DE8704278U1 - Hydraulic circuit for narrow-track tractors - Google Patents

Description

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Fritz Krieger Jr., 6741 Rhodt unter Rietbürg

Hydraulic circuit for narrow-gauge shuttle

The invention relates to a hydraulic circuit with a pump, a 4/2-way valve and two hydraulic cylinders for lateral adjustment and optional tensioning of the lower links of a three-point suspension for agricultural tractors, in particular narrow-track tractors for viticulture, and comparable applications.

In DE-GM 86 22 194, a device for laterally adjusting and optionally tightening the lower links of a three-point hitch for agricultural tractors, in particular narrow-track tractors for viticulture, is described, which works with the help of two hydraulic cylinders. A special feature of this known design is that when the lower links are swivelled, their lateral play, once set, is not changed. This lateral play is necessary so that a soil tillage device attached to the three-point hitch can avoid ground obstacles. Another feature of the known

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1 The design is that tightening the lower links does not change the pre-setting, so that after loosening the tightening the side play is restored*

It is clear that such a construction only achieves its full purpose if it can be controlled simply but effectively, and in particular in such a way that errors in the operating procedure are excluded. The hydraulic circuit contained in the above-mentioned utility model uses single-acting hydraulic cylinders, so that only one cylinder is active when swiveling and the tension, once set, can only be released due to vibrations such as those that occur during operation or by shaking by hand*

The present invention is based on the object of providing a hydraulic circuit which is just as easy and safe to operate, but which actively supports all movement processes.

This task is solved by the fact that the hydraulic cylinders are double-acting, that a 4-way tap is connected to the 4/2-way valve, which is connected via hydraulic lines to the 4/2-way valve and the hydraulic cylinders in such a way that the cylinders are set to synchronous rotation in one tap position and to counter-rotation in the other tap position.

The use of double-acting cylinders has the advantage that both cylinders actively support the movement processes when swiveling sideways, as well as when tightening and releasing the lower links, so that smaller cylinders with lower power requirements can be used and all movement processes still run faster. By using the 4-way valve, it is possible to clearly distinguish between the movement processes: "sideways

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Swivel^' or « "Loosen and Spanned" can be preselected so that the operator can be sure that he will get exactly the desired movement sequence when he subsequently operates the 4/2-way valve.

The control system according to the invention can also be used wherever two hydraulic cylinders are either

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According to a preferred development of the invention, the hydraulic cylinders are connected in parallel on the piston rod side and the piston bottom side via a hydraulic line each, whereby one of these lines can be shut off via the 4-way valve.

According to a further development, the non-lockable hydraulic line is routed between the hydraulic cylinders to the hydraulic return line, whereby this connection can be locked via the 4-way valve.

This design variant has the advantage that both hydraulic cylinders are supplied with the same amount of hydraulic fluid at all times and therefore carry out the same movements at all times.

A simplified variant of the invention provides that the hydraulic cylinders are connected in series with each other and that one cylinder can be connected to either the piston bottom side or the piston rod side of the other cylinder via the 4-way valve.

This variant has the advantage that the 4-way valve and the entire piping are simpler and therefore cheaper. However, the hydraulic cylinders no longer always carry out exactly the same movements. In many applications, however, this is tolerable.

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The invention will be explained in more detail in the form of exemplary embodiments using the drawing. They show

Pig* 1 a first embodiment of a and

Pig. 2 a second embodiment of a hydraulic circuit.

In Fig. 1 you can see a hydraulic pump 0, which

for example, driven by the tractor drive motor. The hydraulic fluid flows from the pump 0 via the pressure line P to a 4/2-way valve 1. From connection A of this valve 1, a hydraulic line 10 leads to the piston bottom side of a first hydraulic cylinder 4'. A wide hydraulic line 7 leads to one of the connections of a 4-way valve 2 and continues behind this via another hydraulic line 8, also to the piston bottom side of a wide hydraulic cylinder 4'.

The piston rod sides of the two hydraulic cylinders 4, 4 ¹ are connected in parallel via a connecting line 6.

The connecting line 6 is continued to another connection on the 4-way valve 2 and continues behind this via a line 9 to connection B of the 4/2-way valve 1. The return connection R of the 4/2-way valve 1 is connected as usual to the hydraulic sump 3.

