CA1220067A - Three-point hitch assembly - Google Patents
Three-point hitch assemblyInfo
- Publication number
- CA1220067A CA1220067A CA000445749A CA445749A CA1220067A CA 1220067 A CA1220067 A CA 1220067A CA 000445749 A CA000445749 A CA 000445749A CA 445749 A CA445749 A CA 445749A CA 1220067 A CA1220067 A CA 1220067A
- Authority
- CA
- Canada
- Prior art keywords
- arm
- arms
- piston
- lever
- lift
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
Links
Classifications
-
- A—HUMAN NECESSITIES
- A01—AGRICULTURE; FORESTRY; ANIMAL HUSBANDRY; HUNTING; TRAPPING; FISHING
- A01B—SOIL WORKING IN AGRICULTURE OR FORESTRY; PARTS, DETAILS, OR ACCESSORIES OF AGRICULTURAL MACHINES OR IMPLEMENTS, IN GENERAL
- A01B59/00—Devices specially adapted for connection between animals or tractors and agricultural machines or implements
- A01B59/04—Devices specially adapted for connection between animals or tractors and agricultural machines or implements for machines pulled or pushed by a tractor
- A01B59/042—Devices specially adapted for connection between animals or tractors and agricultural machines or implements for machines pulled or pushed by a tractor having pulling means arranged on the rear part of the tractor
- A01B59/043—Devices specially adapted for connection between animals or tractors and agricultural machines or implements for machines pulled or pushed by a tractor having pulling means arranged on the rear part of the tractor supported at three points, e.g. by quick-release couplings
-
- A—HUMAN NECESSITIES
- A01—AGRICULTURE; FORESTRY; ANIMAL HUSBANDRY; HUNTING; TRAPPING; FISHING
- A01B—SOIL WORKING IN AGRICULTURE OR FORESTRY; PARTS, DETAILS, OR ACCESSORIES OF AGRICULTURAL MACHINES OR IMPLEMENTS, IN GENERAL
- A01B59/00—Devices specially adapted for connection between animals or tractors and agricultural machines or implements
- A01B59/04—Devices specially adapted for connection between animals or tractors and agricultural machines or implements for machines pulled or pushed by a tractor
- A01B59/041—Devices specially adapted for connection between animals or tractors and agricultural machines or implements for machines pulled or pushed by a tractor preventing or limiting side-play of implements
-
- A—HUMAN NECESSITIES
- A01—AGRICULTURE; FORESTRY; ANIMAL HUSBANDRY; HUNTING; TRAPPING; FISHING
- A01B—SOIL WORKING IN AGRICULTURE OR FORESTRY; PARTS, DETAILS, OR ACCESSORIES OF AGRICULTURAL MACHINES OR IMPLEMENTS, IN GENERAL
- A01B59/00—Devices specially adapted for connection between animals or tractors and agricultural machines or implements
- A01B59/06—Devices specially adapted for connection between animals or tractors and agricultural machines or implements for machines mounted on tractors
- A01B59/066—Devices specially adapted for connection between animals or tractors and agricultural machines or implements for machines mounted on tractors of the type comprising at least two lower arms and one upper arm generally arranged in a triangle (e.g. three-point hitches)
- A01B59/068—Devices specially adapted for connection between animals or tractors and agricultural machines or implements for machines mounted on tractors of the type comprising at least two lower arms and one upper arm generally arranged in a triangle (e.g. three-point hitches) the lower arms being lifted or lowered by power actuator means provided externally on the tractor
Landscapes
- Life Sciences & Earth Sciences (AREA)
- Zoology (AREA)
- Engineering & Computer Science (AREA)
- Mechanical Engineering (AREA)
- Soil Sciences (AREA)
- Environmental Sciences (AREA)
- Agricultural Machines (AREA)
Abstract
THREE-POINT HITCH ASSEMBLY
ABSTRACT OF THE DISCLOSURE
A three-point hitch assembly for attachment to a tractor includes a pair of lower lift arms adjust-ably coupled to an upper lifting assembly which can be raised and lowered by a pair of hydraulic cylinders.
In order to provide a float action of the lower lift arms, a lever coupling the upper end of the pistons of the hydraulic cylinders to the lifting assembly can be latched and unlatched to pivot relative to the lift as-sembly. The cylinders are coupled in series so as to ensure even lifting of the lift assembly.
ABSTRACT OF THE DISCLOSURE
A three-point hitch assembly for attachment to a tractor includes a pair of lower lift arms adjust-ably coupled to an upper lifting assembly which can be raised and lowered by a pair of hydraulic cylinders.
