EP3828104B1 - Drive unit for a tilting-lifting device - Google Patents

Description

The present invention relates to a drive unit for a lifting and tipping device.

A large number of lifting and tipping devices for garbage trucks is already known from the prior art. Lifting and tipping devices are used for lifting and tipping garbage containers to be emptied, in particular garbage cans. A refuse container is moved to a dumping opening of the refuse vehicle by the lifting. The subsequent tipping causes the contents of the refuse container to be emptied through the pouring opening into a collection container of the refuse vehicle.

There are also known lifting and tipping devices that have two separate emptying devices, each for a refuse container. With such lifting and tipping devices, two garbage cans can be emptied independently. Each emptying device has there a lift truck for receiving a garbage container. The lift trucks of two emptying devices can be coupled. Large garbage containers can also be emptied in this way.

In the past, the lifting and tipping functions were often considered separately and performed by two independent drives. In the DE 25 17 247 A1 discloses an electric push and pull device, in particular for lifting and/or tilting loads. The DE 2 146 653 provides separate pressure or lifting cylinders for the lifting movement on the one hand and the tilting movement on the other.

The pamphlets DE 44 17 737 A1 and DE 44 23 718 C1 show devices in which a stationary toothed element, namely the rolling segment, is provided. A cam segment/gear element is provided on the tilting shaft of a lifting truck, which, after a certain vertical stroke of the lifting truck, engages in the stationary rolling segment, as a result of which a tilting movement is triggered. With these devices, there is a risk that the engagement between the rolling segment and the curve segment will fail, which can lead to damage to the device. Furthermore, both the rolling segment and the curve segment can become soiled by the contents of the refuse container, which can impede or impede the tilting movement.

From the U.S. 2011/0091309 A1 a mechanism for flipping containers or other objects is known. The mechanism rotates the container or object a full 180 degrees, allowing motion control without the use of hydraulic actuators.

The DE 26 30 440 A1 shows an emptying device for large-capacity refuse containers with a frame and a cylinder that can be actuated hydraulically or pneumatically via at least one, as well as a pivoting frame that can be rotated about a horizontal axis and grasps the container with a fork claw each. In the upper area on each side, the pivoting frame is guided into a substantially vertically extending guide channel via pivots with a diameter corresponding to the width of the guide channels, and in the lower area on each side it has at least one additional guideway that is supported on a substantially vertically extending guide track pivot on.

From the DE 844 262 a tilting device for emptying garbage cans into garbage containers is known, in which the garbage can or a storage area carrying the garbage can is connected to a tilting rocker that is inevitably connected Device is placed on the floor or on the roadway during the last pivoting period of the rocker arm.

The DE 844 262 C discloses a drive device for a lifting and tipping device with a carriage, linear guide and a gear unit for converting the linear movement of the carriage into a rotary movement.

The DE 26 30 440 A1 discloses an emptying device for bulky refuse containers. The DE 44 23 718 C1 discloses a lifting and tipping device for emptying garbage containers, in particular for garbage trucks.

The object of the invention is to create a new drive for a lifting and tipping device, with which the lifting and tipping is carried out by a single drive.

This object is achieved by a drive unit according to claim 1.

The drive unit for a lifting and tipping device has at least one carriage, a linear guide for the carriage and a drive device for moving the carriage along the linear guide.

The object is achieved in particular in that the carriage has a gear unit with at least two interacting gear parts for converting the linear movement of the carriage into a rotary movement of one of the gear parts, at least one of the interacting gear parts being able to be blocked by a blocking part.

The gear part, which is rotated, is preferably connected or can be connected to the lifting carriage of the lifting and tipping device and then, in the case of a rotary movement, leads to a tipping movement of the lifting carriage.

