US2961015A

US2961015A - Power operated device for selectively moving load elements to predetermined positions

Info

Publication number: US2961015A
Authority: US
Inventors: Burton T Randall
Original assignee: C AND D LUMBER CO
Current assignee: C AND D LUMBER CO
Priority date: 1957-11-12
Filing date: 1957-11-12
Publication date: 1960-11-22
Anticipated expiration: 1977-11-22

Description

Nov. 22, 1960 B. T. RANDALL 2,951,015

POWER OPERATEO DEVICE FOR SELEOTIVELY MOVING LOAD ELEMENTS TO 'PREOETERMINED POSITIONS 5 Sheets-Sheet 1 Filed Nov. l2, 1957 INVENTOR. BURTON 'E RANDALL.

BY BUCKHORN9 CHEATHAM BLORE.

lill. lll

ATTORNEYS Nov. 22, 1960 B. T. RANDALL.

POWER OPERATED DEVICE FOR SELECTIVELY MOVING LOAD ELEMENTS To PREOETERMINEO POSITIONS Filed Nov. 12, 195'.

5 Sheets-Sheet 2 amv Ow @me omooooooo \oooooooo\oo ooo ooooo NU IIIkMV INVENTOR. BURTON T. RANDALL BUCKHORNQCHEATHAM BLORE A TTONEYS Nov. 22, 1960 B. T. RANDALL 2,961,015

POWER OPERATEO DEVICE FOR SELEOTIVELY MOVING LOAD ELEMENTS To PREDETERMINED POSITIONS Filed Nov. l2, 195'? 5 Sheets-Sheet 5 u t, y h @Q t a m a S l l :u V I IH i n "2 Se Q Ll.. s: S

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"l 'L v l a 1 1 A Ilm "l INVENTOR.

n BURTON T. RANDALL ll" BY BUCKHORN CHEATHAM K BLORE AT TORNEYS Patented Nov. 22, 1560 PGWER GiERATEIB DEVECE FR SELECTIVELY li/lOVlNG LAD ELEMENTS T PREDETER- MINED PSlTIGNS Burton T. Randall, Roseburg, Greg., assigner to C. & D. Lumber Co., Riddle, reg., a partnership anni Nov. 12, 1957, ser. NQ. 695,728

14 claims. (ci. 143-37) This invention relates to a power operated device and more particularly to a device in which a piston actuated by fluid under pressure in a cylinder containing such piston may be stopped in yany one of a plurality of predetermined positions relative to the cylinder and such stopping of the piston is cushioned in any of such positions by controllable release of fluid pressure from a supplemental variable volume chamber in the cylinder, the invention also relating to a power operated device in which a plurality of pistons and cylinders are connected in series so that a plurality of load elements may each be moved to any one of a plurality of predetermined positions relative to each other and to a lxed element, such arrangement employing the stop device referred to above and preferably also the cushioning arrangement also referred to above.

In my copending application Serial No. 583,162, filed May 7, 1956, now Patent No. 2,821,172, issued January 28, 1958, I have disclosed a power operated device in Awhich a piston is moved in either direction relative to its cylinder to any one of a plurality of predetermined positions and in which the final movement of the piston relative to the cylinder is always in one direction. Movement in such direction from one of the predetermined positions to another is accomplished by rst moving the piston in the opposite direction, releasing the stop device and then moving the piston in the lirst direction until the desired predetermined position is approached at which time the stop device is engaged to stop the piston. Movements from one predetermined position to another in the other direction is accomplished by moving the piston away from the stop device past the desired predetermined position then reversing the direction of the travel of the piston and engaging the stop device. Such device does accurately enable a piston driving a load to be accurately brought to predetermined positions relative to the cylinder but in cases where the load is of relatively large size so as to produce high inertia forces during the stopping of the piston and load, the stop mechanism is subjected to excessive stresses. In the copending application referred to above, a supplemental piston and cylinder is employed to produce a cushioning action to gradually stop the piston and load moved thereby.

In accordance with the present invention, it has been found that an effective cushioning action can be produced in the same cylinder by employing a second piston providing a variable volume chamber between the two pistons in the cylinder in addition to the variable volume chambers at the ends of the cylinder. The stop device referred to above stops the iirst piston with respect to the cylinder whereas the load is connected to the second piston. Fluid is controllably exhausted from the variable volume chamber between the pistons after the first piston has been stopped and while the second piston connected to the load is still being driven by linid pressure. The variable volume chamber between the pistons becomes a cushioning chamber and is effective at any of the predetermined positions at which the first piston may be stopped relative to the cylinder so that the cushioning operation is the same at all positions.

The present invention also relates to the employment of a series of pistons and cylinders in which each cylinder except one end cylinder of such series is connected to the piston of an adjacent cylinder to be moved thereby. One of the elements of the series, such as a cylinder is connected to a xed element, and a load element is connected to each pair of intermediate movable elements consisting of a piston and a connected cylinder. A load element is also connected to any end element of the series which is movable with respect to the xed element. A stop mechanism is positioned between each cylinder `and its associated piston for selectively stopping such piston relative to its cylinder in any one of a plurality of predetermined positions, which stop mechanism preferably includes a second piston in such cylinder as discussed above to provide for cushioning the stopping `of the lirst cylinder and load connected thereto. A control means is provided for each cylinder and its associated piston so that adjacent load elements may be moved relative to each other, any load elements more remote from the fixed element being also moved. The structure just described has a variety of uses, one use being the moving of the sliding saws of a sawmill edger to selected positions relative to each other.

The present invention also relates to a simplified control system which can be employed either with the power operated device of said copending application or with the power operated device of the present invention, including the series arrangement yof the pistons and cylinders referred to above. In the case of the series arrangement of pistons and cylinders, the control system may include mechanism by which extension of the series beyond the space limits of the machine in which it is incorporated is prevented and by which a deiinite arrangement of the load elements results when the operator actuates the control mechanism in a manner which would cause the series of pistons and cylinders referred to to attempt to expand beyond the space limits of the machine in the absence of the control referred to.

