A reciprocating compressor or pump comprising: a plurality of cylinder liners each having a cylindrical bore therethrough; a plurality of pistons each sealed to a respective one of the cylinder liners within the cylindrical bore thereof; a drive system (24, 44, 52, 54, 64, 66) coupled to each piston to effect reciprocal motion thereof along the cylindrical bore of the respective cylinder liner between a fully extended position furthest from the drive system and a fully retracted position nearest the drive system; an intake valve (96, 78, 250, 260) and an exhaust valve (76, 78) associated with each cylinder liner, the intake valve being arranged to open as the piston retracts toward the fully retracted position and to close as the piston extends away therefrom and the exhaust valve being arranged to open as the piston extends toward the fully extended position and to close as the piston retracts away therefrom; a manifold (12, 202) having a hollow interior fluidly communicating with the cylindrical bore of each cylinder liner when the exhaust valve associated therewith is open; the cylinder liners are disposed in a common plane and extend radially about an axis normal to the common plane; the hollow interior of the manifold defines an annular space extending about the axis to communicate with each exhaust valve; each cylinder liner is disposed at least partially within the hollow interior of the manifold and each exhaust valve is disposed within the hollow interior of the manifold to control flow between the cylindrical bore of the cylinder liner and the surrounding hollow interior; characterized in that: each exhaust valve comprises at least one exhaust port extending through the cylinder liner and a resilient band disposed circumferentially about the cylinder liner, the band being resiliently stretchable about the respective cylinder liner by fluid pressure exerted on the band through the exhaust port during movement of the piston toward the fully extended position; and the plurality of cylinder liners and the drive system, including an electric motor thereof, are carried by the manifold. a plurality of cylinder liners each having a cylindrical bore therethrough; a plurality of pistons each sealed to a respective one of the cylinder liners within the cylindrical bore thereof; a drive system (24, 44, 52, 54, 64, 66) coupled to each piston to effect reciprocal motion thereof along the cylindrical bore of the respective cylinder liner between a fully extended position furthest from the drive system and a fully retracted position nearest the drive system; an intake valve (96, 78, 250, 260) and an exhaust valve (76, 78) associated with each cylinder liner, the intake valve being arranged to open as the piston retracts toward the fully retracted position and to close as the piston extends away therefrom and the exhaust valve being arranged to open as the piston extends toward the fully extended position and to close as the piston retracts away therefrom; a manifold (12, 202) having a hollow interior fluidly communicating with the cylindrical bore of each cylinder liner when the exhaust valve associated therewith is open; the cylinder liners are disposed in a common plane and extend radially about an axis normal to the common plane; the hollow interior of the manifold defines an annular space extending about the axis to communicate with each exhaust valve; each cylinder liner is disposed at least partially within the hollow interior of the manifold and each exhaust valve is disposed within the hollow interior of the manifold to control flow between the cylindrical bore of the cylinder liner and the surrounding hollow interior; characterized in that: each exhaust valve comprises at least one exhaust port extending through the cylinder liner and a resilient band disposed circumferentially about the cylinder liner, the band being resiliently stretchable about the respective cylinder liner by fluid pressure exerted on the band through the exhaust port during movement of the piston toward the fully extended position; and the plurality of cylinder liners and the drive system, including an electric motor thereof, are carried by the manifold. each exhaust valve comprises at least one exhaust port extending through the cylinder liner and a resilient band disposed circumferentially about the cylinder liner, the band being resiliently stretchable about the respective cylinder liner by fluid pressure exerted on the band through the exhaust port during movement of the piston toward the fully extended position; and the plurality of cylinder liners and the drive system, including an electric motor thereof, are carried by the manifold.