A switching valve includes a spool, a first cylinder port that communicates with the piston side chamber, a second cylinder port that communicates with the rod side chamber, a bridge passage having a first opening which is adjacent to the first cylinder port and a second opening which is adjacent to the second cylinder port, a regeneration passage formed in the spool to connect the second cylinder port communicating with the rod side chamber to the first cylinder port in accordance with a switching position of the spool, and a first communication port and a second communication port formed in the spool to communicate with the regeneration passage. The first communication port communicates with the second opening of the bridge passage, which is adjacent to the second cylinder port, and the second communication port communicates with the second cylinder port in accordance with the switching position of the spool.

A regeneration control hydraulic system for an excavator, including at least one hydraulic pump, an actuator, a regeneration oil path, and a regeneration cut-off oil path. The regeneration oil path is configured to send a return oil as a regeneration oil to a cavity having a negative pressure of the actuator. The regeneration oil path is provided with a regeneration valve and a first control valve. The first control valve is configured to control the regeneration oil to enter the cavity having the negative pressure of the actuator when a working device of the excavator retracts inwards, or to control the oil to be discharged from the actuator to the regeneration cut-off oil path when the working device swings outwards. The regeneration cut-off oil path is configured to send the regeneration oil passing through the regeneration valve or the oil discharged from the actuator to other destinations.

The invention relates to a timber handling vehicle (1) and a timber grip, wherein said timber handling vehicle includes a load compartment (2), a crane (3) a timber grip (4), a hydraulic cylinder (4c), a hydraulic system (11, 12), a pump (15), a tank (16), a control valve (18) with which a fluid flow set under a pump feed pressure (P) is directed to a plus side (15:1) via a first pipe (15A) respectively a minus side (15:2) via a second pipe (15B). For efficient timber handling, the hydraulic system (11, 12) includes a third pipe (15C), which results in a regenerative fluid flow from the minus side (15:2) to the plus side (15:1) of the hydraulic cylinder (4c), a valve means (21) in the second pipe (15B), which valve means (21) is configured to; drive in a first operating condition, where the valve means (21) is closed and fluid flow from the minus side (15:2) to the plus side (15:1) of the hydraulic cylinder is directed via said third pipe (15C), receive a pressure indication that indicates a pump feed pressure (P) on the plus side (15:1) of the hydraulic cylinder (4c), determine whether the pump feed pressure (P) exceeds a first operating condition threshold value (Z1) and, if so, drive in a second operating condition, where the valve means (21) is open, and fluid flow from the minus side (15:2) of the hydraulic cylinder (4c) is directed to the tank (16).

To make it possible to control supply, discharge, and recycled flow rates independently of each other for the boom cylinder in a construction machine comprising first and second boom spool valves respectively connected to first and second hydraulic pumps. When the boom cylinder is contracted, the first boom spool valve is configured to control the recycled flow rate from head side oil chamber to rod side oil chamber, the second boom spool valve is configured to control the discharge flow rate from head side oil chamber to oil tank, and both first and second boom spool valves are configured not to supply pressure oil from first and second hydraulic pumps to the boom cylinder.

A regeneration device includes: a regeneration valve that controls the flow rate of an operating fluid being drained from one port of a cylinder; a non-return valve that allows a regenerative flow of the operating fluid from the regeneration valve to the other port of the cylinder and blocks an opposite flow of the operating fluid; and an exhaust valve that controls the flow rate of the operating fluid output from the regeneration valve being drained to a tank. The regeneration valve controls the flow rate independently of the exhaust valve.

A hydraulic actuator includes a housing and with a chamber, which is arranged or formed in the housing and in which a piston is mounted movably and divides the chamber into a flexion chamber and an extension chamber. A channel for hydraulic fluid leads from the flexion chamber and the extension chamber into the housing in order to produce a fluidic connection between the flexion chamber and the extension chamber. At least one valve is arranged in the fluidic connection. The channels lead from the housing to a valve block in which the at least one valve is arranged and is fluidically coupled to the channels, and the valve block is connected to the housing.

A first fluid circuit is a fluid circuit of an air cylinder provided with an air cylinder with a first air chamber and a second air chamber that are defined by a piston; a switching valve that is switched between the drive step and return step of the piston; a first flow channel between the first air chamber and the switching valve; and a second flow channel between the second air chamber and the switching valve. Two speed control valves are provided in series in the second flow channel.

A first fluid circuit is a fluid circuit of an air cylinder provided with an air cylinder with a first air chamber and a second air chamber that are defined by a piston; a switching valve that is switched between the drive step and return step of the piston; a first flow channel between the first air chamber and the switching valve; and a second flow channel between the second air chamber and the switching valve. Two speed control valves are provided in series in the second flow channel.

A hydraulic actuator includes a housing and with a chamber, which is arranged or formed in the housing and in which a piston is mounted movably and divides the chamber into a flexion chamber and an extension chamber. A channel for hydraulic fluid leads from the flexion chamber and the extension chamber into the housing in order to produce a fluidic connection between the flexion chamber and the extension chamber. At least one valve is arranged in the fluidic connection. The channels lead from the housing to a valve block in which the at least one valve is arranged and is fluidically coupled to the channels, and the valve block is connected to the housing.

Provided are an apparatus and a method for controlling spool displacement of a construction machine, which are capable of improving regeneration efficiency of the construction machine, and improving a fuel efficiency characteristic of the construction machine by reducing pressure loss in the operating mode by adjusting the quantity of spool displacement in a regeneration mode when a current pressure of a main pump is less than a predetermined operating pressure, and determining whether the construction machine is in an operating mode or the regeneration mode in real time according to an operating angle of a joystick and the current pressure of the main pump when the current pressure of the main pump is greater than or equal to the predetermined operating pressure to variably change the quantity of spool displacement in the operating mode.