It is therefore an object of the present invention to provide an improved power operated device including a piston and cylinder in which the piston is stopped by a stop mechanism in -any `one of a plurality of predetermined positions and the stopping of such piston is cushioned at any one of such positions by an auxiliary variable volume chamber Within the cylinder.

Another object of the invention is to provide a simplilied control for a power operated device in which a piston is stopped in one direction of its movement relative to its cylinder in any one of a plurality of predetermined positions by a one direction stop device and in which the piston is controlled so that its initial movement is always in a direction away from such stop device and its iinal movement is in a direction toward such a stop device.

Another object of the invention is to provide a power operated device in which a plurality of pistons and cylinders are connected in series and in which a stop device is employed between each cylinder and its associated piston to enable a plurality of load devices connected to said pistons and cylinders to be brought to selected predetermined positions relative to each yother and to a lixed element.

A further object of the invention is to provide a power operated device employing a plurality of cylinders and pistons connected together in series for moving a plurality of load elements to selected predetermined positions relative to each other and to a xed element in which a stop mechanism is employed between each piston and its cylinder to stop said piston in a predetermined position relative to its cylinder and the stopping of each piston relative to its cylinder is cushioned by controllably exhausting duid from an auxiliary variable volume chamber within such cylinder. Y

Other objects and advantages of the invention will appear in the following description of preferred embodiments thereof shown in the attached drawing of which: A Fig. l is a diagrammatic view `of a power operated device in accordance with the present invention with a cushioning cylinderV shown in vertical section;

Fig. 2 is a diagrammatic vertical section longitudinally through a lumber edger showing a possible arrangement of three of the cylinders of the present invention for moving edger saws to preselected positions;

Fig. 3 is a diagrammatic front view on a smaller scale of the cylinder arrangement of Fig. 2 with the various elements spread vertically and with the control elements omitted.

Fig. 4 is a view similar to Fig. 3 on a larger scale showing the racks of the stop mechanism in approximately their relative operating positions and certain of the control elements but -with the cylinders omitted; and

Fig. 5 is a top view of a push button control box for the cylinders of Figs. 2 and 3.

Referring more particularly to the drawings, the power operated device of the present invention includes a cylinder in which are reciprocably mounted a rst piston 12 secured to one end of tubular connecting element 14 extending through a packing gland 16 in one end 18 of the cylinder. The tubular connecting element 14 has secured .thereto exteriorally of the cylinder 10 a load connecting'member 20 which may be connected to a load to move such load as described below. A second piston 22 is also positioned in the cylinder 10 so as to be on the other side of the piston 12 from the end 18 of the cylinder. The piston 22 is secured to a piston rod 24 which extends through the interior `of the tubular connecting element 14 and through a packing gland 26.at the end of the tubular connecting element 14`remote from the piston 12. The cylinder and piston 12 provides `a rst variable volume chamber 28 between the piston 12 and the end 18 of the cylinder; a second variable volume chamber 30 between the pistons 12 and 22 and a third variable volume chamber 32 between the piston 22 and the closed end 34 of the cylinder. The piston rod 24 is securedat its end remote from the piston 22 to a laterally extending rack connecting member 36 having its other end connected to a rack member 38 mounted for reciprocation on a guide 39. It will be apparent that the two pistons 12 and 22 may move together in the cylinder 10 to move the load connecting member 20 and lrack member 38 and also that the piston 12 can have limited movement relative to the piston 22 so that the load connecting member 20 may have limited movement with respect to the rack 38.V

' The rack 38 hasY a plurality of notches therein providing abutments 40 for engagement with a pawl 42 which is pivoted to a bearing member 46 which is stationarily mounted with respect to the cylinder 10, the dotted line 47 indicating that the bearing member 46 Yand cylinder 10 are secured together mechanically. The

pawl 42 is urged toward engagement with the rack 38 by a tension spring 48 extending between one arm of the Y pawl and the bearing member 46. The pawl can be retracted from engagement with the rack 38 by either one of'two

solenoids

50 and 52, the plungers of the solenoids being connected together and to the pawl 42 through a tension spring 54. Y `It will be appreciated that suitable guides (not shown) may be provided for the solenoid plungers to maintain them in alignment with their re- Y spectivesolenoids. v

Fluid under pressure from a pump 56 may be selectively delivered into either of the'variable

volume chambers

28 and 32 under control of a solenoid operated valve 58 through conduits 60 and 62, respectively, and also exhausted from such chambers through such conduits. The power operated device of the present invention is particularly adapted for operation with compressed air in which case the pump 56 may be an air compressor, although the device may be operated by other gases under pressure or by a hydraulic uid under pressure. In the position of the valves 58 shown in Fig. l, fluid from the pump 56 is being delivered through the conduit 68 into the chamber 28 and is being exhausted from the chamber 32 through the conduit 62 and a discharge conduit 64. In the position of the device shown in Fig. l, `the piston 12 is being driven to the left by uid under pressure and the pawl 42 has just engaged an abutment 40 on the rack 38. Under these conditions, uid is being exhausted from the chamber 30 between the pistons 12 and 22 through an annular space 66 within the tubular connecting element 14 and between the walls of such element and the piston rod 24 and then through a conduit 68 and a control valve 70 operated by a link 72 connected to the pawl 42 and through an adjustable metering valve 74. Although the piston 22 by reason of its mechanical connection to the rack 38 has been stopped by the pawl 42 in a selected predetermined position, the piston 12 connected to the load element 20 continues to move by reason of the uid pressure admitted to the chamber 28 but such movement is cushioned by the discharge of fluid from .the chamber 30 under control of the metering valve 74.

