| 摘要 |
An electromagnetic clutch for a vehicle engine cooling fan includes a driving member mounted for rotation by the vehicle engine and a driven member rotatably mounted on the driving member. The driven member carries the engine cooling fan. One end of a band is connected to the driven member, and wraps circumferentially around the driving member in the direction of the rotation of the latter. An electromagnetic coil comprising windings wound circumferentially around the driving member and rotatable therewith exert an electromagnetic force on the band when current is transmitted to the coil, drawing the band into engagement with the outer circumferential surface of the driving member, to thereby engage the clutch and cause the engine cooling fan to be rotated with the driving member. The radial outer edge of the spool, which is engaged by the band when the clutch is engaged, is provided with alternating castellations or projections which cooperate to define a gap having segments extending obliquely with respect to the edges of the spool. Accordingly, the contact area is distributed across the band instead of being concentrated along the edges of the band, thereby substantially decreasing wear on the band and thereby increasing its useful life.
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