| 摘要 |
1,217,159. Positive clutches; controlling clutches. COVENTRY GAUGE & TOOL CO. Ltd. 3 March, 1969 [5 Dec., 1967], No. 55279/67. Headings F2C and F2L. An overload release clutch comprises driving and driven rings 1 and 2 carrying dog teeth 21, 22 and drawn into engagement by a magnet or electromagnet 3 against a spring 6, the sides of the dog teeth being inclined so that when the transmitted torque exceeds a predetermined value the teeth cam over each other to move the members 1 and 2 axially apart until the air-gap 14 is too large for the magnet of electromagnet 3, and spring 6 disengages the clutch. As shown, the ring 1 is fast with a rotating electromagnet 3, and ring 2 is fast with armature 4. Again, the ring 1 may be bearing mounted on a stationary magnet or coil. To ring the predetermined overload torque, the coil 11 is in series with an adjustable resistance (12), Fig. 3 (not shown) which may be set to determine the coil current and hence engaging force of the electromagnet. A switch (10) is mounted parallel to the resistance to enable initial engagement of the clutch. Closure of the switch by-passes the resistance and allows maximum current to flow in the coil to engage the clutch. With the switch open, even when the resistance is at its minimum setting, the current is not large enough to engage the clutch across the air-gap 14. |
