DE8911223U1 - Clamshell grab for an excavator or similar. - Google Patents

Description

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Cx-tyre for an excavator or similar

The innovation relates to a clamshell grab for an excavator or the like according to the preamble of claim 1. Such clamshell grabs, which can also be mounted on a truck or tractor, have been known and used for a long time. They are used primarily for excavation work or for picking up bulk material.

In known swish-halen grippers, the two shells are connected to a hydraulic cylinder via separate joints, whereby they are actuated via a lever arm. The shells, in particular the gripper blades, perform a radius fixation around their joint axis, which is, however, arranged rigidly relative to the carrier device. Such a device is shown and described, for example, in DE-C-34 25 542.

-i~ The problem with known clamshell grabs is that strong displacement forces occur on the back of the clamshell when the clamshells move towards each other in the material to be picked up and close. The material to be gripped is pressed together, so that high friction forces also occur, which must also be overcome by the drive device. It is therefore an object of the innovation to create a clamshell grab of the type mentioned at the beginning, in which the clamshell movement is optimized in such a way that displacement forces on the back of the clamshell are largely avoided. In addition, the energy required to apply the closing forces should generally be reduced. This object is solved according to the innovation with a clamshell grab which has the features in claim 1.

The operation of the gripper shells with the new articulated gear means that the shells no longer perform a radius movement, but a curved movement, in which the shell rear wall is relieved. In addition to reducing frictional forces, this also prevents the material being gripped from being compressed. It is clear that the same closing forces as with conventional clamshell grippers can be applied with less energy. Depending on the arrangement of the joint axes and the length of the lever arms in the articulated gear, an optimal movement sequence can be achieved. The shells are still guided in parallel. In addition, the pair of shells can also perform a pendulum movement.

A particularly advantageous gear arrangement is obtained if the two rocker arms are pivotably connected to the carrier device about a common rocker arm joint axis and/or if the two gripper shells are pivotably connected to one another about a common gripper joint axis. If there is a force resistance on one side at I

a shell, the gripper pair can swing around the rocker arm joint axis, whereby the filling level of the gripper is further optimized. In certain cases, however, it would also be conceivable to attach the two rocker arms to separate joints on the carrier device or to connect the two gripper shells to one another via an intermediate joint.

Further advantages and individual features of the innovation can be seen from the exemplary embodiments described below and from the drawings. They show:

Figure 1 is a perspective view of a clamshell grab according to the innovation,

Figure 2 is a side view of the closed gripper according to Figure 1,

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Figure 3 is a side view of the opened gripper according to Figure l,

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4 and 5 a schematic representation of the articulated gear on the gripper according to Figure 1 in two different positions, and

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6a and 6b show a modified embodiment of a clamshell grab with a central hydraulic cylinder.

As shown in Figures 1 and 2, the two-shell gripper consists of the two gripper shells 1 and 1*. These are connected to each other on both ends with a gripper joint 4. A support tube 7 runs parallel to the gripper joint axis and is connected to the gripper shells in a rotationally fixed manner.

The gripper shells 1 and 1' are suspended from the support tubes 7 with the aid of rocker arms 5, 5* on the carrier device 2. The carrier device is provided with a fork at the top, on which it can be suspended in a cardanic manner. For this purpose, the fork 14 has an upper fork joint 15 and a lower fork joint 16 arranged transversely to the upper fork joint axis.

The two rocker arms 5 and 5* can be pivoted about a common rocker arm joint 6. The rocker arms are articulated to the support tubes 7 by means of the lower rocker arm joints 13, 13*. In the plane of the two rocker arms 5, 5', lever arms 8 are also arranged on the support tubes 7, via which the gripper shells 1, ¹¹ are actuated.

Two hydraulic cylinders 3, 3' serve as the drive device, which are hinged laterally to the carrier device 2.

The piston rods 9, 9' of the hydraulic cylinders 3, 3* are articulated on the piston rod joints 11, 11' at the ends of the lever arms 8. The cylinders 10 are located at the top and are articulated on the support device 2 by the cylinder joints 12, 12'. This embodiment is particularly advantageous, but the hydraulic cylinders 3, 3' can also be articulated with their piston rods 9, 9' on the support device 2 and with their cylinders 10, 10' on the gripper shell 1, 1'. A stop 17 on each side is directed towards the support tube 7 and limits the opening movement of the gripper shells. The gripper blades 18 of both shells are interlocked in the closed position, as can be seen from Figure 2.

As can be seen from Figures 4 and 5, the gripper shells 1, ¹¹ form a coupling 19 and 19' respectively, via which the rocker arms 5, 5' are connected to the piston rods 9, 9'. When the hydraulic cylinders 3, 3' are activated, the lower rocker arm joints 13, 13' and the rocker arms 5, 5' move apart, while the gripper joint 4 moves upwards. The gripper blades understandably no longer perform a radius movement, but instead are on a bearing 2G, which relieves the load on the two shell rear walls. This minimizes the frictional forces that occur.