Due to the gear unit, basically only a single drive device is required both for the linear movement of the carriage and for the tilting movement of the lift truck. The shifting of the transmission unit is particularly simple and reliable, since it is done automatically by the blocking part. In particular, it is provided that a blocking of the blockable transmission part causes the transmission unit to switch from a passive to an active mode. In the passive mode, the gear parts move not relative to each other. In the active mode, a relative movement takes place between the gear parts, as a result of which the linear movement of the carriage is converted into a rotary movement of the rotatable gear part or a tilting movement of the lifting carriage. In particular, it is provided that in the active mode one of the transmission parts does not move relative to the linear guide.

The truck is preferably directly or indirectly connected to at least one of the cooperating transmission parts, in particular the rotatable one, or can be connected, in particular non-rotatably. The lift truck preferably has a receiving comb for receiving a refuse container. The lifting carriage is preferably arranged or can be arranged rotatably on the carriage.

The carriage can be moved along the linear guide, preferably between a pick-up position and an emptying position. In the pick-up position, a refuse container to be emptied can be attached to the carriage or to a component attached thereto, in particular the lift truck. The carriage is then moved into the emptying position by the drive device. The waste container is first lifted and then tilted. In the emptying position, the contents of the refuse container can fall into a collection container, in particular that of a refuse vehicle, in particular through a pouring opening.

The drive device preferably includes a threaded spindle and a spindle nut. The lead screw runs through the lead screw nut. Threaded spindle and nut are rotatable relative to each other. A rotary movement of one of the parts also leads to a relative linear movement between the parts along the axis of rotation. The threaded spindle preferably runs vertically. The combination of lead screw and lead screw nut enables efficient conversion of rotary motion into linear motion for lifting the sled. This makes it possible, for example, to use an electric motor to lift and tilt the refuse container.

The threaded spindle is preferably firmly connected to the linear guide and also preferably runs parallel to the linear guide. When used as intended, the spindle nut thus moves around the threaded spindle and linearly along the main axis of the threaded spindle. The spindle nut is thus preferably fastened in the carriage such that it can rotate about an axis of rotation D1. With this design, only the relatively small weight of the spindle nut has to be moved compared to the threaded spindle, which means that the drive unit can lift more payload and requires less energy for lifting. The axis of rotation D1 preferably runs vertically.

An electric motor is preferably provided which drives the spindle nut and which is firmly connected to the carriage. An electric motor has significant advantages over the hydraulic drives usually installed in garbage trucks. First of all, several components required for a hydraulic drive, such as hydraulic unit, hose lines, etc., are no longer required. Furthermore, hydraulic medium such as oil, which can leak out and lead to environmental pollution, is no longer necessary. In addition, electric motors are quieter, which reduces the noise pollution of the operating personnel and the environment. The use of an electric motor that is operated with 24 V DC voltage is particularly advantageous, since the electric motor can then be connected directly to the on-board power supply of the garbage truck. The use of the drive unit according to the invention with an electric motor in garbage trucks with an electric drive is also particularly advantageous. There, an electric motor can be operated directly with the energy from the traction battery of the garbage truck, so that no separate energy storage is necessary.

Alternatively, it is also possible to use a hydraulic motor instead of an electric motor. The hydraulic motor then drives the spindle nut, whereupon the carriage is moved along the guide.

In other embodiments, the carriage can also be moved in other ways along the guide. For example, it is possible to move the carriage directly hydraulically without using a threaded spindle, spindle nut and motor. In this case, the drive device has a hydraulic cylinder connected to the carriage and a hydraulic unit for moving the hydraulic cylinder.

A further alternative consists in moving the carriage along the guide by means of a traction means, for example a chain or a cable. The drive device then comprises the traction device, drive elements for moving the traction device, with which the traction device is engaged, for example a gear wheel or a roller, and a motor, in particular an electric motor or hydraulic motor, for driving the drive elements.

Irrespective of which other components the drive device comprises, the electric motor is also preferably capable of recuperation, ie in particular able to act as a generator. The electric motor is particularly preferably designed in such a way that it converts kinetic energy into electrical energy during the downward movement of the carriage after the refuse container has been emptied. In this way, the downward movement is slowed down, which means that the refuse container is not accelerated more than necessary. In addition, part of the electrical energy used for the lifting movement is recovered.

