DE1937347A1 - Hydraulic unit - Google Patents

Description

R. 9537
Wd / Fu 16.7.69

Attachment to
Patent and
Utility model auxiliary registration

ROBERT BOSCH GMBH, 7 Stuttgart I ₃ Breitschei dstrasse A

Hydro unit

The invention relates to a hydraulic unit. Consisting of two Axial piston machines arranged one behind the other in the same axial direction, which are connected by one with a motor stationary drive shaft are driven.

Such units are z. B. known from US Pat. No. 2,910,008 or 5,183,845. They serve as double pumps / motors, are very compact and can e.g. B. in pumping operation from "the flow rate zero to the maximum flow rate of both units. However, they have the disadvantage that both axial piston machines are always driven, even when the required amount of pressure medium is low. This leads to unnecessary

009886/1077

ORIGIN INSPECTED

Robert Bosch GmbH -R. 9557

Stuttgart. ·

Leakage oil losses, friction losses, wear and tear and also puddle losses, el, h. the units are not being used optimally. In addition, they are suitable for operation as a pump or engine limited.

It is an object of the invention to avoid these disadvantages, d. H. to create a hydraulic unit of the type mentioned, which can be operated particularly economically, and for a variety of uses is suitable.

This is achieved according to the invention in that the drive shaft consists of two shafts, one of which is an axial piston machine is assigned, and that both waves with. 'Help one Coupling can be optionally connected or disconnected.

This has the advantage that if only a small amount of pressure medium (Pump operation) is required, one of the two axial piston machines can be shut down. Friction losses, wear and tear and splashing losses are kept lower and thus also the power output by the engine. Same There is also an advantage in the engine operation of the unit.

A particularly useful embodiment of the invention results when the pressure medium conveyed by one axial piston machine via a control valve of the other axial piston machine is fed, and when both machines are separated by means of the clutch. In this pail you get a hydrostatic one

Transmission.

In this way the unit can be used as a single pump / motor double pump / motor or operated as a hydrostatic transmission, which makes its application very universal.

■ ..: .-. - -.- .. ■ ■. - 3 ■ - PQ98 86 / 1Q7 7

Robert Bosch GmbH R. 9557

Stuttgart

Such an arrangement can be used, for example, as a hydrostatic ' Serve drive for a vehicle, which is then required work on site when switching to single or double pump able to prepare.

Further useful refinements of the invention emerge from the subclaims. ■

An exemplary embodiment of the invention is shown in the drawing. This shows ini

.. Fig. 1 is a longitudinal section through a Doppelaxialkolben-

machine,

FIG. 2 shows a modification of a detail of the exemplary embodiment according to FIG. 1,

Pig. 3 shows a second embodiment, FIG. 4 shows a section along I-I of FIG 'Fig. 5 shows a section along II-II of Fig. 4, 6 shows a view in the direction of arrow A, FIGS. 7 and 8 applications and extensions of the previous one Exemplary embodiments, shown schematically.

In FIG. 1, 1 designates a housing which is closed with a cover 2. In the housing 1 are one behind the other in the the same axial direction two axial piston machines 3 and arranged. The axial piston machine 3 has a cylinder body 5 in which several parallel bores β are formed are, in many ways piston 7 are guided in a tightly sliding manner. They are supported by a pivot 8 in the housing pivotally mounted swash plate 9, whose.Schwenkwinkel is adjustable with the aid of a force amplifier 10.

009888/1077

^a * Ö ORIGINAL

Robert Bosch GmbH R. 9557

Stuttgart.

The cylinder body 5 is supported on a control plate 11, which is held in the housing 1 in a non-rotatable and non-displaceable manner. The cylinder body 11 is set in rotation by a shaft 12, namely via a spline 1J5. The shaft 12 is of a motor not shown driven.

The axial piston machine 4 also has a cylinder body 14 in which in. Parallel to each other bores 15 pistons 16 are tight and sliding. These are supported on a non-pivotable swash plate 17. The cylinder head l4 is driven by a shaft l8.

