US3738522A - Automatic scoop positioning device for mechanical shovel - Google Patents

Abstract

A mechanical shovel having an automatic scoop positioning device is disclosed. The scoop of a mechanical shovel must, for many operations, be positioned in one of two operational positions when returning from a tipping position. An auxiliary distributor is positioned hydraulically between a scoop control ram and a main distributor and feeds the ram when in a first position. Latching means hold the appropriate valve of the main distributor in the return position when it is moved to that position and the auxiliary distributor is set up to sense when the scoop reaches the predetermined operating position and thereupon to divert the hydraulic fluid to lock open the latching means thereby releasing the valve of the main distributor and shutting off the flow of fluid to the scoop control ram. The distributor holds the latching means open, so that the movement of the scoop is unrestricted, until a further emptying operation is performed, whereupon the latching means is released and reset for a subsequent operating cycle.

Description

United States Patent r1 1 Cecchi June 12, 1973 21 Appl. No.: 165,245

[30] Foreign Application Priority Data July 30, 1970 Italy... 69632 A/70 [52] U.S. Cl. 214/764, 214/776 [51] Int. Cl E02f 3/87 [58] Field of Search 214/764 [56] References Cited UNITED STATES PATENTS 3,420,393 l/1969 Omon 214/764 3,547,293 12/1970 Borer 214/764 X 3,519,155 7/1970 Jefferson... 214/764 3,429,471 2/1969 Austin 214/764 X 3,122,247 2/1964 Beck 214/764 Primary Examiner-Gerald M. Forlenza Assistant ExaminerJohn Mannix Att0rneyRichard C. Sughrue, Gideon Franklin Rothwell, John H. Mion [57] ABSTRACT A mechanical shovel having an automatic scoop positioning device is disclosed. The scoop of a mechanical shovel must, for many operations, be positioned in one of two operational positions when returning from a tipping position. An auxiliary distributor is positioned hydraulically between a scoop control ram and a main distributor and feeds the ram when in a first position. Latching means hold the appropriate valve of the main distributor in the return position when it is moved to that position and the auxiliary distributor is set up to sense when the scoop reaches the predetermined operating position and thereupon to divert the hydraulic fluid to lock open the latching means thereby releasing the valve of the main distributor and shutting off the flow of fluid to the scoop control ram. The distributor holds the latching means open, so that the movement of the scoop is unrestricted, until a further emptying operation is performed, whereupon the latching means is released and reset for a subsequent operating cycle.

4 Claims, 6 Drawing Figures mmm JUN 1 2 ma SHEETIUFS BY 2.0" f tmc n K ATTORNEY SHEUZBF5 PATENIED JUN 1 2 PAIENIE JUN I 2 ma w l l AUTOMATIC SCOOP POSITIONING DEVICE FOR MECHANICAL SHOVEL BACKGROUND OF THE INVENTION The present invention relates to mechanical shovels this name being given to those motor vehicles, with or without endless tracks, provided with a tipping scoop carried at the end of main lifting arms.

For satisfactory operation of a mechanical shovel the scoop must be positioned with the lower face parallel to the ground when the arms are in a fully lowered position in order to load materials collected in heaps, or must be positioned with the lower face an angle in the region of 7 30' to the ground to carry out digging operations.

Therefore, each time a mechanical shovel completes a cycle of operation, the last operation of which is the tipping of the load on to a lorry or similar vehicle, the arms must be lowered to the fully lowered position and the scoop brought to one of the two above mentioned operational positions. This requires several operations on the hydraulic circuit which the operator must perform separately and which require a certain time.

OBJECTS OF THE INVENTION One object of this invention is to provide a device which operates completely automatically to position the scoop of a mechanical shovel in a predetermined angular position with respect to the main lifting arms, without any manual intervention from the operator.

Another object of this invention is to provide a de vice of the above mentioned type which is capable of positioning the scoop during the lowering of the main lifting arms so as to reduce the time necessary for these two operations.

A further object of this invention is to provide a device of the above mentioned type, which is simple, strong and economical to manufacture, easy and convenient in adjustment and safe and precise in use.

