| 摘要 |
1,218,754. Holding device. G. R. POLGREEN. 26 June, 1968 [28 June, 1967], No. 29922/67. Heading H1P. A magnetic device for lifting and/or holding a load (24) comprises a polepiece (12), one or more permanent ferrite magnets (10) around the polepiece for forming a magnetic circuit with the polepiece and the load, and a coil (21) for reducing the flux in the circuit. The cylindrical polepiece 12 and annular plates 13 and 14 may be of mild steel. If D.C. source 22 fails then the load may be released by screwing down 18. Alternatively a lever may be used to release the load. The screw 18 and housing 16 may be aluminium whilst the coil is of edge-wound aluminium or copper wire. A plurality of brickshaped permanent magnets surrounding the polepiece 12 may be used in place of the annular magnet 10. |