1t will be noted that any time the pawl 42 is withdrawn from engagement with the rack 38, the valve 70 is actu ated to connect the conduit 68 and therefor the chamber 30 with the high pressure lside of the pump 56 through.- a conduit '76. Under these conditions fluid under pres-V sure is supplied to the chamber 30 through the conduit 76, valve 70, conduit 68 and annular space 66. ThisA means that the pistons 12 and 22 are separated from each other each time the pawl `42 is retracted rom'the rack 38. This conditions the piston for the cushioning action just `described when the pawl is again employed to stop movement of the rack to the left in Fig. l. Y

The valve 58 is actuated by a solenoid 80, the valve being moved from the position shown in Fig. yl to a position connecting the pump 56 with the conduit 62 and connecting the conduit 60 with the discharge conduit 64 whenever the solenoid `is energized and being returned to the position shown in Fig. l when the solenoid 8G is deenergized. The

solenoids

50, 52 and 80 are controlled by a plurality of push buttons 82, in conjunction with contact strips 84 and 86 secured to the rack 38 and insulated therefrom and also in conjunction with a switch 88 actuated by pivotal movement of the pawl 42 and a limit switch 90 adjacent one end of the rack 38. Each of the push buttons 82 has a contact element 92 stationarily mounted with respect to the cylinder 10 and slidably engaging one or the other of the contact strips 84 or 86 Ydepending upon the position of the rack relative to the cylinder 10, or engaging an insulating member 164) positioned in a gap between the contact strips 84 and 86.' VA contact element 102 is positioned to contactrthe contact strip 84 in any position of such strip and similarly a contact element 104 is positioned to engage the contact strip 86 in any of its positions. The push buttons 82 are part of an assembly of the button locking type in which any button remains depressed when depressed and in which the depression of one button releases any other button previously depressed. Such push button assemblies are conventional and will not be further described.

In Fig. 1, the push button 82.has been depressed but, in the position of the rack shown, any circuit through such'push button has been broken by reason ofthe fact that its associated contact element 92 is in engagement with the insulating member 100. The

solenoids

50, 52

and 80 are all deenergzed so that the valves 7.0 and 58 are in the position shown in Fig. l and the piston 12 will continue to move to the left in Fig. 1 until it engages the piston 22 at which time any load connected to the load connecting element 20 will have reached a predetermined position set by the position of the pawl 42 engaging the abutment 40 on the rack 38 corresponding to the push button 82'.

One contact of each of lthe push buttons 82 is connected to the one side of the line L1 through a conductor 106 and such conductor continues to one of the normally open contacts of the limit switch 90. Each of the other contacts of the push buttons 82 is connected to a corresponding contact element 92 making sliding contact with a contact strip 84 or 86. The contact element 102 engaging the contact strip 84 is connected by a conductor 198 to one side of the solenoid 50, such conductor 108 also continuing to the other normally open contact of the limit switch 90. The conductor 108 is also connected to a conductor 110 through the switch 88 actuated by the pawl 42 and such conductor 110 is connected to one side of both the solenoid 52 and the solenoid 80, the switch 88 being closed when the pawl 42 engages the rack 38. The conductor 110 is also connected to one of the normally closed contacts of the limit switch 90, the other normally closed contact thereof being connected to the contact element 104 in engagement with the contact strip 86 through a conductor 112. The other sides of the

solenoids

50, 52 and 8i) are connected to the other side of the line L2 through

conductors

114 and 116, respectively. In the normal position of the limit switch 90 shown, the conductors 110 and 112 are connected together by a switch element 118. If the rack 38 is moved toward the right in Fig. l, a switch operating element 120 engages the switch element 118 to break the circuit between conductors 110 and 112 and further movement of the rack to the right cause the switch element 118 to complete a circuit between conductors 106 and 108.

If a push button such as button 82x to the left of push button 82 of Fig. 1 is depressed, push button 82' is released from its locked position to open the circuit through such push button and a circuit is closed through the last depressed push button. This closes the circuit from the line L1 through the push button 82x, contact strip 84,

conductor 108 and the solenoid 50 to line L2. This energizes solenoid 50 but solenoid 50 is unable to retract the pawl 42 from the rack 38 until the rack has been moved to the right to move the abutment 40 away from the pawl 42. Since the conductor 108 is connected to conductor 110 through the switch 88, a circuit is also completed from conductor 108 through conductor 110 and through the solenoid 80 to the line L2. The resulting energization of the solenoid 80 operates switch 58 to connect conduit 62 with the pump 56 to introduce fiuid under pressure into the chamber 32 at the left end of cylinder and also connects conduit 60 with discharge conduit 64 to exhaust fluid from chamber 28. The piston 22 moves to the right in Fig. 1 to move the rack 38 to the right to release the pawl 42 from the rack. Pivoting of the pawl 42 breaks the circuit through the switch 88 to deenergize solenoid 80 and allow the valve 58 to return to the position shown in Fig. l. The circuit through the solenoid 50 still remains Vcompleted. to hold the pawl out of contact with the rack 38 and the position of valve 58 just described introduces fluid under pressure through the conduit 60 into the chamber 28 of the cylinder 10 while exhausting uid from the chamber 32 through the conduit 62. The valve 70 was actuated by the pawl 42 when such pawl was released from the rack 38 to a position connecting conduit 68 With conduit 76 so that uid pressure from the pump 56 was delivered into the chamber 30 between the pistons 12 and 22. This caused the two pistons 12 and 22 to separate and the actuation of valve 58 by the solenoid 80 causes the two separated pistons to move to the left in Fig. 1.