In order to provide a float action of the lower lift arms, a lever coupling the upper end of the pistons of the hydraulic cylinders to the lifting assembly can be latched and unlatched to pivot relative to the lift as-sembly. The cylinders are coupled in series so as to ensure even lifting of the lift assembly.
Description
THREE-POINT HITCH ASSEMBLY
BACKGROUND OF THE INVENTION
This invention relates to a three-point hitch assembly particularly of the type which can be attached to the conventional drawbar of an older type tractor which has not been equipped with a three-point hitch.
Various proposals have been made for a device of this type but a requirement remains for a simple rugged construction which has the properties of enabling the lower draft arms of the three-point hitch to be raised by hydraulic cylinders, for -the lower draft arms to be locked in ~he raised position or for them to be free to float above the raised position. It will be appreciated that some implements require the three-point hitch to be effectively fixed at a desired height and yet ot'ner implements require some floating action so that if the implement hits an obstacle it can lift or float over t'ne obstacle by lifting away from the other-wise fixed position of the hydraulic lifting mechanism.
20 `~` It is a Eurther important requirement of a device of this type that the two arms be lifted at the same rate of movement despite different loads being applied to the arms by the implement.
.......
BACKGROUND OF THE INVENTION
This invention relates to a three-point hitch assembly particularly of the type which can be attached to the conventional drawbar of an older type tractor which has not been equipped with a three-point hitch.
Various proposals have been made for a device of this type but a requirement remains for a simple rugged construction which has the properties of enabling the lower draft arms of the three-point hitch to be raised by hydraulic cylinders, for -the lower draft arms to be locked in ~he raised position or for them to be free to float above the raised position. It will be appreciated that some implements require the three-point hitch to be effectively fixed at a desired height and yet ot'ner implements require some floating action so that if the implement hits an obstacle it can lift or float over t'ne obstacle by lifting away from the other-wise fixed position of the hydraulic lifting mechanism.
20 `~` It is a Eurther important requirement of a device of this type that the two arms be lifted at the same rate of movement despite different loads being applied to the arms by the implement.
.......
- 2 -SUMMARY OF THE INVENTION
~ .......... .
It is a first object of the invention there-fore to provide a three-point hitch device which is of simple, rugged and effective construction and which provides the alternative of the lower draft arms being fixed or locked in position, or alternatively free to float above the position.
Accordingly~ the invention provides a three-point hi-tch assembly for attachment to a tractor com-prising a pair of lower draft arms for extending rear-wardly of the tractor, frame means for attachment to the tractor and for supporting said lower draft arms for pivotal movement about a first horizontal axis, a pair of lift arms mounted on the frame for pivotal move-ment about a second horizontal axis above said first axis, a pair of connecting links each for connecting a respective lift arm to a respective lower draft arm, a pair of hydraulic cylinder and piston devices each con-necting between the frame and the respective lift arm whereby the lift arms can be raised and lowere~ by ope-ration of the hydraulic cylinders to raise and lower the lower draft arMs, loose coupling means between each cy-linder and piston device and the respective lift arm to allow floating movement of the lower draft arms and ... .
~ 7
~ .......... .
It is a first object of the invention there-fore to provide a three-point hitch device which is of simple, rugged and effective construction and which provides the alternative of the lower draft arms being fixed or locked in position, or alternatively free to float above the position.
Accordingly~ the invention provides a three-point hi-tch assembly for attachment to a tractor com-prising a pair of lower draft arms for extending rear-wardly of the tractor, frame means for attachment to the tractor and for supporting said lower draft arms for pivotal movement about a first horizontal axis, a pair of lift arms mounted on the frame for pivotal move-ment about a second horizontal axis above said first axis, a pair of connecting links each for connecting a respective lift arm to a respective lower draft arm, a pair of hydraulic cylinder and piston devices each con-necting between the frame and the respective lift arm whereby the lift arms can be raised and lowere~ by ope-ration of the hydraulic cylinders to raise and lower the lower draft arMs, loose coupling means between each cy-linder and piston device and the respective lift arm to allow floating movement of the lower draft arms and ... .
~ 7
- 3 -the means for locking/loose coupling means to prevent said floating r,lovement.
It is a particularly advantageous feature of the i.nvention that the loose coupling means comprises a lever pivotally connected to the lift arm and to the cylinder and pis~on device and means for limiting pivot-al movement of the lever relative to the lift arm.
It is a further advantageous feature of t'ne invention that the lift arm comprises a channel section member with the lever mounted within the channel sec-tion for pivotal movement about a transverse axis out of the channel section, and a channel guide connected to the channel section so the movement of the lever is de-limited by engagement with the channel section and with a closed end of the channel guide.
