US2814872A - Fluid actuated tool - Google Patents

Description

Dec. 3, 1957 w. A. GERRANS FLUID ACTUATED Toor.

2 Sheets-Sheet 1 Filed July 5. 1955 iff/14,144]

Il l' ATTORNEYS Dec. 3, 1957 W. A. GERRANSA FLUID ACTUATED TOOL 2 Sheets-Sheet 2 Filed July 5. 1955 ATTORNEYS Unite States Patent 2,814,872 FLUID ACTUATED TOOL William A. Gerrans, Colusa, Calif. Application July 5, 1955, Serial No. 520,057 2 Claims. (Cl. 30-228) This invention relates to manually manipulated tools and more particularly to a fluid actuated tool which is adapted for heavy duty work. Although the invention will be described as embodied in a pair of pruning shears, it will be understood that the novel features of construction and method of operation lend themselves to use in other devices.

Heretofore various attempts have been made to evolve power driven pruning shears and like tools, but thus far few practical structures have been achieved. In some devices there has been an attempt to employ compressed air for actuating the tool, but the resulting structure has usually been slow in operation and capable of only light duty. The few attempts to employ a liquid such as oil, as opposed to air and other uids, have not been successful mainly because the resulting structures have been too cumbersome for manual manipulation, or if made within reasonable size limits, have not provided sucient power for heavy duty work.

It should be noted that a device which purports to lend itself to use with any fluid, including oil, must not be provided with an exhaust po-rt. Thus, when oil is employed as the uid medium, it is necessary that the exhaust oil be returned to the power means although if air is used it may be discharged into the atmosphere.

Another shortcoming of prior art devices is that, in general, they are not readily manipulated manually. In the case of pruning shears for example, it is desirable that the cutting blades be arranged to turn relative to the power cylinder, so that the operator can, with one hand, direct the cutting blade at any desired angle While maintaining a iirm hold on the power cylinder with the other hand.

The main object of the present invention is therefore to overcome the disadvantages of prior art devices of like nature.

Another object of the invention is the provision of a uid actuated tool lending itself to use with any uid including oil and other liquids and which does not discharge the operating fluid out of the mechanism.

Still another object of the invention is the provision of a fluid actuated tool such as pruning shears which is constructed so that the working head is swivelly mounted to facilitate manual handling of the tool in various positions.

Other objects and advantages will be seen in the following specication and in the drawings.

Fig. l is a part sectional part elevational view of the hydraulic cylinder end of a pair of iluid actuated pruning shears showing one embodiment of the invention.'

Fig. 2 is a continuation of the pruning shears of Fig. 1 showing the working end of the same. Figs. 1 and 2 are considered as one view and are separated so as to accommodate the view to the sheet.

Fig. 3 is a schematic piping and wiring diagram of the invention.

Figs. 4 and 5 are similar to Figs. 1 and 2, but show a modified form of the invention.

In detail, and referring to Figs. l and 2, the invention comprises a hydraulic cylinder generally designated 1. The rear end of cylinder 1, that is, the end remote from the working head of the tool, is provided with the removable plug 2 to which is secured a handle 3 by which the device may be grasped in one hand of the operator.

' Mounted on handle 3 is a switch 4 and a switch arm ice 5 which may be conveniently actuated by the operator. The function of switch 4 will be subsequently described in connection with the piping and wiring diagram.

At the forward end of cylinder 1 is a closure plug 6 which may be screwthreadedly secured to the cylinder (Fig. l). If desired, a packing element 7 may be interposed between cylinder 1 and plug 6 to prevent leakage out of said cylinder.

Plug 6 is provided with a threaded opening for receiving therein the threaded fitting 8 of a supply conduit 9 through which iuid, such as oil, is conducted to the forward end of cylinder 1.

Reciprocable within cylinder 1 is a piston 10 to which is secured a piston rod 11 extending through a bore 12 in plug 6. A packing element, such as an O-ring 13 may be provided to prevent leakage of oil through bore 12 and past piston rod 11.

The plug 6 is centrally recessed as at 14, to permit oil under pressure from conduit 9 to be impressed on the forward, or piston rod side of piston 10. Piston 10 may be provided with any suitable packing means, such as O-ring 15, to prevent leakage therepast. In order to vent the rear end of cylinder 1, one or more holes 16 may be provided in the sidewall of said cylinder adjacent rear end plug 2.