SUMMARY OF THE INVENTION According to the present invention there is provided an automatic scoop positioning device for a mechanical shovel of the type having a scoop supported at the ends of main supporting arms, comprising latching means operative to latch a valve plunger of a main distributor valve in position when moved to a position where the valve feeds an hydraulic scoop control ram to return the scoop from an emptying position, at least one auxiliary distributor hydraulically connected between the main distributor valve and the scoop control ram, the auxiliary distributor having a plunger which is biased to a first position where the auxiliary distributor allows fluid from the main distributor to flow to the ram and which is movable to a second position by means of an arm rigidly connected to the movable part of the scoop control ram where the auxiliary distributor diverts at least part of the fluid from the main distributor to lock the latching means in an open position and release the said main distributor valve plunger to return under the action of biasing means to a neutral position, the auxiliary distributor plunger returning to the first position and releasing the latching means when the scoop is next moved to the emptying position, thereby setting the latching means for asubsequent operating cycle.

Further characteristics and advantages of this invention will become apparent in the course of the following detailed description with reference to the accompanying drawings, given merely as an example without limitations.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic side view, partially in section, of a mechanical shovel provided with an automatic scoop positioning device constructed in accordance with the present invention;

FIG. 2 is a schematic axial section on an enlarged scale of an auxiliary distributor forming part of the scoop positioning device of FIG. 1, shown in a first position;

FIG. 3 is a partial axial section taken on the line III- III of FIG. 2;

FIG. 4 is a view similar to that of FIG. 2, illustrating the auxiliary distributor in a second position;

FIG. 5 is a partial axial section, taken on the line V-V of FIG. 4; and

FIG. 6 is a view similar to FIGS. 2 and 4, illustrating the auxiliary distributor in a third operational position.

DESCRIPTION OF THE PREFERRED EMBODIMENT .With reference to FIG. 1, there is shown schematically the body 1 of a mechanical shovel to which two main lifting arms 3, are pivotally mounted by means of pivots 2. The position of the arms 3 is controlled by hydraulic rams comprising cylinders 7 having pistons 6, the piston rods 5 of which are connected by pivots 4 to the main lifting arms 3; the cylinders 7 are mounted on the body 1 of the mechanical shovel by means of pivots 8. The piston 6 divides the cylinder 7 into two chambers which are fed through conduits 9, 10 respectively from a main distributor 11.

A scoop 13 is carried at the free ends of the lifting arms 3. The scoop 13 is pivotally mounted on the arms 3 by means of a pivot 12. The angular position of the scoop 13 is controlled by a pair of arms 15, pivoted at 14 to the scoop l3 and at 16 to a pair of control levers 17 which, in turn are pivoted at 17a to the main arms 3. The levers 17 are pivoted at 18 near their mid points to respective piston rods 19 of pistons 20 of two hydraulic control actuators or rams having cylinders 21. The cylinders 21 are pivoted at 22 to the body 1 of the mechanical shovel. The pistons 20 divide the cylinders 21 into two opposite chambers 21a, 21b and these chambers are connected by conduits 23, 24 respectively to the main distributor 11. The chamber 21a will be termed the extend chamber of the cylinder 21 and the chamber 2lb will be termed the retum chamber.

The return chamber 21b of at least one of the cylinders 21 communicates with a positioning device 25 which is connected to the main distributor 11 by a conduit 24, and is secured on the cylinder 21 itself. The device 25 is operated by means of a regulating arm 26 attached to an arm 27 which is rigidly attached to the piston rod 19 of the cylinder 21.

The main distributor 11 is provided with movable valves controlled by levers which are operated by the operator. The valve of the main distributor which controls the operation of the cylinders 21 to determine the angular position of the scoop 13 includes a valve plunger 28, the operating movement of the valve plunger is resisted by a spring 30 which tends to return the valve plunger, and thus the valve to a neutral or inoperative position. The valve plunger 28 is manually operable by means of a lever 29.

The valve plunger 28 cooperates with two small latching pistons 31, biased by springs 32 towards a position where they locate in a groove in the valve plunger 28 to hold the valve in the operative position corresponding to rotation of the scoop in a return direction from an emptying-position, that is, clockwise as shown in FIG. 1.

