Various assemblies that can be used in a mud pump with a plunger-style piston to reduce seal failures, to offer control in variability of the circumference of the piston to thereby control fluid pressure, and to provide visibility into seal condition during operation. In one embodiment, a sleeve that can vary the overall effective circumference of the piston enables fluid pressure control. In some embodiments, seal failure within a pump can be monitored via a drain port that would receive drilling fluid leaking past a seal during operation of the pump. A discharge valve can be provided between an inlet and an outlet of the mud pump to reduce the load on pump components during start-up. Additional systems, devices, and methods are also disclosed.

A self-aligning mud pump apparatus is provided. In one embodiment, the mud pump includes a rotatable crankshaft, a crosshead, a crosshead guide, and a hub disposed in a housing. The hub is disposed on the crankshaft and is operable to convert rotating motion of the crankshaft to reciprocating motion of the crosshead within the crosshead guide. The hub is coupled to the crosshead via a connecting rod, which is connected the crosshead such that the connecting rod has five degrees of freedom with respect to the crosshead guide. The mud pump may also or instead include a piston coupled to the crosshead with five degrees of freedom between the piston and the crosshead. Additional systems, devices, and methods are also disclosed.

A self-aligning mud pump apparatus is provided. In one embodiment, the mud pump includes a rotatable crankshaft, a crosshead, a crosshead guide, and a hub disposed in a housing. The hub is disposed on the crankshaft and is operable to convert rotating motion of the crankshaft to reciprocating motion of the crosshead within the crosshead guide. The hub is coupled to the crosshead via a connecting rod, which is connected the crosshead such that the connecting rod has five degrees of freedom with respect to the crosshead guide. The mud pump may also or instead include a piston coupled to the crosshead with five degrees of freedom between the piston and the crosshead. Additional systems, devices, and methods are also disclosed.

A pump comprises: a plurality of pistons each of which is slidable inside a cylinder so as to vary volume of a corresponding chamber, a plurality of suction valves, each of which is associated with a chamber and is operable to allow a liquid to enter the chamber, the suction valves being arranged in a first sequence, a plurality of delivery valves, each of which is associated with a chamber and is operable to allow said liquid to exit from the chamber, the delivery valves being arranged in a second sequence, an adjusting valve for adjusting pressure of the liquid exiting from the pump.

The adjusting valve is interposed between two consecutive valves of a sequence chosen from said first sequence and said second sequence.

The pump further comprises: an outlet conduit arranged downstream of the delivery valves, a shutter device interposed between an initial portion of the outlet conduit and a final portion of the outlet conduit, so as to put the initial portion in fluid communication with the final portion, or alternatively separate the initial portion from the final portion, a connecting hole for connecting a portion of the outlet conduit arranged downstream of the shutter device with the adjusting valve.

A priming pump may include a housing; an inlet passageway inside of the housing; an outlet passageway inside of the housing; a divider, inside of the housing, separating the inlet passageway and the outlet passageway; a connecting passageway through the divider in fluid communication with the inlet passageway and the outlet passageway; a valve, disposed in the connecting passageway, configured for one-way fluid flow from the inlet passageway to the outlet passageway; a rotary pump, inside of the housing, having an inlet in fluid communication with the inlet passageway and an outlet in fluid communication with the outlet passageway; and a shaft connected to the rotary pump and extending through the housing, the shaft configured for rotation by an external driving mechanism.

A pump system (120) has a central pump unit (110), with which at least one hook-up unit (130). The at least one hook-up unit (130) is from a group of a plurality of hook-up units (130) that can be combined in modular form for setting an operating point of a pump (10) that forms the pump unit (110). A method uses such a hook-up unit (130) in a pump system (120) for setting an operating point of the pump unit (110) thereof. A medical device is provided with such a pump unit (110) or with such a pump unit (110) and at least one hook-up unit (130) combined with the pump unit (110).

A pump system (120) has a central pump unit (110), with which at least one hook-up unit (130). The at least one hook-up unit (130) is from a group of a plurality of hook-up units (130) that can be combined in modular form for setting an operating point of a pump (10) that forms the pump unit (110). A method uses such a hook-up unit (130) in a pump system (120) for setting an operating point of the pump unit (110) thereof. A medical device is provided with such a pump unit (110) or with such a pump unit (110) and at least one hook-up unit (130) combined with the pump unit (110).

A system includes a source that provides air, a first compressor stage that receives the air from the source and is configured to compress the air to a first pressure, and a second compressor stage that receives the air from the first compressor stage and is configured to compress the air to a second pressure. The system also includes a first component, a second component, valves that control flow of the air, and a controller that is configured to control the valves according to a first control mode, in which the air is supplied to the first component by the first compressor stage, and a second control mode, in which the air is supplied to the second component by the second compressor stage.

Refrigerant compressor for refrigeration systems, comprising an electric motor, at least two cylinder banks and a mechanical performance control unit for activating and deactivating at least one of the cylinder banks in order to activate or deactivate its refrigerant output, wherein, for the purpose of operation in partial performance conditions, the refrigerant compressor is operable in at least two different operating modes, of which each provides an activation or deactivation of the cylinder banks that is different from the other operating modes, wherein associated with the refrigerant compressor is a frequency converter for controlling the speed of the electric motor, wherein associated with the refrigerant compressor is an operating condition controller that, in accordance with a performance request signal supplied to it for operation of the refrigerant compressor in the partial performance condition corresponding to this performance request signal, operates the refrigerant compressor in an operating mode that is selected from at least two different operating modes and at a speed adapted to the selected operating mode, for the purpose of achieving this partial performance condition.

A hydraulic apparatus including an electronically commutated machine having a plurality of working chambers which are controlled on each cycle of working chamber volume to carry out active or inactive cycles of working chamber volume allows only a plurality of defined fractions of cycles to be active cycles to avoid generating frequencies of active cycles which cause low frequency resonances. The demand signal may be quantised into fractions m/n where n is an integer below a threshold selected to avoid repeating patterns of active cycles of more than a cut-off length.