US3270546A

US3270546A - Drives for forge tongs

Info

Publication number: US3270546A
Application number: US78901A
Authority: US
Inventors: Wuppermann August Theodor
Original assignee: Hydraulik GmbH
Current assignee: Hydraulik GmbH
Priority date: 1959-12-28
Filing date: 1960-12-28
Publication date: 1966-09-06
Anticipated expiration: 1983-09-06
Also published as: DE1153593B

Description

p 1966 A. T. WUPPERMANN 3,270,546

DRIVES FOR FORGE TONGS 4 Sheets-$heet 1 Filed Dec. 28. 1960 INVENTOI? Sept. 6, 1966 A. TQWUPPERMANN 3,270,545

- I DRIVES FOR FORGE TONGS Fil ed Dec. 28. 1960 4 Sheets-Sheet 2 P 6, 1966 A. T. WUPPERMANN 3,270,546

mums FOR FORGE TONGS 4 Sheets-Sheet 3 Filed Dec. 28. 1960 W sm A. T. WUPPERMANN 3,270,546

DRIVES FOR FORGE TONGS 4 Sheets-Sheet 4 mmswrop Sept. 6, 1966 Filed Dec. 28, 1960 mw i RUE

United States Patent 3,270,546 DRIVES FOR FORGE TONG August Theodor Wupperrnann, Leverkusen-5chlebusch, Germany, assiguor to Hydraulik G.m.h.H., Duisburg, Germany Filed Dec. 28, 1960, Ser. No. 78,901 Claims priority, application Germany, Dec. 28, 1959, 1-1 38,265; Jan. 16, 1960, H 38,401 11 Qlaims. (Cl. '72419) The present invention relates to forge tongs.

More particularly, the present invention relates to heavy forge tongs of the type which are mounted on a travelling support so that the tongs can travel to and from the forging "hammer or forging press.

Such forge tongs have components which are required to carry out rotary movements. For example the carrier for the tongs themselves is generally an elongated horizontal element which is required to turn in both directions about its horizontal axis so as to be able to place the work at a desired angular position. Moreover, at least one or more of the wheels of the forge tongs are required to turn in opposite directions so as to enable the forge tongs to travel in opposite directions. With relatively large forge tongs a considerable advantage is obtained from operating all of the movable components hydraulically with a pressure fluid which is derived from a hydraulic pressure accumulator. With such an arrangement there is the advantage that a single pump is required to cooperate only with the pressure accumulator while all of the lines for pressure fluid going to all of the various movable components derive their fluid under pressure only from the pressure accumulator. In forge tongs of this type the rotary components are usually driven from a hydraulic device which includes a cylinder and a reciprocating piston and these elements are quite heavy and the piston usually operates a rack which must cooperate with the rotatable element which it drives through a suitable reversing transmission so that it is possible to continuously rotate the rotary component in a chosen direction of rotation irrespective of the direction of movement of the piston. Such drives for the rotary elements of a forge tongs.

are extremely complex and expensive as well as quite massive, and they represent a considerable disadvantage to forge tongs of the above type. Furthermore, particularly with relatively heavy forge tongs, it is conventional to guide the tongs on tracks which do not provide the possibility of steering the forge tongs. Relatively light forge tongs are capable of being steered and do not travel on tracks, but such forge tongs are light enough to be driven by electric motors, for example.

It is accordingly one of the primary objects of the present invention to provide a forge tongs in which all of the components, including the rotary components, are driven from a single hydraulic pressure accumulator while at the same time the rotary components are driven with a structure which is quite light and which is capable of operating the rotary component in one direction or the other without necessitating the use of a heavy piston and cylinder arrangement or of a reversible transmission.

Another object of the present invention is to provide hydraulic drives for rotary forge tong components in such a way that these hydraulic drives are quite light and compact while at the same time being capable of exerting the required force and also being easily controlled and easily accessible and serviced.

It is furthermore an object of the present invention to provide a forge tongs which while being quite heavy nevertheless can be steered and does not require tracks to guide it.

An additional object of the present invention is to pro- 3,275,546 Patented Sept. 6, 1966 vide for a heavy forge tongs which can be steered, hydraulic drives which are light and compact, which can be mounted quite close to the driven elements, and which are capable of producing the necessary power in an eflicient, simple manner.