In accordance with a yet further important feature of the inven.ion there is provided first fluid connection means for connecting pressurized hydraulic fluid from a supply to an expansion side of the piston of one of the cylinders, second fluid connection means for connection of the fluid from the retraction side of the piston of said one cylinder to the expansion side of the piston of the other cylinder and third fluid con-nection means for connecting fluid from the retraction 6~
side of the piston o the other cylinder for return to the supply, said one cylinder and piston being greater in diameter than said other whereby the swept volume on the retraction side of said one is equal to the swept volume on the expansion side of said other whereby the cylinders operate in series at the same rate of move-ment.
With the foregoing in view, and other advan-tages as will become apparent to those skilled in the art to which this invention relates as this specifica-tiuon proceeds, the invention is herein described by reference to the accompanying drawings forming a part hereof, which includes a description of the best mode known to the applicant and of the preferred typical em-bodiment of the principles of the present invention, in which:
DESCRIPTION OF THE FIGURES
.
Figure 1 is a cross sectional view of the hitch assembly in a locked position, the cross section taken along lines 1-1 of Figure 3.
Figure 2 is a side elevational view similar to that of Figure 1 showing the assembly in a floating position.
Figure 3 is a front elevational view of the ~:2~;7 assembly of Figure 1.
Figure 4 is a top plan view of the assembly of Figure 1.
In the drawings like characters of reference indicate corresponding parts in the different figures.
DETAILED DESCRIPTION
The hitch assembly for attachment to the con-ventional drawbar of a tractor comprises a support frame generally indicated at 10 including a lower angle iron section 11, an upper angle iron section 12 and two sup-port legs 13, 14 thus forming a rectangular frame which can sit on the drawbar of the tractor. A pair of pads 15 are welded to the underside of the lower angle iron - 11 in order to rest upon the drawbar of the tractor.
The legs 13~ 14 are formed of square section tubing and are welded to the angle iron sections 11 and 12 to form a rigid structure.
Within the upper angle iron section 12 at the top of the legs 13, 14 respectively is welded a pair of collars 16, 17 for rotatably supporting a shaft 18 in the form of a pipe which extends along the full length of the section 12 and beyond the ends to a posi-tion beyond the collars 16, 17. Centrally of the upper section 12 is provided a third collar 19 which again sup-~. ,, ~
.... , ~ ,........ .
ports the shaft 18 and also receives a bracket 20 which can be attached to the upper control arm of the three-point hitch in a conventional manner.
Rearwardly of the frame at the bottom section 11 and adjacent the legs 13~ 14 is positioned a pair of flanges 21, 22. The flanges extend rearwardly from the frame and provide a pivotal support by way of a bolt 23 for a pair of lower lift arms 24, 25 which extend from the flanges 21, 22 forwardly beyond the frame 10 to a forwardly extending coupling member 26 for attachment to an implement in a conventional manner. Thus, the arms 24, 25 together with the upper support arm attached to the coupling 20 provide the three-point hitch arrange-ment which can pivot upwardly and downwardly relative to the pivot pins 23 and also the coupling 20.
To accommodate sideways movement of the lower lift arms 24, 25 a pair of plates 27, 28 are provided which lie inwardly of the arms 24~ 25 either in contact therewith or slightly spaced therefrom so that as the arms 24, 25 pivot upwardly, they slide against the plates 27, 28 thus inhibiting sideways or lateral movement of the arms 24, 25. The plates 27, 28 are mounted upon the outer side of the legs 13, 14 by way of a welded plate 29 and a pair of bolts 30 which include spacers to set .. .. ..
~ 7 the position of the plates 27, 28 re].ative to the arms 24, 25.
The shaft 18 supports a lift assembly for the lower lift arms 24, 25 generally indicated at 31. The lift assembly comprises a pair of outer arms 32~ 33 which extend from the shaft 18 forwardly to a position parallel to and above the lift arms 24, 25. The outer arms 323 33 are coupled to the lower lift arms 24, 25 respectively by a pair of linkages 34. The lower end of the linkage 34 includes a bifurcated support 35 for receiving a transverse pin 36 which passes through an opening 37 in the upper edge of the lift arm~ The length of the link-age is adjustable by a male and female co-operating screw thread 38 with the upper end of the male screw thread being attached to a furth~r bifurcated link 39 coupled in turn to a flange 40 of the upper outer arms 32, 33 by a pin 41. The arms 32, 33 are of square cross sectioned tubing and the flange 40 is formed in a slot along the length of the tubing and welded to the tubing so as to extend downwardly beneath the arm for receiving the pin 41.
