A continuous substrate and a continuous absorptive sheet are fed to a press station, and pressed continuously or intermittently. The differential includes a gear assembly connected to the outputs and one or more hydraulically-actuated clutches for selectively and variably coupling the outputs. Pressurized fluid is introduced into the first annular passage and a first restricted annular orifice leads from the first annular passage to the third annular passage. The lower end of the tubular receiving member is adapted to be mounted in the ground.