On the 'shaft l8 at its end facing the shaft 12 is a Coupling 19 mounted, the two shafts 12 and l8 either able to connect or disconnect. For this purpose, an external spline 20 is arranged on the end of the shaft 12 facing the shaft 18, which is an external spline 21 formed on the 'shaft l8. The external spline 21 has a certain distance from the end of the shaft facing the shaft 12 18th

The coupling has two internal splines 22, 2j>, of which the internal spline 22 is always connected to the external spline 20, while the internal spline: 27) can be separated from the external spline 21 by moving the coupling 19. Between the two internal splines 22, 2J, a bushing 2.4 is arranged on the inner circumference of the clutch 19, which bushing always receives the smooth end 25 of the shaft 18. The clutch I9 also serves as one of the bearing points for the shafts 12 and 18. The shaft 12 is also mounted in a roller bearing 25 arranged in the cover 2 of the housing, while the shaft 18 is mounted in a roller bearing 26 in the lower part of the housing 1 . ·

009886/1077

Robert Bosch GmbH R. 9537

Stuttgart

The external spline 21 on the shaft l8 thus serves at the same time to connect the shaft l8 with the cylinder body 14 and to Coupling the shaft 12 to the shaft l8.

On the outer circumference of the coupling 19, several lugs 27 are arranged, of which connecting rods 28 lead through bores 29 in the cylinder body 14 to an adjusting member 30 arranged on the shaft 18, on which they are also fixedly arranged. The adjusting member is slidably but not rotatably mounted on the shaft 18, and is located outside the rotating parts of the Axialkolbenmaschina 4. The adjusting member 30 has a collar 31> which is engaged by a pivotable lever arranged on the housing 1 32nd This is actuated with the aid of a push rod 33. It is sealed to the outside by a displaceable sealing arrangement Jk in such a way that no pressure medium can escape from the housing.

In the control plate 11 are each axial piston machine in a known manner facing kidney-shaped recesses 35j 36 and 37, 38 arranged. The recesses 35 and 37 are connected to one another; of them leads a bore 39 (it is shown in dashed lines in the drawing) to a connection, not shown, which is with a pressure medium tank is in communication.

The two ring-shaped recesses J>& and 38 are also connected to one another. An extension 4o is formed in the connecting part, in which a check valve ^ is arranged, which is able to open in the direction from the recess 38 to the recess 36. The check valve is designed as a hollow body 42 with a conical seat part and several through bores 43. From the upper part of the extension 4o, ie the one facing the recess 36, a channel 44 leads to a bore 45 which penetrates the housing and is connected to a consumer via a line. The bore 39 in the recesses 35 and

009886/1077

193734-

Robert Bosch GmbH 'R. 9557

Stuttgart. . ·

37 is similar but without the interposition of one Check valve connected to the container.

In operation as a single or double pump, the "shaft 12 is driven by a motor (not shown). If the coupling is in the position shown, the axial piston machine 4 is separated from the shaft 12 and thus the motor, ie it is at a standstill and only the axial piston machine 3 is in operation From there it flows to the outlet 45 and the consumer connected there. Since the swash plate 17 is not adjustable in this exemplary embodiment and always assumes the inclined position shown, the axial piston machine 4 could rotate freely if there were a connection between the recesses 36 and 38 however, prevented by the check valve 4l, which is now, as shown in the drawing, on its seat le gt and blocks the passage from recess 36 to recess 38. In operation as a single engine, pressurized medium is supplied under high pressure to the bore 45, which is relaxed during the rotation of the cylinder body and flows out at the bore 39. It can be seen from this that there is always high pressure at the recesses 36, 38 and that there is always low pressure at the recesses 35> 37. ·

If the hydraulic unit is to work as a double pump, then with With the help of the lever 32, the adjusting member 30 downwards, d. H. from the Cylinder body 14 moved away, - It also pulls the coupling 19 downwards via the connecting rods 28, whereby the internal spline 23 with the external spline 21 the shaft l8 is connected. The shift only takes place so far that the internal spline 22 with the external spline

009888/1077

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Robert Bosch GmbH 'R. 9557 ^:

