DE1108970B - Control device for a hydraulic power lift for automatic weight shift - Google Patents

Description

The invention relates to a control device for a hydraulic system attached to a tractor Power lift for automatic weight transfer that allows a weight transfer from one Agricultural attachment attached to the tractor that exerts a tensile load on the tractor transfers, depending on this tensile load on the tractor. Such a one Control device is with a pressure cylinder actuated by a pressure medium, that of a Pump pressure medium is supplied and arranged between the tractor and the attachment is that it can exert a lifting force on the attachment, as well as provided with a control valve, which regulates the supply of the printing medium to the printing cylinder and the return flow from the printing cylinder, wherein the control means includes a first actuating linkage that engages the control valve and can control the complete raising and lowering of the attachment, as well as a second operating linkage which can come into engagement with the control valve and is mounted on a support arm is to change the engagement ratios between the second operating linkage and the control valve is adjustable, the control device being provided with levers that can be operated by hand is the independent actuation of the first actuation linkage and an adjustment of the support arm effect of the second actuating linkage.

Such a control device is already known in which a combined control of the lifting and lowering of the device in connection with an automatic draft regulation application finds. In this device, two actuators act independently of one another on one common control valve tappet. In the case of a device for automatic weight transfer is it is desirable to change the size of the desired weight transfer from case to case. to be able to hire which are then also obtained when the device is actuated for complete raising and lowering should stay. The known device is not suitable for this purpose.

The aim of the invention is to provide a control device of the type described, in which with the same hydraulic device the desired movements of the attachment can be achieved, without having to change a weight shift setting once it has been made.

According to the invention this object is achieved in that for the actuation of the pressure cylinder two separate control valves, namely a first control regulating device for a hydraulic one

Power lift for automatic

Weight shift

Applicant:

Allis-Chalmers Manufacturing Company,
West Allis, Wis. (V. St. A.)

Representative: Dr. W. Muller-Bore

and Dipl.-Ing. H. Gralfs, patent attorneys,

Braunschweig, Am Bürgerpark 8

Claimed priority:
V. St. v. America March 3, 1958

Walter Frank Strehlow, Wauwatosa, Wis. (V. St. A.), has been named as the inventor

valve, which only regulates the supply of pressure medium to the pressure cylinder, and a second control valve, which only controls the return flow of pressure medium from the pressure cylinder, are provided and that the first actuator is alternately opened by adjusting the manually operated lever for raising and lowering the attachment one or the other control valve acts.
The invention is shown in the drawing, for example.

Fig. 1 is a side view of part of a tractor equipped with a plow, which with a control device according to the invention is provided;

Fig. 2 shows schematically and partially in section a hydraulic pump and control device as well Control members with which the device is operated according to the invention;

Fig. 3 shows - partly in section - a detail from Fig. 2 and shows the control device and the control members in a different position from FIG. 2;

109 617/132

Fig. 4 is - partly in section - a view of the control device according to the invention.

In the drawing, in particular FIG. 1, the control device according to the invention is together with a tractor 11 is shown, which has drive wheels 12 and a frame 13. To the tug is a mounted plow 14 is grown, which has two plow bodies engaging in the ground and rigidly with a carrier 16 are connected.

The carrier 16 is pivotably connected to a pull rod 17. With a screw spindle 18 can the carrier 16 can be pivoted counterclockwise from the position shown in FIG. 1. if the plow is pulled by the tractor, the plow bodies penetrate the ground until the Plow has set approximately parallel to the surface of the earth, with the plow body at a predetermined working depth intervention.

The pull rod 17 is hooked into a hook 23 which is fastened in one under the tractor bell-shaped housing 22 is seated and rotatably connected to a further rod 24, which is in a Spring housing 26 is mounted such that it can move back and forth. A compression spring 27 is biased within the Spring housing 26 housed so that they a reciprocating movement of the rod 24 Resists.

Furthermore, a lifting rod 28, which forms part of a power lift, is connected to the articulated connection connected between the carrier 16 and the tie rod 17.

Since the carrier 16 does not move in a clockwise direction relative to the pull rod 17 via the one shown in FIG Can move position addition, the carrier 16 and the pull rod 17 by the lifting rod 28 as Whole to be raised.

The upper end of the lifting rod 28 is connected to a lifting arm 29 which is attached to a lifting shaft is, which is rotatably mounted in the tractor frame. A crank arm 31 is rigidly attached to the lifting shaft, which is connected to the piston rod of a hydraulic pressure cylinder 32 on the tractor frame is rigidly attached. Actuation of the piston rod causes the lift arm 29 to move over the lift rod 28 exerts a lifting force on the plow.

