An integrated power drive system (136,236,336 for a big square baler (28), 36,436) slip clutch (154,254,354,454) system is used to control a devolution of authority from a tractor (26) to baling press (28). Clutch (254) system includes a slip clutch (154,254,354,454) with some clutch plates (388). Slip clutch (154,254,354,454) is movable between a kind of relationship of release, it is transferred without power from a power drive system (136,236,336,36,436) to a gearbox (140,240,340,40,440) relationships engaged with one or more, wherein from power drive system (136,236,336,36,436) gearbox (140,240,340 is arrived, 40,440), the amount of power is transferred. What the movement (for example, by centrifugal force) of the slip clutch (154,254,354,454) between engagement relationship or electronically can be mechanically controlled. For being controlled electronically, one controller receives input data from the sensor (504) of the operation about baling press (28), control first valve arrives or from a clutch cylinder (276,376,476) or a double acting cylinder (496) introduces or removes hydraulic fluid, and basis makes the hydraulic pressure controlling profile for having inclined-plane to realize engagement relationship by level.