The blockable gear part can be blocked in particular with regard to a movement relative to the linear guide. This means that the lockable gear part and the linear guide do not move relative to each other when the lockable transmission part is blocked. The blockable transmission part is preferably blocked by the linear guide itself or an element arranged on it. Alternatively, blocking by an element of the lifting and tipping device or of the garbage truck, for example an element arranged on the collection container, is also possible. Blocking by the linear guide itself or an element arranged thereon has the advantage that no changes need to be made to the garbage truck, in particular to its collection container.

The blockable transmission part is preferably not blocked in positions of the carriage between the receiving position and a switching position and is blocked between the switching position and the emptying position. When the carriage moves up along the linear guide, the switching between passive and active mode of the gear unit takes place at the moment of blocking. In this way, no separate switching device is required for the transmission unit, which limits the complexity of the drive unit.

With the devices in the publications DE 44 17 737 A1 and DE 44 23 718 C1 two gear parts are provided, which are not in engagement with each other at the beginning of the lifting movement and only contact each other later, whereupon the tilting movement is triggered. The cooperating gear parts of the invention are preferably in mesh with each other in every position of the carriage. This avoids the risk of incorrect engagement of the transmission parts with one another. Rather, it is ensured that the tilting movement takes place immediately when the lockable threaded part is blocked.

A toothed rack and a toothed element, in particular a toothed wheel, are preferably provided as interacting gear parts. This enables the linear movement of the carriage to be easily converted into a tilting movement of the pallet truck. The lifting carriage is preferably directly or indirectly connected or connectable to the toothed element. The toothed element can, for example, also be a partial (eg half) toothed wheel or the like if a complete toothed wheel is not necessary for the tilting movement. In such a case, a weight saving is achieved by using a partial gear.

The toothed element is preferably connected to a pivot shaft. The lift truck is preferably connected or can be connected to the pivot shaft. In this way, the pivot shaft and the lifting carriage are rotated as the toothed element rotates. This will tip the garbage can. The toothed element is particularly preferably fastened as a spur gear at one end of the pivot shaft. The toothed element is then located as far as possible outside of the area in which the refuse container to be emptied is arranged. The pivot shaft can be designed in one or more parts. In particular, a spur gear shaft can be provided, which forms the gear wheel or is connected to the separate gear wheel. A further shaft can then be plugged coaxially onto the spur gear shaft, with the lifting carriage being connected to the further shaft. Due to the multiple parts, assembly is simplified.

The toothed rack is preferably the blockable transmission part. The effort to block an elongated rack is less than the effort to block a gear. The blocking of the toothed rack is also to be preferred because the carriage and with it the toothed rack perform a linear movement anyway, so that only the linear movement of the toothed rack has to be prevented in order to block the toothed rack.

The linear guide is preferably arranged vertically. The toothed rack is preferably arranged parallel to the linear guide, ie in particular also vertically. The axis of rotation of the toothed element then runs horizontally, so that it in addition to the toothed element, no further transmission parts are required in order to effect a tilting movement. This limits the complexity of the drive unit.

The blocking part is preferably a stop for the rack. A stop can be implemented in a simple manner and can be made robust, as a result of which the drive unit has a long service life. The stop is preferably arranged on the linear guide. The blocking part is preferably made of plastic, caoutchouc or rubber. In this way, the blocking process does not take place suddenly but is dampened. This limits the noise generated and protects the components involved in the blockage.

The linear guide preferably comprises two parallel round rods. The round rods preferably run vertically. This minimizes the floor space required by the linear guide and, in this way, the installation space required. The round rods are preferably connected by at least one upper connecting web, particularly preferably by an upper and a lower connecting web, as a result of which the linear guide gains in rigidity. The connecting webs are preferably arranged at vertically opposite ends of the rods. The connecting webs also prevent the slide from falling off the rods.