With the above objects in view the invention includes, in a forge tongs which includes one or more rotary elements, a source of hydraulic fluid under pressure and a hydraulic motor connected to the source of fluid under pressure and operatively connected with the rotary element so as to drive the latter. With the use of a hydraulic motor, as distinct from a cylinder in which a piston reciprocates, the weight and complexity of the hydraulic driving structure is greatly reduced and simplified.

The novel features which are considered as characteristic for the invention are set forth in particular in the appended claims. The invention itself, however, both as to its construction and its method of operation, together with additional objects and advantages thereof, will be best understood from the following description of specific embodiments when read in connection with the accompanying drawings, in which:

FIG. 1 is a diagrammatic, partly sectional, side elevation of a forge tongs which includes the structure of the invention, FIG. 1 showing particularly the structure for turning the tongs carrier;

FIG. 2 is a transverse view of a wheel assembly of FIG. 1 and shows in particular the hydraulic wheel driving structure of the invention;

FIG. 3 is a diagrammatic, partly sectional side view of another embodiment of a forge tongs, the tongs of FIG. 3 being capable of steering without the use of tracks;

FIG. 4 is a view of the structure of FIG. 3 as being in the direction of tht arrow A of FIG. 3, FIG. 4 illustrating the structure for driving and steering a wheel of the forge tongs;

FIG. 5 is a view corresponding to FIG. 4 on an enlarged scale as compared to FIG. 4 showing the hydraulic structure of the invention for driving a wheel of the forge tongs;

FIG. 6 is a partly sectional fragmentary view on an enlarged scale showing the structure for carrying out steering of the forge tongs of FIGS. 3 and 4;

FIG. 7 is a partly sectional elevation of another embodiment of a drive according to the invention for a wheel which is capable of being turned so as to steer the forge tongs; and

FIG. 8 shows the structure for turning the wheel of FIG. 7 so as to steer the forge tongs.

Referring to FIG. 1, the forge tongs diagrammatically illustrated therein includes a frame 1 made up of a plurality of interconnected heavy metal plates. A pair of wheel-carrying shafts extend turnably through the plates of the frame 1 and carrying the

wheels

3 and 3a which support the forge tongs for movement. Thus, there are a pair of front wheels 3a and a pair of rear driving wheels 3, and all of these wheels are guided on suitable tracks, as is particularly apparent from FIG. 2. FIG. 1 shows the rear shaft 2 which carries the rear wheels 3. These wheels 3 are fixed to the shaft 2 so that when the latter is turned the wheels 3 turn and produce travelling movement of the forge tongs.

As is shown at the left of FIG. 1, the forge tongs include the jaws 4 which grip the work, and these jaws are carried by bell cranks which are pivotally connected and which are supported for pivotal movement by the elongated carrier 5 which extends horizontally and which is axially bored, as is indicated in FIG. 1. The elongated tongs carrier 5 is supported for rotary movement by the tubular element 6 through which the carrier 5 passes, this tubular member 6 having in its interior suitable bearings which engage journal portions of the carrier 5 so as to support the latter for rotary movement about its horizontal axis. The tubular member 6 is suspended from four arms 7, and these arms are respectively pivotally suspended from the arms 3 which are shown extending horizontally in FIG. 1. Thus, there are four arms 8 and these arms are turnably carried by a pair of horizontal shafts 9 which are respectively supported by the extensions 10 of the frame plates of the forge tongs. Unillustrated cylinder and piston means cooperate with the arms 8 to tilt the latter to selected angular positions so as to raise or lower the carrier 5 and so as to provide the carrier 5 with a selected degree of inclination.

The jaws 4 are actuated by axial movement of the bar 11 which is pivotally connected at its left end to the bell cranks which directly support the jaws and which are turnably carried by the rotary carrier 5, as indicated diagrammatically in FIG. 1. At its right end, as viewed in FIG. 1, the bar 11 is fixed to a piston 12 which is in a cylinder adapted to receive fluid under pressure so that through this hydraulic arrangement it is possible to move the bar 11 axially so as to actuate the jaws of the tongs.

All of the above-discussed structure is conventional and well known.

