Material or article handling – Vertically swinging load support – Shovel or fork type
Reexamination Certificate
2000-07-06
2001-10-30
Underwood, Donald W. (Department: 3652)
Material or article handling
Vertically swinging load support
Shovel or fork type
C414S697000
Reexamination Certificate
active
06309171
ABSTRACT:
The invention relates to a mobile loading machine with front-end loading equipment, in particular a construction machine, having a lifting frame which is rotatably mounted by the rear end on a front frame part of the loading machine in a lifting-frame pivot point and which can be raised and lowered by means of at least one lifting cylinder, a working shovel, fork or the like being coupled to the front end of the lifting frame in a shovel pivot point, and a tipping lever being coupled in a central region of the lifting frame in a tipping-lever pivot point, the lower end of which lever is connected in a tipping-cylinder coupling point in an articulated manner to a tipping cylinder, which is coupled at the other end in a tipping-cylinder pivot point to the frame part, and whose upper end is coupled in a tipping-rod pivot point to a tipping rod which is coupled by its other end to the working shovel in a tipping-rod coupling point above the shovel pivot point.
In the case of wheel loaders essentially two areas of use are distinguished, namely earth moving and industrial use. The so-called Z-kinematics is widespread for the first-mentioned application. The Z-kinematics carries out the requirements of earth moving in an advantageous manner, since it has large tear-out forces within the range of the lower lifting-frame position, and the shovel tips back while being raised in order to avoid losses of material during transportation, and it has sufficient holding forces within the upper lifting range while the shovel is being tipped out. However, the profile of the holding force above the shovel angle in the upper position of the lifting frame is such that it reaches the minimum value of the holding force in the furthest forward position of the center of gravity of the shovel. That this holding force is nevertheless sufficient in this position is based on the fact that in this position a large part of the material has already fallen out of the shovel, so that the load has been greatly reduced as a result. This fact makes this system unsuitable for industrial use, since in this case the goods being transferred, such as pipes, tree trunks etc., have to be secured until the largest tipping-out angle is reached or, when picking them up from a stack, have to be tipped back for transfer into the transportation position. A further disadvantage of the Z-kinematics is the profile of the angular speed of the working implement in the upper positional range of the lifting frame. The speed sharply decreases in the region of large tipping-out angles and, as a result, knocking out of material residues adhering in the shovel is possible only to a limited extent.
A further feature of the Z-kinematics is that the tear-out force, which is configured to meet the requirements of removing material, has its highest value within the range of a horizontal shovel (ground) position, but sharply decreases with an increasing tipping angle. The tear-out force in the maximum tipping angle has fallen so far, in the shovel lifting height which is customary for transportation, that in the event of sharp braking deceleration actions and/or in the event of very uneven terrain, the shovel can no longer be pressed on with the necessary force, which causes sharp impacts associated with a corresponding production of noise.
For industrial purposes a parallel kinematics is generally used. A parallel kinematics of this type enables the shovel to be guided parallel via the lifting movement of the lifting frame, and also there is a more favorable profile of the holding forces within the upper lifting-frame region during the tipping-out process. There is also a continuous increase in the angular speed even within the last angular range during the tipping-out process, which makes it possible to beat out material adhering in the shovel. A disadvantage of this system is that for removing the material the tipping cylinder or tipping cylinders is/are only subjected to hydraulic pressure over their annular surface, and so these surfaces have to have appropriately large dimensions.
A further disadvantage of the parallel kinematics is that the tipping cylinders have to be arranged on the front frame of the loader at a considerable distance above the coupling point of the lifting frame, which produces a pillar-like construction of the front frame which impairs the view of the working implement.
These reasons have led, among other things, to the development of dedicated kinematic systems for industrial use, the said systems being based on the Z-kinematics, because of the prevailing advantages with it, but eliminating, by means of further elements, the shortcomings in the upper lifting-frame position in the case of the tipping-out process described. This is predominantly done by attaching an additional four-bar linkage between the links forming the characteristic Z and the working implement. The required holding force can therefore be achieved over the entire angular range of the working implement. When the lift-truck fork is used, industrial use requires it to be largely raised parallel, while in the case of use with a shovel or clamp, tipping back is advantageous in order to bring the center of gravity of the load closer to the vehicle. Since these contradictory requirements cannot be implemented without further precautions, a compromise has to be made when designing a system of this type. Skillful configuring of the kinematic system makes it possible, with the initially horizontal lift-truck fork pulled back only moderately, for the shovel or clamp which is entirely tipped back to be pulled back more strongly in the manner sought during the lifting process. The possibilities produced by the additional number of links in the kinematic linkage permit a far-reaching solution which meets the requirements of the particular use, if with certain trade-offs. Systems having two tipping mechanisms are also opposed here to those having just one tipping mechanism. The first-mentioned systems have the disadvantage that their elements are situated above the lifting-frame front faces and largely conceal the driver's view of the lateral ends of the goods being transported in industrial use. Therefore, solutions are move favorable which have only a centrally arranged tipping mechanism which leaves open the view of the ends of the loaded goods. However, because of their additional elements, these kinematic systems are more complicated and, since they are arranged in the front lifting-frame region, reduce the tipping load and therefore also the permissible loading capacity.
GB 2,266,291 A discloses a loading machine of the generic type with front-end loading equipment, which in principle consists only of a three-part kinematic linkage, namely a tipping cylinder, a tipping lever and a tipping rod, it being possible for the tipping cylinder to be fastened to the tipping lever in different positions, so that different kinematic geometries can be realized in order to be able to satisfy different requirements. However, it has turned out in practice that this known kinematics is still in need of substantial improvement.
The object of the invention is to further improve the kinematic system of a loading machine according to the generic type in order to combine all of the advantageous characteristics of the Z-kinematics, the parallel kinematics and the industrial kinematics in one system and to avoid the disadvantages thereof, the intention being that the complexity and therefore the costs do not exceed those of a conventional Z-kinematics.
According to the invention, this object is achieved with a mobile loading machine of the type described at the beginning by the following geometrical ratios being provided, in each case based on the length l of the lifting frame:
lifting-frame length l
1
between the tipping-lever pivot point and shovel pivot point: l
1
/l=0.25 to 0.4,
distance a from the tipping-lever pivot point to the tipping-rod pivot point: a/l=0.3 to 0.35,
distance b from the tipping-lever coupling point to the tipping-lever pivot point:
Arck Heinrich
Höllwart Robert
Leidinger Gustav
O&K Orenstein & Koppel Aktiengesellschaft
Rosenman & Colin LLP
Underwood Donald W.
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