinder having a head closing its upper end and slidable on the rod, means for continuously delivering compressed air to the cylinder between said head and piston, an exhaust pipe communicating with the cylinder through said head, and extending downwardly along the cylinder, aload-receiving element attached to the lower end of the cylinder, and a valve controlling an outlet from the exhaust pipe in proximity to the load-receiving element, the capacity of said exhaust pipe and its control valve largely exceeding the capacity of said delivery means.

7. A pneumatic lifter and balancer comprising a substantially ver-tical pipe, having closed ends, a support, means pivotally mounting the pipe at its upper end on such support, means for delivering compressed air to the upper portion of the pipe,

piston, and forming a pressure chamber between the piston and such head, the pipe having a restricted passage adjacent to the piston for delivering air to the pressure chamber and having a relatively large passage for the displacement of air into the pipe from the pressure chamber, a check valve resisting ilow through the last-mentioned passage into the pressure chamber, a loadreceiving element carried by and beneath the cylinder, and means for regulably exhausting air from the pressure chamber.

8. A pneumatic lifter and balancer as set Aforth in Iclaim 7, said check valve being carried by the closure engaging the lower end ofthe pipe.

9. A pneumatic appliance comprising a pipe forming an air duct, a piston xed on the pipe substantially atan end thereof, a plug closing such end, a cylinder operatively receiving such piston and having a head slidably fitted on the pipe, said cylinder forming a pressure chamber between the piston and said head, a compressed air delivery line connected to the pipe exteriorly of the cylinder, two passages being provided connecting the pressure chamber and pipe, one thereof being restricted to afford a gradual flow into the pressure chamber and the other having greater capacity and providing-for displacement of air into the pipe from the pressure chamber, a check valve mounted in said plug and resisting flow into the pressure chamber through the 1arger of said passages, and means for regularly exhausting air from the pressure chamber.

JOSEPH P. LANNEN.

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