Stuttgart

20 remains in contact. Both axial piston machines are now grounded driven and demand, as previously described., pressure medium to Consumer. The check valve 4l is lifted from its seat by the pressure medium conveyed by the axial piston machine 4, and the pressure medium can also pass through the bores 4j5 flow into the bore 45. ·

When operated as a double-piston engine, the bore 45 is again under high pressure pressure medium supplied, which the cylinder body set in rotation and depressurized at the bore 39 to Container flows out. ^

With the help of the power amplifier 10, the delivery or swallowing quantity the axial piston machine J in a known manner from zero to, can be changed to the maximum value. That of the Axialkolbenina- j machine 4 is constant.

In the modification according to the embodiment according to the Pig. 2, the liner 24 is replaced by a needle bearing 50, which is arranged in an enlarged part of the Vie I connected to the lüotor. The shaft itself is labeled 51. In turn, the ER \ panded portion 51 'of the shaft 51 carries a Außenkeilver- \ zahnung.52 which can be brought into engagement 54 with an inner spline 53 j of a coupling. This is operated in the same way as described above. The control plate is also designed differently and bears the designation 55. The kidney-shaped recesses 56, 57 * 58, 59 assigned to each piston machine are not connected to one another this time, but each recess has its own channel. These channels are designated 60, oil, 62, 63. Each channel 60, 63 has its own pressure medium outlet hole, not shown, and a pressure medium outlet hole, also not shown, is assigned to each channel 61, 62.

009886/1077

BATH ORIGINAL

Robert Bosch GmbH R. 9557

Stuttgart

Dal ^ uch it is not necessary to arrange a check valve between the kidney-shaped recesses 57> 58th The exemplary embodiment according to FIGS. 7 and 8 shows why. The two exemplary embodiments described have the advantage that the bushing in the couplings 19, 5 ^ also serves as a second bearing part for the two shafts. However, this is not always an advantage, especially when the axial piston machines are designed to be relatively long in terms of their dimensions.

In the exemplary embodiment according to FIG. 5, each shaft has two. Storage locations. The axial piston machines are designed in the same way as before and therefore also have the same designations. FiIa? however, each axial piston machine has its own control plate. The control plate of the Axia3.kolbenraas chine pist is denoted by 65, that of the axial piston machine 4 is denoted by 66. The control plate 63 receives a roller bearing 67, which serves as a second bearing point for the shaft 68. The control plate 66 has a roller bearing 69, which forms the second bearing point for the shaft 70.The end of the shaft 68 facing the shaft 70 has an external spline 71 * while the end of the shaft 70 facing the shaft 68 has an external spline 72. The outer wedge toothing 71 is at least twice as long as the outer wedge toothing 72.

A coupling 77 is seated on the external spline teeth 71 and carries a spline 74 corresponding to the two external splines. The coupling 74 is in turn displaced with the aid of a lever 75. The H '/ bel 75 is rotatably mounted in an intermediate part 76 on which the two control plates 65 and 66 are supported. The lever 75 engages a non-rotating flange 77 which is arranged on the coupling 73. The plane 75 is sealed to the outside by a sliding sealing arrangement 73, so that no pressure medium from the interior of the housing

0 09886/107 7 _BAD

Robert Bosch GmbH R. 9537

Stuttgart

can pass through to the outside.

In the control plate 65 there are passages 79 * ^{which lead to} kidney-shaped recesses 80, 81 in the intermediate part 76. These are also in Pig. 4 shown.

In the control plate 66 passages 82 are formed which lead to kidney-shaped recesses 83, 84 in the intermediate part 76. They correspond in shape and size to the. Recesses 79 * Sun.

Of the recess 80, a channel going from 85, which penetrates the central part 76 and the housing wall, 'and terminates at a flange 86 of the housing. Such a channel 87 starts from the recess 85. Corresponding channels 88 and 89 also run from the recesses 81 and 84 to the flange surface. 86. The opening points of the channels can be seen in FIG. A control valve is attached to the flange surface 86. This is shown schematically in FIGS.

