FIELD OF THE INVENTION

This invention relates to an integral hoisting cable arrangement for a shaft maintenance device, and in particular to a hoisting cable arrangement for use during construction that not only is able to support the maintenance device within the shaft but that also integrally includes data and power conductors for use by the shaft maintenance device.

BACKGROUND OF THE INVENTION

Depending on the nature of the surrounding ground, it may be necessary to conduct maintenance on the side wall defining a drilled shaft, such as reinforcing the side wall or inserting supporting rock bolts into the side wall. One way of achieving this, as disclosed in applicant's co-pending South African patent application no. 2008/08935, is to lower a shaft maintenance device in the form of a robot into the shaft. However, such a robot requires numerous separate cables to be provided, for example, a hoisting cable, a network cable and a power conducting cable. Such an arrangement is, however, complicated, and thus it is an aim of the present invention to provide an integral hoisting cable arrangement that combines a number of these functionalities into one. SUMMARY OF THE INVENTION

According to the invention there is provided an integral hoisting cable arrangement for a shaft maintenance device, the cable arrangement having a first end that is connectable to the shaft maintenance device and a second end that is connectable to a hoist drum to enable the cable, and thus the shaft maintenance device, to be raised out of and lowered into a drilled shaft as needed, the cable arrangement integrally comprising at least: a support cable to support the shaft maintenance device; a data network cable to facilitate communications between the shaft maintenance device and a remote control station; and a power conducting cable to conduct electrical power to the shaft maintenance device.

In an embodiment, the hoist drum is mounted to an overhead gantry. In an embodiment, the shaft maintenance device comprises: a support frame having a central hub to which the first end of the cable arrangement is connected; and a carrier arm for supporting an apparatus for conducting maintenance on a side wall defining the drilled shaft, the carrier arm being rotatably mounted to the support frame; a controller for accumulating and transmitting data regarding the device to the remote control station via the cable arrangement, and for receiving operating instructions from the remote control station for controlling at least the carrier arm; and actuating means in communication with the controller, for controlling at least the carrier arm.

In an embodiment, a slip ring arrangement is fitted adjacent the hoist drum, to enable the cable arrangement to extend to the remote control station. Typically, the apparatus for conducting maintenance on the side wall is selected from a group comprising; a bolter for fitting an anchor bolt into the side wall; a mesher for placing a mesh on the side wall; and a reinforcing device for spraying a reinforcing substance onto the side wall.

BRIEF DESCRIPTION OF THE DRAWINGS

Figure 1 shows a schematic side view of a cable arrangement according to an example embodiment; and

Figure 2 shows a detailed cross-sectional view of the cable arrangement shown in Figure 1. DESCRIPTION OF PREFERRED EMBODIMENTS

Referring first to Figure 1 , an integral hoisting cable arrangement 10 for a shaft maintenance device 12 is provided. The cable arrangement 10 defines a first end 14 that is connectable to the shaft maintenance device 12 via a load cell 16, and a second end 18 that is connectable to a motorized hoist drum 20. The hoist drum 20 enables the cable arrangement 10, and thus the shaft maintenance device 12, to be raised out of and lowered into a drilled shaft 22 as needed.

Turning now also to Figure 2, the cable arrangement 10 integrally comprises at least a support cable 24 component to support the weight of the shaft maintenance device 12, a data network or optical fibre cable 26 to facilitate communications between the shaft maintenance device 12 and a remote control station 28, and a power conducting cable 30 to conduct electrical power to the shaft maintenance device 12. The remote control station 28 thus receives data from a controller fitted to the shaft maintenance device 12, and also generates and transmits operating instructions to the device 12. In an embodiment, the remote control station 28 is located on ground level, proximate an opening 32 to the drilled shaft 22. In an example embodiment, the controller of the device 12 accumulates and transmits the following operational data: the thickness of the shaft-defining wall, and video data recorded by a camera fitted to the device 12. In an example embodiment, the operating instructions include instructions for controlling various actuating arrangements on the device 12, as will be described in more detail further on in the specification.

In an embodiment, the hoist drum 20 is mounted to an overhead gantry 34. The shaft maintenance device 12 typically comprises a support housing 36 supported by the first end 14 of the cable arrangement 10 (via the load cell 16). The support housing 36 is positioned within the drilled shaft 22 using a plurality of actuable arms 38 that terminate in rollers 40.

The device 12 further comprises a carrier arm 42 for supporting an apparatus 44 for conducting maintenance on a side wall 46 defining the drilled shaft 20. As mentioned above, the device 12 comprises a controller for accumulating and transmitting data regarding the device 12 to the remote control station 28 via the cable arrangement 10, and for receiving operating instructions from the remote control station 28 for controlling at least the carrier arm 42. As also mentioned above, the device 12 further comprises various actuating arrangements in communication with the controller, for controlling at least the arms 38 and the carrier arm 42. A power plant 43 comprising a motor and a compressor are advantageously also carried by the support housing 36 for powering the various hydraulic actuators on the device 12.

Referring back to Figure 1 , a slip ring arrangement is fitted adjacent the hoist drum 20, to enable the cable arrangement 10 to extend to the remote control station 28, as indicated by portion 10.1 . As is well known in the art, the slip ring arrangement provides an electrical connection and allows data communication between the rotating hoist drum 20 and the stationary portion 10.1 . In one version, the apparatus 44 for conducting maintenance on the side wall 46 comprises a reinforcing device 48 for spraying a reinforcing substance onto the side wall 46, preferably using slip forming. In an embodiment, the reinforcing device 48 comprises a spray nozzle that can be fitted to a conduit 50 for conveying the reinforcing substance from a storage drum 52 accommodated by the support housing 36. The arrangement shown in Figure 1 is for applying wet concrete, and so a vibration screen 54 and a concrete pump 56 would typically also be provided between the drum 52 and the conduit 50. For dry concrete as the reinforcing substance, the support housing 36 would typically accommodate a pressure vessel arranged to dispense the dry concrete, which would then be wetted just prior to being sprayed by a nozzle.

In other versions, the apparatus 38 for conducting maintenance on the side wall may comprise a bolter for fitting an anchor bolt into the side wall or a mesher for placing a mesh on the side wall.

It is envisaged that owing to the simple and neat setup provided by the present invention, a plurality of apparatuses may be suspended in the opening 30 simultaneously, thus greatly reducing the time spent on a particular project.