A method for operating a pressure control system in a vehicle includes controlling a flow-control valve in a charging line, which conveys a charging pressure medium, in dependence upon an admission pressure and/or upon an admission volume flow. The admission pressure and/or the admission volume flow characterizes a prevailing or currently to be expected loading of a pneumatic consumer of the pressure control system during the supply of the charging pressure medium with a charging volume flow and at a charging pressure into the pneumatic consumer. The method further includes adjusting a flow-control cross-section, which acts on the charging pressure medium as it flows through the flow-control valve, or adjusting an average flow-control cross-section so as to limit the charging volume flow to a limit volume flow. The method additionally includes outputting the volume-flow limited charging pressure medium to the pneumatic consumer.

Unloader for a compressor, said unloader (1) comprising a housing (2) with an inlet (3) and an outlet (4), and whereby the unloader (1) is further provided with a piston rod (5) which is arranged moveably in a reciprocating manner in the housing (2), whereby on one end (5a) of the piston rod (5) a valve (7) is provided to be able to close the outlet (4) and whereby on the other end (5b) of the piston rod (5) a piston (8) is arranged, the piston being arranged moveably in a reciprocating manner in a thereto provided cavity (9) of the unloader (1), said cavity (9) being at least partially delimited by a lid (10) which is provided on the housing (2) and which is also part of the unloader (1), whereby sealing means (11) are provided for the leakage-free movement of the piston (8) in said cavity (9), whereby the cavity (9) in which the piston (8) is arranged moveably in a reciprocating manner is provided at least partially in the lid (10).

Unloader for a compressor, said unloader (1) comprising a housing (2) with an inlet (3) and an outlet (4), and whereby the unloader (1) is further provided with a piston rod (5) which is arranged moveably in a reciprocating manner in the housing (2), whereby on one end (5a) of the piston rod (5) a valve (7) is provided to be able to close the outlet (4) and whereby on the other end (5b) of the piston rod (5) a piston (8) is arranged, the piston being arranged moveably in a reciprocating manner in a thereto provided cavity (9) of the unloader (1), said cavity (9) being at least partially delimited by a lid (10) which is provided on the housing (2) and which is also part of the unloader (1), whereby sealing means (11) are provided for the leakage-free movement of the piston (8) in said cavity (9), whereby the cavity (9) in which the piston (8) is arranged moveably in a reciprocating manner is provided at least partially in the lid (10).

A reciprocating piston air compressor includes a programmable logic controller, a tank, a motor, a pump, a variable speed drive, a head unloader and a cooling system. The programmable logic controller and/or variable speed drive are utilized to monitor the operating state of the air compressor and to control various operational variables, such as motor and pump speed. The air compressor can utilize the variable speed drive to operate a three phase motor on single-phase power.

A reciprocating piston air compressor includes a programmable logic controller, a tank, a motor, a pump, a variable speed drive, a head unloader and a cooling system. The programmable logic controller and/or variable speed drive are utilized to monitor the operating state of the air compressor and to control various operational variables, such as motor and pump speed. The air compressor can utilize the variable speed drive to operate a three phase motor on single-phase power.

A relief device in air pump includes a main body defining an interior space and a discharge passage fluidly communicating with the interior space. The discharge passage is selectively closed and opened by a valve device. The valve device is movable in the discharge passage. The valve device includes a first sealing portion and a second sealing portion selectively engaging with the discharge passage. The valve device is movable between a first position in which one of the first and the second sealing portions engages with the discharge passage and a second position in which the other of the first and the second sealing portion engages with the discharge passage. The discharge passage has a length measuring from the first end to the second end thereof, which is smaller than a length which measures a separation distance between the first and the second sealing portions.

A hydraulic pump includes a work port, a high-flow piston, multiple high-pressure pistons, and an unloading valve. The work port couples to a fluid supply line of a hydraulic tool. The high-flow piston supplies fluid along a first flow path to the work port. The high-pressure pistons supply fluid along a second flow path to the work port. The unloading valve is fluidly coupled to the first flow path and the second flow path, and actuatable between an open state and a closed state. The unloading valve is configured to (i) permit fluid to flow from the high-flow piston to the work port in the open state, (ii) inhibit fluid from flowing from the high-flow piston to the work port in the closed state, and (iii) actuate from the open state to the closed state when a pressure of the fluid in the second flow path exceeds a threshold pressure.

An air stop sheet of a piston of a cylinder, the piston is accommodated in an air compressor, and an air stop sheet is accommodated on a head of the piston. The air stop sheet includes a bending section having a positioning zone and an acting zone and configured to be a boundary line of the acting zone and the positioning zone. The acting zone backing the cylinder turns on relative to the plane of the head at an open angle θ, thus producing an air flowing space. A piston rod extends downward from the head and includes a cavity, an air conduit, a column, and a spring configured to abut against the acting zone of the air stop sheet. The air stop sheet is pushed by the spring to turn on at an open angle θ, and the air conduit and the air channel communicate with atmosphere.

An air stop sheet of a piston of a cylinder, the piston is accommodated in a compressor, and an air stop sheet is accommodated on a head of the piston. The air stop sheet includes a bending section having a positioning zone and an acting zone. The bending section is a boundary line of the acting zone and the positioning zone so that a positive surface of the air stop sheet forms an obtuse angle less than 180 degrees, and a back surface of the acting zone of the air stop sheet backing the top of the cylinder turns on relative to the plane of the top of the head at an open angle θ, thus producing an air flowing space. A piston rod extends downward from the head and includes an air conduit communicating with the air channel.

A hydraulic apparatus has a plurality of pump modules each of which is formed by a plurality of working chambers having a common high pressure manifold. A connecting circuit switchably connects pump modules to first and second hydraulic circuit portions to allocate capacity as first and second demands for hydraulic fluid vary. In an apparatus which may have two or more connecting circuit outputs, valves may be controlled or working chamber pumping cycles made inactive to facilitate the reallocation of a pump module from one output to another, and a control strategy addresses pump module allocation when the demands for hydraulic fluid exceed available capacity.