The shaft 70 carries an end protruding from the housing External spline 90. Coaxial with the shaft 70 runs outside the housing 1 'an output shaft 91j which is also on its, the end facing the shaft 70 carries an external spline 92. The shaft 90 can be connected to the output shaft 91 by an arbitrarily actuatable connecting element 92. The connecting element 95 is slidably guided on the output shaft 9I and carries a non-rotating flange 94 on its outer circumference, on which a lever 95 engages. The connecting element 93 also has an internal spline 96 which corresponds to the external splines • 90, 92.

The mode of operation of the exemplary embodiment according to FIG. 3 is

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. SAD

009886/1077

Robert Bosch GmbH - R. 9537

Stuttgart ■

again the same as in the embodiment according to the Pig. I. It is also explained using the exemplary embodiments according to FIGS. 7 and 8. The exemplary embodiment corresponds here according to FIG. 6 essentially that of FIG. 1 with or without check valve 4l.

To the outlet bore 45 is a control valve 100 with two Positions, namely a through position I and a blocking position II connected. A line is attached to the bore 39

101 connected, which leads to a control valve 102 and continues runs to a container 105. Furthermore-is a feed pump 104 is provided, from which a line 105 leads via the control valve to the line 101, as well as a return line 10β leading from the control valve 102 leads to the container. From the control valve 100 one leads Line 107 to a consumer. Both axial piston machines are at a standstill directly to one another via channels 108 and 109 in the control plate 11 ' in connection.

The hydraulic unit works as a single pump when the clutch does not connect shafts 12 and 18, d. H. is disengaged, and even if the connecting element 93 separates the shaft 18 and the output shaft 91 according to the embodiment of FIG. H. is also disengaged. If the shaft 12 is driven by a motor, only the axial piston machine 3 works. Both control valves 100, 102 are in the switch position Ί. The axial piston machine 3 sucks through line 101 and the control valve

102 pressure medium from the container 103 and conveys it via the Directional valve 100 and line 107 to a consumer. The swash plate 17 ', which in this case is also adjustable, is in the neutral position, i.e. H. in a horizontal position so that the axial piston machine 4 cannot rotate freely.

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($ 09886/1077

- li -

Robert Bosch GmbH R. 9557

Stuttgart

The hydraulic unit works as a single motor when the Leitimg 107 pressure medium is supplied. This flows over relaxed the line 101 into the container.

The hydraulic unit works as a double pump when the clutch 19 connects the V / ellen 12 and 18. The connecting element 95 is after v-fie before disengaged. The swash plate 17 is in a desired Brought position, and both machines convey pressure medium via the channel 108 and the control valve 100 and the line 107 to the consumer. When operated as a double motor, hydraulic fluid is used via the line 107 and the control valve 100.

There is a major advantage of the training according to the invention in that the hydraulic unit is also operated as a hydrostatic transmission can be. For this purpose, the clutch 19 is disengaged so that it separates the two V / ellen 12 and 18 from each other. Now the connecting element 95 is engaged, whereby it the VJellen 18 and 91 connects. The two control valves 100 and 102 are brought into their position marked II.

The axial piston machine 5 is driven by the motor, the pressure medium delivered by it flows, since the valve 100 blocks the connection to the consumer, directly via the channel 108 of the axial piston machine h su. It brings this to rotation ₅ and the axial piston machine K drives over the Vie lie l8 and the connecting element 95 ^ ie output shaft 91. The hydrostatic transmission works in a closed circuit, i.e. Ii, the pressure medium displaced by the axial piston machine 5 and supplied to the axial piston machine 4 flows directly from the axial piston machine K in turn to the axial piston machine 5 via the channel 109. The connection from the line 101 to the container 105 is blocked.

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BATH ORIGINAL

009886/1077

Robert Bosch GmbH R. 95357

Stuttgart

In operation of a hydrostatic transmission in a closed Circuit it is necessary to compensate for the resulting leakage losses. This is done with the aid of the feed pump 104, which is now Via line 105 pressure medium under low pressure of the Low pressure side on channel 109 supplies.

