Abstract: A planetary gear includes a planet carrier, a sun wheel, a gear ring, and planet wheels meshing with the sun wheel and with the gear ring. Each planet wheel shaft of the planetary gear is arranged to rotatably support a respective planet wheel so that, in an unloaded situation, a geometric axis of rotation of the planet wheel is skewed (?) with respect to the axial direction (z) of the planetary gear. In a loaded situation, torque directed to the planet carrier causes twisting deformation in the planet carrier and thereby the skewedness of the geometric axis of rotation is at least partly eliminated by the twisting deformation. Thus, in the loaded situation, the direction of the geometric axis of rotation can be closer to the axial direction than in a planetary gear where there is no skewedness in an unloaded situation.

Abstract: A planet wheel shaft includes a bearing portion for acting as a slide-bearing in cooperation with a planet wheel of a planetary gear. On at least one axial region of the bearing portion, a cross-sectional shape deviates from a circular shape so that the bearing portion is thicker in a first direction than in a second direction perpendicular to the first direction. The deviation from the circular shape widens a wedge-shaped gap that is between the bearing portion and the planet wheel when there is load in the first direction. This facilitates oil supply to an area where hydrodynamic oil pressure is formed for carrying load in the first direction because the widening the wedge-shaped gap compensates for narrowing the gap due to ovalization of the planet wheel caused by load in the second direction.

Abstract: A gear system includes a planetary gear and a frame structure including connection sections for attaching the frame structure to an external mechanical structure such as a nacelle of a wind power plant. The planetary gear includes a planet carrier, a sun wheel, a gear ring, and planet wheels meshing with the sun wheel and with the gear ring. The planet carrier includes a mechanical interface structure for connecting to an external rotating element such as a wind rotor. The frame structure includes a front cover shield that is a single piece of material, attached to the gear ring, and shaped to constitute a bearing cover for covering and supporting a bearing that supports the planet carrier. Thus, there is no need for a separate bearing cover.

Abstract: A planetary gear includes a planet carrier, a sun wheel, a gear ring, and planet wheels meshing with the sun wheel and with the gear ring. Each planet wheel shaft of the planetary gear is arranged to rotatably support a respective planet wheel so that, in an unloaded situation, a geometric axis of rotation of the planet wheel is skewed (?) with respect to the axial direction (z) of the planetary gear. In a loaded situation, torque directed to the planet carrier causes twisting deformation in the planet carrier and thereby the skewedness of the geometric axis of rotation is at least partly eliminated by the twisting deformation. Thus, in the loaded situation, the direction of the geometric axis of rotation can be closer to the axial direction than in a planetary gear where there is no skewedness in an unloaded situation.

Abstract: A planet wheel carrier for a planetary gear includes a carrier body for supporting shafts of planet wheels and a slide bearing for rotatably supporting a first end of the carrier body with respect to a frame of the planetary gear. The carrier body includes oil channels for conducting oil to bearings of the planet wheels. The slide bearing includes an oil channel for conducting oil from an oil channel of the frame to the oil channels of the carrier body. The planet wheel carrier includes one or more conical roller bearings for rotatably supporting a second end of the carrier body with respect to the frame. Thus, the slide bearing conducts pressurized oil to the rotating planet wheel carrier whereas the conical roller bearings receive axial forces directed to the planet wheel carrier.

Abstract: A planet wheel shaft includes a bearing portion for acting as a slide-bearing in cooperation with a planet wheel of a planetary gear. On at least one axial region of the bearing portion, a cross-sectional shape deviates from a circular shape so that the bearing portion is thicker in a first direction than in a second direction perpendicular to the first direction. The deviation from the circular shape widens a wedge-shaped gap that is between the bearing portion and the planet wheel when there is load in the first direction. This facilitates oil supply to an area where hydrodynamic oil pressure is formed for carrying load in the first direction because the widening the wedge-shaped gap compensates for narrowing the gap due to ovalization of the planet wheel caused by load in the second direction.

Abstract: A planet wheel assembly includes a planet shaft, a planet wheel having radial contact surfaces and axial contact surfaces, bushings connected to the planet shaft, radial sliding elements between radial contact surfaces of the bushings and the radial contact surfaces of the planet wheel, and axial sliding elements between axial contact surfaces of the bushings and the axial contact surfaces of the planet wheel. The planet wheel is shaped to constitute a circumferential projection which protrudes radially towards the planet shaft, is axially between the radial sliding elements, and forms the first and second axial contact surfaces of the planet wheel. This arrangement, where the radial sliding elements are axially outmost and the axial sliding elements are on the middle, improves the ability of the radial sliding elements to act against forces tilting the planet wheel.