The linkage 34 therefore, acts to communicate movement of the outer arms 32, 33 to the lower lift arms 24, 25 with the screw thread 38 providing adjustment o , . . . .
~ ~2~6~
the angle between the arms 32, 33 and the lower lift arms 24, 25. As shown in Figure 1, the arms are arran-ged parallel but this can be adjusted in order to lift or lower the coupling 26 while maintaining the arm 33 stationary.
The lift assembly 31 also includes a second pair pair of arms 42, 43 parallel to the outer arms and posi-tioned inwardly thereof. It will be noted that the col-lars 16, 17 are positioned respectively so that the out-er arm lies on one side of the collar and the inner armlies on the other side of the collar with the collar sub-stantially filling the space therebetween. The length of the arms 42, 43 is less than the respective outer arms 32, 33.
A coupling bar 44 is welded to the outer end of the arms 32, 42 and 33, 43 so as to provide a rigid coupling therebetween which coop~rates with the rigidity of the shaft 18 so that the inner and outer arms co-rotate about the axis of the shaft 18. In addition, as a further supporting bracket, a gusset 45 is connected between the arms 42, 43 and the shaft 18, so that the shaft, arms 42, 43 and arms 32, 33 comprise a rigid as-sembly which together rotates around the axis of the shaft 18.
The arms 42, 43 are again formed from square section tubing but include a transverse opening 46 for receiving a pivot pin ~7 of a lever ~8. In addition, the lowermost face of the s~uare section tubing of the arm is cut away at a position forwardly of the pivot pin 47 to allow a flange 49 of the lever 48 to project downwardly out of the tubing of the arm. Furthermore, beyond the cut away section indicated at 50, the lower edge of the tubing is extended by an extension portion 51 oE the same width as the tubing to provide a slideway for the end of the lever 48 so that this can move up-wardly and downwardly from a raised position where it is received wholly within the tubing of the arm 43 to a lowered position where it is received within the ex-tension portion 51.
These positions are illustrated respectively in Figures 1 and 2.
In order to latch the lever 48 in the upper position illustrated in Figure 1, an opening 52 is pro-vided at the junction between the tubing and the exten-sion portion 51 so that a pin 53 can be inserted be-neath the lower surface of the lever.
The flange 49 of the lever 48 is attached by a bifurcated coupling 54 to a piston rod 55 of a cylin-.... ~..
~2~
der 56. The other end of the cylinder is attached again by a bifurcated coupling 57 to a lug 58 on the angle iron 11 using a pivot pin 59.
Turning to Figure 3 particularly, it will be noted that there are two cylinders 56, the left hand one of which is indicated at 561 and the right hand one of which is indicated at 562. The cylinders are arranged in respective vertical planes and extending from a posi-tion within the frame 10 to a position at the end of the piston rod slightly forwardly of the frame 10 so that by extension of the piston within the cylinder 56, the lever 48 can be raised thus raising the arms ~2, 43.
Observing the hydraulic linkage to the cylin-ders 62, 562 it will be noted that they are ranged in series rather than in parallel. Thus, fluid supply from a pump 60 is connected to the extension side of the piston indicated at 62 of the cylinder 562 and thus acts to expel the cylinder to extend the piston rod to lift the lever 48. The fluid expelled from the downstream side of the piston 62 is communicated via a duct 63 to the expansion side of the piston 64 of the cylinder 561.
Fluid ejected by movement of the piston 64 is connected to a sump schematically indicated at 61 rom a cylinder 561. It will be noted furthermore that the . .
~2~ '7 diameter of the cy].inder 562 is greater than that of the cylinder 561 so that the volume of fluid swept by the upper side of the piston 62 is equal to the volume of fluid causing movement of the piston 64. The differ-ences in diameter therefore accommodates the piston rod 55 of the piston 62 which takes up some of the volume above the piston 62.
Thus, coupling the cylinder in series as oppo-sed to in parallel ensures that the arms 42, 43 are lift-ed at the sa~e ratè. regardless of any difference of loadapplied thereto.
It will be apparent that lifting of the arms 42, 43 via the levers 48 will also cause lifting move-- ment of the arms 32, 33 and therefore the lower lift arms 24, 25.
