CONTROLLER FOR DRIVEN MACHINE DRIVEN BY PRIME MOVER

PURPOSE: To prevent excessive output of a secondary mover and failure of a prime mover such as a stop beforehand by providing an adjustment means for adjusting the secondary mover and a means for driving the adjustment means according to the AC signal with a frequency in proportion to the speed of the prime mover. CONSTITUTION: In an adjustment means 90, a piston 33 which is a swashplate urging mechanism is slideably inserted in a pipe 70. The piston 33 is driven by a control pressure Pc impressed via an annular groove 72 in a fixed cylinder 71 and a passage 73 in the pipe 70. The control pressure Pc is generated from a supply pressure Pi and an output pressure Pa in a limiting spool valve assembly 75 formed at one end of the fixed cylinder 71. The position of a spool 77 is determined by the balance between a limiting control pressure P1 and a force impressed to a core 82 via a solenoid 81. The solenoid 81 is energized by the AC driving current impressed to a motor. In this way, it is possible to prevent excessive output of the secondary mover and failure of the prime mover such as a stop beforehand.