Figure 3 shows the position of the hydraulic cylinders 3 when the gripper shells 1, 1* are fully open. The support tubes 7 rest against the stops 17 and the piston rods 9 are practically completely retracted into the cylinders 10 and are no longer visible. Easily removable fastening means are preferably provided for fastening the gripper shells 1, 1' to the support tubes 7, so that the gripper shells can be replaced quickly.

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The shell suspension according to the innovation can also be driven in another way, as can be seen in Figures 6a and 6b. The left half of the image in Figure 6a shows a clamshell grab in the closed position and the right half of the image in Figure 6b shows the same grab in the open position. The relative position of the two shell halves 1 and 1' shown is never actually reached, since the two shells always move synchronously.

Instead of the two hydraulic cylinders 3 and 3 arranged laterally and synchronously pressurized with pressure medium, the gripper is only provided with a single, centrally arranged hydraulic cylinder 21. Its driven element is provided with movable joint elements 23 on the side, which can be moved up and down when the hydraulic cylinder 21 is activated. Articulated arms 22, 22* are attached to the joint elements 23, which in turn are articulated to the gripper shells 1 and 1*. These gripper shells can also be provided with support tubes and lever arms, as in the previously described embodiment. The arrangement of the rocker arms and the other joints or joint axes can also be the same as in the embodiment with two hydraulic cylinders. When the movable joint elements 23 are moved, the same movement occurs; ) process on the gripper shells, which results in the execution of a curved path 20.

With the new shell suspension, the force could also be introduced at another point on the articulated gear. For example, it would be conceivable for a central hydraulic cylinder to act directly on the gripper joint 4. The correct dimensioning and arrangement of the hydraulic cylinders is known to the expert and is therefore not described in more detail here. The drive device does not necessarily have to be formed by a hydraulic cylinder. In certain cases, other drive elements of a hydraulic, pneumatic or electrical type would also be conceivable.

Claims (1)

Reinhard, Skuhra, Weift ; Patent Attorney ' :: :,: j:..·.;··;: '■ Ffledrtchttf. 31, D-8000 Munich 40 '· '' · '.'"·''. '. " I P3632 20.09.1989 Franz Eder Maschinenfabrik GmbH & Co. KG Expectations 1. A two-shell grab for an excavator or the like, with a carrier device (2) and a pair of grab shells (1, 1') which are articulatedly attached to the carrier device (2) and which can be pivoted towards or away from each other in an arcuate movement by at least one preferably hydraulic drive device (3, 3') which is attached to the carrier device (2) and engages the grab shells (1, ¹ '), characterized in that the two grab shells (1, 1') are connected to each other via at least one grab joint (4) which is independent of the carrier device, and that each grab shell (1, ^1' ) is suspended from the carrier device (2) via a respective rocker arm (5, 5') which is mounted at a distance from the grab joint (4) on the gripper shell (1, I ¹ ) is articulated, so that the relative position of the gripper joint (4) to the carrier device (2) changes when the drive device is activated J J vcLajiuc J 2. Clamshell grab according to claim 1, characterized in that the two rocker arms (5, 5') are pivotably connected to the carrier device (2) about a common rocker arm joint axis. 3. A clamshell grab according to claim 1 or 2, characterized in that the two gripper shells (1, I ¹ ) are pivotally connected to one another about a common gripper joint axis (4). 4. A clamshell grab according to one of claims 1 to 3, characterized in that each clamshell (I ₇ I ¹ ) · ■ · is provided with a support tube (7) running parallel to the gripper joint axis, and that the rocker arms (5, 5") are hinged to the support tubes. 5. Clamshell grab according to claim 4, characterized in that each support tube (7, 7 ¹ ) has a lever arm (8, 8 ¹ ), and that the drive device acts directly or indirectly on the lever arms. 6. A clamshell grab according to one of claims 1 to 5, characterized in that a hydraulic cylinder (3, 3·) is articulated to each grab shell (1, I ¹ ). 7. Two-shell grab according to claim 6, characterized in that the hydraulic cylinders (3, 3') are articulated with the piston rod (9, 9') on the grab shell (1, 1') and with the cylinder (10, 10·) on the carrier device (2). 8. Clamshell grab according to claim 6, characterized in that the hydraulic cylinders (3, 3 ¹ ) are each articulated with the piston rod (9, 9·) to the carrier device (2) and with the cylinder (10, 10*) to the grab shell (1, 1'). 9. Two-shell grab according to one of claims 1 to 5, characterized in that a hydraulic cylinder (21) is arranged centrally on the carrier device (2), the movable element of which is connected to a grab shell (1, 1') via an articulated arm (22, 22').