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Although it has some advantages compared to the traditional [[lever filler]], such as greater mechanical simplicity and the aesthetic merit of not needing a lateral opening on the body of the pen, the main defect of this system, which decreed its substantial failure, was the greater ease with which the rubber tank could break due to the considerable effort imposed on it by the torsion.  

Although it has some advantages compared to the traditional [[lever filler]], such as greater mechanical simplicity and the aesthetic merit of not needing a lateral opening on the body of the pen, the main defect of this system, which decreed its substantial failure, was the greater ease with which the rubber tank could break due to the considerable effort imposed on it by the torsion.  

The system was mainly used by [[A. A. Waterman]] who around [[1902]] acquired a patent ({{Cite patent|US|744642}}, attributed to ''Harry W. Stone'') relating to it. Other companies introduced similar systems, or inspired by the same principle of rotating the bottom of the pen to squeeze the tank, such as the [[leverless]] of the [[Swan]]. A very particular version of this type of loading was used on a prototype pen of the [[Nettuno]] never marketed.<noinclude>

The system was mainly used by [[A. A. Waterman]] who around 1902 acquired a patent ({{Cite patent|US|744642}}, attributed to ''Harry W. Stone'') relating to it. Other companies introduced similar systems, or inspired by the same principle of rotating the bottom of the pen to squeeze the tank, such as the [[leverless]] of the [[Swan]]. A very particular version of this type of loading was used on a prototype pen of the [[Nettuno]] never marketed.<noinclude>

==Related Patents==

==Related Patents==

{{ListsPatentsFeature|Twist filler}}

{{ListsPatentsFeature|Twist filler}}

[[Category:Translated Pages]]

[[Category:Translated Pages]]

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