When the rack approaches the desired position corresponding to push button 82x, the sliding contact element 92x associated with push button 82x engages the insulating member 1,00 so that the circuit through solenoid 50 is broken. The pawl 42 is pivoted by the spring 48 into position to engage the abutment 46x corresponding to push button 82x and at the same time valve 70 returns to the position shown in Fig. l so that the chamber 30 is connected to exhaust through the metering valve 74. When the rack abutment 40x strikes the pawl 42, the piston 22 connected thereto is stopped but piston 12 continues to move to the left carrying the load connecting element 20 therewith and such movement is cushioned by throttling of iluid through the valve 74 until the piston 12 engages the piston 22. The load is thus stopped in a predetermined position corresponding to the push button 82x and the stopping of the load is cushioned by the controlled iinal movement of piston 12.

lf a push button, such as push button 82y to the right of the previously depressed push button 82' is depressed, push button 82 is released to break any circuit therethrough and a circuit is completed through the push button 8251. This circuit may be traced from the line L1 through conductor 106, push button 82)', contact element 92) corresponding to push button 82y, contact strip 86, contact element 104, conductor 112, the normally closed contacts of switch 90, conductor 110, conductor 114, and solenoid 52 to the other side of the line L2. This energizes solenoid 52 to condition it to retract pawl `42 from the rack 38 but such pawl will not be retracted until the rack 38 has moved to the right. The circuit just traced also energizes solenoid 80, since the circuit is also completed from the conductor 110 through the solenoid to the other side of the line L2. The energization of solenoid 80 actuates the valve 58 to supply fluid under pressure through conduit 62 to the chamber 32 at the left of the cylinder 10 and exhaust fluid from the chamber 28. As soon as the rack moves toward the right, the pawl 42 is retracted. The rack 38 continues to move to the right until the insulating member moves under the contact element 92)) to break the circuit through such contact element. This occurs after the abutment 40y corresponding to the push button 82y has progressed a short distance to the right of the pawl 42 of Fig. l. When the circuit referred to is broken, both the solenoid 52 and the solenoid 80 are deenergized so that the pawl is positioned to engage the abutment 40) and at the same time the valve 58 is returned to its position shown in Fig. l so as to again move the pistons '12 and 22 toward the left in such ligure. At the time the pawl was retracted from the rack 38 and during the movement of the rack 38' to the right just described, the valve 70 was actuated to supply luid under pressure to the chamber 30 between the pistons 12 and 22 so that such pistons are separated and as soon as the pawl returns to the position shown in Fig. l, the chamber 36 is connected to be exhausted through the metering valve 74 to cushion the final movement of piston 12 toward piston 2,2.

The limit switch 9i) is not, in general, needed with a system having a single cylinder 10 but is preferably employed with a system having several cylinders and pistons connected in series, as described below. Such a limit switch is of primary importance where the combined travel of the pistons of several cylinders connected in series is greater than the space available in a given machine. Its operation will be explained below. The switch 90 can be eliminated from a single cylinder system by connecting the conductors and 112 together.

A possible arrangement of a series of three cylinders 10, 10a and 10b is shown diagrammatically in Fig. 3. In such ligure, the

piston rods

24, 24a and 24h of the respective cylinders are shown connected to

racks

38, 381i and 38b through the rack connecting members 36, 36a and 36h, respectively, the racks sliding on guides 39.

"7 The rload connecting member 20 associated with the piston 10 is connected to the hub of an edger saw 124 sliding on an'arbor 126 journaled in a frame 128, the guides 39 for the racks 38 being supported in such frame. The load connecting member a associated with Vthe cylinder 10a is connected to the hub of a second edger saw 124x: sliding on the arbor 126 and also to the cylinder 10 so as to move the cylinder 10 with the tubular member 14a of the cylinder 10a. Similarly the load connecting member 20b connected to the tubular connecting element 14 associated with Vthe cylinder 10b is connected to the cylinder 10a to move such cylinder and also to the hub of a third edger saw 124b sliding on the arbor 126. It will be apparent from Fig. 3 that movement of the tubular connecting element 14 relative to its cylinder 10 will move the edger saw 124 relative to the other edger saws. Also, movement of the connecting element 14a relative to cylinder 10a will move both edger saws 124 and 12411 relative to edger saw 124b and movement of the tubular connecting element 14b relative to cylinder 10b will move all three

edger saws

124, 124a and 124b relative to the frame 128 of the edger. It will be further appreciated that the

racks

38, 38a and 38b will move on their respective guides concurrently with the tubular connecting members-14, 14a and 14b, respectively, except for the cushioning movements of the tubular connecting elements with respect to the racks as described with reference to Fig. l.

The

racks

38, 38a and 38b in Fig. 3 have been shown as being spaced vertically from each other in order to provide room to show the cylinders 10, 10a and 10b, but in Fig. 4 the cylinders have been omitted, since they would be largely behind the racks, and the racks are shown in approximately the relative positions they would assume in an actual machine. In Fig. 4, the pawls 42, 42a and 42b with their associated

operating solenoids

50 and 52 are shown along with their associated pawl operated control valves 70 and control switches 8S. The other elements of the control mechanism is also omitted from Fig. 4.

