US3412880A

US3412880A - Material-handling boom having straight line motion

Info

Publication number: US3412880A
Application number: US592932A
Authority: US
Inventors: Ralph L Tweedale
Original assignee: Massey Ferguson Inc
Current assignee: Massey Ferguson Inc
Priority date: 1966-11-08
Filing date: 1966-11-08
Publication date: 1968-11-26
Anticipated expiration: 1985-11-26

Description

Nov. 26, 1968 R. L. TWEEDALE 3,412,330

MAIERIAL'HANDLING BOOM HAVING STRAIGHT LINE MOTION Filed Nov. 8, 1966 Z mm mm L W m A TTOK/VEKF.

rate

ABSTRACT OF THE DISCLOSURE The disclosure is concerned with material handling booms, and particularly with booms for excavators of the type commonly referred to as backhoes. A boom is mounted on a tractor mounted supporting frame in such a manner that it can move upwardly and downwardly as well as from side to side relative to the frame. Pivotally mounted on the free end of the boom is a dipper stick which carries at its free end an excavating bucket. The boom and dipper stick are foldable and unfoldable relative to each other such that the bucket can be extended away from and retracted toward the supporting frame for excavating. Operation of the boom, dipper stick and bucket is accomplished hydraulically. Compensating mechanism is incorporated into the boom assembly to cause the bucket to move in a straight line path.

BACKGROUND OF THE INVENTION Field of the invention The invention relates to material handling boom assemblies wherein a material handling member is movable in various paths relative to a support.

Description of the prior art Conventional backhoes and similar material handling apparatus are limited to operation in a curved path since the excavating bucket moves about the pivotally supported end of the dipper stick, which in turn is pivotally mounted on a boom carried by a supporting frame. An example of such backhoes is disclosed in US. Patent- 3,270,894, Elliott et al., dated September 6, 1966. As a consequence, such devices are generally limited in their use to excavating and trenching operations and have been found unsuitable for grading, contouring and shaping operations.

SUMMARY OF THE INVENTION In accordance with the present invention, compensating mechanism is provided for causing vertical movement of the pivotal support of the dipper stick in a direction opposite to the vertical movement of the bucket as it swings about said pivotal support. As a result, the bucket travels in a straight line path as it moves toward and away from the support upon extension and retraction of the boom assembly. In a preferred embodiment, the compensating mechanism comprises a compensating cylinder in fluid communication with the actuating cylinder for the boom. The piston of the compensating cylinder follows the surface of a cam carried by the dipper stick such that hydraulic fluid is pumped into or out of the boom cylinder by the compensating cylinder in accordance with the angular position of the dipper stick relative to the boom. As the bucket swings downwardly about the pivoted end of the dipper stick the compensating cylinder causes the boom to move upwardly to maintain the bucket in a straight line path, and as the bucket swings upwardly about the end of the dipper stick, the compensating cylinder causes the boom to correspondingly move downwardly to maintain the bucket in a straight line path.

atent BRIEF DESCRIPTION OF THE DRAWING The single figure of the drawing is an elevational view of a backhoe embodying the invention with the boom dipper stick and bucket shown in various positions by phantom lines.

DESCRIPTION OF THE PREFERRED EMBODIMENT In the drawing, a transverse supporting frame 2 is mounted on the rear end of a tractor 4 having rear wheels 6, only one of which is visible in the drawing. Supported on frame 2 is a boom mounting assembly or swing unit designated collectively by reference numeral 8. Swing unit 8 may include a support bracket 10 to which is pivotally connected a boom frame 12, with a hydraulic motor 14 being received between the pivotally connected arms of the bracket and boom frame in a manner disclosed in the above referred to Elliott et al. Patent 3,270,894. The boom mounting may further include a rotatable mounting plate 16 for selectively tilting the boom about a fore and aft axis of the type disclosed in my co-pending application filed concurrently herewith and entitled, Mounting for Material Handling Masts, Serial Number 592,935, the entire disclosure of which is incorporated herein by reference.

A boom 18 is pivotally mounted by a pin 20 on the lower end of boom frame 12, and is actuated for vertical pivotal movement about pin 20 by a hydraulic boom actuator in the form of a cylinder 22 pivotally connected by a pin 24 with boom 18, and a piston 26 reciprocable in cylinder 22 which is pivotally connected at 28 to the boom frame 12. Cylinder 22 communicates with the tractor hydraulic system through hoses 30 and 3.1. Admission of fluid into cylinder 22 through hose 30 causes piston 26 to retract into the cylinder and move the boom 18 upwardly about pivot point 20. If fluid is withdrawn from the same side of piston 26, the piston will extend from cylinder 22 as the boom 18 lowers about pin 20.

