The patent document describes an important improvement in the mechanism of a manual hand drill, especially a breast drill. The invention was made by George O. Leopold from Philadelphia, Pennsylvania, and the patent was granted on August 14, 1917. The main purpose of this invention was to improve the clutch mechanism used in hand-operated drilling tools.
In a manual drill, the user turns a handle to create rotational movement. This movement is transferred to the spindle, which holds the chuck and the drill bit. However, older drill mechanisms had limitations in speed control and locking ability. Leopold’s invention aimed to solve this problem by using a clutch system connected to two different gear wheels. These gear wheels could rotate at different speeds, allowing the spindle to operate at either a slow speed or a high speed.
One of the most important features of this design is the shifting key. This key can move inside a slot in the spindle and engage with either one of the two gear wheels. When the key engages one gear, the drill works at one speed. When it engages the other gear, the drill works at another speed. This made the tool more practical because the user could choose the proper speed depending on the drilling task.
Another useful feature is the central locking position. When the key is moved to the middle, it engages both gear wheels at the same time. Since the two gears rotate differently, they lock each other and stop the spindle from turning. This helps the user open or close the chuck more easily and safely.
Overall, this patent shows how manual drills became more advanced before electric drills became common. It improved control, efficiency, and usability. The design also shows the importance of gear systems, clutch mechanisms, and user-friendly engineering in early hand tools.
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