A kit for use with a drivetrain of a rotatable assembly includes a tapered bushing, a tapered adapter, and a bushing lock. The tapered bushing includes a flange, a sleeve portion, a central opening, a keyway located along the central opening, at least one fastener hole, and a tapered mating surface facing outward. The tapered adapter includes a hub body with an end face portion, an interior cavity, a threaded shaft, at least one fastener hole extending substantially axially through the hub body, and a tapered mating surface facing inward. The fastener hole(s) of the tapered adapter and tapered bushing are configured to align. The bushing lock includes a bushing lock central opening extending axially, a keyway located along the bushing lock central opening, and a fastener hole extending substantially radially.

Pressure booster (1) for boosting the pressure of petroleum fluids, produced water or seawater, comprising a pressure booster (2) with a motor (3), a rotatable motor shaft (4) and a rotatable pump or compressor shaft (5) where the pressure booster in the form of a centrifugal pump (2) or compressor is arranged. The pressure booster further comprises: a hydraulic variable speed drive (6) arranged between the motor and the pressure booster, the hydraulic variable speed drive comprising an impeller (7) and a turbine (8), wherein the impeller of the hydraulic variable speed drive is arranged on the motor shaft and the turbine of the hydraulic variable speed drive is arranged on the pump or compressor shaft, a common driver side fluid (10) for cooling, lubricating, flushing and powering of the hydraulic variable speed drive, and cooling, lubricating and flushing of the motor and bearings, circulated by one of an impeller (9) on the motor shaft, a pump and a hydraulic power unit, a control system (11) for controlling the coupling of the motor shaft to the pump or compressor shaft by the hydraulic variable speed drive, wherein the motor shaft drives the pump or compressor shaft via the hydraulic variable speed drive.