Abstract: A system for the purpose of condition monitoring of gearboxes includes processing equipment that is configured to receive data that contains information of a spectrum of mechanical vibrations measured from a gearbox being monitored. The processing equipment is configured to search, from the spectrum of mechanical vibrations, at least two spikes on such frequencies which correspond to a phenomenon such as for example a bearing fault. The phenomenon is defined with at least two phenomenon-specific frequencies and with reference values of amplitudes relating to these phenomenon-specific frequencies. The processing equipment is configured to form an indicator of probability of occurrence for the phenomenon on the basis of amplitudes of the searched spikes and the reference values of the amplitudes. The fact that the indicator is formed on the basis of amplitudes of two or more spikes which relate to this phenomenon improves the reliability of the indicator.

Abstract: A gear unit comprises shafts (101, 102) for connecting to an external mechanical system, at least one gear stage (103) between the shafts, a lubricant oil room (104) for storing lubricant oil, an oil channel (105) for transporting the lubricant oil from the lubricant oil room to the at least one gear stage, and an immersion heater (106) for heating the lubricant oil flowing in the lubricant oil room towards an inlet of the oil channel. The gear unit further comprises a mechanical flow guide (108) located in the lubricant oil room and configured to modify flow of the lubricant oil flowing towards the inlet of the oil channel so as to increase flow velocity of the lubricant oil on the surface of the immersion heater. The increased flow velocity on the surface of the immersion heater makes it possible to use higher heating power without damaging the lubricant oil.

Abstract: A planet wheel assembly includes a planet shaft, a planet wheel having radial contact surfaces and axial contact surfaces, bushings connected to the planet shaft, radial sliding elements between radial contact surfaces of the bushings and the radial contact surfaces of the planet wheel, and axial sliding elements between axial contact surfaces of the bushings and the axial contact surfaces of the planet wheel. The planet wheel is shaped to constitute a circumferential projection which protrudes radially towards the planet shaft, is axially between the radial sliding elements, and forms the first and second axial contact surfaces of the planet wheel. This arrangement, where the radial sliding elements are axially outmost and the axial sliding elements are on the middle, improves the ability of the radial sliding elements to act against forces tilting the planet wheel.

Abstract: A planet wheel carrier for a planetary gear includes a carrier body for supporting shafts of planet wheels and a slide bearing for rotatably supporting a first end of the carrier body with respect to a frame of the planetary gear. The carrier body includes oil channels for conducting oil to bearings of the planet wheels. The slide bearing includes an oil channel for conducting oil from an oil channel of the frame to the oil channels of the carrier body. The planet wheel carrier includes one or more conical roller bearings for rotatably supporting a second end of the carrier body with respect to the frame. Thus, the slide bearing conducts pressurized oil to the rotating planet wheel carrier whereas the conical roller bearings receive axial forces directed to the planet wheel carrier.

Abstract: A maintenance tool for a planetary gear comprises a force generating device (101) comprising an actuator (102) for fastening to an end of a planet wheel pin of the planetary gear and for directing axial force to the planet wheel pin, and a body structure (104) for mechanically supporting a frame of the force generating device with respect to the planet carrier of the planetary gear so as to allow the actuator to move the planet wheel pin axially with respect to the planet carrier. In many cases, the maintenance tool enables removal of a planet wheel pin and installing, the same or another planet wheel pin at an operating site of the planetary gear. Thus, there is no need to move the planetary gear away from its operating site, e.g. a nacelle of a wind power plant, for maintenance work comprising removal of one or more planet wheel pins.

Abstract: A gear unit includes shafts for connecting to an external mechanical system, at least one gear stage between the shafts, a lubrication pump for circulating lubricating oil through the at least one gear stage and bearings of the gear unit, a temperature sensor for measuring temperature of the lubricating oil and supplying a temperature signal, an electrical motor for driving the lubrication pump, and an electrical device for controlling the electrical motor so that torque directed to the lubrication pump is below a torque limit. The torque limit is determined dynamically on the basis of the measured temperature of the lubricating oil. This arrangement makes it possible to protect the lubrication pump against mechanical faults during a cold start process so that an unnecessarily strict torque limitation, which would slow down the cold start process, can be avoided.