In accordance with the present invention, in order to rotate the carrier 5 about its axis in one direction or the other, a suitable transmission is operatively connected with the carrier 5, and this transmission includes the gear 13 which is fixed to the rear end of the carrier 5 projecting beyond the tubular member 6 and the pinion which meshes with the gear 13. The pinion 15 itself is driven through a suitable step-down transmission 14 from the hydraulic motor 16, in accordance with the present invention. Both the step-down transmission 14 and the hydraulic motor 16 are carried by the tubular member 6 so as to be always maintained in proper operative relationship with respect to the pinion 15 and gear 13, and flexible

hydraulic conduits

36 and 37 communicate with the hydraulic motor 16 so as to supply the latter with a hydraulic fluid such as oil under pressure for driving the motor 16 and thus bringing about the turning of the carrier 5. In accordance with the present invention the hydraulic motor 16 is a simple gear motor. In other words the motor 16 has the structure of a conventional gear pump, but instead of being driven by a motor so as to pump a fluid, fluid under pressure is supplied to the gear pump structure so that this structure will act as a gear motor. These motors are extremely simple and rugged in construction as well as reliable in operation, and by the use of such a drive, in accordance with the present invention, the necessity of heavy and complex racks, cylinders and pistons for reciprocating the same, and reversing drives :are completely eliminated. It will be noted that the pinion 15, the transmission 14, and the motor 16 are all coaxially arranged.

Referring now to FIG. 2, the structure of the invention includes a gear 17 which is fixed to the shaft 2 which is in turn fixed to the wheels 3 coaxially therewith. A pinion 18 meshes with the gear 17 and is driven through a suitable step-down transmission from a hydraulic motor 19 which may be identical with the motor 16. The transmission 20 and the hydraulic motor 19 are supported on a bracket which is carried by one of the plates of the frame 1, and the bracket has a wall extending over the shaft 2 so that the transmission 20 and the motor 19 as well as the pinion 18 are all coaxially arranged. In this case also the use of a hydraulic gear motor for the drive of the wheels 3 permits the drive to be greatly simplified and enables the use of racks and reversing drives to be eliminated.

Not only do the motors 16 and 20 provide a great simplicity in the drive of the rotary components in one direction, but in addition it is a simple matter through the use of a suitable valve and conduit arrangement to reverse the direction of flow of hydraulic fluid, if desired, so as to reverse the direction of drive. However, it is preferred to use for the transmissions 14 and 2t) transmissions which include reversing gears so that by simply adjusting these transmissions it is possible for the operator to control the direction of rotation of the pinion 15 by the motor 16 and the tranmission 14 or the pinion 18 by the motor 1Q and the transmission 20. By using the transmissions themselves for producing the reversing it is possible to operate the motors 16 and 1: in one direction at all times and to greatly simplify the conduit arrangement.

FIG. 1 shows at the right portion of FIG. 1, in a diagrammatic manner, the hydraulic pressure accumulator which includes the stationary cylinder 21. A pair of tanks 22 which contain a suitable gas under pressure communicate with the conduit 29 which in turn communicates with the upper end of the cylinder so as to supply gas under pressure to the interior of the cylinder in the space 23 thereof on the upper side of the piston 24 which is slidable in the cylinder. The space 25 within the cylinder on the underside of the piston 24 is filled with a liquid such as oil under pressure. The piston rod 2s extends fluid-tightly and slidably through the lower wall of the cylinder to the exterior thereof and carries at the exterior of the cylinder a motion transmitting means 27 which moves with the piston 24. This motion transmitting means 27 has an extension which moves along a path in which a valve 28 is located, so that when the piston 24 reaches a predetermined elevation the motion transmitting means 27 will engage and open the valve 28, this valve otherwise being closed.