The connecting webs are preferably parts of a frame that is fixed to the collection container of the garbage truck. The use of such a frame facilitates the fixation since standardized fixation points are usually specified on the collection container. The stop for the toothed rack is preferably arranged on the frame, in particular on the upper connecting web. The frame offers sufficient stability for the forces that occur when the rack and stop come into contact.

The carriage advantageously has a housing for the gear unit. A housing limits the contamination of the transmission parts, with at least those sections of the transmission parts that have teeth being arranged in the housing. It is particularly advantageous here if the cooperating gear parts are in engagement with one another in every position of the carriage. This results in a compact housing, which protects the toothed sections of the transmission parts from dirt. In addition, the housing reduces the risk of injury, since the gear parts are not directly accessible, and thus increases work safety.

In advantageous developments, a spring, in particular a compression spring, is provided which interacts with one of the transmission parts, in particular the toothed rack. The compression spring is arranged in such a way that it is compressed by the toothed rack during the upward movement of the carriage and is thereby prestressed. If the toothed rack is then blocked, nothing changes in the spring at first. If the refuse container is to be moved downwards again and to be tilted back, the compression spring supports the tilting back. This ensures that the bin is tipped back in the first place. In any case, however, the tilting back is accelerated. The compression spring is preferably arranged in a protective sleeve, into which the toothed rack is pushed during the upward movement of the carriage.

The spindle nut and the electric motor, in particular moving parts of the electric motor, are preferably arranged in the housing of the carriage. This also protects these parts from dirt and minimizes the risk of injury. The electric motor is preferably firmly connected to the housing. In this way, relative movement between the electric motor and the housing is prevented.

The toothed element and/or the pivot shaft, in particular its spur gear shaft, are preferably arranged or can be arranged rotatably on the carriage, in particular relative to the housing. As a result, the housing does not have to be rotated, which again limits energy consumption.

The housing preferably has guide bores for the linear guide, in particular for the round rods of the linear guide. In this way, the housing can be displaced along the linear guide and the housing is stabilized by the linear guide. Bearings, in particular a roller bearing, are preferably provided in the guide bores for the round rods of the linear guide.

Also disclosed is a lifting and tipping device with at least one emptying device, the emptying device having at least one drive unit. The drive unit has a carriage, a lifting carriage for receiving a refuse container, a linear guide for the carriage and a drive device for moving the carriage along the linear guide. The drive unit is preferably a drive unit as described above.

The carriage has a gear unit for converting the linear movement of the carriage into a tilting movement of the lifting carriage, the gear unit comprising at least two interacting gear parts, at least one of which can be blocked by a blocking part.

The lifting and tipping device preferably has two emptying devices. The axes of rotation of the toothed elements are then preferably identical. The linear guides and/or the threaded spindles of the emptying devices are preferably arranged at opposite ends of the lifting and tipping device. In this way, the space between the linear guides and/or threaded spindles is the greatest, so that even large garbage containers can be picked up and emptied by the lift trucks.

In preferred embodiments of the lifting and tipping device, two emptying devices are provided in accordance with the above description, the lifting carriages of the emptying devices being able to be coupled to one another. The coupling connects the pallet truck to a stable unit. The coupling is controlled mechanically, electromechanically or electrically. In this way, a lifting of so-called large garbage containers is possible. Large garbage containers usually have a volume of 660 l, 770 l, 1000 l or 1100 l and have four wheels. Normal garbage containers that can be lifted with a pallet truck regularly have a volume of 60 l, 80 l, 120 l, 140 l, 180 l, 240 l, 340 l or 360 l and only two wheels. When the lifting carriages are coupled, the carriages are preferably controlled in such a way that they carry out the lifting movement at the same time.

The linear guide, and with it the direction of movement of the carriage, preferably runs vertically, as described. The axis of rotation of the toothed element preferably runs perpendicularly to the linear guide and perpendicularly to the direction of travel of the garbage truck.

