Abstract: The invention relates to cranes or the like in which two hoist lines control a clamshell bucket. If the winch for one line is operated to draw in this line, it closes the clamshell bucket and hoists it. During this hoisting, the winch for the other line must also be operated to pull in the slack. If this other line is reeled in excessively, it will dump the bucket. A system is provided for automatic control of the winch being used for slack-takeup, thus avoiding the need for great care and delicate finesse by an experienced hand on a second control lever. The system puts the slack-takeup winch in hydraulic series or tandem with the discharge from the hoisting winch, but limits the hydraulic pressure supplied to the slack-takeup winch so that it is barely enough to accomplish the takeup of its line, and cannot cause dumping.