As is indicated diagrammatically in FIG. 1, a reservoir 38 for a liquid such as oil is provided, and the pump 30 is driven by the motor 33 and sucks the oil from the reservoir 38 to supply this oil into the cylinder in the space 25 thereof through the conduit 34. This conduit carries a non-return valve 35 so that once the oil flows from the pump 31) past the valve 35, the oil cannot flow back toward the pump 30. A circulating circuit is provided, and this circulating circuit includes the conduits 31 and 32. The conduit 31 leads from the pump 31 to the valve 28, while the conduit 32 leads from the valve 28 back to the reservoir 38. Thus, the conduits 31 and 32 are normally maintained out of communication with each other by the closed valve 28. However, when the piston 24 reaches a predetermined elevation in the cylinder, the motion transmitting means 27 will actuate the valve 28 so as to open the same and place the conduits 31 and 32 in communication with each other, so that now the liquid which is pumped by the pump 30 will simply circulate through the circulating circuit and the pump 30 will not deliver any more liquid to the cylinder of the hydraulic pressure accumulator 21. Of course, other arrangements may be provided for limiting the supply of oil under pressure to the hydraulic pressure accumulator, although the abovedescribed circulating circuit is preferred. For example, it is possible to have the motion transmitting means 27 open a switch when the piston 24 has reached a predetermined elevation, and this switch may be included in the circuit of the electric motor 33 so as to turn off the motor and thus stop the operation of the pump 30. FIG. 1 shows the pressure conduit 36 which receives oil under pressure from the accumulator so as to deliver the oil to the pump 16, and the oil returns from the pump 16 through the conduit 37 back to the reservoir 38. A similar pair of conduits interconnect the hydraulic pressure accumulator with the motor 19 used to drive the wheels of the forge tongs, and in the case of the motor 16 the conduits are flexible so that the motor 16 is free to move with the tubular member 6. Of course, all of the various other elements are operated hydraulically from the hydraulic pressure accumulator 21, but the drawings show only the gear pumps 16 and 19 used to drive the rotary components in accordance with the present invention. It should be noted that instead of using gear pumps Which are operated as motors, it is possible to use piston pumps of the axial or radial type which are again supplied with fluid under pressure so that they will operate as motors, although the use of gear motors is preferred since such motors are extremely compact and simple.

The embodiment of the invention which is illustrated in FIGS. 3-8 differs from that of FIGS. 1 and 2 only with respect to the transportation of the forge tongs. Thus, instead of providing wheels guided by tracks, as indicated in FIGS. 1 and 2, the forge tongs of FIGS. 3-8 can ride on a floor without the use of tracks and can be steered by the use of the hydraulic structure of the invention for driving as Well as steering purposes, even though the forge tongs are quite heavy.

Thus, referring to FIGS. 3-6, it will be seen that the frame of the vehicle is connected with a fork 40 which includes a downwardly directed bifurcated portion and an upwardly directed shank 42. The forge tongs includes a single rear wheel 39 which is located between the bifurcations of the fork 40 and which is supported on a suitable shaft extending between these bifurcations of fork 40 for rotation therein. This arrangement is shown in particular in FIGS. 4 and 5. It should be noted that the shaft which extends through the bifurcations of the fork 40 is fixedly connected with the wheel 39. A pair of hydraulic motors 41 which may also be in the form of gear motors of the type described above are connected operatively with the wheel 39 to drive the latter. The shank 42 is turnable in a vertical sleeve 43 which is fixedly carried by the frame 1, and as is diagrammatically indicated at the right portion of FIG. 3, the hydraulic fluid flows to and from the motors 41 through conduits parts of which are in the form of bores passing through the shank 42 and communicating with annular recesses which are supplied with the oil under pressure in the manner indicated diagrammatically in FIG. 3. The oil flows in the direction of the arrows shown in FIG. 3 at the upper part of the shank 42. With this arrangement, which is to say by directing the oil along bores formed in the shank 42 itself, all of the structure carried by the fork 40 and used to drive the wheel 39 can turn with the fork 40 about the axis of its shank 42 so as to remain in operative relation with respect to the wheel 39.

In order to be able to steer the forge tongs, the shank fixedy carries a pinion 48 above the bifurcated portion of the shank, and this pinion 48 meshes with a rack 47 which is guided for longitudinal movement and which is fixed to the piston rod 46 of a piston 45 which reciprocates in a stationary horizontal cylinder 44 carried by the support means formed by the frame 1. The hydraulic conduit system which communicates with the cylinder 44 communicates therewith on opposite sides of the piston 45 and the valve structure is such that it is possible to deliver fiuid under pressure to either side of the piston 45 so as to move the rack 47 in one direction or the other to bring about the desired direction of turning of the forge tongs. This construction is shown partly in FIG. 4 and most clearly in FIGS. 3 and 6. i