The latching pistons 31 can be retracted so as to free the valve plunger 28 of the main distributor 11, by means of fluid under pressure from the automatic positioning device 25, via a conduit 33, upon which the spring returns the valve to the inoperative position and the scoop 13 stops in the angular position determined by the device 25.

As illustrated in FIG. 2 the automatic positioning device 25 comprises an auxiliary distributor having a distributor body 25a in which slides a plunger 34 which projects out from the front of the body 25a and is engaged at its end 34a, by a lever 35 which is pivoted at one end to a pivot 36 carried by a lug 37 extending from the main body 25a. The upper end 35a of the pivoted lever 35 is engaged by the end 26a of an arm 26 which is rigidly attached to the arm 27 of the piston rod 7 19 of the cylinder 21. The distributor plunger 34 has a solid portion adjacent the end 340 and a hollow portion 34d adjacent the other end.

To the body 25a is rigidly attached a connecting block to which the conduit 24 which leads from the main distributor 11 is connected. The connecting block communicates with a transverse passageway 39 in the body 25a which leads into a chamber 40 which communicates through a narrow passage 41 with a second chamber 42 to one side of the chamber 40. The chamber 42 communicates through a transverse passageway 43, with the return chamber 21b of the cylinder 21.

The-conduit 33 which leads to the latching pistons 31, is connected to the auxiliary distributor body 24a through a connection union 44, communicating with a transverse passageway 45, which leads into an annular chamber 46 which surrounds the plunger 34; the chamber 46 can communicate with a second annular chamber 48, through an axial passageway 47 in which the plunger slides 34.

The chamber 48 has a side opening 49 which communicates with a chamber 50, controlled by a ball valve 51 biased by a spring 52 the other end of which presses against a threaded plug 53; the chamber communicates with the chamber 40 through an oblique passageway 54.

The solid front part of the plunger 34 cooperates with an oil seal 55 in the body 25a and with a dust excluding seal 56 located in a cover 57 attached to the distributor body 25a. The hollow end 34d of the plunger 34 cooperates with an oil seal 58 located at the rear end of the body 25a and held in place by a plate 59 held tightly between the body 25a and a protecting cover 60 having a small breather hole 61.

Inside the cover 60 there is a biasing spring 62 which acts between the cover 60 and a threaded plug 63 which is screwed into the end of the hollow portion 34d of the plunger 34; an oil seal 64 between the plug 63 and the plunger 34 seals the inside of the hollow portion from the atmosphere.

Near the center of the plunger 34 there are two reduced portions 34b, 34c, separated by a portion 65 of the same diameter as the rest of the plunger. Where the hollow portion 34d of the plunger 34 joins the solid portion there is formed a transverse passageway 66 which communicates with an axial passageway 67 which leads to a chamber 68 inside the hollow portion 34d. A ball valve 69, biased by a spring 70 the other end of which acts on the threaded part 63a of the plug 63 controls fluid flow into the chamber 68.

The hollow portion 34d of the plunger 34 has a portion 72 of reduced diameter the function of which will be described below.

The chamber 68 within the plunger 34 has a radial aperture 71 which communicates between the chamber 68 and the chamber 47 of the distributor body 25a.

The main distributor valve 11 is so arranged that, although the valve plungers are biased to a neutral inoperative position where the associated hydraulic actuators are isolated from the source of fluid pressure, each valve plunger has a groove and an associated pair of pistons such as the pistons 31 illustrated as associated with the valve plunger 28 which controls the operation of the scoop control ram. The pistons 31 latch into the groove in the plunger 28 so that when the lever 29 has been moved to an operating position it may be released and the pistons 31 will hold the valve plunger 28 in the operating position without further attention from the operator.

The automatic scoop positioning device operates as follows:

When any material in the scoop has been emptied by tipping forward the previously raised scoop the operator moves the lever 29 to control the return of the scoop thus latching the main distributor valve plunger 28 in position by the small pistons 31. The operator can then operate the lever which controls the lowering of the main arms 3 which will descend solely under gravity because the scoop control circuit has been already operated and the distributor does not allow the simultaneous operation of two hydraulic circuits.