Swivelly secured to plug 6 of cylinder 1 is a tubular extension member generally designated 19 which is preferably made in two sections 20, 21. Section 20 is preferably provided at its forward end with a bearing block 22 (Fig. 2) which may be rigidly secured to section 20 by welding or brazing as indicated at 23. The forward section 21 of the extension member 19 is provided at its rear end with a nut 24 integrally secured to said section 21 by welding or brazing. Nut 24 and bearing block 22 are complementarily threaded to permit the sections to be releasably, but securely attached together (Fig. 2). To further facilitate assembly and disassembly of the device, section 21 may be made in two parts connected by a coupling 25.

Fixedly secured to the forward end of section 21 of the extension is a fixed work element such as a pruning blade 26.

Referring again to Fig. 1, the piston rod 11 is provided at its outer or forward end with a plug 30 which may be screwthreadedly secured to the piston rod 11. In alignment with piston rod 11 is a linkage rod 31 providedwith a swivel collar 32 rigidly secured thereto as by soldering. The collar 32 is received within a swivel cap 33 which in turn is screwthreadedly secured to the plug 30. By this structure it will be seen that the linkage rod 31 may rotate freely within cap 33. To insure against loosening of the above described elements a pin 34 may be press fitted into a through bore extending transversely of the plug 30 and cap 33.

lnterposed between plug 30 on connecting rod 11 and the end plug 6 on cylinder 1 is a helical compression spring 35 which urges the piston 10 in a forward direction at all times.

Linkage rod 31 passes through a bore 37 in the bearing block and is reciprocable therein. Thus, said linkage rod is slidably supported at both of its ends to facilitate reciprocation within the extension member 19. A second linkage rod 38 may be connected end to end with rod 31 (Fig. 2), but rods 31 and 38 act as if they were one rod.

The forward end of rod 38 is connected by a pin 39 to one end of an actuating arm 40 which in turn is pivotally secured by bolt 41 to one end of a movable blade 42 Movable blade 42 is swingably secured to fixed blade 26 by a bolt 43. Slot 44 is provided in extension section 21 for passing arm 40.

By the above described structure it will be apparent upon the introduction of fluid into cylinder 1 through conduit 9 the piston 10 will be forced rearwardly (to the left, Fig. 1) causing blade 42 to swing into cutting engagement with blade 26. At the same time spring 35 is compressed so that upon release of pressure of the uid in conduit- 9, blade 42 will return to its normal inoperative position of Fig. 1.

Referring now to Fig. 3, conduit 9 is connected to a three way valve 48 of the solenoid actuated type. The solenoid of valve 48 is in a circuit 49 which includes `a source of electrical power 50 and switch 4 hereinbefore referred to (Fig. 1).

Oil is received in a reservoir 51 which may conveniently be placed on a tractor (not shown) together with the other apparatus to be described. Oil is pumped from reservoir 51 through pipe 57 and through a suitable relief valve 52 by pump 53 to an accumulator 54. Accumulator 54 may be set for the proper working pressure of the shears (up to about 1000 p. s. i.) and is connected with the Pressure side of the three way valve 48.

A suitable overload valve 55 and check valve 56 may be provided as shown in Fig. 3. The return from the valve 48y is through conduit 58 to reservoir 51 and the return from valve 55 is through conduit 59.

The provision of the three way solenoid actuated valve 48 permits fast action of the shears. When the operator desires to cut a branch, he merely positions the blades 26, 42 in proper position and squeezes on switch arm 5 to close switch 4. Upon release of said switch 4 valve 4S disconnects conduit 9 from pressure conduit 57 and connects it with return conduit 58 thereby permitting spring 35 to return the blades 26, 42 to open position and move piston forwardly. The spring 35 must of course be relatively strong to exhaust cylinder 1 of oil and return the shears to the normal inoperative position.

The action of the blades is much faster when oil is employed than when compressible air is used. However, it will be apparent that the device may be operated with air as well as with liquids.

An extremely important feature of the invention resides in the fact that the extension 20, 21 may swivel relative to the cylinder 1. For this purpose the rear end of extension section is provided with an integral collar 62 similar to collar 32 on rod 31 and a plug 63 is threadedly secured in the forward end of plug 6 on cylinder 1. Plug 63 is bored to receive section 20 therethrough and collar 62 is. permitted to rotate within the space between plugs 6 and 63. Axial thrust on section 20 is of course taken bythe rear end of plug 63 and the forward end of plug 6 just as axial thrust is taken by cap 33 and plug 30 from collar 32.

