A group transmission device includes a main transmission which has a main shaft, a countershaft and a spur gear pair which includes a first spur gear arranged coaxially and axially overlapping with the main shaft and a second spur gear arranged coaxially and axially overlapping with the countershaft. A range group has a first shaft non-rotationally connected to the main shaft, a second shaft non-rotationally connected to a transmission output shaft, a third shaft and a blocking switching unit. A first switching unit non-rotationally connects the third shaft to a housing. A second switching unit has an axially shiftable switching element and non-rotationally connects the third shaft to the first spur gear. The main shaft is coupled non-rotationally to a transmission input shaft. A third switching unit has an axially shiftable further switching element and non-rotationally connects the first spur gear to the first shaft of the range group.

A group transmission device includes a main transmission which has a main shaft, a countershaft and a spur gear pair which includes a first spur gear arranged coaxially and axially overlapping with the main shaft and a second spur gear arranged coaxially and axially overlapping with the countershaft. A range group has a first shaft non-rotationally connected to the main shaft, a second shaft non-rotationally connected to a transmission output shaft, a third shaft and a blocking switching unit. A first switching unit non-rotationally connects the third shaft to a housing. A second switching unit has an axially shiftable switching element and non-rotationally connects the third shaft to the first spur gear. The main shaft is coupled non-rotationally to a transmission input shaft. A third switching unit has an axially shiftable further switching element and non-rotationally connects the first spur gear to the first shaft of the range group.

A hydraulic fracturing system for fracturing a subterranean formation is described according to various embodiments. In an embodiment, the system can include a multi-plunger hydraulic fracturing pump fluidly connected to a well associated with the subterranean formation, the multi-plunger pump configured to pump fluid into a wellbore associated with the well at a high pressure so that the fluid passes from the wellbore into the subterranean formation and fractures the subterranean formation. In an embodiment, a plurality of motors can be positioned to power the multi-plunger pump, and a planetary gear train can have a plurality of pinion gears in rotational contact with each of the plurality of motors. In an embodiment, a gear ratio of the planetary gear train and a speed at which the plurality of motors operates can be selected so as to limit a maximum pump speed associated with the multi-plunger pump.

A hydraulic fracturing system for fracturing a subterranean formation is described according to various embodiments. In an embodiment, the system can include a multi-plunger hydraulic fracturing pump fluidly connected to a well associated with the subterranean formation, the multi-plunger pump configured to pump fluid into a wellbore associated with the well at a high pressure so that the fluid passes from the wellbore into the subterranean formation and fractures the subterranean formation. In an embodiment, a plurality of motors can be positioned to power the multi-plunger pump, and a planetary gear train can have a plurality of pinion gears in rotational contact with each of the plurality of motors. In an embodiment, a gear ratio of the planetary gear train and a speed at which the plurality of motors operates can be selected so as to limit a maximum pump speed associated with the multi-plunger pump.

Three controls, three variable gear assemblies, an optional hatch or variable propeller pitch, and a variable overlap generator (VO generator), as well as one or more commutator and brush-less free direct current generators may be used independently and together to provide constant frequency and voltage output power and to increase the amount of output power generated with the same input water flow or wind speed in a plurality of embodiments useful in wind power generation and water renewable energy generators for any of tidal and ocean current or wave conditions. Two Transgear assemblies side-by-side and sharing the same central shaft may comprise a constant speed motor control, produce required constant frequency and voltage and be reduced in part count and complexity. The variable overlap generator of a marine hydrokinetic or wind power generator may be used as a low torque generator, a high power-rated generator or a control in these applications and may generate more electric power than a conventional fixed power generator (the rotor axially aligned to overlap the stator in a conventional manner) over a wider input range. An electromotive force (EMF) embodiment generates alternating current at constant frequency and voltage in varying wind and water speed conditions.

