DE1047510B - Double-acting hydraulic power lift, especially for agricultural tractors - Google Patents

Description

GERMAN

The invention relates to double-acting hydraulic power lifts, in which each position of the Control lever of the hydraulics is assigned a certain depth position of the implement, in particular for agricultural tractors.

In the known systems of this type, the device is in constant permanent connection with a double-acting one Hydraulic piston, d. This means that the device can only change its position if the piston does too shifts in the working cylinder. Since the system is double-acting, the piston can only move shift when the hydraulic control lever is also operated.

However, it is in certain cases, especially when a three-point hitch is used to connect the device it is imperative that the working unit tractor device is able to cope with the unevenness of the ground can customize. This means that there is no rigid connection between the tractor and the implement allowed.

In order to achieve this, an adjustment option is provided according to the invention for power lifts with a preselected working depth provided, which makes the hydraulic piston freely movable in the working cylinder without the Hydraulic control lever needs to be operated.

According to the invention, this device consists in the fact that the control unit of the power lift also has a so-called "float position circuit" is equipped, which enables either both Pressure sides of the working piston connected to the usual return lines to the collecting tank whereby the working piston can move freely in the cylinder, or these connections are interrupted and the controller works normally. Floating positions are in themselves with double-acting Hydraulic systems with control by sight known. By the combination according to the invention a double-acting hydraulic system, in which every position of the hydraulic control lever. one is assigned to a certain position of the implement, but with a floating position result opposite the known prior art significant advantages.

It is known that when working with devices on the usual double-acting hydraulics Float position, e.g. B. when using a three-point hitch, short-term slip conditions on the Drive wheels of the tractor occur. These can be overcome in that the floating position is switched off and then the device by pressing the control lever as briefly as possible Hydraulics is raised a little. However, there is always due to the rapid response of the system the risk of the device being lifted more than

Double acting

hydraulic power lift,

especially for farm tractors

Applicant:

International Harvester Company,
Chicago, 111. (V. St. A.)

Representative: Dipl.-Ing. H. Zoepke, patent attorney,
Munich 5, Erhardtstr. 11

Claimed priority:
France March 15, 1956

Oscar Efraim Lindstrom,

St. Dizier, Haute-Marne (France),

has been named as the inventor

would be necessary to increase the adhesion weight of the drive wheels; it even becomes very common lifted completely out of the ground.

These disadvantages are avoided and the process becomes extremely simple when in accordance with the invention a double-acting hydraulic system in which each position of the hydraulic control lever has a specific one Position of the implement is assigned, is combined with a float position device. Here it is necessary that the control lever of the Hydraulics is set to a working depth that is slightly less than that reached in the floating position. If slip occurs, then only the float position needs to be switched off so that the device is raised to the preselected height. This setting can be made very precisely, and there will be an uncontrollable change in working depth or accidental tearing out of the device from the ground.

Further features and advantages of the invention can be found in the description of various exemplary embodiments refer to.

Fig. 1 shows a longitudinal section through a first embodiment of the invention;

Fig. 2 shows a section of the floating position slide according to FIG. 1 with the floating position switched off;

Fig. 3 shows a longitudinal section through a second embodiment of the invention;

80S 700/170

3 4

4 shows a further modification in section. These constrictions correspond to three annular grooves

of the second embodiment. 23 a, 23 b and 23 c in the wall of the cylinder 18.

As can be seen from Figs. 1 and 2, the

zen a working cylinder, which consists of a cylinder 1 pressure line 8 and the lines 12 α and 12 b , in which a working piston 2 is guided, whose 5 their way to the control unit via one of the ring connecting rod 3 with its free end 4 at a lever grooves 23 a, 23 b and 23 c out,
arm 5 engages, which is connected to the lifting shaft 6, the control piston 17 is in the position

by rotating the lifting of the devices according to Fig. 2, the individual lines are from one another known linkage is effected. the other separate and unobstructed to the control valve 10

The oil circuit has a reservoir 7, carried out io.

from which a pressure line 8 goes out, into which one If the control lever 19 is moved in direction F7 ,

Pump 9 is switched on, and which leads to a control so the control piston 17 moves in the direction of device 10 of a known type. The control unit is F 8 and is then in the position according to FIG. 1. Via a return line 11, the lines 8, 12 α and 12 b are connected to the storage tank 7 with one another. 15 and connected to the storage container 7. The ar-

The ends of the working cylinder 1 are via two beitskolben 2 can therefore move freely and the working lines 12 α and 12 & with the control unit oil return is pressureless. The control lever can be connected so that, depending on the position of the control slide 13, remain set to each preselected stroke height, over 10 a one side of the working piston 2 is immediately taken up by the pressure when only the control oil is applied and the other side with the 20 lever 19 is operated.
Container 7 is connected. In the embodiment shown in Fig. 3

The position of the control slide 10 a is through play it is a control unit with additional Control lever 13 is determined in the hand range of the borrowed check valves.

Driver is arranged and above the rod 14, the In this version are in addition to the

Joint 15 & and the two-armed lever 15 control the 25 already described in the first embodiment slide 10 α operated. In the joint 15 β of the two-armed and provided with the same reference numerals EIemigen Lever 15 is hinged to a rod 16, the menten two shut-off valves related, which in turn from a zy is movably mounted on the lever arm 5, there are cylindrical bore 24 in which two pistons which causes the rotation of the lifting shaft6. 25 a and 25 & are constantly pressed against each other.