By the above described structure it will be apparent that the operator may maintain the same grip on the handle 3 with one hand and turn the extension 19 as desired with the other hand to suit the position of the branches to be cut. It should also be noted that relatively little resistance to turning extension 19 will be experienced because of the existence of the two swivels 32 and 62. The pressure of the fluid and the force of the spring are not transferred to the` swivelling parts and this is very important because of the very high loads that may be involved.

A modied form of the invention is shown in Figs. 4, 5 which is adapted for somewhat lighter duty than the structure of Figs. 1, 2. In this case the blade positions are changed so that the iixed blade 70 is secured to butt alongside extension 71.. Movable blade 72 is connected by means of a linkage generally designated 73 with the forward end of the piston rod 74 of piston 75. In this case, forward movement of the piston (toward the working head) is required to cause the working stroke.

The rear section 76 of extension 71 may be bored out to provide a cylinder in which piston 75 is reciprocable. The handle 77 of this form of the invention may be formed with an enlargement 78 extending coaxially toward piston 75, from handle 77.

Threadedly secured to the rear end of section 76 is a swivel nut 8i) which is formed with an annular shoulder 8l abutting the enlargement 78 of handle 77 The spring 79 acts between the bearing block 82 of extension 71 and piston 75 -to urge the latter into engagement with a shoulder 83 formed in swivel nut 80. By this structure the force of the spring 79 is not brought to bear through the shoulder 81 against the enlargement 78 of handle 77. In other words, there is no resistance to swivelling the extension relative to the handle except the resistance created by the O-ring or other sealing element 84. Of course when the oil pressure is brought to bear on piston 75 the force of friction resisting swivelling is enlarged, but it is never desired to swivel the extension when the pressure is on. It should be noted in this connection however, that in the heavy duty form of Figs. 1, 2 the sealing means does not resist swivelling of the extension relative to the cylinder member. ln other respects the pruning shears of Figs. 4, 5 is similar to that of Figs. 1, 2 and the piping and wiring is the same.

The above described detailed description should not be taken as restrictive of the invention as it is obvious that various changes in design may be resorted to without departing from the invention as deiined in the following claims.

l claim:

l. In a hydraulically actuated tool having a stationary work element and a movable work element cooperating with said stationary element, a cylinder member adapted to be grasped in one hand of an. operator and an extension member adapted to be grasped in the other hand, a driving linkage operatively connected with said movable work element and reciprocably mounted in said extension member, a piston member reciprocable in said cylinder member and connected with said driving linkage, a `conduit for introducing Huid under pressure into said cylinder for so reciprocating said piston in one direction, spring means for urging said piston in the opposite direction, said extension member and said cylinder member being swivelly connected to permit relative rotation of said members for angularly positioning said work elements as desired, an electrical circuit including a switch on said tool and a solenoid actuated valve remote from said cylinder member for directing fluid to and from said cylinder.

2. In a hydraulically actuated tool having a stationary work element and a movable work element cooperating with said stationary element, a cylinder member adapted to be grasped in one hand of an operator and an extension member adapted to be grasped in the other hand, an elongated driving element operatively connected to said movable work element and reciprocable cylinder member and operatively connected with said driving element, means for introducing a fluid under pressure into said cylinder for so moving said piston, and means swivelly connecting said cylinder and extension members and means swivelly connecting said piston member and said driving element whereby said extension member may be rotated to different positions relative to said cylinder member as desired without rotating said piston.

References Cited in the file of this patent UNITED STATES PATENTS 2,127,265 Martin Aug. 16, 1938 2,163,627 Peterson lune 21, 1939 2,228,635 Magennis Ian. 14, 1941 2,336,887 Piron Dec. 14, 1943 2,366,121 Hurst Dec. 26, 1944 2,366,909 Johnson lan. 9, 1945 2,493,696 Potstada Jan. 3, 1950 2,543,109 Holowka Feb. 27, 1951 2,631,369 Carnesecca Mar. 17, 1953 2,666,417 Harsch Ian. 14, 1954 2,751,940 Miller June 26, 1956

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