In position I of the 4-way valve 2, the piston bottom sides of both hydraulic cylinders 4, 4' are connected in parallel to each other and are connected to the connection A of the 4/2-way valve 1. The piston rod sides of both hydraulic cylinders 4, 4 ^' are connected in parallel via the line 6 and are connected to the connection B of the 4/2-way valve 1. Depending on the position of the 4/2-way valve 1, the two pistons 5,

5 ¹ synchronous movements.

If the 4-way valve 2' is switched to position II, the connections between lines 6 and 9 or 7 and 8 are opened and a connection is established between lines 8 and 9. The 4-way valve 2 has two auxiliary bores 11 for this purpose. The pistons 5, 5 ¹ of the two hydraulic cylinders 4, 4' now carry out equal but opposite movements depending on the position of the 4/2-way valve 1.

Fig. 2 shows a hydraulic circuit in which both the lines and the design of the 4-way valve are simpler. The piston bottom side of one hydraulic cylinder 14 is connected to the connection A of the 4/2-way valve 1 via a line 20. From the piston rod side of the hydraulic cylinder 14, a line 16 leads to the 4/2-way valve 12 and from there via a line 17 to the piston bottom side of the second hydraulic cylinder 14'. From the piston rod side of the second hydraulic cylinder 14', a hydraulic line 18 leads to the 4-way valve 12 and from there via a hydraulic line 19 to the connection B of the 4/2-way valve 1.

In position I of the 4-way valve 12, the piston rods 15, 15' of both hydraulic cylinders 14, 14' move in the same direction. However, since the piston rod side of the first hydraulic cylinder 14 is connected to the piston bottom side of the second hydraulic cylinder 14', there is a piston travel difference due to the volume difference. However, this difference is tolerable in many applications and is offset by the simplified design <

In the position ti, in which the piston rods 15, 15' of the two hydraulic cylinders 14, 14' move in opposite directions

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, the two piston rod sides of the hydraulic cylinders 14, 14' are connected to each other via the lines 16 and 18. Now there is no difference in volume and the piston travels are exactly the same. When using the hydraulic circuit to swivel the lower links of a three-point suspension sideways, there is no risk of the lower links jamming; the function is fully guaranteed.

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Claims (4)

Hydraulic circuit for narrow-track tractors · y DIPL.-ING.'f! W. MOLL DIPL.-ING. H. CH. BITTERICH ADMISSIONABLE REPRESENTATIVES BEFORE THE EUROPEAN PATENT OFFICE 6740 LANDAU/PFALZ LANGSTRASSE5 20 March 1987 Co. Fritz Krieger Jr., 6741 Rhodt unter Rietburg Protection claims 1. Hydraulic circuit with a pump, a 4/2-way valve, and two hydraulic cylinders for lateral adjustment and optionally tensioning the lower links of a three-point suspension for agricultural tractors, in particular narrow-track tractors for viticulture, and comparable applications, characterized in that the hydraulic cylinders (4, 4 ¹ ; 14, 14') are double-acting, that the 4/2-way valve (1) is followed by a 4-way tap (2, 12) which is connected via hydraulic lines (6... 10) to the 4/2-way valve (1) and the hydraulic cylinders (4, 4'; 14, 14') by pipes and hoses in such a way that the cylinders are set to synchronize in one tap position; (2, 12) and to counter-rotate in the other tap position (2 ¹ , 12'). POSTf ¹ AClI 2080 · T£Lttpft(O6i'4\\i<ft>iSjfiÖoo'> ■ /TEJX*^53333 TELEGRAMMS! INVENTION DEUTSCHEBANk LANDAU »glMoj (Bik,S4610i9Si. &iacgr;* »■ 5 POSTAL CHECK LUDWIÖSHAFEN «562*6« &bull; ■ · O
&bull; ■ &igr; *£- 2. Hydraulic circuit according to claim 1, characterized in that the hydraulic cylinders (4, 4 ¹ ) are connected in parallel on the piston rod side and the piston bottom side via a hydraulic line (6; 7, 8) each and that one of these lines (7, 8) can be shut off via the 4-way valve (2). 3. Hydraulic circuit according to claim 1 or 2, characterized in that the non-closable hydraulic line (6) is led between the hydraulic cylinders (4, 4') to the hydraulic return line (9) and can be closed off via the 4-way valve (2). 4. Hydraulic circuit according to claim 1 or 2, characterized in that the hydraulic cylinders (14, 14') are connected in series with one another and that one cylinder (14) can be connected either to the piston bottom side or the piston rod side of the other cylinder (14') via the 4-way valve (12). K »Hill,