| 摘要 |
The head drum of VCR comprises a shaft (1) forming grooves (1a,1a',1b, 1b',1c) on the circumference surface, an upper drum (4) including rotary heads (2,2') and fixed on a flange (3), a lower drum (5) fixed on a motor stator (7), a motor rotor (13), and a motor magnet (14). The shaft is formed to tube type at which a number of holes (11,11') for flowing the air are there at the middle position of the grooves. The air pressure difference between the shaft and a housing (6) is occured by rotation of the shaft. Then the outer air flows into the grooves and holes so that enough air increasing the lubrication effect of the bearing is supplied between the shaft and housing.
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