Figur 1

ein Müllfahrzeug mit einer Hub-Kipp-Vorrichtung in einer Rückansicht;

Figur 2

die Hub-Kipp-Vorrichtung der Figur 1 in einer Seitenansicht mit einem Schlitten in einer Aufnahmeposition;

Figur 3

das Detail A der Figur 2 in vergrößerter Darstellung;

Figur 3a

einen Schnitt durch die Hub-Kipp-Vorrichtung in gleicher Ansicht wie Figur 3;

Figur 4

die Hub-Kipp-Vorrichtung der Figur 1 in einer Seitenansicht mit dem Schlitten in einer Schaltposition;

Figur 5

die Hub-Kipp-Vorrichtung der Figur 1 in einer Seitenansicht mit dem Schlitten in einer Entleerposition;

Figur 6

das Detail B der Figur 5 in vergrößerter Darstellung.

The invention is illustrated and explained below by way of example with reference to the figures. They show:

figure 1

a garbage truck with a lifting and tipping device in a rear view;

figure 2

the lifting and tipping device figure 1 in a side view with a carriage in a receiving position;

figure 3

the detail A the figure 2 in an enlarged view;

Figure 3a

a section through the lifting and tipping device in the same view as figure 3 ;

figure 4

the lifting and tipping device figure 1 in a side view with the carriage in a switching position;

figure 5

the lifting and tipping device figure 1 in a side view with the carriage in an emptying position;

figure 6

the detail B the figure 5 in an enlarged view.

That in the figure 1 Garbage truck 10, shown only partially, has a collection container 12 and a lifting and tipping device 14, which is arranged in the area of a pouring opening 16 on the collection container 12. Garbage is introduced into the collection container 12 through the pouring-in opening 16 when used as intended. A pressing plant (not shown) can be provided there, which compresses the refuse. Two retaining elements (not shown) are arranged in the area of the pouring-in opening 16 for retaining refuse containers 100 during the pouring-in process.

The lifting and tipping device 14 comprises two emptying devices 20, each with a lifting truck 78 for lifting and tipping refuse containers 100, the lifting truck 78 being arranged on a pivot shaft. Each lifting carriage has a receiving comb 48 and an abutment element 49 . Each emptying device 20 is associated with a retaining element. The lifting takes place along the Y-axis and the tilting around the X-axis of a Cartesian coordinate system, with the Z-axis of the coordinate system running parallel to the direction of travel of the garbage truck 10 . The emptying devices 20 are identical in construction, but on a YZ plane running centrally through the garbage truck arranged mirrored. Therefore, only one emptying device 20 is described in detail below.

One of the emptying devices 20 is in the figures 2 , 3 and 3a shown in more detail and has a drive unit 50 . The drive unit 50 has a linear guide 22 with two round rods running parallel to one another as guide elements for a carriage 40 . The rods run vertically, i.e. parallel to the Y-axis. The linear guide 22 has two connecting webs 28, 29 at vertically opposite ends, which connect the round rods to one another. The connecting webs 28, 29 are parts of a frame 30 which is fixed to the collection container 12 of the garbage truck 10.

The carriage 40 has a housing 42 with guide holes for the rods. Bearings 46 (see Fig. Figure 3a ) arranged so that the carriage 40 is linearly movable along the rods.

The drive unit 50 also has a drive device 60 for moving the carriage 40 along the linear guide 22 . The drive device 60 comprises a threaded spindle 62 and a spindle nut 64. The threaded spindle 62 runs vertically between the round rods and is firmly connected to the connecting webs 28, 29. The spindle nut 64 is mounted in the housing 42 in such a way that it can be rotated about an axis of rotation D1 parallel to the Y-axis. However, translational relative movements between the housing 42 and the spindle nut 64 are not possible. The axis of rotation D1 corresponds to the main axis of the threaded spindle 62.