Three controls, three variable gear assemblies, an optional hatch or variable propeller pitch, and a variable overlap generator (VO generator), as well as one or more commutator and brush-less free direct current generators may be used independently and together to provide constant frequency and voltage output power and to increase the amount of output power generated with the same input water flow or wind speed in a plurality of embodiments useful in wind power generation and water renewable energy generators for any of tidal and ocean current or wave conditions. Two Transgear assemblies side-by-side and sharing the same central shaft may comprise a constant speed motor control, produce required constant frequency and voltage and be reduced in part count and complexity. The variable overlap generator of a marine hydrokinetic or wind power generator may be used as a low torque generator, a high power-rated generator or a control in these applications and may generate more electric power than a conventional fixed power generator (the rotor axially aligned to overlap the stator in a conventional manner) over a wider input range. An electromotive force (EMF) embodiment generates alternating current at constant frequency and voltage in varying wind and water speed conditions.

A speed converter converting infinitely variable reciprocating input to uni-directional output, for example, comprising a driver, the driver comprising a variable pitch cam and a rack gear and one-way clutch bearings or Sprags and output shaft, the driver having an oblong shape may be converted to provide direction control in either of two directions and free-wheeling. The one-way clutch bearings or Sprags of a first Goldfinch speed converter are modified to comprise, concentric with the output shaft, a permanent magnet imbedded in a driven gear and direction controlling stator coils. A plurality of four (or more) electrical pulses (sine curves) may be applied to the stator coils to provide three possible outputs of desired speed: a forward output direction, a neutral or free-wheeling output and a reverse output direction. In this manner, an electro-magnetic ratchet control system may modify the speed converter to incorporate speed control, engine braking, and clockwise and counterclockwise output shaft direction control as well.

A speed converter converting infinitely variable reciprocating input to uni-directional output, for example, comprising a driver, the driver comprising a variable pitch cam and a rack gear and one-way clutch bearings or Sprags and output shaft, the driver having an oblong shape may be converted to provide direction control in either of two directions and free-wheeling. The one-way clutch bearings or Sprags of a first Goldfinch speed converter are modified to comprise, concentric with the output shaft, a permanent magnet imbedded in a driven gear and direction controlling stator coils. A plurality of four (or more) electrical pulses (sine curves) may be applied to the stator coils to provide three possible outputs of desired speed: a forward output direction, a neutral or free-wheeling output and a reverse output direction. In this manner, an electro-magnetic ratchet control system may modify the speed converter to incorporate speed control, engine braking, and clockwise and counterclockwise output shaft direction control as well.

A group transmission device includes a main transmission which has a main shaft, a countershaft and a spur gear pair which includes a first spur gear arranged coaxially and axially overlapping with the main shaft and a second spur gear arranged coaxially and axially overlapping with the countershaft. A range group has a first shaft non-rotationally connected to the main shaft, a second shaft non-rotationally connected to a transmission output shaft, a third shaft and a blocking switching unit. A first switching unit non-rotationally connects the third shaft to a housing. A second switching unit has an axially shiftable switching element and non-rotationally connects the third shaft to the first spur gear. The main shaft is coupled non-rotationally to a transmission input shaft. A third switching unit has an axially shiftable further switching element and non-rotationally connects the first spur gear to the first shaft of the range group.

A group transmission device includes a main transmission which has a main shaft, a countershaft and a spur gear pair which includes a first spur gear arranged coaxially and axially overlapping with the main shaft and a second spur gear arranged coaxially and axially overlapping with the countershaft. A range group has a first shaft non-rotationally connected to the main shaft, a second shaft non-rotationally connected to a transmission output shaft, a third shaft and a blocking switching unit. A first switching unit non-rotationally connects the third shaft to a housing. A second switching unit has an axially shiftable switching element and non-rotationally connects the third shaft to the first spur gear. The main shaft is coupled non-rotationally to a transmission input shaft. A third switching unit has an axially shiftable further switching element and non-rotationally connects the first spur gear to the first shaft of the range group.