US 3297183 A
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Jan. 10, 1967 I R. A. KLAVITER ETAL 3,297,183 HYDRAULIC SELF-'LEVELING DEVICE FOR A FRONT MOUNTED BUCKET TYPE MATERIAL LOADER 3 Sheets-Sheet 1 Filed July 21, 1965 50 &-
2 I 33 23 25 2Z6 '2; 2.3/6 2 W -23 INVENTORS Robert A. Klaviter Robert D. W2 Niams Jan. 10, 1967 R vrr ET AL 3,297,183
HYDRAULIC SELF-LEVELING DEVICE FOR A FRONT MOUNTED BUCKET TYPE MATERIAL LOADER Filed July 21, 1965 2 Sheets$heet 2 INVENTORS Robe-rt A. Klaviter Robert D. Williams BY w W ATTY.
United StatesPatent O 3,297,183 HYDRAULIC SELF-LEVELING DEVICE FOR A FRONT MOUNTED BUCKET TYPE MA- TERIAL LOADER Robert A. Klaviter, Hickory Hills, and Robert D. Williams, La Grange, Ill., assignors to International Harvester Company, Chicago, 111., a corporation of Delaware Filed July 21, 1965, Ser. No. 473,615 7 Claims. (Cl. 214-771) This invention relates to material loaders including a prime mover and a loader frame having a boom and a bucket, and more particularly to a device for maintaining aspecific bucket position relative to the boom as the boom and bucket are raised and lowered from and to a ground level position.
An object of the invention is to provide an eflicient economical device for better maintaining, at a desired level or position in relation to the horizontal at all stages of operation, the bucket of -a material loader, which is raised and lowered by a hydraulically operated boom type structure.
Another object of the invention is to provide such a device utilizing the hydraulic system of the implement to operate an auxiliary hydraulic mechanism including a slave cylinder automatically to maintain the bucket in a desired posture as it is raised and lowered.
Other objects and advantages of the invention will appear as the description proceeds in relation to the drawings in which:
FIG. 1 is a schematic diagram of an embodiment of the invention including a side elevation of a material loader of the type mentioned with parts of the mechanism indicated in operated position;
FIG. 2 is a perspective view of a material loader equipped with the invention.
The loader 11 with which the invention is associated for present purposes, as illustrated in FIG. 2, comprises a dual hydraulic system 12 for manipulating and operating the bucket 13, which is supported on a dual boom structure 14 pivotally mounted at 15a on sub-frame 15 of the loader. In view of this duality of mechanism, the description will proceed inthe singular with the understanding that it is duplicated on the opposite side of the loader.
The hydraulic system 12 which is connected with a source of fluid (oil') under pressure on the loader (not shown) comprises a boom cylinder 16 operable under control of boom valve 17 to raise and lower the boom structure 14, and a bucket cylinder 18 operable under control of bucket valve 19 to manipulate bucket 13 to positions of operation for filling and emptying it.
Boom cylinder 16 is pivotally connected at its head end 16a to boom structure 14 and at its rod end 1617 to sub-frame 15 and operates, upon the introduction of fluid under pressure at its head end, to raise the boom and the bucket to a position as indicated in broken lines in FIG. 1, and upon release of that pressure to return the boom and bucket to a lower position.
The self-leveling device of the present invention comprises the interposition in such a system of a third cylinder 21, called a slave cylinder, in association with a pair of relief valves respectively called a first relief or anticavi-tation valve 22 and a second relief, or diverter valve 3,297,183 Patented Jan. 10, 1967I Slave cylinder 21 is pivotally attached at its head end 21a to sub-frame 15 and at its rod end 21b to boom structure 14. Cylinder 21 is also connected hydraulically at its head end with the rod end of cylinder 18 and arranged to operate in synchronism therewith. Because cylinder 21 has only a single hydraulic connection, it is known in the art as a single acting cylinder, since hydraulic pressure can act on only one side of the piston therein. 7
Valves 22 and 23 being relief valves are generally similar in type. Each has opposed upper and lower chambers 22a, 22b, 23a, 23b with a passage 22c, 23c therebetween, and normally closed by a spring pressed ball 22d, 23d in the upper chamber 22a, 23a.
