Fluid-actuated clamping apparatus and circuit

In a load-clamping apparatus including a pair of opposed, relatively movable clamping arms which are movable relatively toward one another in a clamping mode to clamp onto a load, and relatively away from one another in a releasing mode to release a load,

• a pair of double-acting fluid-operated motors, one for each arm, operatively connected to the arms for moving the same in said two operating modes,
• conduit means for supplying pressure fluid to and exhausting it from said motors, and
• changeable-condition fluid-flow-directing means operatively interposed between said motors and said conduit means for directing fluid flow therebetween during operation of said motors in said clamping and releasing modes,
• said fluid-flow-directing means including means responsive, during said clamping mode, to the difference in pressure between a pair of spaced points in said conduit means to place said motors in a series-connected condition with such pressure difference below a certain level, and in a parallel-connected condition with the pressure difference above another level which is greater than said certain level.

In a load-clamping apparatus including a pair of opposed clamping arms which are movable toward and away from each other for clamping against and releasing a load,

• a pair of double-acting fluid-operated motors for moving the arms, each motor being operatively connected to a different one of the arms,
• conduit means for supplying pressure fluid to and exhausting it from said motors, and
• valving means operatively interconnecting said motors and said conduit means for directing fluid flow therebetween,
• said valving means including sensing means for sensing the difference in pressure at a pair of spaced-apart points in said conduit means, said sensing means effecting operation of said valving means to place said motors effectively in a series-connected condition with the sensed pressure difference being below a certain level, and effecting operation of the valving means to place the motors effectively in a parallel-connected condition with the sensed pressure difference being above another level which is greater than said certain level.