Brushing – scrubbing – and general cleaning – Implements – Mason's trowel or float
Reexamination Certificate
2000-11-16
2003-05-27
Chin, Randall E. (Department: 1744)
Brushing, scrubbing, and general cleaning
Implements
Mason's trowel or float
C033S334000
Reexamination Certificate
active
06568021
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates generally to hand tools for finishing concrete, plaster, and similar materials, and more specifically to a trowel or float which includes leveling means for measuring the inclination of the trowel and underlying surface when finishing a level or sloped floor or smoothing a sloped wall.
2. Description of Related Art
The concept of using a flat, smooth tool for finishing a hard setting material before it sets, has been known for ages. As the technology developed, different types of trowels or floats were developed in order to facilitate the operation using different materials and under different conditions for forming differently shaped structures. Heretofore, such trowels and floats have universally depended upon the skill of the user to provide a smooth and level surface, or to impart a desired slope in a floor for drainage or the like. While a skilled worker can produce reasonably accurate work under these conditions, some means of indicating the level or slope of the surface being worked, is almost always required. Accordingly, workers finishing concrete, plaster, etc. almost always resort to the use of a separate level, which is generally periodically placed across the surface in at least two directions in order to determine the level or slope of the surface.
This use of a separate level indicator, and the need to stop work to position and reposition the level as required, obviously results in additional time and expense for the worker, which is of course passed on to the end user of the structure. Accordingly, a need will be seen for a finishing trowel or float which incorporates some form of level indication means therewith, allowing the worker to quickly and easily determine the level or slope of the surface upon which he is working without need for a separate level indicator device.
A discussion of the related art of which the present inventor is aware, and its differences and distinctions from the present invention, is provided below.
U.S. Pat. No. 1,490,220 issued to William C. Lawrence on Apr. 15, 1924, titled “Bricklayer's Trowel,” describes a trowel having an asymmetrical rhomboid blade with a cantilevered handle extending from the more blunt end of the blade. The handle includes a single spirit level, aligned with the elongate axes of the handle and blade. The single spirit level of the Lawrence trowel can at best indicate the level of the underlying surface in only a single direction or orientation; the Lawrence trowel must be reoriented for each direction in which it is necessary to check for level. In contrast, the present trowel or float with levels includes at least two mutually orthogonal levels, enabling the device to determine level simultaneously in two mutually perpendicular directions. Moreover, the cantilevered handle of the Lawrence trowel is prone to bending between the handle and blade, thus making the Lawrence level inaccurate. This cannot happen with the present trowel and levels, as the handle extends across the center of the blade and is secured at each end of the handle to the blade. In addition, the present trowel and levels also provides for electronic leveling means, which may produce an audible signal so the worker need not divert his visual attention to the level displays themselves.
U.S. Pat. No. 2,198,974 issued to Charles D. Pilant on Apr. 30, 1940, titled “Plasterer's Float,” describes a float or trowel with an arched handle secured across the float blade or plate. The blade is symmetrically tapered in planform from its center, and includes a slight upward angle to each blade half from a lateral centerline and an upwardly turned outer edge or fence along each edge. The Pilant trowel or float is intended to reduce the tendency for the device to cut or plow into the still plastic surface of uncured plaster or other material being worked. No leveling instrument or means is provided by Pilant for his float or trowel.
U.S. Pat. No. 2,771,325 issued to Leigh S. Brunson on Nov. 20, 1956, titled “Cement Mason's Float,” describes a trowel or float wherein the plate or blade portion is formed of extruded magnesium material. A central rib or spine is formed along the plate, with sockets machined therein for accepting the ends of a removable handle attachment. The general configuration only superficially resembles that of the present invention, and in any event, the Brunson float has no provision whatsoever for any level indication means therewith, as provided by the present trowel with levels invention.
U.S. Pat. No. 3,140,500 issued to Anthony Pilla on Jul. 14, 1964, titled “Floats For Spreading Concrete Or The Like,” describes a float having an arched handle secured to the float blade or plate by screws. The blade or plate is formed of an acrylic plastic material, with the bottom surface thereof being finished in a regular pattern of rhomboid, circular, or elliptical geometric shapes. A generally U-shaped handle is secured to the upper surface of the plate by screws which pass through the plate. The resulting configuration is generally conventional, with no level indication means being provided with the Pilla trowel or float.
U.S. Pat. No. 3,302,233 issued to Martin Sebastiani on Feb. 7, 1967, titled “Mortar Dressing Device,” describes a wedge shaped tool having a hollow core. The tool has no handle means, but may include a pair of mutually orthogonal bubble or spirit levels set into open windows or passages through the blade body. The placement of the levels in the blade body itself, greatly increases the chances of the levels becoming covered with mortar, plaster, or other material during the working process. In contrast, the present trowel with levels places the level indicator means in the handle, well away from the trowel blade or plate portion of the tool, to protect the levels from contamination or impact with other objects.
U.S. Pat. No. 5,046,387 issued to Rodney D. Levake on Sep. 10, 1991, titled “Stabilized, Multifunctional Tool Handle,” describes a large number of embodiments of various tool handles, some of which include level indicators therein. Levake also discloses plasterer's floats or darbys with handles, each of which incorporate a single spirit level therein. The drawbacks of having a single level indicator in the handle of such a device, were noted further above in the discussion of the '220 U.S. Patent to Lawrence. In contrast, the present trowel with levels incorporates at least two mutually orthogonal levels in the handle thereof, so the user may quickly and easily determine the level or slope being worked, simultaneously in two mutually perpendicular axes.
U.S. Pat. No. D-230,466 issued to Maurice H. Miller on Feb. 26, 1974, titled “Wall Washing Trowel,” illustrates a design for a trowel which incorporates a nozzle and controls for pressure washing. No level indicating means is apparent in the Miller trowel design.
U.S. Pat. No. D-238,652 issued to William S. Halvala et al. on Feb. 3, 1976, titled “Concrete Finishing Tool,” illustrates a design for a trowel having a handle attached at two points to the underlying blade or plate. No level indicator means is apparent.
U.S. Pat. No. D-289,882 issued to Donald Gringer on May 19, 1987, titled “Trowel,” illustrates a design for a trowel with an open handle secured to the underlying blade or plate. No leveling means is apparent in the Gringer design.
U.S. Pat. No. D-296,294 issued to Roy M. Neece on Jun. 21, 1988, titled “Concrete Trowel,” illustrates a design for a trowel with an open ended handle secured to the blade or plate. The handle is grooved or inset along the sides thereof, but no leveling means is apparent in any component of the Neece design.
U.S. Pat. No. D-323,271 issued to Roger S. Barenthsen on Jan. 21, 1992, titled “Adjustable Trowel,” illustrates a design for a trowel which blade includes a live hinge along the centerline thereof. Two arcuate arms extend from each blade portion, with a handle extending between the arms at each end. The arms may be adj
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