As this takes place the arm 27 rigidly attached to the piston rod 19 of the scoop control cylinder 21 approaches the auxiliary distributor 25 which forms part of the automatic positioning device. Up to this point the auxiliary distributor 25 is in the position illustrated in the FIGS. 2 and 3; the hydraulic fluid under pressure which arrives from the main distributor 11 through the conduit 24 passes through the passageway 39, the chamber 40, the narrow passage 41, the chamber 42 and the transverse passageway 43 to the return chamber 21b of the cylinder 21, the piston 20 of which therefore moves so as to return the scoop in a clockwise direction as seen in FIG. 1 from the emptying position.

The lowering of the arms 3 continues under gravity and the rotation of the scoop 13 eventually causes contact between the extension 26 of the arm 27 and the end of the pivoted lever 35 which therefore moves the plunger 34 of the auxiliary distributor 25, to the right as shown in FIG. 2. After the plunger has moved a distance of about 6 mm the auxiliary distributor takes up the position illustrated in FIGS. 4 and 5.

The plunger 35 is now in a position where the annular portion 65 which separates the two portions of reduced diameter 34b, 34c, partially blocks the narrow passage 41 and prevents the free flow of the oil from the chamber 40 to the chamber 42. As the fluid continues to be fed under pressure to the chamber 40 there is an increase of pressure in this chamber and the pressure moves back the ball 69 of the ball valve and flows through the apertures 66 of the plunger along the axial passageway 67 and into the chamber 68, against the re sistance of the spring 70.

Through the radial aperture 71 the oil under pressure flows into the chamber 46 which communicates through the passageway 45 and the union 44 with the conduit 33 which leads to the latching pistons 31. Because of the increase of the pressure in the chamber 40 the fluid can now move apart the latching pistons 31 which were holding the control plunger 28 of the main distributor valve in the operating position. When the latching pistons are moved out of the latching position the plunger 28 returns to neutral position under the action of the spring 30 thereby closing off the flow of fluid to the ram 21 and stopping the returning movement of the scoop, the arms 3 continue to descend under gravity until they stop. When the arms 3 have reached the end of their travel the scoop is located in the predetermined position, that is with the front face parallel to the ground or in the desired angular position suitable for digging, according to the presetting of the automatic positioning device.

Thus the automatic positioning device allows the scoop to be moved by means of hydraulic control actuators until it reaches a predetermined angle with respect to the main lifting arms'at which point the rotation control'is terminated. Once the automatic positioning has been achieved the scoop can be moved in any direction to load the material; the operator moving the control lever 29 from the neutral position to a control position and holding it in position for the duration of the operation. During such operations the arms 26, 27 cause a further axial shifting of the plunger 34 of the auxiliary distributor 25 causing it to move, for example, a further distance of up to about 8 mm to the position illustrated in FIG. 6.

In this position the latching pistons cannot move to hold the plunger 28 in position because the oil under pressure enclosed in the conduits 33, 45 and in the chamber 46 keeps the latching pistons apart and away from the plunger 28; therefore it is necessary for the operator to hold the operating lever 29 in any control position during this stage of the operating cycle.

The oil, which arrives under pressure through the conduit 24 reaches thereturn chamber 21b of the cylinder 21 through the conduit 39, the chambers 40, 42 and the passageway 43. When the scoop is laden and moved to the desired position the operator allows the control lever to return to the neutral position and the movement of the scoop stops. The operator then causes the arms 3 to raise and stops them at the desired point, after which he can proceed to empty the scoop by moving the lever 29torward and holding it in position for the duration of the emptying operation. while the scoop rotates anticlockwise.

During the emptying of the scoop the hydraulic cylinder 2 which controls the rotation of the scoop is extended by oil entering under pressure into the chamber 21a. The arms 26, 27 move away from the auxiliary distributor 25 allowing the plunger 34 to return to the first position under the action of its return spring 62.

