NZ210746A - Plough reversing mechanism uses limited motion single-acting hydraulic cylinders - Google Patents

Description

ft 2 1074 ! Priority Datefs}: Ccmpieis Specification Filed: Class: . (tol63.|00., @ f)0!&J.ia|00.

Publication Dats: 5>(XJUIL1987....

P.O. Journal, No: Patents Form No. 5 NEW ZEALAND PATENTS ACT 1953 COMPLETE SPECIFICATION "PLOUGH REVERSING JIECHANISM" WE KVERNELAND A/S, a Norwegian joint-stock company, N-4344 Kverneland, Norway, hereby declare the invention, for which ^T/we pray that a patent may be granted to p£~/us, and the method by which it is to be performed, to be particularly described in and by the following statement 1. (followed by page IA.) 2107-56 This invention concerns a reversing mechanism, particularly for reversible semi-ploughs. Such ploughs usually have 4-8 double plough shares fixed permanently or rotatably to a plough frame. The plough frame is rotatably fixed to a carriage which at its front edge is arranged to be hung on the tractor's three-point mounting, and which at the back is equipped with a back wheel which serves both as steering wheel and depth wheel.

Several disadvantages of the known reversible semi-ploughs relate to t£ie reversing mechanism which turns the plough frame 180 degrees in the carriage when the direction in which one is ploughing shall be swapped from left to right, or vice versa. The known reversing mechanisms of this type have one or two double-acting hydraulic cylinders which are attached to the plough carriage, to a tower on the carriage, or to a special arm which extends out from the carriage. These reversing mechanisms are characterized by having many, in part complicated, components, and by the outer measurements being large, so that the distance between the tractor and plough is large, which brings wjth it technical ploughing disadvantages.

A good reversing mechanism of this kind must be able, inter alia, to use the tractor hydraulics, turning the plough evenly and swiftly and preventing the reversing mechanism from being exposed to large internal forces. Furthermore, the back wheel of the plough should be arranged to be steered by hydraulic steering cylinders which are hydraulically tied to the reversing mechanism in such a way that the back wheel is automatically adjusted correctly upon reversal of the plough. The reversal must also be stoppable at any point without pressure from the weight of the plough having an unfavourable effect on the steering cylinders of the back wheel and moving these uncontrollably, causing pressure build-up in the hydraulic system.

The objective of this invention is to provide a reversing"ffie cha n ism," p'arfifc ula rly for reversible semi-ploughs, in which the above-mer^eriet^^sad vantages. are 2 ?! 07''6 eliminated, and which at the same time satisfies the above-mentioned requirements for a good reversing mechanism.

This objective is achieved by a reversing mechanism with the features stated in the following claims.

An example of the execution of the invention is shown on the drawing, where: Figure 1 shows, from above, a reversible serai-plough with reversing mechanism according to the invention.

Figures 2, 3, 4 and 5 show in larger scale, from the front, the reversing mechanism at four stages of a reversing operation, and Figure 6 shows the hydraulic diagram for the reversing mechanism according to the invention. send- On the drawing, reference no. 1 indicates the reversible/ , plough carriage which at the front is suspended from the three-point mounting 3 of a tractor 2, and which at the back is equipped with a back wheel 4 which serves both as steering wheel and depth wheel. A plough frame 5 to which is rotatably attached a number of double plough shares 6 is arranged at the back edge so as to be able to turn about a shaft 7 fastened to the carriage 1. The uppermost lying plough share of the double plough shares 6 is, for the sake of clarity, not drawn on the drawing. At its front edge, the plough frame 5 is attached to one end of a lifting arm 8, whose other end is rotatably supported on a shaft 9 fastened to carriage 1. The plough frame 5 may, with the aid of two single-acting hydraulic reversing cylinders 10, 11 which are rotatably attached to lifting arm 8 and connected to the tractor 2 hydraulics, be turned approximately 180 degrees to and fro about the shafts 7, 9 mentioned.

When plough frame 5 is to be turned from the working position as shown in Figure 2 to the working position as shown in Figure 5, pressure is applied to cylinder 10 via hose 12, and cylinder 11 is connected for return to the tractor 2 hydraulics via hose 13. The force from cylinder 10 acts via an abutment ring 14, which is rotatably attached to the cylinder 10 piston rod with aid of a bolt 15, against an abutment screw 16 which is fixed to the carriage 1 and provides a moment which turns lifting arm 8, and thus the ploughj-.fr.ame., &,_about the shaft 9. A pressure arm 17, of which one end is rotatably supported oriJJie cylinder 10 piston rod with the aid of the bolt 15, is at its other end iipl^Wbl/Vu^ported on shaft ./'V 1 OAPRi987^; 3 2\0746 9. A corresponding pressure arm 18, one end of which is rotatably supported on the cylinder 11 piston rod with the aid of bolt 19, is at its other end rotatably supported on shaft 9. An abutment ring 20 is rotatably attached to the cylinder 11 piston rod with the aid of the above-mentioned bolt 19. When pressure from the cylinder 10 causes lifting arm 8 to rotate about shaft 9, pressure arm 18 is simultaneously caused to rotate about shaft 9, so that cylinder 11 will remain at rest and follow lifting arm 8 until the latter has turned s<S far that the abutment ring 20 on the cylinder 11 piston rod abuts against the abutment screw 21 fixed to the carriage 1, as shown in Figure 3, and the piston rod is pressed into the cylinder 11, upon which oil will flow out from the cylinder 11 via a choke valve 22 and hose 13 to return to the tractor 2 hydraulics.