As is shown most clearly in FIG. 5, the structure for driving the wheel 39 so as to move the forge tongs includes a pair of hydraulic motors 41 communicating through suitable conduits with the single hydraulic pressure accumulator. Both of these motors 4-1 are coaxially arranged with respect to the wheel 39 as well as with respect to a pair of stepped-down transmissions 49 which are operatively connected with the shaft which fixedly carries the Wheel 39. Thus, the pair of transmissions 49 and the motors 41 are all coaxial with each other and with the wheel 39. With this arrangement it is possible to direct the oil under pressure to one of the motors 41 for driving the wheel in one direction and to the other of the motor 41 for driving the wheel in the opposite direction, or, if desired, both motors may operate simultaneously on the wheels and the transmissions 49 may be provided with the reversing gears as was described 6 above in connection with the other transmissions. These motors 41 are preferably gear motors, although it is also possible to use oil piston motors of the radial or axial type.

FIGS. 7 and 8 show another embodiment of a drive for the wheel. Thu-s, as may be seen from FIG. 7, the lower bifurcated portion of the fork 40 directly carries the hydraulic motor 41. The shaft driven by the motor 41 extends through a suitable bore formed in one of the bifurcations of the fork 40 and is fixed at its right end, as viewed in FIG. 7, to a pinion 54. The wheel includes a pair of

stationary plates

51 and 52 which are quite heavy so as to be very stiff and which are fixedly carried by the bifurcations of the fork 40 in the manner illustrated in FIG. 7. These

plates

51 and 52 are circular and coaxial, and they are surrounded by a ring 53 which is fixed at its exterior to an outer ring 50 which directly engages the floor. The ring 53 surrounds and engages the exterior periphery of the

plates

51 and 52 and is freely turnable with respect to the peripheries of these plates, the ring 53 sliding along the exterior periphery of the

plates

51 and 52. In its interior the ring 5-3 is integral with an internal ring gear having inwardly directed teeth. The pinion 54 meshes with a gear 55 which is fixed to a shaft which is supported for rotation by and extends between the

plates

51 and 52, and this shaft carries a gear 56 meshing with a gear 57 which is fixed to a shaft also supported by the plate 52 and fixedly carrying the pinion 58 which meshes with the internal ring gear which is integral with the ring 53. Thus, with this embodiment the step-down transmission is located entirely within the space between the

plates

51 and 52 of the wheel and an exceedingly compact arrangement is provided. The wheel of FIGS. 7 and 8 is turned about the axis of its shank through the same structure as was described above in connection with FIGS. 3-6.

It will be understood that each of the elements described above, or two or more together, may also find a useful application in other types of forge tongs differing from the types described above.

While the invention has been illustrated and described as embodied in drives for rotary elements of forge tongs, it is not intended to be limited to the details shown, since various modifications and structural changes may be made without departing in any way from the spirit of the present invention.

Without further analysis, the foregoing will so fully reveal the gist of the present invention that others can by applying current knowledge readily adapt it for various applications without omitting features that, from the standpoint of prior art, fairly constitute essential characteristics of the generic or specific aspects of this invention and, therefore, such adaptations should and are intended to be comprehended within the meaning and range of equivalence of the following claims.

What is claimed as new and desired to be secured by Letters Patent is:

1. In a forge tongs, in combination, at least one rotary component; hydraulic motor means operatively connected to said rotary component for rotating the same; a hydraulic pressure accumulator communicating with said motor means for driving the same, said hydraulic pressure accumulator including a cylinder, a piston extending transversely through said cylinder and engaging with its peripheral surface the inner surface of said cylinder so as to be slidably guided therein, and a piston rod extending from said piston slidably through an end of said cylinder to the exterior thereof; pump means rotating only in one direction communicating with the interior of said cylinder on one side of said piston for delivering liquid under pressure to the interior of said cylinder at said one side of said piston to displace said piston in said cylinder and increase the volume in said cylinder on said one side of said piston; gas pressure means communicating with the interior of said cylinder on the other side of said piston for supplying gas under pressure to the interior of said cylinder at said other side of said piston, the volume in said cylinder at said other side of said piston decreasing during operation of said pump means to supply liquid under pressure to the interior of said cylinder on said one side of said piston; motion transmitting means carried by said piston rod at the exterior of said cylinder for movement with said piston rod; and control means located in the path of movement of said motion transmitting means and cooperating with said pump means to terminate the supply of liquid under pressure to said one side of said piston in said cylinder when the volume in said cylinder on said other side of said piston has been decreased to a predetermined extent.

