A pump system/method configured to provide substantially constant flow of concrete, cement, or other material is disclosed. The system integrates a trapezoidal cutting ring and spectacle plate in conjunction with lofted transitional interfaces to the hydraulic pump cylinder rams and output ejection port to ensure that pressurized discharge concrete material is not allowed to be relaxed nor backflow into the material sourcing hopper. The trapezoidal cutting ring is configured to completely seal off the trapezoidal spectacle ports as it smoothly transitions between the hydraulic pump input ports during cycle changes thus generating a more uniform output flow of concrete while eliminating hopper backflow and hydraulic fluid shock. A control system is configured to coordinate operation of the hydraulic pump cylinder rams and cutting ring to ensure that output ejection port pressure and material flow is maintained at a relatively constant level throughout all portions of the pumping cycle.

A multistage air pump has a cylinder assembly, a second piston assembly slidably mounted through the cylinder assembly, and a first piston assembly protruding in the second piston assembly. Multiple chambers are defined in the multistage air pump, and communicate with each other via multiple one-way mechanisms. Air drawn into the multistage air pump is compressed in multiple stages within a single push, such that a large amount of high pressure air is provided.

An oil feeder and a linear compressor including the same are disclosed. The oil feeder includes an oil cylinder defining an oil supply hole configured to extend in a first direction, an accommodation groove formed concavely at a side, and a communication hole configured to communicate the oil supply hole with the accommodation groove, an oil piston accommodated in the accommodation groove and configured to reciprocate in a second direction perpendicular to the first direction, a first ball accommodated in the oil supply hole and disposed below the communication hole, a second ball accommodated in the oil supply hole and disposed on the communication hole, and an elastic member comprising an outer portion coupled to the accommodation groove and an inner portion coupled to the oil piston.

An improved air compressor includes a cylinder that is fitted with a piston body and defines at its top wall a plurality of exit holes which are approximately equal in diameter and can be regulated by plugs to enable the cylinder to communicate with an air storage container. The exit holes are normally sealed by the plugs with the assistance of compression springs when the air compressor is not in operation. The exit holes allow the compressed air produced in the cylinder to quickly enter the air storage container, so that the piston body can conduct reciprocating motion more smoothly and thus the performance of the air compressor can be increased.

A piston plug includes a cylindrical body having a longitudinal axis and an outer cylindrical surface. The outer cylindrical surface extends longitudinally between a first surface and a second surface opposite the first surface. The outer cylindrical surface defines a hole extending radially inward. The hole has a central axis perpendicular to the longitudinal axis of the cylindrical body. A first channel and a second channel are defined by cylindrical body. The first channel is in fluidic communication with the first surface and the hole. The second channel is in fluidic communication with the second surface and the hole. The first channel, the second channel, and at least a portion of the hole form a non-collinear flowpath. The piston plug is disposed in a plug hole in a piston and is retained in the plug hole via an interference fit between the piston plug and the plug hole.

A vacuum pump includes a motor, a pump coupled to the motor to receive torque therefrom, and a trestle including an inlet port, an outlet port, and a fluid pathway therebetween, the outlet port being fluidly connected to the pump. The vacuum pump also includes a first valve positioned within the fluid pathway and adjustable between an open state, in which an airflow induced by the pump is drawn through the inlet port, and a closed state, in which a reverse airflow through the inlet port is prevented, and a second valve positioned within the fluid pathway in series with the first valve and adjustable between an open state, in which the airflow induced by the pump is drawn through the inlet port, and a closed state, in which the reverse airflow through the inlet port is prevented when the motor is deactivated.