Abstract: The present invention relates to a control apparatus for a construction machine such as a hydraulic shovel, and the control apparatus for a construction machine includes a revolving operation member for operating a construction machine revolving unit (14), a fluid pressure pump (2) and an accumulator (5) for accumulating working oil from the fluid pressure pump (2), a fluid pressure actuator (7) for driving the construction machine revolving unit (14) to revolve with the working oil from the fluid pressure pump (2) and the accumulator (5), a first control valve (8) interposed between the fluid pressure actuator (7) and the fluid pressure pump (2), a second control valve (11) for controlling an inflow condition of the fluid from the fluid pressure actuator (7) into the accumulator (5), and control means (9) including first valve control means (9a) for controlling the first control valve (8) and second valve control means (9b) for controlling the second control valve (11).

Abstract: The present invention pertains to an improvement for a tracking servo circuit which controls the tracking of an optical pickup on an optical disc in an apparatus for reproducing a sound or image recorded on the optical disc. The present invention is characterized by the provision of a circuit for detecting modulation of an RF signal from the optical pickup caused when the optical pickup encounters a defect such as a flaw in the disc or dust adhering thereon, a circuit for detecting modulation of the RF signal caused when an impact is externally applied to the optical pickup, and an adjusting circuit which decreases the loop gain of the tracking servo circuit when the former modulation is detected and which increases the loop gain when the latter modulation is detected, whereby the responsiveness of the optical pickup is improved and track jumping prevented.