In a locked position of the lever 48 as shown in Figure 1, the arms ?4, 25 are effec~ively rigidly coupled to the piston rods 55 and therefore are locked in position by the hydraulic cylinders 56. Thus, they can be raised to a required position and then retained in that position and cannot raise from that positionO
However, in the position illustrated in Figure ~ where the pin 53 is removed thus releasing the lever 48, the arms 43 can lift relative to the lever 48 un-der force from the arms 24, 25. The degree of lifting or floating movement is controlled by the portion 51 of the arms 42, 43 but within the limits of that control the arms 24, 25 and therefore the couplings 26 can lift up and down without adjustment of the cylinders 56. Such floating action is required in relation to equipment which needs to lift over uneven t~rrain but to return to the required adjusted position as soon as the uneven terrain is passed.
Since various modifications can be made in my invention as hereinabove described, and manay apparent-ly widely different embodiments of same made within the spirit and scope of the claims without departing from such spirit and scope, it is intended that all matter contained in the accompanying specification shall be interpreted as illustrative only and not in a limiting sense.
.
It is a particularly advantageous feature of the i.nvention that the loose coupling means comprises a lever pivotally connected to the lift arm and to the cylinder and pis~on device and means for limiting pivot-al movement of the lever relative to the lift arm.
It is a further advantageous feature of t'ne invention that the lift arm comprises a channel section member with the lever mounted within the channel sec-tion for pivotal movement about a transverse axis out of the channel section, and a channel guide connected to the channel section so the movement of the lever is de-limited by engagement with the channel section and with a closed end of the channel guide.
In accordance with a yet further important feature of the inven.ion there is provided first fluid connection means for connecting pressurized hydraulic fluid from a supply to an expansion side of the piston of one of the cylinders, second fluid connection means for connection of the fluid from the retraction side of the piston of said one cylinder to the expansion side of the piston of the other cylinder and third fluid con-nection means for connecting fluid from the retraction 6~
side of the piston o the other cylinder for return to the supply, said one cylinder and piston being greater in diameter than said other whereby the swept volume on the retraction side of said one is equal to the swept volume on the expansion side of said other whereby the cylinders operate in series at the same rate of move-ment.
With the foregoing in view, and other advan-tages as will become apparent to those skilled in the art to which this invention relates as this specifica-tiuon proceeds, the invention is herein described by reference to the accompanying drawings forming a part hereof, which includes a description of the best mode known to the applicant and of the preferred typical em-bodiment of the principles of the present invention, in which:
DESCRIPTION OF THE FIGURES
.
Figure 1 is a cross sectional view of the hitch assembly in a locked position, the cross section taken along lines 1-1 of Figure 3.
Figure 2 is a side elevational view similar to that of Figure 1 showing the assembly in a floating position.
Figure 3 is a front elevational view of the ~:2~;7 assembly of Figure 1.
Figure 4 is a top plan view of the assembly of Figure 1.
In the drawings like characters of reference indicate corresponding parts in the different figures.
DETAILED DESCRIPTION
The hitch assembly for attachment to the con-ventional drawbar of a tractor comprises a support frame generally indicated at 10 including a lower angle iron section 11, an upper angle iron section 12 and two sup-port legs 13, 14 thus forming a rectangular frame which can sit on the drawbar of the tractor. A pair of pads 15 are welded to the underside of the lower angle iron - 11 in order to rest upon the drawbar of the tractor.
The legs 13~ 14 are formed of square section tubing and are welded to the angle iron sections 11 and 12 to form a rigid structure.
Within the upper angle iron section 12 at the top of the legs 13, 14 respectively is welded a pair of collars 16, 17 for rotatably supporting a shaft 18 in the form of a pipe which extends along the full length of the section 12 and beyond the ends to a posi-tion beyond the collars 16, 17. Centrally of the upper section 12 is provided a third collar 19 which again sup-~. ,, ~
.... , ~ ,........ .
ports the shaft 18 and also receives a bracket 20 which can be attached to the upper control arm of the three-point hitch in a conventional manner.
Rearwardly of the frame at the bottom section 11 and adjacent the legs 13~ 14 is positioned a pair of flanges 21, 22. The flanges extend rearwardly from the frame and provide a pivotal support by way of a bolt 23 for a pair of lower lift arms 24, 25 which extend from the flanges 21, 22 forwardly beyond the frame 10 to a forwardly extending coupling member 26 for attachment to an implement in a conventional manner. Thus, the arms 24, 25 together with the upper support arm attached to the coupling 20 provide the three-point hitch arrange-ment which can pivot upwardly and downwardly relative to the pivot pins 23 and also the coupling 20.