The output shaft 91 can drive the wheels of a vehicle, for example, or, as shown in the exemplary embodiment in FIG. 1, directly a V-belt pulley arranged on the shaft 18. 110 drive. With such an arrangement it is therefore possible to drive a vehicle to the place of use, to switch the hydraulic unit there to a single pump or a double pump, and to carry out the necessary work in this way. With an arrangement according to FIG. 7, it is not possible to reverse, ie the direction of rotation of the output shaft 91 cannot be reversed if the direction of rotation of the motor remains the same. This is possible with a design according to the embodiment of FIG. For this it is necessary that the training and inlets of both axial piston machines are formed separately, as described, for example, in the embodiments according to FIGS. 2 and J>, is incorporated by reference.

A line 112 leads from channel 85 and a line from channel 87 to a 3/5-way valve 114. This is capable of three different ones ™ To take switch positions I, II, III and is expedient electromagnetically operated. ·

The channels 88 and 89 are connected to one another by a line 115. A line Tl 6 leads from the directional control valve Il4 to a consumer. Furthermore, two lines 117 and 118 lead from line II5 to directional control valve 102. Line 117 is via the directional control valve 102 connected to the feed pump 104, the line HS leads via the directional control valve 102 to the container 10j5. The. Return line the feed pump to the tank is marked with II9 »Vom Wegeventil

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009 886/107 7 _υ

Robert Bosch GmbH R. 9537

Stuttgart

114 another line 120 goes out, which opens into the line 117. A check valve 121 is arranged in line 117 and a check valve 122 is arranged in line 120. Their free flow direction is in the direction of the directional control valve 102 to the hydraulic unit.

The hydraulic unit according to the Pig. 8 works as a single pump when the directional control valve 114 is in its switching position III is located, the directional control valve 102 in its switching position II when the clutch 73 is disengaged and when the connecting element 93 does not connect the shaft 70 to the output shaft 91. The swash plate 9 is in the dot-dash position. That " The pressure medium required by the axial piston machine 3 flows via the line 112 to the directional control valve 114 and passes from it the line 116 to the consumer .. The axial piston machine 4 can not flow pressure medium because the connection to it at the directional control valve 14 is blocked. It stands still, even if the swash plate 17 is inclined, as shown in the drawing. Pressure medium is supplied from the container 103 via the lines 118 and 115 sucked in to duct 88. The feed pump 104, when it is driven, conveys through the line 117 without pressure into the container return. When Be.t, rubbed as a single motor, only the pressure medium flow is reversed, i. H. pressurized fluid under high pressure flows from line 116 via directional control valve 114 and line 112 to axial piston machine 3.

When operating as a double pump, the two shafts 68 and 70 are connected by the coupling 73 and the directional control valve 114 in its Switch position II brought. Pressure medium is now also fed from the axial piston unit 4 to the control valve 114 via the line 113 and merges there with the pressure medium flow of the axial piston machine 3 · Both flows flow via the line 116 to the consumer. Pressure medium is sucked in from the container 103 via the lines 118 and 115. When operated as a double engine

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ÖÖ98 86/1077

Robert Bosch GmbH 'R. 9557

Stuttgart '

again, only the pressure medium flows are reversed. High-, and low pressure side remain the same. This applies to operation as a single-pump motor or double-pump motor.

The hydraulic unit works as a hydrostatic transmission when the directional control valve 114 is brought into its switching position I (as shown) and the directional control valve 102 is brought into its switching position I (also shown as shown). The clutch 75 is disengaged ₃ the connecting element 91 is engaged; it connects the shaft 70 with the

^ Output shaft 91 · The swash plate 9 is still in the dash-dotted 'location. That displaced by the axial piston machine 3 Pressure medium flows via line 112 to the directional control valve and from there via line 115 through duct 87 to the axial piston machine 4 and sets it in rotation. The high pressure side is therefore on the channels 85 and 87. The system works in a closed manner Circulation, d. H. the pressure medium relaxed in the axial piston machine 4 flows from the channel 89 via the line 115 directly to channel 88 of the axial piston machine 5 · The high pressure of the Transmission so lead the lines 112 and II5. As previously described, it is necessary when operating in a closed circuit to supplement the leakage oil losses. For this purpose, the feed pump 104 conveys pressure center 1 via the directional control valve 102 into the line

W 117 and via the check valve 121 into the line 115. The check valve 122 is closed because there is high pressure in the line II5. This check valve is necessary so that the pressure medium flowing under high pressure in lines 112 and II5 cannot penetrate into low pressure line II5 or II7. When shaft 68 is driven clockwise by the motor, shaft 9I also rotates clockwise.