The drive device 60 also includes an electric motor 66 which is firmly connected to the housing 42 . The electric motor 66 drives the spindle nut 64 so that it rotates about the axis of rotation D1. The rotation causes a linear movement between the spindle nut 64 and the threaded spindle 62 along the axis of rotation D1. Since the spindle nut 64 is connected to the housing 42, the housing 42 and components attached thereto are also moved along the axis of rotation D1 and thus vertically.

The carriage 40 also has a gear unit 70 for converting the linear movement of the carriage 40 into a tilting movement of the lifting carriage 78 . The gear unit 70 comprises two cooperating gear parts, namely a toothed rack 72 and a gear wheel 74. The toothed rack 72 and toothed wheel 74 mesh with one another in every position of the carriage 40. The rack 72 runs vertically. A pivot shaft 76 (see Fig. 1 ) on, wherein the gear 74 is designed as a spur gear of the pivot shaft 76. The pivot shaft 76 is in several parts. The axis of rotation D2 of gear 74 and pivot shaft 76 is parallel to the X-axis. The lifting carriage 78 is arranged on the pivot shaft 76 . Gear wheel 74, pivot shaft 76 and lifting carriage 78 are connected to one another in a rotationally fixed manner, so that rotation of gear wheel 74 automatically causes lifting carriage 78 to tilt.

The figures 2 , 3 and 3a show the carriage 40 in a pick-up position in which a refuse container 100 can be arranged on the lift truck 78. If the carriage 40 is now raised by means of the drive device 60, the pivot shaft 76, the lifting carriage 78 and the refuse container 100 move with the carriage 40 upwards.

The carriage 40 is moved upwards until it has reached a switching position which is shown in figure 4 is shown. Gear 74, pivot shaft 76, lift truck 78 and refuse container 100 are not tilted in the shift position compared to the pickup position. The toothed rack 72 rests against a stop 23 of the upper connecting web 28 in the switching position. The rack 72 is blocked in a further movement of the carriage 40 upwards by the stop 23 in a further movement in the same direction is prevented. The stop 23 thus forms a blocking part 21 for the toothed rack 72. Since the toothed wheel 74, on the other hand, continues to move vertically upwards with the carriage 40, it rolls on the toothed rack 72, which is also the toothed rack 72 which is also moving vertically upwards Axis of rotation D2 rotates. This results in a rotation of the pivot shaft 76 and a tilting movement of the lift truck 78 and the refuse container 100 about the axis of rotation D2.

The carriage 40 has a protective sleeve 73 for a lower end of the toothed rack 72 on its housing 42 . When the toothed rack 72 rests against the stop 23, the carriage 40 moves further past the toothed rack 72, so to speak. During this movement of the carriage 40, the protective sleeve 73 is pushed over the lower end of the toothed rack 72. In this way, the toothed rack 72 is protected from damage and dirt. A compression spring (75) is arranged in the protective sleeve 73 . If the carriage 40 and thus the protective sleeve 73 are moved upwards relative to the toothed rack 72 , the toothed rack 72 preloads the compression spring 75 . The compression spring 75 is also protected from damage and dirt by the protective sleeve 73 .

If the carriage 40 is moved further upwards from the switching position by the drive device 60, it finally arrives in the figures 5 and 6 shown emptying position. The refuse container 100 is then completely tilted in, so that the refuse present in the refuse container 100 falls through the pour-in opening 16 into the collection container 12 . The carriage 40 can then be moved back down into an end position that corresponds to the receiving position. For this purpose, the electric motor 66 capable of recuperation is switched to a recuperation mode. The electric motor 66 then no longer drives the spindle nut 64 but is instead able to convert a rotation of the spindle nut 64 into electrical energy and to store it in an energy store (not shown) of the garbage truck 10 . The spindle nut 64 is set in rotation because the carriage 40 moves downwards due to gravity and the lack of drive. In this way, part of the energy used to lift the refuse container 100 is recovered. The downward movement of the carriage 40 is also braked by the recuperation. This limits the noise level of the lifting and tipping device 14 and there is also a lower risk of injury from the garbage container 100 driving down.

