| 摘要 |
The disclosure involves a machine, e.g., a portal crane, having two components such as bridge support legs or rail-riding trucks. Each component is driven by a separate motor and each is moving at a speed, perhaps a different speed. A method for maintaining the speeds of the two components substantially equal to one another includes the steps of providing a differential signal representing a difference between the speeds of the two components and generating an equalizing signal reducing the speed of the higher-speed component. Preferably, a second equalizing signal is also generated to increase the speed of the lower-speed component. A new drive system is also disclosed. The method and system are particularly useful for maintaining the "squareness" of a double-leg portal crane.
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