Cylinder 10 turns the lifting arm 8 and thus the plough frame 5 further until the center of gravity of the plough frame 5 passes a vertical line, though shaft 9, after which both the weight of the plough frame 5 and the cylinder 10 will turn the lifting arm 8 further until the cylinder 10 has traversed its full length of stroke, having turned approximately 110 degrees, and the abutment ring 14 on its piston rod departs from the abutment screw 16, as shown in Figure 4.

The weight of-the plough frame 5 will turn the lifting arm 8 further with the cylinder 11 as counter-force, as the oil which is pressed out of cylinder 11 is choked by choke valve 22 before flowing onward through flowline 13 to return to the tractor 2 hydraulics. The lifting arm 8 turns onward in this way until the piston rod is completely pressed into cylinder 11 and the plough frame 5 rests against the abutment screw 21 on the carriage 1, as shown in Figure 5.

Because a choke valve 23 is also provided between the cylinder 10 and the flowline 12, and because both the cylinders 10, 11 and the pressure arms 17, 18 are mutually identical and installed symmetrically in relation to lifting arm 8, it will be apparent without further ado that, when plough frame 5 is to be turned in the reverse direction, i.e. from the working position shown in Figure 5 to the working position shown in Figure 2, this occurs in the same way as described above, but in the reverse sequence.

On the carriage 1 of the reversible semi-plough are attached two identical, double-acting hydraulic steering cylinders 24, 25 which a^re c6rmected4n-pacalleL, with the reversing cylinders 10, 11 as shown in Figure 6, and j^ict|^9^eby are O 2 10746 automatically arranged to adjust the back wheel 4 to the correct position upon reversing the plough, and hold the back wheel in place during ploughing. When reversal of the plough is initiated by pressurizing reversing cylinder 10 or 11, respectively, the two double-acting hydraulic steering cylinders 24, 25 will simultaneously be pressurized, as shown in Figure 6, and traverse their full length of stroke in the opposite direction and steer the back wheel 4 from one extreme position to the opposite extreme position.

Any pause in the reversal of the plough from a working position equal to 0 degrees to approximately 90 degrees will cause the weight of the plough frame 5 to apply pressure to the same side of the hydraulic system as was the original pressure side, so that the back wheel 4 is held in its new position.

Upon a pause in the reversal between approximately 90 and 110 degrees, the {\^J weight of the plough frame 5 will apply pressure to the original return side of the hydraulic system, and steering cylinders 24, 25 will return to the position they had before the reversal started, and thus swing the back wheel 4 back again, as return oil from the steering cylinders 24, 25 enters into the reversing cylinder 10, respectively 11, which was pressurized when reversal started, and consequently this reversing cylinder will turn lifting arm 8 further until steering cylinders 24, 25 have returned to their original position, or until lifting arm 8 has rotated to approximately 110 degrees and the initially activated reversing cylinder 10, respectively 11, has traversed its full length of stroke. This causes no pressure build-up and consequential unfortunate effects on the reversing mechanism, because the oil quantity in the hydraulic system is constant, because the reversing cylinders 10 and 11 are single-acting.

Upon a pause in the reversal between approximately 110 and approximately 180 degrees, corresponding to accomplished reversal, the weight of the plough frame 5 will act on the reversing cylinders 10, 11 and apply pressure to the original return side of the hydraulic system, and this pressure will propagate via steering cylinders 24, 25 to original pressure side of the initially activated reversing cylinder 10, respectively 11, but because the initially activated reversing cylinder 10, respectively 11, has traversed its full length of stroke, this pressure will not move the steering cylinders 24, 25, because return oil from these cannot enter into the initially activated reversing cylinder 10, respectively 11, because this has already traversed its full length of stroke. This also locks the movement of steering cylinders 24, 25. 2 t074 Because not only reversing cylinders 10, 11 but also pressure arms 17, 18 are mutually identical and are installed directly onto lifting arm 8 and symmetrically in accordance with the invention, an ideal reversing function is achieved with a minimum of components.