To accommodate sideways movement of the lower lift arms 24, 25 a pair of plates 27, 28 are provided which lie inwardly of the arms 24~ 25 either in contact therewith or slightly spaced therefrom so that as the arms 24, 25 pivot upwardly, they slide against the plates 27, 28 thus inhibiting sideways or lateral movement of the arms 24, 25. The plates 27, 28 are mounted upon the outer side of the legs 13, 14 by way of a welded plate 29 and a pair of bolts 30 which include spacers to set .. .. ..
~ 7 the position of the plates 27, 28 re].ative to the arms 24, 25.
The shaft 18 supports a lift assembly for the lower lift arms 24, 25 generally indicated at 31. The lift assembly comprises a pair of outer arms 32~ 33 which extend from the shaft 18 forwardly to a position parallel to and above the lift arms 24, 25. The outer arms 323 33 are coupled to the lower lift arms 24, 25 respectively by a pair of linkages 34. The lower end of the linkage 34 includes a bifurcated support 35 for receiving a transverse pin 36 which passes through an opening 37 in the upper edge of the lift arm~ The length of the link-age is adjustable by a male and female co-operating screw thread 38 with the upper end of the male screw thread being attached to a furth~r bifurcated link 39 coupled in turn to a flange 40 of the upper outer arms 32, 33 by a pin 41. The arms 32, 33 are of square cross sectioned tubing and the flange 40 is formed in a slot along the length of the tubing and welded to the tubing so as to extend downwardly beneath the arm for receiving the pin 41.
The linkage 34 therefore, acts to communicate movement of the outer arms 32, 33 to the lower lift arms 24, 25 with the screw thread 38 providing adjustment o , . . . .
~ ~2~6~
the angle between the arms 32, 33 and the lower lift arms 24, 25. As shown in Figure 1, the arms are arran-ged parallel but this can be adjusted in order to lift or lower the coupling 26 while maintaining the arm 33 stationary.
The lift assembly 31 also includes a second pair pair of arms 42, 43 parallel to the outer arms and posi-tioned inwardly thereof. It will be noted that the col-lars 16, 17 are positioned respectively so that the out-er arm lies on one side of the collar and the inner armlies on the other side of the collar with the collar sub-stantially filling the space therebetween. The length of the arms 42, 43 is less than the respective outer arms 32, 33.
A coupling bar 44 is welded to the outer end of the arms 32, 42 and 33, 43 so as to provide a rigid coupling therebetween which coop~rates with the rigidity of the shaft 18 so that the inner and outer arms co-rotate about the axis of the shaft 18. In addition, as a further supporting bracket, a gusset 45 is connected between the arms 42, 43 and the shaft 18, so that the shaft, arms 42, 43 and arms 32, 33 comprise a rigid as-sembly which together rotates around the axis of the shaft 18.
The arms 42, 43 are again formed from square section tubing but include a transverse opening 46 for receiving a pivot pin ~7 of a lever ~8. In addition, the lowermost face of the s~uare section tubing of the arm is cut away at a position forwardly of the pivot pin 47 to allow a flange 49 of the lever 48 to project downwardly out of the tubing of the arm. Furthermore, beyond the cut away section indicated at 50, the lower edge of the tubing is extended by an extension portion 51 oE the same width as the tubing to provide a slideway for the end of the lever 48 so that this can move up-wardly and downwardly from a raised position where it is received wholly within the tubing of the arm 43 to a lowered position where it is received within the ex-tension portion 51.
These positions are illustrated respectively in Figures 1 and 2.
In order to latch the lever 48 in the upper position illustrated in Figure 1, an opening 52 is pro-vided at the junction between the tubing and the exten-sion portion 51 so that a pin 53 can be inserted be-neath the lower surface of the lever.
The flange 49 of the lever 48 is attached by a bifurcated coupling 54 to a piston rod 55 of a cylin-.... ~..
~2~
der 56. The other end of the cylinder is attached again by a bifurcated coupling 57 to a lug 58 on the angle iron 11 using a pivot pin 59.
Turning to Figure 3 particularly, it will be noted that there are two cylinders 56, the left hand one of which is indicated at 561 and the right hand one of which is indicated at 562. The cylinders are arranged in respective vertical planes and extending from a posi-tion within the frame 10 to a position at the end of the piston rod slightly forwardly of the frame 10 so that by extension of the piston within the cylinder 56, the lever 48 can be raised thus raising the arms ~2, 43.
Observing the hydraulic linkage to the cylin-ders 62, 562 it will be noted that they are ranged in series rather than in parallel. Thus, fluid supply from a pump 60 is connected to the extension side of the piston indicated at 62 of the cylinder 562 and thus acts to expel the cylinder to extend the piston rod to lift the lever 48. The fluid expelled from the downstream side of the piston 62 is communicated via a duct 63 to the expansion side of the piston 64 of the cylinder 561.
