Importance

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Abstract

The apparatus adjusts the arching of the trowelling bar used in the heads of flat finishing boxes. The trowelling bar and the guide strip in which it is mounted form an assembly which, for use with the subject apparatus, is straight in its free state. The apparatus comprises two plungers which are attached with some angular freedom to the guide strip at its quarter points, i.e. the two points essentially midway between its center and each of its ends. When the plungers are moved upward the guide strip/trowelling bar assembly is arched upward. When the plungers move downward the assembly is arched downward. The plunger motions are caused and controlled by two leaf springs, the first disposed to move the plungers upward, the second downward. The influence of one spring is adjusted by a cam which is adjustable so that: (1) the influence of the springs are equal and the assembly is straight; (2) the influence of the first spring prevails by various amounts to produce varied upward arching of the assembly and (3) the influence of the second spring prevails by various amounts to produce varied downward arching of the assembly. In an alternate embodiment one leaf spring is replaced by two helical compression springs which serve the same purpose.

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First Claim