Patent Application
20070063175
The present invention relates generally to theatrical rigging systems, and more particularly to rigging systems that utilize counterweights to raise and lower the load.
Most existing rigging systems use manually operated rigging sets (or “sets”), which are counterbalanced with weights for ease of operation. When loads (scenery, curtains, lighting equipment, etc.) are changed, the counterbalancing weights must be adjusted to properly balance the load. This normally happens when the load is at floor level and counterbalancing weights are substantially above the floor, making access difficult.
In their most basic form, conventional rigging sets, such as the one illustrated in
In addition, it is necessary to ensure that a rope lock 28 is engaged to prevent sudden movement of the control line and counterweights when the operator balances the load with the counterweights. If the rope lock 28 fails or is not engaged in the first place, the arbor will rise or fall at significant speed, inevitably causing serious injury and perhaps killing the operator. In addition, the amount to balance the load must be done perfectly in order to prevent the load from being moved too rapidly which in and of itself can cause injury or death to the operator and the people on the stage below the load.
Many of these rigging systems are used in middle school and high school theatres. There are concerns about the ability of the operators (frequently students) to properly balance the loads, and the requirement for the balancing work to be done at substantial heights.
One aspect of the invention contemplates a counterweight balanced rigging system for raising and lowering a load of predetermined weight, comprising a winch having a rating of at least one half the predetermined weight; an arbor having counterweights positioned thereon, wherein the weight of the counterweights is about one half of the predetermined weight; a first control line interconnecting the arbor to the load; and a second control line interconnected between the arbor and the first control line and positioned in movingly and lockingly engaged relation to the winch.
By eliminating the need to adjust counterbalancing weights on a regular basis, operational safety and convenience are improved.
In addition to being used as a retrofit device, this device can be used in new installations in conjunction with a fixed counterweight set.
The present invention will be more fully understood and appreciated by reading the following Detailed Descript no in conjunction with the accompanying drawings, in which:
Referring now to the drawings, wherein like reference numerals refer to like parts throughout, there is seen in
The present invention substitutes drive chain 106 and motor driven winch 104 for conventional control line 16, rope lock 28 and tensioning floor block 14. In addition, arbor 108 is initially loaded with a predetermined amount of weight equal to 50% of the counter weight system capacity, and does not need to be adjusted after it is fixed. Winch 104 is preferably rated at 50% of the counterweight system capacity, anywhere between 0% to 100% of the counterweight system rated capacity. Therefore, if batten 120 (and hence the load) needs to be raised or lowered, winch 104, in conjunction with the fixed counterweight, raise and lower a load anywhere between 0% to 100% of the counterweight system rated capacity without having to increase or decrease the amount of counterweights loaded on arbor 108.
With reference to
The motorized winch 104 could be located at any point along the drive chain 106, although it is preferred that it be located at or near the floor. Other positioning locations are, however, possible and well known to those skilled in the art.
In addition to the preferred embodiment disclosed herein, there are several other different approaches to how the winch drives the control line.
For example, on existing systems the control line (collectively, the drive chain 106 and rope 112 in the preferred embodiment) is a manila or synthetic rope, typically 3/4 diameter. A winch that could engage the rope in a manner that would provide a positive drive (no slipping) could be implemented using serpentine rollers or similar structure.
Alternatively, the control line could be replaced entirely with a roller chain, or other flexible medium with the ability to be positively driven. The challenge with this approach is that the head block and floor block of existing systems typically have grooves to accommodate 3/4″ diameter rope. Replacing the head block is labor intensive and expensive.
The motorized winch 104 would preferably include a motor, gear reducer, mechanism to drive the control line (serpentine rollers, sprocket wheel, etc.), a limit switch to control the limits of travel, a starter or variable speed drive, and a control system. The control system could be simple Up/Down pushbuttons or one of the programmable position controllers developed for use with the PowerLift™ rigging system manufactured and sold by J.R. Clancy, Inc. of Syracuse, N.Y. Other sensing and safety devices could be added.
To ensure the winch/system are not overloaded a method of ensuring weight cannot be added to or taken from the arbor must be included. The weights could be banded in place with steel strapping tape, and a filler installed on top of the weights to prevent the addition of more weights.