When the carriage 40 moves downwards, the refuse container 100 must be tilted back again so that it has the same orientation in the end position as in the receiving position. The compression spring 75 in the protective sleeve 73 supports the backward tilting movement of the refuse container 100 by transferring the stored spring energy to the toothed rack 72 as soon as the toothed rack 72 is no longer in contact with the stop 23 . The rack 72 is thereby moved upwards, whereupon the gear 74 and with it the pivot shaft 76 and the lifting carriage 78 are pivoted back and the refuse container 100 is tilted back.

Reference List

10

garbage truck

12

collection container

14

Lift-tilt device

16

pouring opening

20

emptying device

21

blocking part

22

linear guide

23

attack

28

upper connecting bar

29

lower connecting bar

30

Frame

40

Sleds

42

Housing

46

camp

48

pick-up comb

49

abutment element

50

drive unit

60

drive device

62

lead screw

64

spindle nut

66

electric motor

70

gear unit

72

rack

73

protective sleeve

74

gear

75

Feather

76

pivot shaft

78

pallet truck

100

trash can

D1

axis of rotation

D2

axis of rotation

Claims (15)

1. Drive unit (50) for a lifting/tipping device (14), wherein the drive unit (50) has at least one carriage (40), one linear guide (22) for the carriage (40) and one drive mechanism (60) for moving the carriage (40) along the linear guide (22),

   characterized in that the carriage (40) has a gear unit (70) with at least two co-operating gear parts for converting the linear movement of the carriage (40) into a rotational movement of one of the gear parts,

   wherein at least one of the co-operating gear parts is blockable by a blocking part (21).
2. Drive unit (50) according to claim 1,
   characterized in that a blocking of the blockable gear part brings about a switching of the gear unit (70) from a passive mode, in which the gear parts do not move relative to each other, to an active mode, in which a relative movement between the gear parts takes place.
3. Drive unit (50) according to claim 1 or 2,
   characterized in that the carriage (40) is moveable along the linear guide (22) between a receiving position and an emptying position.
4. Drive unit (50) according to one of the preceding claims,
   characterized in that the drive mechanism (60) comprises a threaded spindle (62) and a spindle nut (64).
5. Drive unit (50) according to claim 4,
   characterized in that the threaded spindle (62) is firmly connected to the linear guide (22) and runs parallel to the linear guide (22).
6. Drive unit (50) according to claim 4 or 5,
   characterized in that an electric motor (66) is provided, which drives the spindle nut (64) and which is firmly connected to the carriage (40).
7. Drive unit (50) according to one of the preceding claims,
   characterized in that the blockable gear part is blockable with respect to a movement relative to the linear guide (22).
8. Drive unit (50) according to one of the preceding claims,
   characterized in that the blockable gear part is not blocked in positions of the carriage (40) between the receiving position and a switching position and is blocked between the switching position and the emptying position.
9. Drive unit (50) according to one of the preceding claims,
   characterized in that the co-operating gear parts are in engagement with each other in every position of the carriage (40) and/or in that a toothed rack (72) and a tooth element, in particular a gear wheel (74), are provided as co-operating gear parts.
10. Drive unit (50) according to claim 9,
    characterized in that the toothed rack (72) is the blockable gear part.
11. Drive unit (50) according to claim 9 or 10,
    characterized in that the toothed rack (72) is arranged parallel to the linear guide (22).
12. Drive unit (50) according to one of claims 9 to 11,
    characterized in that the blocking part (21) is a stop (23) for the toothed rack (72).
13. Drive unit (50) according to one of the preceding claims,
    characterized in that the linear guide (22) comprises two rods running parallel.
14. Drive unit (50) according to claim 13,
    characterized in that the rods are connected at least by an upper connecting web (28), wherein the stop (23) for the toothed rack (72) is arranged on the upper connecting web (28).
15. Drive unit (50) according to one of the preceding claims,
    characterized in that the carriage (40) has a housing (42) for the gear unit (70).

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