2. In a forge tongs, in combination, a Wheel; support means supporting said wheel for rotary movement about its own axis for transporting the forge tongs and for rotary movement about an axis perpendicular to the wheel axis for steering the forge tongs; first hydraulic motor means operatively connected to said wheel for turning the latter about its own axis so as to transport the forge tongs; and second hydraulic motor means operatively connected to said wheel for turning the latter about said axis perpendicular to the wheel axis for steering the forge tongs.

3. In a forge tongs, in combination, a fork having a downwardly directed bifurcated portion and an upwardly directed shank portion; support means supporting said shank portion of said fork for rotary movement about the axis of said shank portion; a wheel located in said bifurcated portion of said fork and supported for rotation about its axis by said bifurcated portion of said fork, said wheel axis being perpendicular to said shank axis; first hydraulic motor means carried by said bifurcated portion of said fork and cooperating with said wheel for rotating the same so as to transport the forge tongs; and second hydraulic motor means operatively connected with said shank for turning the latter about its axis so as to steer the forge tongs.

4. In a forge tongs as recited in claim 3, said first hydraulic motor means including at least one hydraulic motor positioned coaxially with respect to said wheel axis.

5. In a forge tongs as recited in claim 3, said first hydraulic motor means including at least one hydraulic motor and a step-down transmission located between and operatively connected to said motor and said wheel, said transmission and motor forming a single unit coaxially arranged with respect to said wheel.

6. In a traveling forge tongs, in combination, an elongated tongs carrier; support means supporting said carrier for rotary movement about its axis; a first gear coaxial with said carrier and fixed thereto; a first pinion meshing with said first gear; first hydraulic motor means operatively connected to said first pinion for driving the same so that said drive is transmitted from said first pinion through said first gear to said carrier to rotate the latter; rotary wheel means connected to said support means for transporting the same, said rotary Wheel means including a shaft; a second gear fixed to said shaft; a second pinion meshing with said second gear; second hydraulic motor means operatively connected to said second pinion for driving the same so as to turn said wheel means for transporting said support means and said tongs carrier mounted thereon; and a single hydraulic pressure accumulator means operatively connected to said first and second motor means for driving the same.

7. In a traveling forge tongs, in combination, an elongated tongs carrier; support means supporting said carrier for rotary movement about its axis; a first gear coaxial with said carrier and fixed thereto; a first pinion meshing with said first gear; first hydraulic motor means operatively connected to said first pinion for driving the same so that said drive is transmitted from said first pinion through said first gear to said carrier to rotate the latter; rotary wheel means connected to said support means for transporting the same, said rotary wheel means including a shaft, a wheel mounted on said shaft, and means supporting said shaft and the wheel thereon for rotary movement about the shaft axis for transporting the forge tongs and for rotary movement about an axis perpendicular to the shaft axis for steering the forge tongs; a second gear fixed to said shaft; 2 second pinion meshing with said second gear; second hydraulic motor means operatively connected to said second pinion for driving the same so as to turn said wheel means for transporting said support means and said tongs carrier mounted thereon; third hydraulic motor means operatively connected to said means for supporting said shaft for turning said last named means about said axis perpendicular to the shaft axis for steering said forge tongs; and a single hydraulic pressure accumulator means operatively connected to said first, second and third motor means for driving the same.

8. In a traveling forge tongs, in combination, an elongated tongs carrier; support means supporting said carrier for rotary movement about its axis; a first gear coaxial with said carrier and fixed thereto; a first pinion meshing with said first gear; first hydraulic motor means operatively connected to said first pinion for driving the same so that said drive is transmitted from said first pinion through said first gear to said carrier to rotate the latter; rotary wheel means connected to said support means for transporting the same, said rotary Wheel means including a shaft; a second gear fixed to said shaft; a second pinion meshing with said second gear; second hydraulic motor means operatively connected to said second pinion for driving the same so as to turn said wheel means for transporting said support means and said tongs carrier mounted thereon; and a single hydraulic pressure accumulator means operatively connected to said first and second motor means for driving the same, said hydraulic pressure accumulator means including cylinder and piston means, pump means communicating with the interior of said cylinder means on one side of said piston means for delivering liquid under pressure to the interior of said cylinder means at said one side of said piston means, gas pressure means communicating with the interior of said cylinder means on the other side of said piston means for supplying gas under pressure to the interior of said cylinder means at said other side of said piston means, and control means operatively connected to said piston means to terminate the supply of liquid under pressure to said one side of said piston means in said cylinder means when said piston means has moved under the pressure of the liquid pumped by said pump means thereinto to a predetermined extent.