Fluid ejected by movement of the piston 64 is connected to a sump schematically indicated at 61 rom a cylinder 561. It will be noted furthermore that the . .
~2~ '7 diameter of the cy].inder 562 is greater than that of the cylinder 561 so that the volume of fluid swept by the upper side of the piston 62 is equal to the volume of fluid causing movement of the piston 64. The differ-ences in diameter therefore accommodates the piston rod 55 of the piston 62 which takes up some of the volume above the piston 62.
Thus, coupling the cylinder in series as oppo-sed to in parallel ensures that the arms 42, 43 are lift-ed at the sa~e ratè. regardless of any difference of loadapplied thereto.
It will be apparent that lifting of the arms 42, 43 via the levers 48 will also cause lifting move-- ment of the arms 32, 33 and therefore the lower lift arms 24, 25.
In a locked position of the lever 48 as shown in Figure 1, the arms ?4, 25 are effec~ively rigidly coupled to the piston rods 55 and therefore are locked in position by the hydraulic cylinders 56. Thus, they can be raised to a required position and then retained in that position and cannot raise from that positionO
However, in the position illustrated in Figure ~ where the pin 53 is removed thus releasing the lever 48, the arms 43 can lift relative to the lever 48 un-der force from the arms 24, 25. The degree of lifting or floating movement is controlled by the portion 51 of the arms 42, 43 but within the limits of that control the arms 24, 25 and therefore the couplings 26 can lift up and down without adjustment of the cylinders 56. Such floating action is required in relation to equipment which needs to lift over uneven t~rrain but to return to the required adjusted position as soon as the uneven terrain is passed.
Since various modifications can be made in my invention as hereinabove described, and manay apparent-ly widely different embodiments of same made within the spirit and scope of the claims without departing from such spirit and scope, it is intended that all matter contained in the accompanying specification shall be interpreted as illustrative only and not in a limiting sense.
.
Claims
CLAIMS:
(1) A three-point hitch assembly for attach-ment to a tractor comprising a pair of lower draft arms for extending rearwardly of the tractor, frame means for attachment to the tractor and for supporting said lower draft arms for pivotal movement about a first horizontal axis, a pair of lift arms mounted on the frame for pivotal movement about a second horizontal axis above said first axis, a pair of connecting links each for connecting a respective lift arm to a respective lower draft arm, a pair of hydraulic cylinder and piston de-vices each connecting between the frame and the res-pective lift arm whereby the lift arms can be raised and lowered by operation of the hydraulic cylinders to raise and lower the lower draft arms, loose coupling means between each cylinder and piston device and the respective lift arm to allow floating movement of the lower draft arms and means for locking loose coupling means to prevent said floating movement.
(2) The invention according to Claim 1 where-in the loose coupling means comprises a lever pivotally connected to the lift arm and to the cylinder and piston device and means for limiting pivotal movement of the lever relative to the lift arm.
(3) The invention according to Claim 2 where-in the lift arm comprises a channel section member with the lever mounted within the channel section for pivotal movement about a transverse axis out of the channel sec-tion, and a channel guide connected to the channel sec-tion so the movement of the lever is delimited by enga-gement with the channel section and with a closed end of the channel guide.
(4) The invention according to Claim 2 where-in the cylinder and piston device is connected to the lever intermediate the length of the lever.
(5) The invention according to Claim 3 where-in the cylinder and piston device is connected to the lever intermediate the length of the lever.
(6) The invention according to Claim 1 where-in the lift arm comprises a first arm portion project-ing forwardly from the frame and attached to said loose coupling means and a second arm portion mounted for common pivotal movement with said first arm portion about said second horizontal axis, said second arm por-tion being connected to said connecting link and said portions being spaced axially.
(7) The invention according to Claim 2, 3 or 4 wherein the Lift arm comprises a first arm portion projecting forwardly from the frame and attached to said loose coupling means and a second arm portion moun-ted for common pivotal movement with said first arm por-tion about said second horizontal axis, said second arm portion being connected to said connecting link and said portions being spaced axially.
(8) The invention according to Claim 6 where-in the arm portions are spaced axially either side of a bearing member.
(9) The invention according to Claim 8 where-in the frame includes transverse frame members and ver-tical frame members and wherein the vertical frame mem-bers are each arranged to support a respective one of the bearing members whereby the first and second arm por-tions are spaced on either side of a respective vertical frame member.