When the auxiliary distributor 25 returns to the position illustrated in FIGS. 2 and 3, the chamber 46 communicates with the chamber 48 by means of the annular region 72 of reduced diameter of the plunger 34, and the oil which was enclosed in the chamber 46 and which held the latching pistons away from the plunger 28 can now flow towards the chamber 48. Urged by the springs 32 which act on the latching pistons 31, the oil in the chamber 46 passes into the chamber 48 forces open the valve 51, penetrates into the chamber 50 and reaches, via the oblique passageway 54, the chamber 40. The oil then passes through the auxiliary distributor and out into the conduit 24 towards the main distributor 11. At this stage the oil in the return chamber 211) of the control cylinder 21 runs in the opposite direction through the passageway 43, the chambers 42, 40, the passageway 39 and the conduit 24.

In this way the latching pistons are released and can thus once again latch the plunger 28 of the main distributor 11 in the next return operation.

Naturally still keeping to the principle of this inven tion, the forms of realization and the manufacturing details can be amply varied, in respect to what has been described and illustrated, without departing from the scope of this invention.

What is claimed is:

1. In a mechanical shovel of the type having a scoop,

main support arms on which said scoop is pivotally mounted, scoop control means on said main support arms, at least one scoop control actuator cylinder operating said scoop control means and controlling the angular position of said scoop with respect to said main support arms, said scoop control cylinder having a piston dividing said cylinder into first and second chambers,

a main hydraulic fluid distributor, said main distributor including a scoop control valve the operation of which determines the angular position of said scoop by controlling the flow of hydraulic fluid to said scoop control cylinder,

said scoop control valve, having a valve member moving between a first position controlling said valve to direct fluid to said first chamber of said scoop control cylinder to move said scoop toward an emptying position, and a return position controlling said valve to direct fluid to said second chamber of said scoop control cylinder to return said scoop to operating position,

biasing means biasing said valve member to an inter mediate neutral position where said scoop control cylinder is hydraulically isolated,

the improvement comprising an automatic scoop positioning device having latching means, biasing means urging said latching means to latch said valve member in said return position when said valve member is moved to said return position,

at least one auxiliary distributor mounted on said scoop control cylinder, said auxiliary distributor being hydraulically connected between said main distributor and said second chamber of said scoop control cylinder, and having a movable distributor member,

biasing means biasing said distributor member to wards a first position where said distributor directs said fluid to said second chamber of said scoop control cylinder, and

an arm rigidly attached to the piston rod of said scoop control cylinder,

said arm in operation of said shovel moving said distributor member against the action of said biasing means as said scoop control cylinder moves said scoop in said return direction, said auxiliary distributor diverting said fluid to lock open said latching means when said scoop reaches a predetermined operating position thereby releasing said valve member, stopping said returning movement of said scoop and locking said scoop in said predetermined operating position, said auxiliary distributor member returning to said first position and releasing said latching means when said scoop is next moved to said emptying position, thereby setting said latching means for a subsequent operating cycle, said distributor member of said auxiliary distributor having a hollow portion adjacent one end, said hollow portion being closed by a threaded stopper, a return spring biasing said distributor member to said first position acting on said stopper, said spring reacting against and enclosed by a cap on the end of said auxiliary distributor, said distributor member having two adjacent regions of reduced diameter, said distributor having two cooperating chambers, a first chamber communicating with said main distributor and a second chamber communicating with said second chamber of said scoop con trol cylinder, said two adjacent regions of reduced diameter forming communicating passageways between said first and second chambers when said auxiliary distributor member is in said first position and interrupting said communication when said auxiliary distributor member is in said predeterchamber communicating with said latching means, radial apertures in said hollow portion of said auxiliary distributor member, said radial apertures forming, together with said hollow portion of said auxiliary distributor member, a passageway communicating with said first chamber and said third chamber, a ball valve in said hollow portion allowing fluid flow only from said first chamber to said second chamber.

2. The automatic scoop positioning device of claim 1 wherein there is a pivoted lever on said auxiliary distributor, said arm rigidly attached to said piston rod of said scoop control cylinder moving said distributor member by means of said pivoted lever.

3. The automatic scoop positioning device of claim 1, a fourth chamber in said auxiliary distributor, a passageway allowing said fourth chamber to communicate with said first chamber, a ball valve allowing fluid flow only from said fourth chamber to said first chamber, said auxiliary distributor member having a third region of reduced diameter allowing communication between said third chamber and said fourth chamber when said auxiliary distributor member is in said first position whereby a passageway is completed between said latching means and said main distributor allowing said latching means to release under the action of said biasing means to reset for a subsequent cycle of operation.