A possible arrangement of the various cylinders 10, 10a and 10b with associated

racks

38, 38a and 38b is shown in diagrammatic vertical section in Fig. 2, also showing one of the edger saws 124, the usual drive Vrolls and hold down rolls for the lumber passing through suchY edger being omitted. The racks are shown as being mounted upon the guide 39 and as being connected to the

piston rods

24, 24a and 24b, respectively, through the rack connecting members 36, 36a and 36b, respectively. Also the load connecting element 20 associated with piston 10 is connected to the hub of the saw 124 whereas the load connecting element 20a associated with the cylinder 10a is also connected to the cylinder 10 as well as to one of the saws and the load connecting element 20b associated with the cylinder 10b is connected to the cylinder 10a as well as to one of the saws. The relative positions of the pawls 42, 42a and 42b with respect to their racks X38, 38a and 38b is also indicated in Fig. 2, as is also the relative positions o"Y the contact strips 86 and contacts 104 for the respective racks. In Fig. l, a row of push buttons 82 is shown associated with the control system for the cylinder 10 and, as indicated in Fig. 5, a control panel 130 may contain such row of push buttons 82 and also a row of push buttons 82a for the cylinder 10a and a row of push buttons 8217 for Ithe Vcylinder 10b.y

Each of the push buttons 82 may correspond to a definite distance between the

saws

124 and 124a, for example, the push button at the left of the row of push buttons 82 may correspond to distance of two inches between saws, the next push button to the right corresponding to a distance o four inches between the saws and so on, the distance corresponding to each push button progressively toward the right increasing by an increment of two inches. Such increment corresponds to the distance between twosuccessiveabutments-40 on a 8 rack 38. Thus, pushing any one of the push buttons 82 will automatically cause the

saws

124 and 124a to assume the distance apart which correspondsV to the push button 82 which is depressed. `In a similar manner, the push buttons 82a `set the distance between the saws 124:1 and 1'24b and the push buttons 821? set the distance of the saw 124b from a xed point on the frame 128. Thus in most cases' the edger Voperator can make a desired change in the positions of the edger saws for a particular Y board by pushing one push Vbutton and in any case, not more than one push button for each saw to be moved. It will be apparent that a greater or lesser number of saws with associated pistons can be employed and that the particular control system illustrated can be employed in other environments where it is desired to bring one or more load elements to a precise predetermined position relative to another load element or to a xed element.

It will be further apparent that any attempt to spread all of the edger saws of Fig. 4 their maximum distance apart would, in general, exceed the maximum space available in an edger. If it be assumed that the saws in Fig. 4 are spread so as to occupy all of the space available in the edger, the control system of the present invention is such that the saws 124a and 124b, either individually or together, can be moved further to the right in Fig. 4 by depressing a correctly selected single push button even though the saw 124 cannot be moved further to the right. That is to say,V if a push button at the right end of the row of push buttons 82 in Fig. 5 were depressed, the cylinder 10 (Fig. 3) would attempt to move the saw 124 further to the right in Fig. 4 and this would cause engagement of the switch element 11S of IFig. l by the switch operating element 120, thus opening the circuit between conductors 110 and 112. The elect is the same as if the circuit through a push button were broken during motion of the rack 38 to the right by the insulating member moving under the corresponding contact element 92. The mechanism proceeds through the stopping cycle above described in which the motion of the rack is reversed and the pawl is engaged againstrone Vofthe abutments 40`of the rack 38. The switch 90 is such that the circuit between the conductors 110, 112 remains broken until subsequent motion of the rack to the left is eected by depressing a push button to the left of a previously depressed push button in one of the rows of control push buttons.

Depressingany of the

push buttons

82a or 82b at the right of Fig. 5 would cause movement of the saws l24a or 124b, or both to the right and this would also cause movement of the rack 38 to the right of Fig. 4 or Fig. l. 'If the motion of the rack 38 continues to the right in Fig. l, past the position merely opening the circuit between the conductors and V112, the switch element 118 completes a circ-uit between the conductors 106 and 108. The effect is the same as depressing a push button I82 associated with the cylinder 10 to the left of the previously depressed push button and the rack is moved to the left in Fig. 1 in the same manner as described above until the switch member 118 is released to open the circuit between the conductors 106 and 10S. This causes stopping 'of the rack relative to the cylinder as described above. 'If the range of movement of the saws 124a and 124b is sulicient to exceed 'the'distance available for movement of the saws in the edger when the saw 124 is immediately adjacent the sawY 124a, a limit switch 90 may be includedV in the control circuit for the saw 124a and cylinder 10a. Y

The general operation of the control system of Fig. 1 is asfollows'. 'I'he'apparatusl will'normally be at rest with one of the push buttons, such as push button 82 depressed, and the two pistons 12 and 22 Vwill under such conditions be in contact Vwith-each other such'that Vthe positionV of the load connecting element 20Ybears a detinite'relaton tothe position of the rack 38 as established by the pawl 42. The pawl 42 and cylinder 1li are either xed to the frame of the machine or connected so as to move together. Upon depressing a push button, such as push button 82V, to the right of the previously depressed push button 82', such previously depressed push button is released and also valve 58 is actuated by the solenoid 843 to supply `lluid under pressure into the chamber 32 to drive the pistons to the right, uid being exhausted from a chamber 2S through the valve 58. As soon as the rack 38 starts to move to the right, the pawl 42 is withdrawn from engagement with the rack by the solenoid 52 to actuate the valve 70 which supplies fluid pressure to the chamber 30 between the pistons 12 and 22 to separate the pistons. When the circuit through the push button 82v is broken by the insulating member lill) moving under the contact element 92y, the pawl 42 returns to the position shown in Fig. l to cause the valve 79 to connect the chamber 3i) vfor regulated discharge through the valve 74. Simultaneously, the valve 58 is returned to its position shown in Fig. l so as to supply fluid pressure to the chamber 28 and exhaust fluid from the chamber 32. This causes the rack 38 to return until it engages the pawl 42. After the rack 38 is stopped, the piston 12 continues to move while being cushioned by iluid in the chamber 30 until the piston 12 contacts the piston 22 at which time the -load element 20 is stopped in a delinite position with respect to the rack 38.