Should the shaft 91 turn counterclockwise with the same direction of rotation of the shaft 68 rotate, the hydrostatic transmission

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009886/1077

Robert Bosch GmbH R. 9537

Stuttgart

be reversed. For this purpose, the swash plate 9 is brought into the opposite angular position, i. H. in the one as shown in Fig. 8 in full. As a result, the high and low pressure sides of the transmission are swapped, and the Axial piston machine 3 conveys pressure medium via channel 88 and line 115 to channel 89 of axial piston machine 4. This is set in rotation, but now in the opposite direction Dreeinricht as before. The one from the axial piston machine 4 displaced pressure medium flows via line 113 * the ball valve 114 and the line 112 of the axial piston machine relaxed too. It can be seen from this that the lines 112 and 113 now carry the low pressure of the transmission. The valves 102 and 114 remain in their previous switch position during reversing operation.

The feed pump 1θ4 delivers via line 117 ″ and the check valve 122 Pressure medium in the line 120, and from this it reaches the lines 112 and II3. The jerk valve 121 is closed so that the line II5 is under high pressure standing pressure medium cannot flow into the line 120 carrying the low pressure.

The check valve required in the embodiment of FIG. 1 is omitted if the swash plate 17 '* as is generally the case is usual, can also be adjusted. You then only have to make sure that the swashplate is used when operating as a single-pump motor 17 * is brought into neutral position so that the axial piston machine 4 cannot rotate, which would be the case if the swash plate were inclined.

In the embodiment according to FIG. 8, there is absolutely no risk of this, even if the swash plate 17 is inclined, since the VJegeventil 114 takes over all control functions. here

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0098 86/107 7 bath

Robert Bosch GmbH R. 9537 '

Stuttgart.

Pressure medium can never flow from channel 85 to channel 87, if operation as a single pump motor is intended.

Usually, the feed pump 104 is inevitably of one of the Axial piston machines driven. When the hydraulic unit is operating as a pump / motor, the feed pump then always delivers without pressure to the container 10J5 back. ■ Seüb of course "it would also be possible shut down the feed pump in this operating state. When operating the hydraulic unit as a hydrostatic transmission, the promotes The feed pump usually enters "the low-pressure side" with a pressure of 4 to 8 atmospheres.

The valves 100, 102 and 114 as well as the various couplings I9, 54, 72j 92 are expediently actuated electromagnetically or, set hydraulically via a remote control.

As the embodiment of FIG. 1 "shows, it is at Operation as a hydrostatic transmission not necessary, a special one Provide output shaft 91. The downforce can be in this Case take place directly over the shaft l8 and the V-belt pulley.

The couplings I9, 54 or 75 can be positive or non-positive couplings of any conceivable type. This only depends on the structural conditions, e.g. B. den.space requirements. The lines shown in the exemplary embodiments can be channels within the housing of the unit.

The unit according to the invention is particularly suitable for systems in which very different amounts of pressure medium arise or required are. But it is particularly suitable, for example, for vehicles, where it can be used partly as a drive and partly as a pump is. There are therefore no limits to the possible applications.