Each relief valve has a port 222, 23e in communication with a fluid reservoir 25, 26, with this difference as :will be further noted, namely, that port 222 is in communication with passage 220 whereas port 23e is in communication with upper chamber 23a. Other ports and their function will be noted.
Only valve 22 has a piston 22 in its lower chamber with an upwardly extending rod receivable in the passage 22c between chambers 22a, 22b and arranged when the piston 22 is in upper position to push the ball upwardly out of closing relation with the passage and enable communication between the two chambers. Manually operable means 27 are provided for unseating valve 23 to render the self-leveling device inoperative. 1
Valves 22 and 23 are arranged in hydraulic communication with slave cylinder 21 and with valve 19 and 'cylinder 18 through their several ports.
-Port 22g of valve 22 provides hydraulic communication between the upper chamber of valve 22 through line 31, 32 with the head end 18a of bucket cylinder 18- and one side of valve 19. Port 22h of valve 22 provides like communication through line 33, 34 with the interior of the head end 21a of slave cylinder 21 and port 23g of valve 23 leading to chamber 23b thereof. Port 23h of the latter valve provides hydraulic communication between chamber 23b through lines 35, 36 with the lower or rod end 18b of cylinder 18 and another side of valve 19.
Opposing end portions 16a, 16b of cylinder 16 are in communication with corresponding sides of valve 17.
The self-leveling device operates in the following manner:
Upon raising the boom structure 14 and bucket 13 through a conventional operation of valve 17-which involves the introduction of oil under pressure to cylinder 16 at its head end 16a, thereby projecting the piston rod 16c outwardlyoil in the rod end of cylinder 18 is exhausted intocylinder. 21 at its head end 21a correspondingly thereby supporting the piston thereof as it is drawn upwardly in the raising 'ofthe boom structure and steadying the latter.
As the bucket 13 is raised, and assuming that the bucket is loaded, the rod 1800f cylinder 18 is projected due to the downward pull of the loaded bucket (valve 19 being inoperative), therebytending to create a vacuum in the head end of cylinder 18. This vacuum is communicated to valve 22, causing ball 22d to become unseated, thereby allowing oil to flow from reservoir 25 through port 222, passage 22c, chamber 22a and port 22g and thence into the head end 18a of cylinder 18, thus replacing the vacuum, correcting imbalance in the cylinder, steadying' the operation of the cylinder, and preventing unrestrained rocking or bouncing f the bucket 13, especially during travel of the implement over rough terrain.
Upon lowering the boom structure 14 and bucket 13, oil in cylinder 21 is exhausted correspondingly into the rod end of cylinder 18, thus tending to equalize the pres sure on opposite sides of the piston thereof, steadying the lowering operation, and averting disturbance of the posture of the bucket 13.
As the piston and rod of cylinder 18 are retracted, pressure builds up in cylinder 18 and chamber 22b of valve 22, causing upward movement of piston 22 and its associated rod, to lift ball 22d against the bias of its associated spring and open passage 22c, thereby allowing the escape of oil through port 22e to the reservoir 25, the rod being of sufficiently less diameter than the passage to permit this, thus supplementing the stabilizing of the lowering operation.
During lowering of the boom structure 14 from top raise or lift position, when the rod of cylinder 18 is retracted to a point where the displacement of the piston is less than that of cylinder 21, oil in the latter is not fully exhaustible into cylinder 18. Hence pressure tends to build up to a value exceeding that of the setting of valve 23 thereby lifting ball 230? out of closing position and allowing oil to flow from head end of slave cylinder 21 into port 23g through chambers 23a, 23b, passage 23c and port 23:: to the reservoir 26, thus relieving the condition of imbalance and averting its consequence.
When the self-leveling device is not needed, the valve plunger 23f is actuated by operation of the manual means 27 to unseat ball 23d thereby allowing oil to pass from cylinder 21 through line 34, port 23g, chamber 23a and port 23e to the reservoir 26, port 2311 being closed.
It will be apparent that the synchronous operation of the components of the device described in the manner stated in relation to the loader mechanism substantially stabilizes the raising and lowering of the boom structure and the bucket and substantially maintains the desired posture of the bucket automatically in the course thereof, thus providing an improved, simple, efiicient and economical self-leveling device for the intended purpose.
