| 摘要 |
A rotary spindle, or a rotary sleeve mounted on a dead blade, is vibrationally-damped by means comprising an annular member capable of moving radially with the spindle, and in frictional contact with a second annular member which is not free to move radially, the members being biased together axially. In the case of a spindle in a footstep bearing, (a) Fig. 1 (not shown), the spindle foot revolves in a bushing in a first disc of smaller diameter than an outer fixed cup-shaped bushing; the resulting lateral space is occupied by an annulus of centering-material, and a second disc, which slides in the cup is urged against the first disc by a spring. (b) In Fig. 4, (not shown), the footstep is a conical cup inside a fixed bushing. The upper walls of the cup form a bushing for a collar bearing in which the spindle rotates, and have laterally extending flanges providing a groove for a centering-spring. The lateral extermities of the flanges are spaced from the walls of the outer bushing. The weight of the spindle forces the lower flange of the footstep against a fixed disc and a spring forces a sliding disc against the upper flange. In the case of a collar bearing for a spindle driven by gearing at its foot, (c) the outer race of the bearing has an external groove receiving a spring as centering-element and engages discs axially urged towards it by plate springs, Fig. 5 (not shown), (d) in Fig. 2 (not shown), between an outer bushing of the bearing and an outer fixed bushing are placed a number of annular discs one above the other. The discs are of smaller diameter than the annular space between the bushings to leave gaps between the discs and one or other of the bushings. Discs with the gap adjacent the bearing-bushing, alternate with discs with the gap adjacent the other bushing; some of the gaps are filled with resilient centering-material according to the degree of damping required. The discs are spring-urged together and have holes of decreasing diameters to receive grease for lubricating the contacting surfaces. (e) In Fig. 3 (not shown), between the bearing and fixed bushings are arranged two grooved annular discs kept apart by centering material in the groove of the first disc, while the second disc is separated from the fixed bushing by material in its groove. These discs rest on others, the meeting edges of which are chamfered, urged upwardly by springs separately adjustable by annular nuts; the upper surfaces of the first and second discs engage a fixed disc (f) finally, in a form, Fig. 7 (not shown), where a rotary drive is mounted on a dead blade, the upper part of the sleeve is coupled to the lower whorl part by teeth allowing relative movement between the two. The upper part runs on a bearing of which the bushing is separted from the blade by a series of superposed annular discs, of which discs slidably keyed to the blade alternate with discs separated from the blade with gaps filled with centering-material. A resilient coil on a fixed platform urges the discs against a fixed upper disc. The discs may be made of brake lining or plastics material and such discs may be disposed between metal discs when metal discs are used, the contact surfaces may be coated with molybdenum sulphide. |
