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 fluid valve is described to help reduce oil sump pressures of a variable speed compressor and a fixed speed compressor working in parallel in a HVAC system. The fluid valve can be a ball valve. Openings of a variable flow through structure of the ball can be configured to elongate along an equator the ball. When the ball rotates along a rotation axis, a size of a variable fluid path formed between the openings can be varied, resulting in a variable pressure drop across the ball. In operation, when the variable speed compressor is operated at different operation speeds, the ball can be rotated to different positions relative to the rotation axis, which may help reduce the pressure differential between the sumps of the variable speed compressor and the fixed speed compressor.

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.

The present invention is directed to a hydraulic double-acting hand pump in which a high and low pressure side fluid supply grooves are formed in a top surface, a fluid inlet is formed in a bottom surface, a body in which the fluid outlet is formed in a side surface is provided, a piston is inserted into and coupled to the high and low pressure side fluid supply grooves, an upper end of the piston is connected and fixed to a handle rotatably installed in the low pressure side fluid supply groove of the body, the piston alternately and repeatedly ascends and descends to supply fluids to the high and low pressure side fluid supply grooves, and the fluids are discharged through the fluid outlet of the body by pushing the fluids inside the high and low pressure side fluid supply grooves.

A submersible well pump assembly has a pump housing with a pump discharge on upper end. A pump barrel is located within the pump housing, defining an annular passage between the barrel and the pump housing. A plunger is reciprocally carried in the barrel. A motor mounted below the pump housing and operatively couples to the plunger causes the plunger to reciprocate between an upstroke and a down-stroke. A valve and porting arrangement directs well fluid in the barrel below the plunger into the annular passage and out the discharge during a down stroke of the plunger. The valve and porting arrangement admits well fluid into the barrel below the plunger during the up stroke of the plunger. A connecting rod extends between the motor and the plunger. The connecting rod is in tension during the down-stroke.

An air pump includes a pumping system, a storage tank, a discharge passage, and a valve. The discharge passage includes a first section and a second section wider than the first section. The valve is movable in the discharge passage. The valve, disposed in a first position, includes a first seal end disposed in the first section and abutting a periphery thereof and includes a second seal end disposed in the second section and abutting a periphery thereof. The valve, disposed in a second position, includes the first seal end disengaging from the first section and not abutting the periphery thereof and includes the second seal end disposed in the second section and abutting the periphery thereof. The first and second seal ends respectively have first and second cross-sectional areas. The ratio of the second cross-sectional area to the first cross-sectional area is at least 2 to 1.

An air pump includes a pumping system, a storage tank, a discharge passage, and a valve. The discharge passage includes a first section and a second section wider than the first section. The valve is movable in the discharge passage. The valve, disposed in a first position, includes a first seal end disposed in the first section and abutting a periphery thereof and includes a second seal end disposed in the second section and abutting a periphery thereof. The valve, disposed in a second position, includes the first seal end disengaging from the first section and not abutting the periphery thereof and includes the second seal end disposed in the second section and abutting the periphery thereof. The first and second seal ends respectively have first and second cross-sectional areas. The ratio of the second cross-sectional area to the first cross-sectional area is at least 2 to 1.

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 mechanical 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 mechanical 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 pumping device may include a pump housing partially delimiting a working chamber, and a piston arranged therein, axially movable between first and second positions in which the working chamber has maximum and minimum volumes, respectively. The pumping device may include first and second fluid lines for introducing and discharging fluid to/from the working chamber, respectively. The first fluid line may be an annular fluid channel, fluidically connected to the working chamber via a breakthrough formed in the pump housing at an end face of the working chamber opposite the piston, running transversely to the axial direction at least in the area of the breakthrough. The second fluid line may open obliquely into the working chamber in an area of the second position, relative to the axial direction in an end face delimiting the working chamber towards the first fluid line. The pumping device may include first and second valves for fluid-tight closures of the first and second fluid lines, respectively, the second valve communicating fluidically with the working chamber directly.

A compressed air supplying device of a sewing machine includes an air pump unit including a piston; a piston driving spring applying biasing force to the piston in an exhaust air direction which is a direction in which the air pump unit exhausts air for driving the piston in the exhaust air direction by the biasing force; a lever making the air pump unit perform intake air movements; and an operating force transmitting mechanism transmitting operating force of the lever to the piston for actuating the piston only in an intake air direction which is a direction in which the air pump unit intakes air against the biasing force of the piston driving spring by the operating force.