The hydraulic pressure cylinder 32 is actuated by a pressure medium, which the pressure cylinder via a line 33 is fed from a pump 34. A control valve, which is described below, is connected to the pump and can be operated so that the amount of the supplied to the pressure cylinder Print medium is changed. The control valve is in turn controlled by two control devices actuated.

The first control device is a transmission linkage 36, which is under spring preload Rod 24 connects to the control valve. This linkage, which is referred to as the weight shift linkage can be, acts by means described below in such a way that changes of the cultivated plow The tractive force transmitted to the tractor is a raising or lowering of the plow and thus a Shift your weight to the rear wheels of the tractor.

The second control device for the hydraulic control valve contains two hand levers 37 and 38 the control column 39 of the tractor. The lever 37 is a control lever for raising and lowering and can optionally be set so that the control valve feeds the pressure medium to or allows the pressure medium to flow back out of the pressure cylinder.

The lever 38 is used to regulate the weight shift and can optionally be set so that that the amount of deflection which is required in the rod 24 is changed to a predetermined one Raise the plow through the lift arm 29 to effect.

Referring to Fig. 2, the hydraulic pump 34 and the control device comprising a spool A and a control valve will now be described.

The hydraulic pump 34 is a multi-piston pump with a constant flow rate, which has three large pump pistons 40 and a small pump piston 41, which are moved up and down via rollers 42 by cams that sit on a camshaft 43. The pressure medium is supplied to the pump cylinders from a storage container 44 via inlet channels 46. When the pistons are pushed up by the cams, the inlet channels 46 are closed, the medium is pressurized and is fed to a control slide chamber 47 which forms part of a first control slide A and is connected by shunt channels 49 to the storage container 44 for the medium is. A pressure manifold 51 is arranged above the slide chamber 47, which is connected to the slide chamber 47 by connecting channels 52 which are provided with spring-loaded overflow valves 53. The collecting line 51 is connected to the control valve via a check valve.

The small pump piston 41 is not connected to the pressure manifold 51, but protrudes the slide chamber 47 and a check valve directly connected to the control valve.

The pressure manifold 51 is connected to the left end of a relief slide via a connecting channel 62 61 in connection, the right part of which is provided with two outlet channels 63 and 64 which establish a connection to the storage container 44. The relief slide is of the usual design, where a relatively high pressure is required to initiate opening of the valve, whereas only a small amount of pressure is required to keep the slide open. The training of the Relief slide should not be described in detail, since it is not the subject of the invention is.

Between the pressure side of the small piston 41 and the reservoir 44 for the pressure medium an overflow valve 66 is provided. This overflow valve can be operated so that it is the outlet side of the small piston 41 connects to the reservoir when the pressure of this Piston conveyed medium has reached a predetermined pressure.

Inside the cylindrical control slide chamber 47 of the control slide A is a cylindrical sleeve which consists of individual sections lying next to one another in the axial direction, which are provided on the circumference with grooves which connect the pump outlet channels to the collecting line. Furthermore, each section is provided with a transverse bore which connects the interior of the sleeve with the grooves running on the circumference. The next to each other

lying ends of the sections are designed to complement each other so that the interior of the cylindrical Sleeve with the bypass channels 49 is connected.

The section on the right is provided with grooves and a transverse bore, which represent connections with the control valve B and the return flow channel.

Within the cylindrical sleeve sections is a control slide piston 86, which is a Number of piston parts 87 has. Such a sub-piston is provided for each pump piston 40 or 41. Furthermore, at the right end of the cylindrical control slide chamber 47 there is an additional one Partial piston 88 which controls the return flow channel 83.

The shunt channels 49 connect the interior of the control slide chamber 47 with the return flow line 83 for the medium. The partial pistons 87 and 88 are shaped and within the portions of the Control spool sleeve arranged in such a way that, when the control piston is in the rightmost position, which can be seen in Fig. 3 and corresponds to the position of the power lift for complete lowering, the pressure medium of each of the four pump pistons into the cylindrical control slide chamber 47 enters and exits through the bypass channels 49 and flows to the storage container 44. When the control piston 86 is moved to the left in the position shown in Fig. 2, the shunt channels 49 through the partial piston 87 is shut off, and the pressure medium passes through the grooves arranged on the circumference and via the pressure manifold 51 to the channel leading to the control valve. The sections of the Control slide sleeve are arranged relative to the piston parts 87 and 88 so that the control piston can be adjusted that the pressure medium of each pump, starting with the small pump piston 41, can be conveyed successively to the control valve.

The control valve B (Pig. 2, 3 and 4) is a ball valve 97 which is pressed onto a seat by a spring and can be lifted from this seat by a valve tappet 96.

