| 摘要 |
The magnet is mounted on a carrier that can be extended from and retracted into a magnetic shield that is affixed to the distal end of an extended hollow flexible tube. A stiff control wire is connected at its distal end to the magnet carrier, and its proximal end is connected to a knob that is moved distally with respect to the hollow flexible tube to push the magnet carrier partially out of the magnetic shield thereby exposing the magnet for use. A soft steel insert is bonded to the proximal side of the magnet, and its presence increases the pulling force of the magnet by 12 to 15 percent. At the proximal end of the tool, a compression spring acting between the hollow flexible tube and the knob keeps the magnet biased within its magnetic shield. When the magnet has been exposed by pushing the control knob in a distal direction, the magnet can be locked in the exposed position by a simple latch that prevents inadvertent withdrawal of the magnet after the sought-after object has been acquired.
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