When a push button, such as push button 32x, to the left of the previously depressed push button 82 is depressed, push button 82 is released and the circuit completed through the push button 82x causes energization of solenoids 50 and 8l), the solenoid 8i) actuating valve 58 to supply fluid under pressure to the chamber 32 and exhaust fluid from the chamber 28. rIhis starts movement of the rack 38 tothe right in Fig. l so that the pawl 42 can be withdrawn by the solenoid 59, such withdrawal of the pawl also actuating valve 70 to supply uid under pressure to the chamber 3l) between the pistons 12 and 22. Also actuation of the pawl 42 breaks the circuit through the solenoid 80 at the switch V88 so that Huid under pressure is then supplied by the valve 58 to the chamber 28 and exhausted from the chamber 32 to drive the pistons 12 and 22 to the left. VAs soon as the insulating member 109 cornes under the contact 92x, the circuit to solenoid 50 is broken to cause the spring 48 to again position the pawl 42 in the path of an abutment 40 to stop the rack 38 and piston 22. Return movement of the pawl 42 to the position shown in Fig. l actuates the valve 70 to exhaust fluid from the chamber 30 between the pistons 12 and 22 through the metering valve 74 to cushion the stopping movement of the load connecting element 20 and load connected thereto,

When a plurality of cylinders, such as cylinder 10, a and 10b of Fig. 3 are connected in series with the pistons of one cylinder moving the next cylinder, the distances between load elements, such as the saws 124, 12451 and 124k, may be independently set. In the system shown, any movement of saw 124b with respect to a stationary element causes movement of

saws

124a and 124 concurrently therewith and any movement of saw 124a with respect to saw 12419 also causes movement of saw 124. The movement of saw 124 relative to saw 124a is under control of the series of push buttons 82 of Fig. 5, whereas the movement of saw 124a relative to saw 124b is under control of the series of push buttons 82a and movement of the saw 124b relative to the frame of the machine is under control of the series of push buttons 82]). The limit switch 9i? of Fig, l stops the movement of saw 124 if the total extension of the various saws relative to a stationary element exceeds the space available for such extension, and also allows continued movement of

saw

124a or 124a and 124b toward the saw 124 after such saw has been stopped. Upon return movement of saw 124a to the left in Fig. 4, the saw 124 remains at its extreme right position until the distance between

saws

124 and 124a corresponds to the distance set by push buttons 82 after which it follows saw 124a at such distance.

While I have disclosed the preferred embodiments of my invention, it is to be understood that the details thereof may be varied and that the scope of the invention is to be determined by the following claims.

I claim:

l. A fluid operated power device for moving a load element selectively to any one of a plurality of predetermined positions comprising a cylinder, a rst piston positioned in and movable longitudinally of said cylinder to provide a rst variable volume chamber at one end of said cylinder, a second piston positioned in and movable longitudinally of said cylinder, said pistons having limited movement relative to each other longitudinally of said cylinder to provide a second variable volume chamber between said pistons, means for supplying a uid under pressure to said first and second chambers to cause said pistons to separate and to move together in one direction, a movable load element moved by said rst piston, a stop mechanism for selectively stopping said second piston in any one of a plurality of predetermined positions, and means to controllably exhaust fluid from said second chamber to provide for cushioned further movement of said first piston by said fluid under pressure in said first chamber until said rst piston and said load element reaches a predetermined position relative to said second piston.

2. A lluid operated power device for moving a load element selectively to any one of a plurality of predetermined positions comprising a cylinder, a first piston positioned in and movable longitudinally of said cylinder to provide a rst variable volume chamber at one end of said cylinder, a second piston positioned in and movable longitudinally of said cylinder, said pistons having limited movement relative to each other longitudinally of said cylinder to provide a second variable volume chamber between said pistons, means for supplying a fluid under pressure to said first and second chambers to cause said pistons to separate and to move together in one direction, a movable load element moved by said rst piston, a stop mechanism for selectively stopping said second piston in any one of a plurality of predetermined positions, and means to controllably exhaust lluid from said second chamber to provide for cushioned further movement of said lirst piston by said lluid under pressure in said first chamber until said rst piston and said load element reaches a predetermined position relative to said second piston, said second piston providing a third variable volume chamber at the other end of said cylinder, mid means for alternately supplying a fluid under pressure to said third chamber tomove said pistons in the other direction.

3. A Huid operated power device for moving a load element selectively to any one of a plurality of predetermined positions comprising a cylinder, a rst piston positioned in and movable longitudinally of said cylinder to provide a lirst variable volume chamber at one end of said cylinder, a second piston positioned in and movable longitudinally of said cylinder, said pistons having limited movement relative to each other longitudinally of said cylinder to provide a second variable volume chamber between said pistons, means for supplying a lluid under pressure to said first and second chambers to cause said pistons to separate and to move together in one direction, a movable load element moved by said iirst piston, a stop mechanism for selectively stopping said second piston and load element in any one of a plurality of predetermined positions, and means to controllably exhaust fluid from said second chamber to provide for cushioned further movement of said rst piston by said fluid under pressure in said first chamber until said iirst piston and said load element reaches a predetermined position relative to said second piston, said second piston providing a third variable volume chamber at the other end of said cylinder, means for alternately supplying a Huid under pressure to said third chamber to move said pistons in the other direction, control means for causing said pistons to selectively move` said load element to any one of said positions in either direction,

said control means including means toV cause the .final movement of said pistons to any of said positionstto be in said onel direction against said stop mechanism and to cause the initial movement of said pistons from any of vsaid positions to be in the reverse of said one direction.