As can be seen in FIG. 4, the manual control lever 37 for raising and lowering is connected to a two-armed lever 89, which is to be referred to as a raising-lowering lever. This lever, which can come into engagement with the control slide 4 as well as with the control valve, is provided with a long lever arm which can come into engagement with the piston slide 86 of the control slide v4, and has a short lever arm that connects with the valve tappet 96 of the valve B can come into engagement so that the lever can act alternately on the piston slide 86 and the tappet 96.

The hand lever 38 for shifting weight is connected to a support arm 91 on which in A second two-armed lever 92, the so-called weight shift lever, is articulated to a pivot point 93 whose upper lever arm can also come into engagement with the piston valve 86. Of the Pivot 93 of the weight shift lever can be when the pivotable support arm 91 by actuation of the hand lever 38 is moved, move on a specified path so that the effective engagement between the lever 92 and the piston valve 86 is changed.

When the hand lever 37 is moved to the full raise position for raising and lowering is, the lifting-lowering lever 89 is rotated clockwise, the long lever arm this Lever comes to rest on the slide piston 86 and pushes all sub-pistons all the way to the left until a collar formed at the right end of the slide piston in the position shown in FIG. 2 against the plate 72 abuts. The short lever arm of the

ίο lever 89 has moved away from valve tappet 96, which therefore remains in its outer position, so that the ball valve 97 on its seat remain. If the control piston 86 is held in the extreme left position shown in FIG. 2, the plow is fully raised to the transport position; then the relief slide 61 the pressure medium conveyed by the three large pistons 40 and the overflow valve 66 let that of the small piston conveyed pressure medium to the

so that the reservoir flows back.

If the plow is to be raised by less than the highest lifting height, as in Fig. 4, is through Actuation of the hand lever 37 of the raise / lower lever 89 initially to engage the control slide piston 86 brought so that the pressure medium is fed to the hydraulic pressure cylinder 32. if the plow is raised to the desired height, the hand lever 37 is in a holding position between the position for full lifting and the position

3ö ment for complete lowering on the switching arch emotional. As can be seen in Fig. 4, the long end of the lever 89 has in this holding position in moved a position in which it does not abut the slide piston 86, which is therefore by a helical spring 95 is pressed outwards to the rightmost position, which is the position for the complete Lowering corresponds to.

Furthermore, the short lever arm of the lever 89 is also not in contact with the valve tappet 96, so that the pressure medium is retained by the ball valve 97 in the hydraulic pressure cylinder. at In this state, all four pump pistons convey the pressure medium through the bypass channels 49 back into the hopper 44 and the plow is held in the desired raised position.

When the hand lever 37 is moved to the position for complete lowering, the lever 89 is rotated counterclockwise to the position shown in FIG. In this position the long lever arm of the lever is removed from the control slide piston 86, while the short lever arm of the lever 89 pushes the plunger 96 of the valve B inwards and causes the ball valve 97 to be lifted from its seat. The pressure medium retained in the hydraulic pressure cylinder 32 can now flow back to the storage container 44, as a result of which the mounted plow drops. All pump pistons convey the pressure medium back to the storage container 44 through the bypass channels 49.

The automatic weight transfer to the tractor rear wheels is controlled by the weight transfer lever 92 causes which acts on the control slide piston 86 and through the weight shift linkage 36 is actuated. This linkage contains a spring-loaded push rod 99 that is articulated is connected to the lower end of the weight shift lever 92, and a rotatably mounted

7 8

th angle lever 101, which can plow with the push rod 99. Thereby, it would be very undesirably effectively engaged and by means of a spring 100 if the adjustment of the pivot point 93 would each be carried out by the push rod 99 against one of the cam levers 102 which are raised when the plow is pressed at the end of a row must, must be lifted. With the aid of the end it is rotatably connected to the rod 24. According to an invention, it is not necessary to change the increased tensile force acting on the rod 24 until another setting is fully attempted to turn the cam lever 102 counterclockwise to adapt to others. The angle lever 101 follows the ground conditions must be made.
Cam lever 102 and rotates clockwise. When the end of a row is reached, the

under the action of the spring-loaded push io hand lever 37 for raising and lowering the bar 99 force exerted on him. The movement position for full lifting moves as it moves the spring-loaded push rod 99 to the right results has already been described. This movement causes a rotation of the weight shift lever 92 causes the lever 89 to be rotated clockwise, whereas clockwise around its pivot point 93, through the long lever arm of the lever 89 to the plant so that its upper end comes to the control piston 86 to 15 to the control slide piston 86 and this in Plant is coming. moves the extreme left position, as shown in Fig. 2