Pivotally mounted on the free end of boom 18 by pin 34 is a dipper stick 32 which is actuated about its pivotal connection with the boom by a hydraulic dipper stick actuator in the form of a cylinder 36 pivotally connected at 38 with the boom, and a piston 40 reciprocable in cylinder 36 and pivotally connected at 42 with the dipper stick. Carried by the free end of the dipper stick is an excavating bucket 44 which is pivotally connected at 46 with the dipper stick. Bucket 44 is actuated about its pivotal connection 46 by a lever 48 having one end pivotally connected at 50 with a dipper stick and its other end pivotally connected at 52 with a link 54 projecting from the bucket. The link and lever 54, 48 are actuated by a hydraulic bucket actuator in the form of a cylinder and piston 56, 6t pivotally connected at 58 with the dipper stick and at 52 with the link and lever 54, 48.

Retraction of piston 40 into cylinder 36, and extension of piston 26 from cylinder 22 causes the bucket to move to the extended positions indicated in phantom lines at A or B in the drawing. Retraction of the bucket toward the supporting frame is accomplished by simultaneous retraction of piston 26 into cylinder 22 and extension of piston 40 from cylinder 36 in a well known manner to cause the dipper stick to fold toward the boom. The retracted position is indicated in phantom lines at C in the drawing.

In accordance with the present invention, bucket 44 is caused to move in a straight line path from its extended to retracted positions by means of a compensating mechanism designated collectively by reference 63. The compensating mechanism includes a compensating cylinder 64 mounted on the boom at 24 and having a piston 66 reciprocable therein with a cam follower 68 on the free end of the piston rod. Cam follower 68 engages the surface of a compensating cam 70 secured to the dipper stick by conventional fasteners 72. The configuration of cam 70 is such that movement of the dipper stick about pin 34 causes appropriate movement of piston 66 into or out of cylinder 64. Cylinder 64 is hydraulically connected with the cylinder 22 by a hose 76 such that as piston 66 is retracted into cylinder 64, hydraulic fluid on the left side of piston 66 is forced through hose 76 into cylinder 22 on the side of piston 26 causing piston 26 to retract into cylinder 22 and raise boom 18 about pivot point 20. Conversely, as piston 66 extends from the compensating cylinder 64, fluid is withdrawn from cylinder 22 on the side of piston 26 causing extension of piston 26 from cylinder 22 and lowering of boom 18 about pin 20.

The configuration of cam 70 is such that when the bucket 44 swings in a downward path relative to pin 34, piston 66 is caused to retract into cylinder 64 and force fluid through hose 76 into cylinder 22 in a direction to raise boom 18 about its pivot 20 a distance corresponding to the downward movement of bucket 44. As the bucket starts in an upward path relative to pivot pin 34, the configuration of cam 70 is such that piston 26 begins to extend from cylinder 64 to cause withdrawal of fluid through hose 76 from cylinder 22 and cause piston 26 to extend from cylinder 22 and lower boom 18 about pivot 20 a distance corresponding to the upward movement of the bucket relative to pin 34. As a result, pivot point 34 moves upwardly about pivot point 20 while bucket 44 moves in a downward path relative to pivot point 34, and pivot point 34 moves downwardly relative to pivot point 2!} when bucket 44 begins moving upwardly relative to pivot point 34 as it moves past the vertical. Consequently, the resultant path of the bucket is in a straight line as indicated at D and E in the drawing. The initial position of the boom 18 is determined by manipulation of manual control levers 78 which in turn determines the initial working position of the bucket teeth 62 along paths D or E, or other straight line paths,

While a specific form of the intention has been illustrated and described, it will be apparent to those skilled in the art that the invention is not limited to the exact construction shown but that it may take various other forms without departing from the scope and spirit of the invention.

I claim:

1. In material handling apparatus including a support, a dipper stick, a material handling member carried by one end of the dipper stick, and means mounted on the support pivotally supporting the other end of the dipper stick such that the material handling member is swingable in an arcuate path about said other end of the dipper stick toward and away from the support, the improvement comprising compensating means for moving said one end of the dipper stick vertically in accordance with the angular position of the dipper stick to cause said material handling member to move in a straight line path relative to the support; said compensating means including an actuator on said means supporting the other end of the dipper stick operable to cause raising and lowering of said other end of the dipper stick relative to the support, means on the dipper stick operatively engaging said actuator to cause the actuator to raise said other end of the dipper stick during downward travel of the material handling member relative to said other end of the dipper stick, and to lower said other end of the dipper stick during upward travel of the material handling member relative to said other end of the dipper stick, said actuator including a hydraulic compensating cylinder having a piston reciprocable therein to cause hydraulic fluid to flow into and out of the compensating cylinder to respectively cause said other end of the dipper stick to lower and raise andwherein said means on the dipper stick engaging the actuator i causes the piston to force fluid from the compensating cylinder as the material handling member moves upwardly relative to said one end of the dipper stick, and causes the piston to move in a direction to cause fluid to flow into the cylinder as the material handling member moves downwardly relative to said one end of the dipper stick.