009886/1077

Claims (14)

Robert Bosch GmbH R. 9557 ·. Stuttgart A η s ρ r ü c h, e: M..yHydroaggregat, consisting of two axial piston machines arranged one behind the other in the same axial direction, which are driven by a drive shaft connected to a motor, characterized in that the drive shaft consists of two shafts (12, 18; 68, 70), of which each one is assigned to an axial piston machine (3, 4), and that the two shafts can be optionally connected or disconnected with the aid of a coupling (19, 54, 73). 2. Hydraulic unit according to claim 1, characterized in that the coupling is designed as a positive coupling. 3. Hydraulic unit according to claim 1, characterized in that the coupling is designed as a non-positive coupling. 4. Hydraulic unit according to claim 1 or 2, characterized in that the coupling (19 * 54, 73) rotatably, but slidably on one of the two shafts (12, 18; -68,70) is arranged, and that it at the same time forms a bearing point (24, 50) for both shafts. bathroom 0098 86/1077 Robert Bosch GmbH R. 9557 Stuttgart '; · · 5. Hydraulic unit according to one of claims 1, 2 and 4, characterized in that an external spline (20, 29j 71, 72) is formed on or near the facing ends of both shafts, and that the coupling (19, 54, 75 ) is designed as a sliding sleeve which has an internal wedge toothing corresponding to the outer spline teeth (22, 2j5j 55 * 7 ² I-) . '· ■ .-''■■"■ 6. hydraulic unit _according to claim 4 and 5 > characterized in that "the coupling (19) in its interior in addition to the interior ■" .- ';. spline (22, 25) has a sliding bearing point (2k) in which one of the shaft ends rests in each position of the coupling. 7. Hydraulic unit according to one of claims 1 to 6, characterized in that the axial piston machines (j5> ² O in a common housing (l, I ¹ ■) are arranged. 8. Hydraulic unit according to one of claims 1 to 7, characterized in that the coupling (19 * ■ 5 ² I- * 73) is adjustable with the aid of a lever (52, 75) protruding from the common housing (l, l ') . . 9. Hydraulic unit according to one of claims 1 to 8, characterized in that that outside of the cylinder body (5, W) one of these two axial piston machines (5, 4) on the one assigned to it - 009886/1077 ^;;; ; ■■■■■■. ', --BAD-OfflGINAL.-' Robert Bosch GmbH R. 9557 '■ Stuttgart 'Shaft' {12-, l8) a \ / "creation disk (50) is arranged, which non-rotatably connected to the shaft, but it is displaceable in relation to it that the adjusting disk is the common one Housing penetrating lever (52) can be actuated, and that the adjusting disk via connecting means (28) with the . Coupling (19, 58) is connected. 10. Hydraulic unit according to one of the claims 1 to 9, characterized in that a first control valve (10O ₃ 11 ^) is provided, with the aid of which the pressure medium conveyed by one axial piston machine (5) is fed to the other axial piston machine (4) , the coupling (19. » 5 ^> 75) not connecting the two shafts (12, l8; 68, 70). 11. Hydraulic unit according to claim 10, characterized in that the control valve (100, ± Kk) has at least two switching positions, in one of which a pressure medium sron at least one axial piston machine (5, 5 ^) is fed to a consumer, in On the other hand, the other one is the one funded by an axial piston machine (5) Supply pressure medium to the other axial piston machine (4) * flows. - ' 12. Hydraulic unit according to one of claims 10 or 11, characterized in that the control valve (ll4) as a j5 / 5-l / egeventil ■ "- ■■■ · - 20 - 0 098 8 6/1077 ⁸ ^ o • Robert Bosch GmbH - R. 9557 Stuttgart ·. ■ "■■" ■. is designed, which in a first switching position only supplies the pressure medium conveyed by an axial piston machine (3) to a consumer, in a second holding position controls the pressure medium supplied to the consumer by both axial piston machines (j, 4), and in a third switching position that of one Axial piston machine conveyed pressure medium is fed to the other axial piston machine. 13. Hydraulic unit according to one of claims 10 to 12, characterized in that an auxiliary pump (1O4) is provided which, via a second control valve (102), supplies pressure medium under low pressure to that axial piston machine which, when the clutch (19 , 54, 73 ) is disconnected from the motor. 14. Hydraulic unit according to one of claims 10 to 13, characterized characterized in that the shaft (l8, 70) with that of the motor separable axial piston machine; can be connected to an output shaft (91) via a connecting element (93). / BATH 009886/1077