Machine element or mechanism – Gearing – With brake means for gearing
Reexamination Certificate
1999-03-26
2001-03-13
Herrmann, Allan D. (Department: 3682)
Machine element or mechanism
Gearing
With brake means for gearing
C074S110000, C188S031000, C188S069000, C192S225000, C212S292000
Reexamination Certificate
active
06199442
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a slewing ring brake for use in heavy machinery including earthworking machinery. More particularly, the present invention relates to a brake for a slewing ring.
2. Description of Related Art
The use of a slewing ring in heavy machinery such as earthworking machinery is well known. In an excavator, for example, there is generally provided a fixed lower chassis and a rotatable upper chassis mounted in a rotary manner to the lower chassis. A circular track or a slewing ring having a tooth system on its outer circumference is generally fixedly attached to the lower chassis. The upper chassis generally includes gears which may be engaged with the tooth system and be rotationally actuated in order to allow rotation of the upper chassis with respect to the fixed lower chassis. This rotation may be actuated by a drive such as hydraulic motors. Thus, in order to rotate the upper chassis with respect to the lower chassis, it is only necessary for the drive to overcome the frictional torque and the moment of inertia of the mass. Therefore, it is relatively easy to rotate the upper chassis in this manner.
However, this relatively easily attained rotation of the upper chassis can cause serious problems in use of these heavy machineries such as earthworking machinery. For instance, if the upper chassis includes a fixed rotary drill for making a hole in the ground, a relatively high torque can act on the upper chassis during the drilling process. This high torque caused by drilling can cause an undesired rotation of the upper chassis with respect to the lower chassis. Of course, this can cause serious problems in safety and can significantly impair the accuracy of the drilled hole.
SUMMARY OF THE INVENTION
Therefore, the primary object of the present invention is to provide a slewing ring brake that will prevent undesired rotational movement between a slewing ring which may be mounted on a lower chassis and a support member which may be mounted on an upper chassis.
In accordance with one embodiment of the present invention, this object is achieved by a slewing ring brake having a slewing ring with a tooth system and a support member which is mounted in a manner to allow rotary movement of the support member relative to the slewing ring. In this embodiment, the slewing ring brake also includes a brake block displaceably mounted on the support member, the brake block being displaceable between a braking position and a freewheeling position. In the braking position, the brake block engages with the tooth system thereby preventing rotary movement of the support member relative to the slewing ring. In the freewheeling position, the brake block disengages the tooth system thereby allowing rotary movement of the support member relative to the slewing ring.
In the various embodiments of the present invention specifically illustrated, the brake block engages the tooth system of the slewing ring. As a result of this wedging action, rotary movement between the support member and the slewing ring is prevented. The brake block can be engaged with the tooth system on the slewing ring by radially displacement or even by axial displacement. In addition, whereas the described tooth system is normally an external tooth system, an internal tooth system is also possible on the circular slewing ring.
To prevent high stressing of a single tooth on the slewing ring and to ensure a durable slewing ring brake, the brake block in accordance with the present invention may be provided with several teeth constructed to mesh with the tooth system. The brake block is formed by a toothed section, which is shaped in correspondence to the tooth system on the slewing ring. For further relieving stresses in the individual teeth, there can also be several brake blocks which simultaneously engage the slewing ring.
It is fundamentally possible to operate the brake block manually, e.g. by means of a screw spindle. However, in accordance with a preferred embodiment of the present invention, a power operated driving unit is provided for displacing the brake block between the braking position and the freewheeling position. For instance, a linear displacement of the brake block can be attained by using an electric motor with a screw spindle or a recirculating ball screw. In accordance with the present illustrated embodiments, a simple driving unit can be comprised of a pressure cylinder with a displaceable piston rod connected to the brake block which displaces the brake block between the brake position and the freewheeling position.
In accordance with another embodiment of the present invention, the power operated driving unit includes at least one pressure cylinder and a transmission device for displacing the brake block in a radial direction substantially radial to the slewing ring. The transmission device converts a tangential displacement motion generated by the pressure cylinder which is substantially tangential to the slewing ring into a radial displacement motion substantially radial to the slewing ring. By having the displacement direction of the brake block at an angle of approximately
90
° to the displacement motion of the pressure cylinder, a very robust construction of the slewing ring brake is attained through which a reliable braking is ensured, even in application of high torques.
In accordance with one embodiment of the present invention, the transmission device for the displacement of the brake block includes a toggle lever mechanism.
In an alternative embodiment, the transmission device includes a sliding wedge mechanism. In this embodiment, especially high forces can be applied to the slewing ring brake since there are no pivot pins or pivot bearings.
According to another embodiment of the present invention, a measuring device for sending rotary movement between the slewing ring and the support member may also be provided. The measuring device may be connected to a control unit through which the displacement of the brake block into the braking position may be prevented when rotary movement is sensed. This ensures that the brake is not operated during rotary movement between the slewing ring and the support member which could damage the tooth system of the slewing ring and the teeth of the brake block. Of course, the measuring device for monitoring rotary movement, particularly monitoring upper chassis rotation, can be located at any appropriate point including the illustrated position or alternatively, on the drive motor, on the transmission or on transmission shafts.
In accordance with the preferred embodiment of the present invention, the measuring device includes a rotatable measuring gear which meshes with the tooth system of the slewing ring and also includes a sensor for sensing rotation of the measuring gear. The sensor may be housed at a protected position at a distance from the slewing ring and may be an incremental encoder or transducer which can emit a pulse indicative of rotary motion on passing of the individual teeth of the measuring gear or a separate measuring disk. This particular embodiment provides a compact arrangement which is relatively simple to implement.
The slewing ring brake in accordance with the present invention is particularly useful in earthworking machinery applications. The slewing ring brake may be located on one of either a first chassis or a second chassis which are mounted in a manner to allow rotary movement between the two chassis. The slewing ring would be provided on the other chassis. For instance, the slewing ring brake may be provided on the upper chassis which houses a drill and be operated to prevent undesired rotation of the upper chassis with respect to the lower chassis during drilling.
These and other objects, features and advantages of the present invention will become more apparent form the following detailed description of the invention when viewed in conjunction with the accompanying drawings.
REFERENCES:
patent: 1210288 (1916-12-01), Farr
patent: 2817418 (1957-12-01), V
Bauer Sebastian
Harthauser Werner
Bauer Spezialtiefbau GmbH
Herrmann Allan D.
Nixon & Peabody LLP
Studebaker Donald R.
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