A prime mover and a plurality of hydraulic actuators, a hydraulic machine having a rotatable shaft in driven engagement with the prime mover and comprising working chambers, a hydraulic circuit between working chambers of the hydraulic machine and the hydraulic actuators, each working chamber of the hydraulic machine comprising a low-pressure and high-pressure valves regulating the flow of hydraulic fluid between the working chamber and a corresponding low-pressure manifold and a high-pressure manifold. The hydraulic machine being configured to actively control the low-pressure valves of the working chambers to select the net displacement of hydraulic fluid by each working chamber on each cycle of working chamber volume, and thereby the net displacement of hydraulic fluid by the working chambers, responsive to a demand signal, wherein the apparatus further comprises a controller configured to calculate the demand signal in response to a measured property of the hydraulic circuit or actuators.

A system for calibrating an electrohydraulic pump for a vehicle having a propel system that includes an engine connected to the electrohydraulic pump. A micro-controller having software and an input device is connected to a plurality of sensors mounted about the vehicle. The software uses a plurality of parameters to convert internal analog drive signals into analog output signals to control the electrohydraulic pump and motion of the machine where the parameters include a forward start current value and a reverse start current value.

A pump monitoring system may include a sensor for monitoring a parameter of a pump system. The sensor may include at least one of an ammeter in electrical communication with an electric motor driving a pump and a torque sensor on a drive shaft that drives a pump. The system may also include a controller in data communication with the sensor to receive sensor data. The controller may be configured to assess the performance of the respective pump in one or more ways. At least one of the one or more ways may include reliance on the sensor data from only one sensor to identify valve or seat wear or failure. Alternatively or additionally, at least one of the one or more ways may identify valve or seat wear or failure without reliance on pump output pressure.

A system and method for automatic selection and control of pumps for well stimulation operations is disclosed. In certain embodiments, a system may comprise a pumping system comprising one or more pumping units, a fluid manifold providing fluid communication between the one or more pumping units and a wellbore, and a controller for determining a torque capability of the one or more pumping units.

A prime mover and a plurality of hydraulic actuators, a hydraulic machine having a rotatable shaft in driven engagement with the prime mover and comprising a plurality of working chambers, a hydraulic circuit extending between working chambers of the hydraulic machine and the hydraulic actuators, each working chamber of the hydraulic machine comprising a low-pressure valve which regulates the flow of hydraulic fluid between the working chamber and a low-pressure manifold and a high-pressure valve which regulates the flow of hydraulic fluid between the working chamber and a high-pressure manifold. The hydraulic machine being configured to actively control at least the low-pressure valves of the working chambers to select the net displacement of hydraulic fluid by each working chamber on each cycle of working chamber volume, and thereby the net displacement of hydraulic fluid by the working chambers, responsive to a demand signal.

A hydraulic pressurizing medium supply assembly includes a hydro machine which has an adjustable swash plate. An angle of the swash plate is able to be adjusted by way of a pilot valve. The pilot valve is able to be adjusted by a control. When the pilot valve is actuated by a neutral current, a valve slide of the pilot valve assumes a central position in which the swash plate does not perform any movement. In order for the pilot valve to be controlled it is provided that the control emits a control variable. The control variable, at the outlet side of the control, is linked and adapted to a preliminary control variable for the neutral current, in order for the neutral current to be pre-controlled.

A prime mover and a plurality of hydraulic actuators, a hydraulic machine having a rotatable shaft in driven engagement with the prime mover and comprising a plurality of working chambers, a hydraulic circuit extending between working chambers of the hydraulic machine and the hydraulic actuators, each working chamber of the hydraulic machine comprising a low-pressure valve which regulates the flow of hydraulic fluid between the working chamber and a low-pressure manifold and a high-pressure valve which regulates the flow of hydraulic fluid between the working chamber and a high-pressure manifold. The hydraulic machine being configured to actively control at least the low-pressure valves of the working chambers to select the net displacement of hydraulic fluid by each working chamber on each cycle of working chamber volume, and thereby the net displacement of hydraulic fluid by the working chambers, responsive to a demand signal.

A prime mover and a plurality of hydraulic actuators, a hydraulic machine having a rotatable shaft in driven engagement with the prime mover and comprising working chambers, a hydraulic circuit between working chambers of the hydraulic machine and the hydraulic actuators, each working chamber of the hydraulic machine comprising a low-pressure and high-pressure valves regulating the flow of hydraulic fluid between the working chamber and a corresponding low-pressure manifold and a high-pressure manifold. The hydraulic machine being configured to actively control the low-pressure valves of the working chambers to select the net displacement of hydraulic fluid by each working chamber on each cycle of working chamber volume, and thereby the net displacement of hydraulic fluid by the working chambers, responsive to a demand signal, wherein the apparatus further comprises a controller configured to calculate the demand signal in response to a measured property of the hydraulic circuit or actuators.

A pump monitoring system may include a sensor for monitoring a parameter of a pump system. The sensor may include at least one of an ammeter in electrical communication with an electric motor driving a pump and a torque sensor on a drive shaft that drives a pump. The system may also include a controller in data communication with the sensor to receive sensor data. The controller may be configured to assess the performance of the respective pump in one or more ways. At least one of the one or more ways may include reliance on the sensor data from only one sensor to identify valve or seat wear or failure. Alternatively or additionally, at least one of the one or more ways may identify valve or seat wear or failure without reliance on pump output pressure.

A pump system may include a hybrid powertrain that includes a gaseous fuel engine, a transmission coupled to the gaseous fuel engine, a driveshaft coupled to the transmission, a hydraulic fracturing pump coupled to the driveshaft, and a motor system coupled to the hydraulic fracturing pump. The pump system may include a power source electrically connected to the motor system. The pump system may include a controller configured to determine a torque distribution between the gaseous fuel engine and the motor system based at least in part on whether a transient event is associated with the pump system, and cause the gaseous fuel engine and the motor system to operate according to the torque distribution such that the motor system assists or brakes the gaseous fuel engine in driving the hydraulic fracturing pump.