4. The automatic scoop positioning device of claim 1 wherein both ends of said auxiliary distributor member are in contact with the atmosphere.

Claims (4)

1. In a mechanical shovel of the type having a scoop, main support arms on which said scoop is pivotally mounted, scoop control means on said main support arms, at least one scoop control actuator cylinder operating said scoop control means and controlling the angular position of said scoop with respect to said main support arms, said scoop control cylinder having a piston dividing said cylinder into first and second chambers, a maiN hydraulic fluid distributor, said main distributor including a scoop control valve the operation of which determines the angular position of said scoop by controlling the flow of hydraulic fluid to said scoop control cylinder, said scoop control valve, having a valve member moving between a first position controlling said valve to direct fluid to said first chamber of said scoop control cylinder to move said scoop toward an emptying position, and a return position controlling said valve to direct fluid to said second chamber of said scoop control cylinder to return said scoop to operating position, biasing means biasing said valve member to an intermediate neutral position where said scoop control cylinder is hydraulically isolated, the improvement comprising an automatic scoop positioning device having latching means, biasing means urging said latching means to latch said valve member in said return position when said valve member is moved to said return position, at least one auxiliary distributor mounted on said scoop control cylinder, said auxiliary distributor being hydraulically connected between said main distributor and said second chamber of said scoop control cylinder, and having a movable distributor member, biasing means biasing said distributor member towards a first position where said distributor directs said fluid to said second chamber of said scoop control cylinder, and an arm rigidly attached to the piston rod of said scoop control cylinder, said arm in operation of said shovel moving said distributor member against the action of said biasing means as said scoop control cylinder moves said scoop in said return direction, said auxiliary distributor diverting said fluid to lock open said latching means when said scoop reaches a predetermined operating position thereby releasing said valve member, stopping said returning movement of said scoop and locking said scoop in said predetermined operating position, said auxiliary distributor member returning to said first position and releasing said latching means when said scoop is next moved to said emptying position, thereby setting said latching means for a subsequent operating cycle, said distributor member of said auxiliary distributor having a hollow portion adjacent one end, said hollow portion being closed by a threaded stopper, a return spring biasing said distributor member to said first position acting on said stopper, said spring reacting against and enclosed by a cap on the end of said auxiliary distributor, said distributor member having two adjacent regions of reduced diameter, said distributor having two cooperating chambers, a first chamber communicating with said main distributor and a second chamber communicating with said second chamber of said scoop control cylinder, said two adjacent regions of reduced diameter forming communicating passageways between said first and second chambers when said auxiliary distributor member is in said first position and interrupting said communication when said auxiliary distributor member is in said predetermined position corresponding to said predetermined operating position of said scoop, a third chamber in said auxiliary distributor, said third chamber communicating with said latching means, radial apertures in said hollow portion of said auxiliary distributor member, said radial apertures forming, together with said hollow portion of said auxiliary distributor member, a passageway communicating with said first chamber and said third chamber, a ball valve in said hollow portion allowing fluid flow only from said first chamber to said second chamber.

2. The automatic scoop positioning device of claim 1 wherein there is a pivoted lever on said auxiliary distributor, said arm rigidly attached to said piston rod of said scoop control cylinder moving said distributor member by means of said pivoted lever.

3. The automatic scoop positioning device of claim 1, a fourth chamber in said auxiliary distributor, a passagewAy allowing said fourth chamber to communicate with said first chamber, a ball valve allowing fluid flow only from said fourth chamber to said first chamber, said auxiliary distributor member having a third region of reduced diameter allowing communication between said third chamber and said fourth chamber when said auxiliary distributor member is in said first position whereby a passageway is completed between said latching means and said main distributor allowing said latching means to release under the action of said biasing means to reset for a subsequent cycle of operation.

4. The automatic scoop positioning device of claim 1 wherein both ends of said auxiliary distributor member are in contact with the atmosphere.

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