' 4. A fluid operated power device for moving a load 'element selectively to any one of a plurality of predetermined positions, said device comprising a cylinder, a first piston positioned in and movable longitudinally of said cylinder to provide a irst variable volume chamber at one end of said cylinder, a second piston posil tioned and movable longitudinally of said cylinder, said lpistons having limited movement relative to each other Ylongitudinally of said cylinder to provide a second variable volume chamber between said pistons, control means for supplyingV a fluid under pressure to said first and second chambers to cause said pistons to separate and to move together in one direction, a movable load Velement moved by said iirst piston, a stop mechanism for selectively stopping said second piston from movement Y in saidl one direction in any one of a plurality of predetermined positions, said control means including means Ysure to said third chamber to move said piston in the other direction, said control means also including means causing the initial movement of said pistons relative to said cylinder from any one of said positions to be in'a direction opposite said one direction and for causing the rnal movementof said pistons relativeVto said piston to any one of said. positions to be in said one direction, said control means alsoincluding means for selectively. releasing and engaging said stop mechanism to provide for controlled movementof said piston member relativerto said cylinder in said one direction.

5. Atfluid/operated power device for moving a load element selectively to any one of a plurality of predetermined positions, said device comprising a plurality of cylinders, a first piston positioned in each of said cylinders andV movable longitudinally thereof to provide a first variable volumechamber at one end of each of said cylinder, a. second piston positionedtand movable longitudinallyof each of said cylinders, said pistons in each cylinder having limited movement relative to each other longitudinally of said cylinders to provide a second variable volume chamber between said pistons in each cylinder, control meansrfor selectively supplying a iiuid under pressure to said lirst and second chambers of each cylinder to cause said pistons in each cylinder to separate andrto move togetheriin one direction, said cylinders and iirst pistons being connected in series, adjacent cylinders except therendA cylinder of said series being connected to the rst piston of an adjacent cylinder in said series, a movable load element moved by said ,t rst piston of each cylinder, a stop mechanism Vfor selectively stopping said second piston of each cylinder in any one of a plurality of predeterminedppositions relative to its cylinder, said control means including means to controllably exhaust fluid from said second chamber of `each cylinder to provide for cushioning further movevment of each iirst piston relative to its cylinder and second piston therein, said second Apiston in each cylinder providing a third variable volume chamber at the other end thereof, said control means including means for supplying a fluid under pressure to said third chamber of each cylinder to move its pistons in the other direction, said controltmeans also including means causing the initial movementof each of said second pistons relative to its cylinder to be in a direction opposite said one direction and for causing final movement of each of said second pistons relative to its cylinder to be in said one direction, said control means also including means for selectively releasing and engaging said stop mechanisms to provide for controlled movement of said second piston members relative to their cylinder in said one direction.

6. A fluid operated device for moving a plurality of load elements selectively to predetermined positions relative to each other and to a fixed element, which device comprises a plurality of cylinder members, first and second piston members positioned in each of said cylinder members and movable longitudinally thereof, said piston members in each cylinder having limited longitudinal movement with respect to each other to provide a variable volume chamber therebetween, said cylinder members and first piston members being connected in a series in which each cylinder member except the end cylinder member of said series is connected to be moved with the iirst piston member of an adjacent cylinder member, one of said members being connected to a fixed member, said iirst piston members being connected to load elements to move said load elements, a `stop mechanism between each cylinder member and its second piston member for selectively stopping its said second piston member against movement in one direction in any one of said predetermined positions relativeV to its cylinder member, control means for each of said cylinder members for selectively introducing uid undertpressure into the ends of each of said cylinder members to move said piston members relative to their cylinder members in either direction to said predetermined positions, said control means including means causing the initial movement of each second piston member relative to its cylinder member from any one of said positions to be in a direction opposite said one direction and Yfor causing the inal movement of each said second piston member relative to its cylinder member to any one of said positions to be in said one direction, Said control means also including means for selectively engaging said stop means for each said second piston member to provide for controlled movement of each said second piston member relative to its cylinder member in said one direction and including means for supplying uid under pressure into said variable volume chamber between the piston members in each of said cylinder members to separate said piston members during movement thereof relative to their cylinder members and to controllably exhaust uid from each said chamber during said iinaltmovement of the associated rst piston in said one direction.

7. A iiuid operated device for moving a plurality of load elements selectively to predetermined positions relative to each other and to a iixed element, which device comprisessa plurality of cylinder members, a piston member positioned in each of said ,cylinder members and movable longitudinally thereof, said cylinder and piston members being connected in a series in whicheach cylinder member except the` end cylinder member ofV said series is connected to be moved with the piston member of an adjacent cylinder member, one of said members being connected to a fixed member and the other of said members being connected to load elements to move said load elements, a stop mechanism between each cylinder member and its piston member for selectively stopping a piston member against movement inVone direction in any one of a plurality of predetermined positions relative to its cylinder member and control means for each-of said cylinder members and its piston member for selectively introducingV uid under pressure into the ends of said cylinder members to move said piston members relative to their cylinder members in either direction to said predetermined positions, said control means including means causing the initial movement of each piston member relative to its cylinder member from any of said positions to be in a direction opposite said one direction and for causing the iinal movement of said piston relative to its cylinder to any of said positions to be in said one direction, said control means also including means for selectively releasing and engaging said stop means to provide for controlled -movement of each piston member relative to its cylinder member to said positions.

8. A fluid operated device for moving a plurality of load elements selectively to predetermined positions relative to each other and to a fixed element, which device comprises a plurality of cylinder members, a piston member positioned in each of said cylinder members and movable longitudinally thereof, said cylinder and piston members being connected in a series in which each cylinder member except the end cylinder member of said series is connected to be moved with the piston member of an adjacent cylinder member, one of said members being connected to a xed member and the others of said members being connected to load elements to move said load elements, control means for each cylinder member for selectively stopping its piston memberin any one of a plurality of predetermined positions including end and intermediate positions relative to its cylinder member and means for each of said cylinder members for introducing fluid under pressure into the ends of each of said cylinder members to move each of said piston members relative to its cylinder member in either direction to said predetermined positions.

