A refuse collection vehicle has various hydraulic actuators including at least one cylinder with an internal seal. A sensor is responsive to movement of the piston and sends a signal to a controller to indicate piston movement information during an associated vehicle body component movement. The controller is configured to determine a motion characteristic of the piston during a predetermined body component movement, compare the determined motion characteristic to a stored reference motion characteristic, and in response to determining that a difference between the determined motion characteristic and the reference motion characteristic is greater than a predetermined value, trigger an indication that the refuse collection vehicle is in need of service.

A fluid actuator arrangement comprises a piston rod member, at least two cylinders each said cylinder having a piston body, and a clamping mechanism associated to each cylinder. Each clamping mechanism is arranged to engage and disengage the piston body of the cylinder to the piston rod member. The fluid actuator arrangement comprises further a control element arranged to control a back and forward movement of the respective piston body so that forward movement is slower than the backward movement and to control the movement of the respective piston bodies in relation to each other such that at least one piston body is always moving forward and such that an overlap exists wherein at least two of the piston bodies are moving forward simultaneously during a cycle.

An actuator system includes a piston-cylinder arrangement including a piston that is movable with respect to a cylinder. A first flow path is in fluid communication with the piston-cylinder arrangement and a second flow path is in fluid communication with the piston-cylinder arrangement. A control system is operable to fluidly connect the first flow path to a source of high-pressure fluid and to connect the second flow path to a drain to move the piston in a first direction. A pressure sensor is fluidly connected to the first flow path and is operable to measure sufficient pressure data during the movement of the piston to generate a pressure versus time curve. The control system is operable to compare the generated pressure versus time curve to a known standard pressure versus time curve stored in the control system to determine the condition of the piston-cylinder arrangement.

A milling machine may have a frame, a milling drum attached to the frame, and ground engaging tracks that support the frame and propel the milling machine in a forward or rearward direction. The milling machine may have height adjustable actuators connecting the frame to the tracks. Each actuator may have a cylinder attached to the frame, a piston slidably disposed within the cylinder, and a rod connected at a first end to the piston and connected to a track at a second end. The milling machine may have a tank storing hydraulic fluid and a fluid conduit connecting the tank to the cylinder. The milling machine may have a control valve selectively controlling a flow rate of the hydraulic fluid in the fluid conduit. The milling machine may also have a controller that determines a height of the frame relative to the ground surface based on the flow rate.

A milling machine may have a frame, a milling drum attached to the frame, and ground engaging tracks that support the frame and propel the milling machine in a forward or rearward direction. The milling machine may have a tank that stores hydraulic fluid. The milling machine may also have at least one actuator connecting the frame to the tracks. The actuator may adjust a height of the frame relative to a ground surface. A fluid conduit may connect the tank to the actuator. The milling machine may have a flow sensor in the fluid conduit. The flow sensor may determine a flow parameter associated with a flow of the hydraulic fluid into or out of the actuator. The milling machine may also have a controller that determines a height of the frame relative to the ground surface based on the flow parameter.

The present invention makes a rotary movement smooth, the rotary movement allowing direct detection of the movement of an output member of a rotary clamp. In a clamp, an output member is accommodated in a cylinder hole. A first valve chamber, to which compressed air is supplied, is provided between a lower wall of a housing and the output member. A second valve chamber is a hollowed out portion of the output member so as to be provided open toward the first valve chamber. A valve rod is inserted into the second valve chamber from the lower wall. A valve rod passage that allows the second valve chamber to communicate with outside air is provided in the valve rod, and a seal section is provided in a peripheral gap where the valve rod and the second valve chamber move relatively to one another. The gap is formed so that, as the valve rod and the second valve chamber are in relative movement, there is a region which is sealed by the seal section against movement of the compressed air through the gap between the valve rod and the second seal chamber and the there is a region which is open from the seal.

An actuator-operation detecting apparatus is configured to check the operating state of a piston of an actuator. The actuator includes a double-acting cylinder, the piston that partitions the cylinder into a first pressure acting chamber and a second pressure acting chamber, and a rod connected to an end face of the piston facing the second pressure acting chamber. The actuator-operation detecting apparatus includes a first pressure detector to detect the pressure in the first pressure acting chamber, a second pressure detector to detect the pressure in the second pressure acting chamber, a differential amplifier circuit to calculate a thrust force acting on the piston based on the pressures detected by the first and second pressure detectors and the pressure-receiving area of the piston, and a microcomputer to monitor the operation of the piston based on the thrust force.

One object is to calculate the position of a rod of a linear actuator with a high precision. The linear actuator includes a rod capable of moving in an axial direction relative to a housing. The rod is moved by rotation of an output shaft of a motor. A position sensor for sensing the relative position of the rod relative to a preset reference position is provided in the housing. A rotation sensor for sensing the rotation angle of the output shaft of the motor is provided in the vicinity of the motor. The linear actuator includes a position calculating unit for calculating the position of the rod based on a position sensing value of the position sensor and a rotation angle sensing value of the rotation sensor.

A hydraulic forceps system includes: robotic forceps including: a gripper, first piston coupled to the gripper, first cylinder forming first pressure chamber, filled with a hydraulic fluid, together with the first piston, second piston, second cylinder forming a second pressure chamber, filled with hydraulic fluid, together with the second piston, communication passage through which the chambers communicate, motor that drives the second piston via a linear motion mechanism; control device that controls the motor based on a command position for the first piston; and position sensor used for detecting a position of the second piston. The control device includes: an observer that derives an estimated position of the first piston based on the position of the second detected by the sensor; and a position controller that derives a target rotational speed of the motor based on a deviation between the estimated position of the first piston and the command position.

A method for operating a valve device for supplying compressed air to compressed air consumer includes the steps of: determination of a first fluid pressure in a first section of a fluid passage of a valve assembly, which extends between an inlet port, and a valve element, determination of a second fluid pressure in a second section of the fluid passage of the valve assembly, which extends between the valve element and an outlet port, determination of a flow value for the valve element from the two fluid pressures and of a flow function, relating of the flow value with a presettable volumetric fluid flow rate or mass fluid flow rate for the pressurised fluid, which flow rate is provided for flow through the fluid passage, to a guide value and determination of a required actuating energy for an actuating device, and provision of the actuating energy to the actuating device.