A system for an unmanned aerial vehicle can include an altitude control system, which further includes a compressor assembly, a valve assembly, and an electronics assembly. The compressor assembly may include a driveshaft and a bearing assembly configured to rotate the driveshaft. The driveshaft may be formed from a first material and a compressor housing may be formed from a second material. The first and second materials may have different rates of thermal expansion. A dynamic preloading mechanism, such as a flexible plate, may be provided within the compressor assembly to exert a preloading force on the bearing assembly. Throughout the duration of the flight of the unmanned aerial vehicle, the preloading mechanism can continually compensate for differences in rates of thermal expansion between the first and second materials throughout.

A system for providing a load on a bearing mounted to a shaft includes an attaching member releasably connectable to the shaft and a press mechanism in fluid communication with a source of fluid and configured to provide a compressive load to the bearing. The press mechanism includes a switch having a base and a piston in communication with the fluid such that an increase in a pressure of the fluid results in the piston extending upwardly from the base and a decrease in the pressure of the fluid results in the piston retracting toward the base. The switch includes a lower proximity sensor and a higher proximity sensor. The piston is configured to extend upwardly from the base past the lower proximity sensor and to trip the higher proximity sensor. The switch is configured to control the increase in the pressure in response to the piston tripping the higher proximity sensor.

An apparatus (10) for preloading a bearing assembly (14) on a shaft (12) includes a first annular threaded member (56) positioned about the shaft (12) and a second annular threaded member (68) positioned about the shaft (12). The first and second threaded members (56,68) have intermeshing threads such that rotation of the second threaded member (68) causes axial translation of the first threaded member (56) to apply a first axial force to the bearing assembly (14) to preload the bearing assembly (14). An actuator is operable to rotate the second threaded member (68) relative to the first threaded member (56) to apply the first axial force to the bearing assembly (14).

A tensioner for preloading a bearing, the bearing including inner and outer bearing rings. The tensioner including a component having a housing and a carrier element that extends radially inwardly from the housing, the outer bearing ring having an outer surface that forms an axially extending radial surface and having a first axial end formed by a radially extending axial surface and directly abutting the carrier element, a support element for supporting the component relative to the inner bearing ring such that a closed force flow arises from the outer bearing ring via the component and the support element, and a sleeve positioned radially between the outer surface of the first bearing ring and the housing such that an inner surface of the sleeve abuts the outer surface of the outer bearing ring and an outer surface of the sleeve abuts a conical surface of the housing.

A structure applies a pre-load to a rolling bearing, which makes pre-load control easier than heretofore and enables low cost production. A pre-load applying structure is configured to apply a pre-load to a bearing of a scanning part of a three-dimensional survey device. The three-dimensional survey device includes the bearing having an inner ring to which a vertically rotating shaft is fixed, a scanning mirror attached to the vertically rotating shaft, and a motor for rotationally driving the vertically driving shaft. The pre-load applying structure has a sleeve that engages with an outer ring of the bearing, a plate spring that detachably engages with the sleeve and is fastened to a housing body with a screw, and a ring that detachably join the sleeve and the plate spring. The plate spring applies the pre-load to the outer ring via the sleeve by elastic deforming.

In a power-transmitting mechanism with rolling-element bearing according to the present invention, an inner ring has plural inner ring members disposed in series in an axial direction, an outer ring has plural outer ring members respectively cooperating with the plural inner ring members. Plural rolling elements are disposed between the cooperating inner ring members and outer ring members. A retainer has plural partitions retaining the plural rolling elements at predetermined intervals in the circumferential direction such that rolling elements disposed between one pair of cooperating inner ring and outer ring members and rolling elements disposed between another pair of cooperating inner ring and outer ring members orbit the corresponding inner ring members in a synchronized manner, and a connector connecting the plural partitions such that the plural partitions integrally rotate around an axis.

A control method configured to control the preload of a bearing includes estimating the preload on the bearing; comparing the estimated preload with a predetermined acceptance range; and correcting the preload on the bearing when the preload is outside the acceptance range.

An adjustable spacer with hardened end portions and a non-hardened intermediate portion therebetween is mountable between a pair of roller bearings also mounted on a shaft such an axle or spindle or the like. The hardened material contacts the faces of the roller bearings but helps prevent wear therebetween and unwanted movement of the bearings on the shaft. The unhardened material allows the spacer to collapse in the axial direction to maintain desired axial loads on the bearings.

A double-row angular contact ball bearing for a CT scanning device includes an inner member including a pair of raceway rings. The raceway rings have positioning holes into which a positioning member is inserted, to thereby suppress radial decentering of the raceway rings. Both the raceway rings are fastened by fixing bolts. The raceway rings have opposed end surfaces, and are fastened by the fixing bolts to bring the end surfaces into abutment against each other to apply a preload at a fixed position between balls and raceway surfaces. The following relationship is set: Db/h0.26, where Db represents a diameter of each of the balls, and h represents a radial dimension from a center of each of the balls to an inner diameter of the inner member.

A bearing assembly unit (5) includes an outer holder (10) configured with a cylindrical member; an inner holder (20) that is configured with a cylindrical member, and inserted into an inner circumferential surface of the outer holder (10) so as to be movable in an axial direction; and a rolling bearing element (30) which is inserted into an inner circumferential section of the inner holder (20) so as to be fixed at least in a circumferential direction, and into which a shaft (40) is inserted so as to be fixed there; wherein, between the outer holder (10) and the inner holder (20), there is provided a rotation restriction mechanism (12, 22) that prevents a relative rotation between the outer holder (10) and the inner holder (20).