As shown in FIGS. 2 and 3, the support can be shown. All pumps 40 and 41 promote handlebar 91 by actuating the hand lever 38 in the immediate pressure medium to the pressure cylinder and lift clockwise to be pivoted until one of the plow out of the ground. When the plow is full of the stop surface 103, which is raised on the support arm 91, the three large pistons 40 that are formed convey pressure medium through the relief valve 61 back 72 of the control slide A to a fixed stop on the plate. In this to the reservoir 44, while the small piston water position is the upper end of the lever 92 41, the pressure medium through the overflow valve 66 in the vicinity of the outer end of the slide piston to the reservoir.
86, so that even a slight increase in the weight to 25 caused in the clockwise direction about its pivot point 93 and FIG. 3 is shown. During this movement, the lever is brought into contact with the slide piston 86, lever 89 is rotated counterclockwise so that pressure medium is supplied to the pressure cylinder 30, the long arm of the lever is removed from the control slide piston and the lift arms on the plow a lifting force 86 is removed and the short arm engages with exercise. the tappet 96 of the valve B comes so that the

In FIG. 4, the support arm 91 is lifted from its seat counter to the clock ball valve 97. Clockwise by actuating the hand lever 38, the pressure medium can be expanded out of the pressure cylinder has been turned around until its stop 35 flows back to the reservoir. The plow surface 104 to another fixed stop which then penetrates again to the depth to which it is a plate 72 comes to the plant. In this position lies is put, with the optimal setting of the rotary the upper end of the lever 92 is not changed much further from point 93 to shift weight the spool 86 removed so that a small one. The weight shift lever 92 can immediately Enlargement of the 40 acting on the rod 24 without any readjustment of its function such as tensile force, which fulfill only a small movement of the weight of the.

shift lever 92 counterclockwise It is still possible to use the plow in any

causes no effect on the spool 86 raised position between the highest and the exerts and accordingly no lifting force to stop from the fully lowered position without the Lift arms is exercised. 45 Adjustment of pivot point 93 for weight adjustment

In operation, the hand lever 37 is used to change storage for lifting. This can be achieved and lowering into the position for complete lowering by setting the hand lever 37 to the lowering lift position, whereby the lever 89 is brought into the position shown in FIG. 3, the hydraulic pressure cylinder being moved into to which it is fed to the print medium. By observing the plunger 96 of the valve B moved inwards and the 50 of the lifting arms 29, the operator can immediately lift the ball valve 97 from its seat, so that it can be determined when the arms have reached the desired pressure medium in each direction through the vening position . At this moment til B can flow through it. it is only necessary to move the hand lever 37 into a

Then the position of the fulcrum 93 of the gelere position between the positions for the complete weight shift lever 92 is brought about by actuating the lifting and the complete lowering of the hand lever 38 for the weight shift, either which is shown in FIG. 4 and in which the Lever 89 adjusted according to the soil conditions. both out of engagement with the tappet 96 of valve B

With this setting, the control slide piston 86 is on and off accordingly. In the tensile force of the weighted position acting on the rod 24, the pump pistons 40 and 41 move the displacement levers 92 counterclockwise. The pressure of the measuring spool piston 86 to the plant and moves it diums in the pressure cylinder is raised by the ball valve in the manner described to the left, so that the 97 of valve B is maintained so that the plow pressure cylinder is supplied with pressure medium, where- in the desired raised Position fixed by a lifting force exerted on the plow. 65 th.

When the end of the field is reached, the above description shows that the invention

It is necessary to raise the plow completely and to lift the tractor with a power lift attached to a tractor by to turn to continue in the other direction - a control device in which the complete

Complete raising and lowering of the attachment without changing a predetermined setting of the control means for weight shifting can be done.

Claims (1)

PATENT CLAIM: Control device for a hydraulic power lift attached to a tractor for automatic Weight shift, which means a weight shift from an agricultural implement attached to the tractor, that transfers a tensile load to the tractor, depending on this tensile load causes on the tractor, with a pressure cylinder actuated by a pressure medium, that of a pump is supplied with pressure medium and between the tractor and the attachment is arranged so that it can exert a lifting force on the attachment, as well as with control valves, the supply of the printing medium to the printing cylinder and the return flow from the printing cylinder regem, the control device having a first actuating linkage with a control valve comes into play and controls the complete raising and lowering of the attachment. and has a second actuating linkage which can come into engagement with the control valve and is mounted on a support arm which is adjustable to change the engagement ratios between the second actuating linkage and the control valve, and wherein the control device is provided with manually operated levers which cause an independent actuation of the first actuating linkage and an adjustment of the support arm of the second actuating linkage, characterized in that two separate control valves, namely a first control valve (A), which only supplies pressure medium to the actuation of the pressure cylinder (32) Pressure cylinder (32) regulates, and a second control valve (B), which only controls the return flow of pressure medium from the pressure cylinder (32), are provided and that the first actuating member (89) is raised by adjusting the manually operated lever (37) and lowering the attachment alternately onto the one (A) or the a Another control valve (B) acts. Considered publications:
French patent specification No. 1139 224. 1 sheet of drawings © 109 617/132 6.61