1. A device for automatically controlling the level of the work bucket of a material loader having (a) a work bucket supported forwardly of the loader by a boom structure mounted on the frame thereof for pivotal movement about a generally horizontal axis extending transversely of said boom structure adjacent one end thereof, said boom structure being mounted adjacent its opposite end for pivotal movement about a generally horizontal axis on the frame of said loader, and
(b) hydraulic power operated mechanism operatively associated with a source of hydraulic power on said loader,
said mechanism comprising a first hydraulic cylinder for actuating said boom structure to raise and lower said bucket under control of a boom valve, and a second hydraulic cylinder for actuating said bucket under control of a bucket valve,
said first cylinder being mounted adjacent its piston rod end for pivotal movement about a generally horizontal axis on said loader frame and having its head end pivotally connected adjacent its outer extremity to said boom structure in predetermined spaced relation with said horizontal axes of said boom structure and said bucket, said second cylinder being mounted adjacent its head end for pivotal movement about a generally horizontal axis on said boom structure and having its piston rod and second relief valves are spring-biased in closed posipivotally connected adjacent its outer extremity to said bucket in predetermined spaced relation with said boom structure, said device comprising auxiliary hydraulically operated mechanism operatively associated with said source including (c) a single-acting third hydraulic cylinder (cl) a first relief, anti-cavitation valve, and (e) a second relief, diverter valve said third cylinder being of the slave type,
said third cylinder and said relief valves being in operative hydraulic communication with one another and with said second cylinder and arranged to operate whereby upon operation of said first cylinder to raise said boom structure and said bucket, said third cylinder and said first relief valve are operated to apply fluid under pressure to said second cylinder opposing retraction of the piston rod thereof thereby to prevent pivoting of the bucket about the said horizontal axis thereof,
said third cylinder and said relief valves being further arranged to operate whereby upon operation of said first cylinder to lower said boom structure and said bucket, said third cylinder and said second relief valve are operated to apply fluid under pressure to said second cylinder enabling retraction of the piston rod thereof thereby to prevent pivoting of the bucket about the said horizontal axis thereof.
2. A device according to claim 1 in which the third cylinder is in hydraulic communication adjacent its head end with the rod end of the second cylinder, said cylinders being arranged to operate in synchronism with one another, whereby upon actuation of the first cylinder to raise the boom structure, said third cylinder is actuated correspondingly to follow the boom structure to raised position.
3. A device according to claim 1 in which the third cylinder is in hydraulic communication adjacent its head end with the rod end of the second cylinder, said cylinders being arranged to operate in synchronisrn with one another, whereby upon actuation of the first cylinder to raise the boom structure, said third cylinder is actuated correspondingly to follow the boom structure to raised position, and said first relief valve is actuated to enable the application of fluid under pressure into said second cylinders adjacent its head end correspondingly opposing retractlon of the piston rod thereof whereby to maintain said bucket in a desired posture.
4. A device according to claim 3 in which, upon actuation of the first cylinder to lower the boom structure from raised position said second relief valve is actuated to relieve said third cylinder correspondingly whereby to enable steady lowering of the boom structure and to maintain said bucket in a desired posture.
5. A device according to claim 3 in which, upon actuatron of the first cylinder to lower the boom structure from raised position said second relief valve is actuated to relieve said third cylinder correspondingly whereby to enable steady lowering of the boom structure and to malntain said bucket in a desired posture, said first relief valve being actuated to relieve said second cylinder correspondingly to enable steady lowering of the boom structure.
6. A device according to claim 3 including manually operable means associated with the second relief valve for rendering said valve and said device inoperative.
7. A device according to claim 1 in which said first tion and arranged to open upon counter-pressure of predetermined amount,
said first relief valve being actuated to open position in the boom raising operation by vacuum in the References Cited by the Examiner system of predetermined value to counteract the UNITED STATES PATENTS same, and in the boom lowering operation by pressure imbalance in the system to counteract the same, ivalsirom and said second relief valve being actuated to open 5 2881931 4/1959 gi 214-140 position in the boom lowering operation by the oc- 2:990:072 6/1961 Mindrum u 214 140 currence of pressure of predetermined value intermediately of the second and third cylinders to re- HUGO O SCHULZ Primmy Examiner lieve the same. 1