Because reversing cylinders 10, 11 are single-acting, they only provide force in the direction in which one wishes to reverse, and only during the first part of the reversing operation, so that only the weight of the plough frame 5 and in part the weight of the reversing mechanism rest against the abutment screw 16, respectively 21, with a minimum of mechanical forces resulting.

The single-acting reversing cylinders 10, 11 cause no undesirable pressure build-up even if the reversing operation is interrupted.

The compact reversing mechanism according to the invention provides minimal distance between the plough and the tractor, which again yields technical ploughing benefits.

It will be apparent without further ado that the reversing mechanism according to the invention can be utilized with advantage for other purposes than that described in the above-mentioned example of execution. o o 6 Summary Reversing mechanism, particularly for semi-reversible ploughs, where the reversing mechanism includes hydraulic reversing cylinders (10, 11). The reversing mechanism, or device (5) to be reversed, includes a lifting arm (8) which at its one end is rotatably supported at a point (9) which the reversing mechanism turns about, and which at its other end is fastened to the device (5) to be reversed. The reversing cylinders (10, 11) have approximately the same volume and approxi- arm (8). The piston rods of the reversing cylinders (10, 11) are rotatably attached (15, 19) with one end of a pressure arm (17, 18) whose other end is rotatably fixed to the point (9) about which the reversing mechanism rotates. Each reversing cylinder (10, 11) is single-acting and arranged to turn the lifting arm (8) approximately 110 degrees from horizontal position before the reversing cylinder (10, 11) has attained full length of stroke and the piston rod of the non-activated reversing cylinder (11, 10) is brought to abut against the abutment screw (21, 16) and brake the remainder of the reversing operation, which takes place with the aid of gravity. To identical double-acting hydraulic steering cylinders (24, 25) are connected in parallel with the reversing cylinders (10, 11) and are thus arranged automatically to adjust, for example, the back wheel (4) of a semi-rever-sible plough when the reversing mechanism is activated. mately the same length of stroke and are affixed symmetrically to the lifting %\ oil

Claims (7)

WHAT WE CLAIM IS:
1. I. A reversing mechanism; particularly for reversible semi-ploughs, which comprises a plough frame with a number of plough shares affixed to a carriage, which at its front is arranged to be suspended from a tractor or other pulling arrangement, and which at the back edge is equipped with a wheel which serves as steering wheel and/or depth wheel; and where the reversing mechanism includes two hydraulic reversing cylinders which are arranged to turn the plough frame approximately 180 degrees in its carriage when the direction towards which one is ploughing is to be switched from left to right or vice versa, the hydraulic reversing cylinders being single-acting, each individual reversing cylinder being arranged to turn the plough frame more than 90 degrees, from approximately a horizontal position before the reversing cylinder has traversed its full length of stroke, and where the non-activated reversing cylinder's piston rod at its free end is arranged to come to abut against a stop, after the activated cylinder has turned the plough frame more than 90 degrees, from approximately a horizontal position; and where the plough frame includes a lifting arm which at its one end is rotatably supported to a shaft which is fixed to the carriage, about which said shaft the plough frame is arranged to turn, and where the reversing cyliners have approximately the same volume and approximately the same length of stroke anfiare.- attached 8 7\ 07 to the outer end of the lifting arm, and where the <■ 1 ^ reversing cylinder piston rods at their free end are rotatably attached to one end of a pressure arm, characterized in that the other end of the pressure arm is rotatably attached to the shaft which the plough frame is arranged to turn about, and that the reversing mechanism is equipped with two identical, double-acting hydraulic steering cylinders for correct automatic adjustment of the steering wheel/depth wheel when the reversing mechanism is activated, in that the steering cylinders steer the reversible semi-plough's steering wheel/depth wheel and are connected in parallel with the reversing cylinders and act in conjunction with these.
2. 2. A reversing mechanism as claimed in claim 1 in which the hydraulic reversing cylinders are equipped with a choke valve.
3. 3. A reversing mechanism as claimed in claim 1 or 2 in which said stop is an abutment screw.
4. 4. A reversing mechanism as claimed in claim 1, 2 or 3 in which the non-activated reversing cylinder's piston rod at its free end is arranged to come to abut against a stop after the activated cylinder has turned the plough frame approximately 110 degrees from approximately a horizontal position.
5. 5. A reversing mechanism as claimed in claim 3, characterized in the piston rods of the reversing cylinders being equipped outermost with-^an .abutment __ ring which is arranged to come to abutment agadfrrsi^ said abutment screw. fC. cU-\ (< A f V jd // * &' 9 2 \ 0 7 A 6
6. 6. A reversing mechanism substantially as herein described.
7. 7. A reversing mechanism substantially as herein described with reference to the accompanying drawings.