An air pump includes a cylinder, a piston rod, and an upper cover. The cylinder forms an opening at a top end thereof and at least one retaining hole adjacent to the opening. The piston rod is configured to be movable within the cylinder and provided with a piston forming a conical lateral face at one end thereof. The upper cover has a top portion forming a hole for the piston rod to penetrate therethrough, at least one extension portion extended from the top portion, and at least one retaining portion extended from the extension portion. The least one extension portion has an abutting edge selectively abutted against the conical lateral face. The retaining portion is engaged with the retaining hole.

An air pump includes a cylinder, a piston rod, and an upper cover. The cylinder forms an opening at a top end thereof and at least one retaining hole adjacent to the opening. The piston rod is configured to be movable within the cylinder and provided with a piston forming a conical lateral face at one end thereof. The upper cover has a top portion forming a hole for the piston rod to penetrate therethrough, at least one extension portion extended from the top portion, and at least one retaining portion extended from the extension portion. The least one extension portion has an abutting edge selectively abutted against the conical lateral face. The retaining portion is engaged with the retaining hole.

An air compressor having a pressure gauge, the pressure gauge contains: a hollow tube, a drive element, an anti-leak spring, a resilient element, and a cap. The hollow tube includes an accommodation chamber, a connector having a conduit, and a display unit. The drive element includes a protection unit, a first open segment, a second distal segment, a receiving portion, a hollow extension, and a protrusion. An anti-leak spring is received in the hollow extension of the drive element, a first end of the anti-leak spring abuts against the protrusion, and a second end of the anti-leak spring contacts with the protection unit. The resilient element is received in the receiving portion of the drive element. The cap includes a seat, a push bolt, and multiple passages. An end of the resilient element contacts with the cap.

Systems and methods to enhance the flow of fracturing fluid into a wellhead during a high-pressure fracturing operation may include providing a pump frame and a crankshaft. A plurality of first plungers may be connected to the crankshaft and may reciprocate in a first plane. The hydraulic fracturing pump also may include a plurality of second plungers connected to the crankshaft and positioned to reciprocate in a second plane. The first plane and the second plane may define a non-zero offset angle between the first plane and the second plane. The crankshaft may include a plurality of crankpins, and each of the crankpins may be connected to one of the first plungers and one of the second plungers. The first plungers may pump a first fracturing fluid and the second plungers may pump a second fracturing fluid different from the first fracturing fluid.

Systems and methods to enhance the flow of fracturing fluid into a wellhead during a high-pressure fracturing operation may include providing a pump frame and a crankshaft. A plurality of first plungers may be connected to the crankshaft and may reciprocate in a first plane. The hydraulic fracturing pump also may include a plurality of second plungers connected to the crankshaft and positioned to reciprocate in a second plane. The first plane and the second plane may define a non-zero offset angle between the first plane and the second plane. The crankshaft may include a plurality of crankpins, and each of the crankpins may be connected to one of the first plungers and one of the second plungers. The first plungers may pump a first fracturing fluid and the second plungers may pump a second fracturing fluid different from the first fracturing fluid.

Pump module for a vacuum apparatus with a flange which can be connected to a vacuum apparatus in a vacuum-tight manner, at least one ion getter pump and at least one volume getter pump, NEG, where the ion getter pump is directly connected to the flange and the NEG is directly connected to the ion getter pump and where the NEG and the flange are arranged separately from each other.

Pump module for a vacuum apparatus with a flange which can be connected to a vacuum apparatus in a vacuum-tight manner, at least one ion getter pump and at least one volume getter pump, NEG, where the ion getter pump is directly connected to the flange and the NEG is directly connected to the ion getter pump and where the NEG and the flange are arranged separately from each other.

A connecting device includes a substantially cylindrical or tubular body provided, at one of its ends, with an outer perimeter projection and co-operative with a duct of channel of a cylinder cap. The device is preferably producible with steel aluminum alloy, or another metal alloy with similar structural and thermal properties mainly due to the stresses it may suffer during use. The device is configured to be able to absorb tolerance variations and to have a resilience capable of providing resistance at the time when a connection undergoes mechanical stresses of performance, especially torsion.

A connecting device includes a substantially cylindrical or tubular body provided, at one of its ends, with an outer perimeter projection and co-operative with a duct of channel of a cylinder cap. The device is preferably producible with steel aluminum alloy, or another metal alloy with similar structural and thermal properties mainly due to the stresses it may suffer during use. The device is configured to be able to absorb tolerance variations and to have a resilience capable of providing resistance at the time when a connection undergoes mechanical stresses of performance, especially torsion.

An integrated air supply unit comprises a compressor housing, a pressure control unit (PCU) body, and a desiccant housing extending between the compressor housing and the PCU body. The desiccant housing defines a desiccant cavity holding a desiccant container for removing moisture from air passing therethrough. A piston is slidably disposed within a piston bore of the compressor housing. The PCU body defines a plurality of fluid passages with solenoid valves selectively controlling airflow therethrough. The integrated air supply unit may also comprise: a manifold, a discharge control valve, a compressor supplying pressurized air in a first pressurized air passage, a dryer configured to remove moisture from the pressurized air in the first pressurized air passage and to supply dried pressurized air in a second pressurized air passage, a supply control valve to control airflow between the second pressurized air passage and the manifold, and a piloted exhaust valve.