9. A fluid operated device for moving a plurality of load elements selectively to predetermined positions relative to each other and to a xed element, which device comprises a plurality of cylinder members, a piston member positioned in each of said cylinder members and movable longitudinally thereof, said cylinder and piston members being connected in a series in which each cylinder member except the end cylinder member of said series is connected to be moved with the piston member of an adjacent cylinder member, one of said members being connected to a fixed member and the others of said members being connected to load elements to move said load elements, means for introducing iiuid under pressure into the ends of each of said cylinder members to cause movement of each said piston member relative to its cylinder member in either direction, and control means for selectively stopping each of said piston members in any one of a plurality of predetermined positions including end and intermediate positions relative to its cylinder member.

l0. A tiuid operated device for moving a plurality of load elements selectively to predetermined positions relative to each other and to a iixed element, which device comprises a plurality of cylinder members, a piston member positioned in each of said cylinder members and movable longitudinally thereof, said cylinder and piston members being connected in a series in which each cylinder member except the end cylinder member of said series is connected to be moved with the piston member of an adjacent cylinder member, one of said members being connected to a xed member and the others of said members being connected to load elements to move said load elements, control means for each cylinder member for selectively stopping its piston member in any one of a plurality of predetermined positions including end and intermediate positions relative to its cylinder member, means for each of said cylinder members for introducing fluid under pressure into the ends of each of said cylinder members to move each of said piston members relative to its cylinder member in either direction to said predetermined positions, and means controlling the 14 introduction of said fluid into the end cylinder of said series spaced from said iixed member for stopping the movement of the end member of said series spaced from said lixed member when said end member reaches the end of the space available for movement of said Vend member away from said fixed member while enabling continued movement of intermediate members of said series relative to said iixed member and said end member.

11. A power operated device for moving load elements of a longitudinally extending series of elements selectively to predetermined positions relative to each -other and to a iixed element positioned at one end of said series, said load elements being movable within a space extending longitudinally of said series and said device comprising power means for moving each of said load elements within and longitudinally of said space, and control means for said power means including selecting means for causing operation of said power means to move any selected load element to any selected position of a plurality of predetermined positions including extreme and intermediate positions relative to an adjacent element of said series which is on the same side of said selected element as said one end of said series, said device also comprising means operated by said operation of said power means to move with said selected load element any other load element which is on the opposite side of said selected load element from said one end of said series and which is at its selected predetermined position relative to it said adjacent element and movable within said space to thereby maintain said other load element at its selected predetermined position relative to its said adjacent element so far as permitted by said space.

l2. A power operated device for moving load elements of a longitudinally extending series of elements selectively to predetermined positions relative to each other and to a xed element position at one end of said series, said load elements being movable within a space extending longitudinally of said series and said device comprising power means including a cylinder and a piston for moving each of said load elements within and longitudinally of said space, and control means for said power means including selecting means for causing operation of one of said pistons to move a selected load element to any selected position of a plurality of predetermined positions including extreme and intermediate positions relative to an adjacent element of said series which is on the same side of said selected element as said one end of said series, said device also comprising means operated by said operation of said one of said pistons to move with said selected load element any other load element which is on the opposite side of said selected load element from said one end of said series and which is at its selected predetermined position relative to its said adjacent element and movable within said space lto thereby maintain said other load element at its selected predetermined position relative to its said adjacent element so far as permitted by said space.

13. A lumber edger comprising, an arbor, a i'ixed element at one end of said arbor, a plurality of edger saws mounted on and movable longitudinally of said arbor and forming a series of elements with said iixed element, a power operated device for moving said saws along said arbor selectively to predetermined positions relative to each other and to said fixed element of said series, said saw being movable within a space extending longitudinally of said arbor and said device including power means for moving each of said saws within and longitudinally of said space, and control means for said power means including selecting means for causing operation of said power means to move any selected saw to any selected position of a plurality of predetermined positions including extreme and intermediate positions relative to an adjacent element of said series which is on the same side of said selected saw as said one end of said arbor, said device also comprising means operated by said operation of said power means to move with said selected saw any other saw which is on the opposite side of said selected saw from said one end of said arbor and which isA at its selected predetermined position relative toits said adjacent element and movable within said space to thereby maintain said other saw at its selected predetermined position relative to its said adjacent element of said series so far as permitted by said space.

14. A lumberpedger comprising an arbor, a iixed element at one end of said arbor, a plurality of edger saws mounted on and movable longitudinally of said arbor and forming a series of elements with said iixed element, a power operated device for moving said saws selectively to predetermined positions relative to each other and to said fixed element of said series, said saws being movable within a space extending longitudinally of said arbor and said device comprising power means including a cylinder and a piston for moving each of said saws within and longitudinally of said space, and control means for said power means including selecting means forrcausing operation of one of said pistons to move a selected saw to any selected position of a plurality of predeterminedpositionps including eXtreme and intermediate positions relative to anradjacent element of said series which is onV the samevside o f said selected Vsaw as said one end of said arbor, saidrdevice also comprising means operated by said operation of said one of said pistons to move with said selected saw any other saw whichpis on the opposite side of said selected saw from said one end of said arbor and which is at its selected predetermined position relative to its said adjacent element and movable within said space to thereby maintain said other saw at its selected predetermined position relative to its said adjacent element of said series sovfar as permitted by said space.

References Cited in the tile of this patent UNITED STATES PATENTS 691,692 r Von Zrweigbergk Ian. 21, 1902 UNITED STATES PATENT OFFICE CERTIFICATION OF CORRECTION Patent No., 961,015 November 22, 1960 Burton T. Randall` It is hereby certified that error appeans in the above numbered patent requiring correction and that the said Letters Patent should read as corrected below.

Column 14., line 36, for positiorf read positioned m- Signed and sealed this 2nd day of May 1961.

SEAL) ttest:

ERNEST W0 SWIDER DAVID L` LADD Attesting Ufficer Commissioner of Patents