Abstract: A hydraulic actuator is operated using a manual operation device, operations from the manual operation device are stored in the path of an operation signal to a valve controller and these are read out as required and operations similar to those from the manual operation device are outputted to the hydraulic actuator so that repeated operations of the hydraulic actuator are performed automatically. Further, a vibration signal to the hydraulic actuator is added to the operation by the manual operation device and outputted so that operation that is not accurately performed by manual operation is made possible. In the case where repeated operations are performed continuously, a correction operation by the manual operation device is taken into account so that a correction operation which is varied every given amount is made simple. Thus, the present invention can be used where the digging process of a construction machine is made deeper every given amount.

Abstract: An apparatus for controlling a variable displacement type hydraulic pump including an engine as a driving power source is disclosed. The subject invention detects the number of revolutions of the engine and the pressure of hydraulic oil delivered from the hydraulic pump, and sets a pump absorption torque characteristic which decreases in relation to the number of revolutions of the engine. The inclination angle of a swash plate in the pump is detected with reference to the pump absorption torque characteristic and the pressure of hydraulic oil delivered from the pump, and the swash plate in the pump can be controlled so as to assure its inclination angle; the number of revolutions of the engine can be reduced without the absorption torque of the hydraulic pump exceeding the allowable torque of the engine. When the controlled apparatus is utilized, the number of revolutions of the engine can be optimally reduced and fuel consumption cost reduced correspondingly.

Abstract: An automatic control system for a vehicle such as a fork lift truck automates the transportation, loading and unloading operations of the vehicle in a work area. Leader cables disposed in the work area are supplied with instruction signals of respectively different frequencies from terminal units in response to commands from a central control device. Any cable or a combination of two cables forms a ehicle guideway along which the travel of the vehicle is controlled by instruction signal pickup coils on the vehicle and along which loading and unloading stations for the vehicle are located. Loading and unloading are effected without using the leader cables, the necessary instruction signals then being received from the central control device by the vehicle from a coil disposed at the loading and unloading station.

Abstract: A vehicle is guided along a desired path forwardly and backwardly by electromagnetically detecting deflection and attitude angle of the vehicle with respect to a guidance cable carrying an alternating current and producing a magnetic field.The deflection of the vehicle thus detected is compared with a predetermined deflection value from the guidance cable to produce an attitude angle setting signal, which is subsequently compared with the detected attitude angle to produce a steering control signal according to which the vehicle is controlled to run a desired path.

Abstract: A steering control system of a type wherein an unmanned vehicle is transferred from one cable to another of two crossing cables by a programmed turning operation. According to the invention, a smooth transferring of the vehicle from the programmed turning to a guided travel along the other cable can be achieved. Conditions for the transferring of the vehicle are: (a) an output of a posture angle detection coil is within a predetermined low range, (b) the vehicle has moved by a predetermined distance after starting of the programmed turning and (c) the vehicle is not out of course, i.e. an output of a reference phase detection coil is greater than a preset value.

Abstract: A mathematical expression is converted and approximations applied to remove complex processes, simplifying the circuitry of system which controls compressor speed in dependence on ambient temperature.

Abstract: Fuel supply control means is operatively connected to an electromagnetic flow control valve applying thereto a fuel control signal for controlling fuel flow supplied through the electromagnetic flow control valve to the combustion chamber of a gas turbine engine. The control signal increases gradually or exponentially from a low value such as corresponds to fuel flow required at engine hot start to a high value corresponds to fuel flow required at engine cold start.

Abstract: A mathematical expression is converted and approximations applied to simplify same and thus circuitry which modifies an electrical signal representing a gas temperature into another one.