This known device acts folgender- 30 Pistons have extensions 27- "and 27 b that measured: Rückschlagventile28α and b 28 press, which in the

When lifting, the control lever 13 will cause the lines 12a and 12b to be arranged and the fixed that corresponds to the desired lifting height in the rieh- position of the piston.

tungFl moves. As a result, both pistons are located above the rod 14. 25 ', 25b in hers

the two-armed lever 15 pivots around the point 15 a center position, they allow the return of the oil, which is fixed at this moment. Via the bore 11 α and the line 11 against the speaking, the control slide 10 α is displaced in the direction of overcoming the force of the springs 26 α and 266. F2 , pressurized oil enters the line 12. &, is used during normal lifting and lowering even

and the line 12a is connected via the line 11 to the rear side of a piston from the pressure medium on the container 7. As a result, the working _{stroke 40} , both pistons are moved to the other side piston 2 in the cylinder 1 in the direction J ⁷ S, and shifted, close the return line 11 a> and the actuating arm 5 pivoted in the direction FS , thereby causing the required pressure increase in the rod 16 is moved in the direction FS .. The two-oil system.

armed lever 15 is thereby around. the. now fixed The cylinder 29, in which the control slide 10 a

Point 15 b pivoted. The control slide 45 is guided, has four bores 30 es, 31 α and 30i>, 10 α automatically in the iJeintralstellung, zariickge- 31 b, which leads arranged in pairs in the same section, as soon as the working piston 2 are vörgewäliliie, and in such a way that it has either reached all the same positions. timely through the control surfaces. 32α and 2> 2h of the control

Quite correspondingly, the Anbaäigesiänge is off erschieliers 10 a ahgeschloasea are, or in pairs, depending lowers, when the control lever 50 generally opposite the position of the control slide with the high pressure direction is operated. or Naederdraickseite are connected.

This usual design is now invention. The holes 30, a and 30b are on the .Leitun-

in accordance with an additional, particularly "simple gene 33." and added 332> with the check valve cylinder 24 SchwimmstellungsvorricixteiJg which causes connected in each case on the side of the koi that both sides of Arbeiäbskolbens independently of, Steltaig tob 55 bens 25awia2S.b, acting on -the Hückholfedem, the control slide on the Line 11 Di & Bohrungen 31.0 jand 31 & lead over.

can be connected to the container 7. iungen, 34ö uiad 3 &£> zn the check valves 28 a

As shown in Fig. 1 -and: 2, with a nor- uad 28b.

paint slide control preferably an additional - With such a design, the floating position,

High valve slide in the form of a control piston 17 60 d. H. the connection of both .Seitenräuine the KoI, which is guided in .einem cylinder 18, which is achieved at hens 2 with the RückfiuJßleituüg 11 and the container 7 of the ISa side with the return line 11 in the VarMn- ßrfindunjgs according to that there is two levers. The valve slide is mainly a .tmafo- 35-a and 35l · on plates. 39a and 39b to the plant pending control lever 19, which come mounted in point 19a, which is with the extensions 27-a and 27b , actuated via the rod 20 '. 65 pistons 250 and 25 $ are connected.

The control piston 17 has three constrictions. The levers 35ta tuad 35 b are in the bearings 36α and

21 α, 21S and 21c, which with each other and with the 36b schwrealsbsaa: supported and have extension piston sides 8a through several transverse bores -and gsn37.a and 37i>, which unite by 1BQ ° against each other -uniform bores 22 with the control piston 17 in. sets mod through the Venbind3iBgsstauige38 -perbunden dung stand. 70 are. One of the four-length maagaa $ 37 is available via the

Lever 19, which is pivotable about bearing 19a , and rod 20 is actuated.

When the control lever 19 assumes the position shown in dashed lines, the levers 35 α and 35 & are pivoted back from the plates 39 α and 39 b and the hydraulic system works normally.

If the control lever 19 is in the drawn out position, the pistons 25 a and 25 b are pulled outwards via the levers 35 α and 35 b and the check valves 28 α and 28 & are pressed outwards, ie opened.

According to the first example, the hydraulic is now in the floating position, since the working spaces in the cylinder on the one side b via the lines 12, 34 b, 11a and 11, and on the other side via lines 12α, 34α, 11 and 11 are connected to the container 7.

For example, a further embodiment is shown in FIG. 4, which is also used in control devices with shut-off valves is applicable.

In this embodiment, additional check valves 40 a and 40 b are used, which are switched into additional connecting lines 41 α and 41 &, which connect the lines 12 a and 12 & to the return line 11 . In this case, the check valves are actuated via the control lever 19, the rod 20 and the angle levers 42 a and 42 b rotatably mounted at 43 a and 43 b.

In these embodiments, the mode of operation corresponds to the mode of operation of the float position device according to the first embodiment.

The invention is expressly not limited to hydraulic systems for agricultural tractors.

Claims (4)

Patent claims: 1. Double-acting hydraulic power lift with every position of the hydraulic control lever a certain depth position of the implement is assigned, in particular for agricultural tractors, characterized in that an additional independent float position circuit is provided, whereby the working spaces on both sides of the working piston (2) with the oil reservoir (7) are connectable. 2. Hydraulic power lift according to claim 1, characterized in that an additional control slide (17) is installed, the optionally the lines (12 α, 12 b) to. Working cylinder (1) and the; Connect the pressure line (8) to the oil tank (7) or allow these lines to pass through to the control unit (10). 3. Hydraulic power lift according to claim 1, characterized in that, when using shut-off valves (28 a, 28 V), an additional control lever (19) is provided which controls the shut-off valves via a linkage (20, 37 a, 37 b, 38 ) opens together. 4. Hydraulic power lift according to claim 1, characterized in that in connecting lines between the supply lines ( 12 a , 12 b) to the working cylinder (1) and the return line (11) check valves (40 a, 40 V) are installed, which are through an additional Control lever (19) and a. Linkage (20) can be opened together. Considered publications:
German patent specification No. 917 394. 1 sheet of drawings © 809 700/170 12.58