Abstract: An electromechanical device having a mechanical interface structure for connecting to an external rotating element, an electrical machine, and one or more gear stages on a mechanical power transmission path between the mechanical interface structure and a rotor of the electrical machine. The electromechanical device also has bearings for connecting the rotor of the electrical machine rotatably to the structure of the electromechanical device. The bearings carry the axial and radial forces of the rotor, and at least partly the axial and radial forces of the driving shaft of the gear stage, directly connected to the rotor.

Abstract: A maintenance tool for a planetary gear comprises a force generating device (101) comprising an actuator (102) for fastening to an end of a planet wheel pin of the planetary gear and for directing axial force to the planet wheel pin, and a body structure (104) for mechanically supporting a frame of the force generating device with respect to the planet carrier of the planetary gear so as to allow the actuator to move the planet wheel pin axially with respect to the planet carrier. In many cases, the maintenance tool enables removal of a planet wheel pin and installing, the same or another planet wheel pin at an operating site of the planetary gear. Thus, there is no need to move the planetary gear away from its operating site, e.g. a nacelle of a wind power plant, for maintenance work comprising removal of one or more planet wheel pins.

Abstract: An electromechanical device comprises a mechanical interface structure (101) for connecting to an external rotating element, for example a wind turbine. The device comprises an electrical machine (102-104), and one or more gear stages (105-112) on a power transmission path between the mechanical interface structure and a rotor of the electrical machine. The device further comprises mechanical structures (113-115) constituting a common lubricant oil room for both the gear stages and the electrical machine. The electromechanical device comprises oil channels (116a) for directing lubricant oil circulated in the device to flow via the gear stages and via bearings (118, 119) of the electrical machine. Therefore, a common lubricating system can be used for both the gear stages and the electrical machine.

Abstract: A gear lubrication arrangement comprises a lubrication pump for circulating lubrication fluid. A power source coupled to the lubrication pump drives the lubrication pump, and a controller controls an output power of the lubrication pump. The gear lubrication arrangement comprises a pressure sensor disposed down-stream of the lubrication pump The pressure sensor is configured to measure a pressure of the lubrication fluid and to produce a pressure indication signal representative thereof. The controller is arranged to vary the output power of the lubrication pump at least partly on the basis of the pressure indication signal.

Abstract: A planet wheel carrier comprises first and second end-sections for supporting shafts of planet wheels (113-114) of a planetary gear so that geometrical rotation axes of the planet wheels are pithed at substantially uniform intervals on a periphery of a circle. The planet wheel carrier comprises a support structure connected to outer rims of the first and second end-sections and located between the first and second end-sections in the axial direction and between the planet wheels in the circumferential direction. The support structure is so far from the geometrical rotational symmetry axis of a sun shaft (111) of the planetary gear and the geometrical rotation axes of the planet wheels are so near to the rotational symmetry axis of the sun shaft that the diameter (D) of the planet wheels is capable of being at least 90% of a distance (d) between the geometrical rotation axes of adjacent planet wheels.

Abstract: A gear unit comprises shafts (101, 102) for connecting to an external mechanical system, at least one gear stage (103) between the shafts, a lubricant oil room (104) for storing lubricant oil, an oil channel (105) for transporting the lubricant oil from the lubricant oil room to the at least one gear stage, and an immersion heater (106) for heating the lubricant oil flowing in the lubricant oil room towards an inlet of the oil channel. The gear unit further comprises a mechanical flow guide (108) located in the lubricant oil room and configured to modify flow of the lubricant oil flowing towards the inlet of the oil channel so as to increase flow velocity of the lubricant oil on the surface of the immersion heater. The increased flow velocity on the surface of the immersion heater makes it possible to use higher heating power without damaging the lubricant oil.

Abstract: A method for controlling lubrication of a gear unit, where the lubrication method of the gear unit is changed between circulating lubrication and splash lubrication during operation of the gear unit, wherein the temperature of the lubrication fluid is measured, and the change between circulation lubrication and splash lubrication is based on the measured temperature of the lubrication fluid. The invention also relates to such a gear unit.