Machine element or mechanism – Control lever and linkage systems – Hand operated
Reexamination Certificate
1999-10-22
2001-07-31
Wright, Dirk (Department: 3681)
Machine element or mechanism
Control lever and linkage systems
Hand operated
C172S439000
Reexamination Certificate
active
06267023
ABSTRACT:
CROSS-REFERENCE TO RELATED APPLICATIONS
This application claims priority upon German application 198 49 070.4 filed Oct. 24, 1998, which is incorporated herein by reference.
BACKGROUND OF THE INVENTION
The invention relates to a lower steering arm assembly for an implement attaching device. The assembly includes a strut pivotably attachable to a tractor or a self-driving working machine. An attaching end is removably fixed to the free end of the strut. The attaching end provides a connection with an implement.
EP0 608 750 A1 describes a lower steering arm assembly for a three-point attaching device of a tractor. A forged strut, at one end, has a ball eye to be connected to a pivot pin at the rear of the tractor. The strut has a rectangular cross-section and is stepped. Near its free end, the strut is forged to be U-shaped. A cover is welded to the arms of the U-shaped portion forming a closed chamber. The forged web of the strut has a formed-in pocket. A blocking pawl is pivotably arranged around a pin connection in the pocket. The blocking pawl is spring loaded into the blocking position where it is pivoted out of the chamber. Two further pins are provided at a distance from the pivot pins. One of the pins is guided outwardly through an opening in one of the arms of the U-shaped portion. A knob is on the end of the pin to enable manual manipulation of the pawl. Thus, it is possible to move the blocking pawl, loaded by the spring, into a position which is withdrawn into the pocket. A stop face is provided at the end of the chamber of the forged strut. An insertable end is inserted into the chamber. The end has a substantially rectangular cross-section. A recess extends through the entire side face of its shank. The end has a supporting face for the locking face of the blocking pawl. The supporting face extends substantially transversely to the longitudinal axis of the insertable end. The end face of the insertable end comes to rest against the stop face of the chamber. At its end projecting from the chamber, the insertable end has a ball eye. The ball eye provides a connection with a corresponding attaching pin of the implement. After the blocking pawl has been retracted, the insertable end may at least be partially extracted from the chamber to facilitate the coupling operation. The setting recesses in the shank enable angular adjustment relative to the strut remaining at the tractor in order to facilitate the coupling operation. By reversing the tractor, the insertable end can be driven into the chamber. As this occurs, the blocking pawl, after the end face of the shank of the insertable end has stopped against the stop face of the chamber, drops into the recess in the side face of the shank.
The stop face at the end of the U-shaped recess of the strut must be machined to be able to observe the tolerances required for accurate locking. The stop face is adapted to the distance between the end face of the shank of the insertable end and the blocking face of the recess, and also to the locking face of the blocking pawl. In practice, close tolerances cannot be observed because subsequent machining, when the cover has already been associated with the U-shaped region, is not possible. This design makes it necessary for the entire strut to be forged, which, in turn, means high costs.
Furthermore, since the blocking pawl is supported by a journal, a great deal of machining is required. Finally, the actuating knob has to be associated with different parts, depending on whether it is used for the left-hand or right-hand steering arm. In addition, due to the direction of the force acting on the actuating knob, remote actuation, by a cable operated from the tractor seat, is not possible.
SUMMARY OF THE INVENTION
It is an object of the present invention to provide a lower steering arm assembly with an actuator for the locking mechanism between the attaching end and the strut. The actuator is suitable for a right-hand and a left-hand lower steering arm without modification.
In accordance with the invention, a lower steering arm assembly includes a strut and an attaching end. The strut constitutes one component and the attaching end a further component. One of the components includes a blocking pawl. With the help of an actuator, the blocking pawl is pivotable between a locked position and an open position. In the locked position, the blocking pawl engages a recess of the other component. In the open position, the blocking pawl is disengaged from the recess. The blocking pawl is loaded by a spring to assume the locked position. The actuator includes an actuating lever. The lever is pivotable around a pivot axis and includes at least one actuating arm which extends radially from the pivot axis. The actuator includes a setting contour on which the actuating arm is at least partially supported. The contour includes an indentation with a base. Setting faces risingly extend in opposing directions of the actuating lever in the supporting region. A connecting element connects the actuating lever with the blocking pawl at a distance from the pivot axis of the blocking pawl.
The setting contour is of a symmetric design. Accordingly, when the actuating arm moves in one of the pivoting directions, whether it is a right-hand or left-hand steering arm, a displacement takes place which is followed, in the opening sense, by the blocking pawl articulating at the actuating lever via the connecting element. Thus, it is possible to associate the actuating arm with a towing element which can be gripped and actuated from the tractor seat. Thus, an unlocking operation can be carried out when depositing or uncoupling the implement. To facilitate the uncoupling operation, the connecting ball joint eye, at the attaching end, is able to carry out vertical movements relative to the strut. In this way, distortion cannot occur. The ball joint eye and the attaching end are load-free so that the operative is able to unfasten the connection between the attaching end and the implement without having to apply any force.
In a preferred embodiment, the connecting element is in the form of a tow bar. The actuating lever is pivotally arranged on the tow bar. The longitudinal axis of the tow bar forms the axis of rotation of the actuating lever. The actuating lever, in at least one direction of the longitudinal axis which corresponds to the direction of movement of the tow bar into the open position, is firmly supported on the tow bar.
Particularly advantageous actuating conditions are obtained if two actuating levers are provided. The levers extend diametrically from the pivot axis of the actuating lever. Both levers are associated with a setting contour. This results in the connecting element being symmetrically loaded. The load on the guiding means for the connecting element is reduced. Accordingly, canting or jamming cannot occur. In a further embodiment of the invention, the blocking pawl is additionally secured by a pre-tensioned spring. The spring holds the blocking pawl in the recess. The actuating lever is associated with at least one securing arm. The securing arm is arranged to be circumferentially offset relative to the actuating arm. Thus, when the actuating arm is in the locked position, the securing arm is in contact with the base of the setting contour. Also, the securing arm is covered by a fixed securing projection which prevents the blocking pawl from being displaced into the open position.
To achieve symmetric loading, two securing arms are provided. The securing arms extend diametrically away from the pivot axis. An advantageous assembly is obtained if the recess of the strut and the blocking pawl, the actuating lever, the connecting element and the setting contour are associated with the attaching end which can be plugged onto the second end of the strut. In this case, the blocking pawl is received in a pocket of the attaching end. The connecting element, in the form of a tow bar, is guided outwardly and, on its outside, rotatably carries the actuating lever.
To secure the blocking pawl in the locked posi
GKN Walterscheid GmbH
Harness & Dickey & Pierce P.L.C.
Wright Dirk
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