(10) The invention according to Claim 1, 2 or 3 including first fluid connection means for connect-ing pressurized hydraulic fluid from a supply to an ex-pansion side of the piston of one of the cylinders, se-cond fluid connection means for connection of the fluid from the retraction side of the piston of said one cy-linder to the expansion side of the piston of the other cylinder and third fluid connection means for connect-ing fluid from the retraction side of the piston of the other cylinder for return to the supply, said one cy-linder and piston being greater in diameter than said other whereby the swept volume on the retraction side of said one is equal to the swept volume on the expan-sion side of said other whereby the cylinders operate in series at the same rate of movement.
(1) A three-point hitch assembly for attach-ment to a tractor comprising a pair of lower draft arms for extending rearwardly of the tractor, frame means for attachment to the tractor and for supporting said lower draft arms for pivotal movement about a first horizontal axis, a pair of lift arms mounted on the frame for pivotal movement about a second horizontal axis above said first axis, a pair of connecting links each for connecting a respective lift arm to a respective lower draft arm, a pair of hydraulic cylinder and piston de-vices each connecting between the frame and the res-pective lift arm whereby the lift arms can be raised and lowered by operation of the hydraulic cylinders to raise and lower the lower draft arms, loose coupling means between each cylinder and piston device and the respective lift arm to allow floating movement of the lower draft arms and means for locking loose coupling means to prevent said floating movement.
(2) The invention according to Claim 1 where-in the loose coupling means comprises a lever pivotally connected to the lift arm and to the cylinder and piston device and means for limiting pivotal movement of the lever relative to the lift arm.
(3) The invention according to Claim 2 where-in the lift arm comprises a channel section member with the lever mounted within the channel section for pivotal movement about a transverse axis out of the channel sec-tion, and a channel guide connected to the channel sec-tion so the movement of the lever is delimited by enga-gement with the channel section and with a closed end of the channel guide.
(4) The invention according to Claim 2 where-in the cylinder and piston device is connected to the lever intermediate the length of the lever.
(5) The invention according to Claim 3 where-in the cylinder and piston device is connected to the lever intermediate the length of the lever.
(6) The invention according to Claim 1 where-in the lift arm comprises a first arm portion project-ing forwardly from the frame and attached to said loose coupling means and a second arm portion mounted for common pivotal movement with said first arm portion about said second horizontal axis, said second arm por-tion being connected to said connecting link and said portions being spaced axially.
(7) The invention according to Claim 2, 3 or 4 wherein the Lift arm comprises a first arm portion projecting forwardly from the frame and attached to said loose coupling means and a second arm portion moun-ted for common pivotal movement with said first arm por-tion about said second horizontal axis, said second arm portion being connected to said connecting link and said portions being spaced axially.
(8) The invention according to Claim 6 where-in the arm portions are spaced axially either side of a bearing member.
(9) The invention according to Claim 8 where-in the frame includes transverse frame members and ver-tical frame members and wherein the vertical frame mem-bers are each arranged to support a respective one of the bearing members whereby the first and second arm por-tions are spaced on either side of a respective vertical frame member.
(10) The invention according to Claim 1, 2 or 3 including first fluid connection means for connect-ing pressurized hydraulic fluid from a supply to an ex-pansion side of the piston of one of the cylinders, se-cond fluid connection means for connection of the fluid from the retraction side of the piston of said one cy-linder to the expansion side of the piston of the other cylinder and third fluid connection means for connect-ing fluid from the retraction side of the piston of the other cylinder for return to the supply, said one cy-linder and piston being greater in diameter than said other whereby the swept volume on the retraction side of said one is equal to the swept volume on the expan-sion side of said other whereby the cylinders operate in series at the same rate of movement.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA000445749A CA1220067A (en) | 1984-01-20 | 1984-01-20 | Three-point hitch assembly |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA000445749A CA1220067A (en) | 1984-01-20 | 1984-01-20 | Three-point hitch assembly |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1220067A true CA1220067A (en) | 1987-04-07 |
Family
ID=4126996
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000445749A Expired CA1220067A (en) | 1984-01-20 | 1984-01-20 | Three-point hitch assembly |
Country Status (1)
| Country | Link |
|---|---|
| CA (1) | CA1220067A (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP2351476A1 (en) * | 2009-10-30 | 2011-08-03 | Sebastian Zunhammer | Three-point suspension and trailer with same |
-
1984
- 1984-01-20 CA CA000445749A patent/CA1220067A/en not_active Expired
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP2351476A1 (en) * | 2009-10-30 | 2011-08-03 | Sebastian Zunhammer | Three-point suspension and trailer with same |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| MKEX | Expiry |