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Application |
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There are a variety of industrial applications where it is necessary for overhead cranes to position loads in areas that have very little clearance between stored materials or stationary machinery on the shop floor. Typical applications include warehouses or manufacturing staging areas. In these applications, the sudden starts or stops of the trolley or bridge will often cause the load to swing in an uncontrolled manner. Even with highly skilled crane operators it is not always possible to adequately limit load swing.
Problem |
Load swing can damage the load on the hook or loads already positioned on the floor. It can also damage surrounding equipment and reduce the duty cycle of the material handling operation. More importantly, swinging loads are often a safety hazard for plant personnel.
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Solution |
The traditional method for preventing load swing was accomplished by using either a special hoist reeving technique and/or by a load block retaining scheme. Although these mechanical methods can be effective they are relatively expensive and are a maintenance concern to crane owners.
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Crane with Anti-Swing Hoist Reeving
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Today's best solution is to use Electromotive Systems' Anti-Swing Control (ASC) on the bridge and trolley motions of the crane. When used in conjunction with an Electromotive Systems IMPULSE® Adjustable Frequency Drive (AFDs), the ASC prevents load swing while improving safety and reliability on each motion.
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Result |
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The amount of acceptable load swing is dependent upon the application requirements and operator preference. The Electromotive Systems ASC can virtually eliminate load swing by optimizing the acceleration and deceleration rates of the trolley and bridge motions. The following benefits are obtained by using the Electromotive Systems ASC system:
- Crane duty cycle is improved by permitting faster traveling speeds without the need to allow for settling time of a swinging load.
- Product and/or equipment damage is avoided in areas with reduced clearances.
- The potential for injury to operating personnel is greatly reduced by preventing uncontrolled swinging loads.
- Operator fatigue is also reduced by eliminating the stress related to numerous jogging and inching operations. This is especially the case for high duty cycle processes that involve reduced clearances. In such applications, the operator must be concerned with meeting production but, at the same time, try to avoid damaging product or equipment.
- Overall operator effectiveness and productivity is improved by eliminating differences between operator techniques in positioning loads.
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Technical Description |
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| The Electromotive Systems ASC consists of a stand-alone microprocessor-based controller operating sophisticated swing control software. The controller uses a key pad with a digital display for entering information about the dynamics of the mechanical system. Load height information is obtained via an encoder (or other device) which is sent to the input terminals of the ASC controller. The software then sends an optimized speed reference signal to the appropriate AFD (bridge or trolley motion) to prevent swing. |
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ASC Programmer
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