9. In a traveling forge tongs, in combination, a plurality of components which are required to carry out reversible rotary movements about their axes; a gear fixed to each of said components coaxially therewith; a pinion for each gear meshing therewith; a single hydraulic pressure accumulator; a hydraulic gear motor for each pinion and communicating with said hydraulic accumulator to be driven thereby; and a reversible stepdown transmission means between each gear motor and the correlated pinion for transmitting a drive from the motor to the pinion, whereby said motor can always be driven in the same direction While the direction of rotation of the respective component may be reversed by the reversible transmission means correlated therewith.

10. In a traveling forge tongs as set forth in claim 9, wherein each gear motor and its transmission means are arranged coaxially with the correlated pinion.

11. In a forge tongs, in combination, at least one rotary component; hydraulic motor means operatively con nected to said rotary component for rotating the same; a hydraulic pressure accumulator communicating with said motor means for driving the same, said hydraulic pressure accumulator including a cylinder, a piston slidable therein, and a piston rod extending from said piston slidably through an end of said cylinder to the exterior thereof; pump means communicating with the interior of said cylinder on one side of said piston for delivering liquid under pressure to the interior of said cylinder at one side of said piston to displace said piston in said cylinder and increase the volume in said cylinder on said one side of said piston; gas pressure means communicating with the interior of said cylinder on the other side of said piston for supplying gas under pressure to the interior of said cylinder at said other side of said piston, the volume in said cylinder at said other side of said piston decreasing during operation of said pump means to supply liquid under pressure to the interior of said cylinder on said one side of said piston; motion transmitting means carried by said piston rod at the exterior of said cylinder for movement with said piston rod; and control means located in the path of movement of s-aid motion transmitting means and cooperating with said pump means to terminate the supply of liquid under pressure to said one side of said piston in said cylinder when the volume in said cylinder on said other side of sai-d piston has been decreased to -a predetermined extent, said control means including a circulating hydraulic circuit through which said pump means circulates liquid Without delivering any liquid to said cylinder, and a valve means locate-d in said circuit and norm-ally maintaining the same closed, said valve means being located in the path of movement of said motion transmitting means to be engaged and opened thereby when said piston has been displaced to a position providing -a reduction in the volume of said cylinder on said other side of said piston to said predetermined extent to be opened by said motion transmitting means so as to open said circuit and allow the pump means to circulate the liquid therethrough so as to terminate the supply of liquid to said cylinder.

References Cited by the Examiner UNITED STATES PATENTS 824,740 7/1906 Poulson 180-10 1,322,028 11/1919 Lehman 180-10 1,828,762 10/ 1931 Brosius 78-96 1,881,169 10/1932 Brosius 78-96 2,257,546 9/ 1941 Dienenthal 7996 2,285,604 6/ 1942 Mercier -51 2,392,471 1/ 1946 Fox 60-51 2,430,528 11/1947 Moon -10 2,532,786 12/1950 Richter 180-79.2 2,554,593 5/1951 Sedille 180/66 2,645,298 7/1953 Hawkins 180-66 2,712,422 7/1955 Gerwig 18079.2 2,720,800 10/1955 Taylor 78-96 2,733,771 2/1956 Sullivan 180-66 2,774,436 12/1956 Ferris 180-66 2,792,954 5/1957 Westling 78-96 2,795,932 6/ 1957 McLuen 60-51 2,918,907 12/1959 Hausmann 180-10 2,954,834 10/1960 Hammar 180-66 3,126,770 3/1964 Wuppermann et al. 78-96 FOREIGN PATENTS 972,409 7/ 1959 Germany.

CHARLES W. LANHAM, Primary Examiner.

WILLIAM W. DYER, JR., WILLIAM J. STEPHENSON,

Examiners.

G. P. CROSBY, Assistant Examiner,