2. The construction claimed in claim 1 wherein said means on the dipper stick comprises a cam rotatable about the pivotal support of said other end of the dipper stick during movement of the material handling member toward and away from the support, said cam engaging the piston to actuate the piston relative to the compensating cylinder in accordance with the angular position of the dipper stick.

3. Material handling apparatus comprising a supporting frame, a boom pivotally mounted on the supporting frame, a dipper stick pivotally mounted on the free end of the boom, a material handling member carried by the dipper stick, hydraulic means for actuating the dipper stick to pivot relative to the boom and the boom to pivot relative to the supporting frame to move the material handling member toward and away from the supporting frame, compensating means for causing the hydraulic means to move the free end of the boom relative to the supporting frame as the material handling member swings about the free end of the boom in a direction such that the material handling member moves toward and away from the supporting frame in a straight line path, said hydraulic means including a piston and cylinder actuator pivotally connected between the supporting frame and boom such that the extension and retraction of the piston relative to the cylinder causes pivotal movement of the boom relative to the supporting frame, and wherein said compensating means causes extension and retraction of the piston in accordance with the angular position of the dipper stick relative to the boom to maintain the straight line path of the material handling member.

4. Material handling apparatus as defined in claim 3 wherein said boom is pivotally movable relative to the supporting frame in a generally upward and downward direction, and wherein said compensating means causes the boom to move upwardly during downward movement of the material handling member relative to the free end of the boom and causes the boom to move downwardly during upward movement of the material handling member relative to the free end of the boom.

5. Material handling apparatus comprising a supporting frame, a boom pivotally mounted on the supporting frame, a dipper stick pivotally mounted on the free end of the boom, a material handling member carried by the dipper stick, hydraulic means for actuating the dipper stick to pivot relative to the boom and the boom to pivot relative to the supporting frame to move the material handling member toward and away from the supporting frame, and compensating means for causing the hydraulic means to move the free end of the boom relative to the supporting frame as the material handling member swings about the free end of the boom in a direction such that the material handling member moves toward and away from the supporting frame in a straight line path, said boom being pivotally movable relative to the supporting frame in a generally upward and downward direction, said compensating means causing the boom to move upwardly during downward movement of the material handling member relative to the free end of the boom and boom to move downwardly during upward movement of the material handling member relative to the free end of the boom, said hydraulic means including a piston and cylinder boom actuator mounted between the supporting frame and boom. such that the piston extends from the cylinder when the boom pivots downwardly and retracts into the cylinder when the boom pivots upwardly, and wherein said compensating means controls the flow of hydraulic fluid to the cylinder to cause the piston to retract into the cylinder as the material handling member moves downwardly relative to the free end of the boom and causes the piston to extend from the cylinder as the material handling member moves upwardly relative to the free end of the boom.

6. Material handling apparatus as defined in claim 5 wherein said compensating means comprises a compensating piston and cylinder actuator hydraulically connected with the boom actuator such that extension and retraction of the compensating actuator causes retraction and extension of the boom actuator, respectively, and a cam on the dipper stick engaged with the piston of the compensating actuator to cause extension and retraction of the compensating actuator in accordance with the angular position of the dipper stick relative to the boom.

7. In material handling apparatus including a support, a bOOm having one end pivotally mounted on the support, a dipper stick having one end pivotally mounted on the other end of the boom, a bucket pivotally mounted on the other end of the dipper stick, a boom actuator mounted between the boom and support for pivoting the boom about the support, a dipper stick actuator between the boom and dipper stick for pivoting the dipper stick relative to the boom, and a bucket actuator between the bucket and the dipper stick for pivoting the bucket relative to the dipper stick, the improvement comprising compensating means for causing the boom actuator to move said one end of the dipper stick vertically in accordance with the angular position of the dipper stick relative to the boom independently of the angular position of the bucket relative to the dipper stick to cause the excavating bucket to move in a straight line path without altering the angle between the dipper stick and bucket.

8. The construction claimed in claim 7 wherein said compensating means includes a compensating actuator on the boom operable to cause raising and lowering of said other end of the dipper stick relative to the support, and means on the dipper stick engaging said actuator tocause the actuator to raise said other end of the dipper stick during downward travel of the bucket relative to the other end of the dipper stick, and to lower the, other end of the dipper stick during upward travel of the bucket relative to said other end of the dipper stick.

References Cited UNITED STATES PATENTS 3,343,693 9/1967 Becker 214---138 HUGO 0. SCHULZ, Primary Examiner.