Geometrical instruments – Indicator of direction of force traversing natural media – Level or plumb – terrestrial gravitation responsive
Reexamination Certificate
1998-11-16
2002-05-07
Fulton, Christopher W. (Department: 2859)
Geometrical instruments
Indicator of direction of force traversing natural media
Level or plumb, terrestrial gravitation responsive
C033S451000
Reexamination Certificate
active
06381859
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a water level including a hollow metal section having at least one bottom measuring surface and side walls, and at least one position sensor, preferably a bubble level. Usually two bubble levels are provided. The metal section is closed by end caps.
2. Description of the Related Art
Millions of water levels of the above-described type are in use today in the world. They are used for aligning objects precisely in the horizontal and vertical directions. They are usually composed of an elongated base body having a rectangular cross-section and are made of wood, metal or also synthetic material.
Water levels with a base body of synthetic material are disclosed, for example, in DE-U 72 12 246 or DE-U 77 04 713. However, these water levels did not find acceptance.
The water levels used most are those whose base body is of a hollow section having a rectangular cross-section. The material of the base body predominately is light metal because this material can be shaped by the extrusion molding method and has a light weight and is corrosion-resistant. However, water levels produced from a hollow section are sensitive to impact. The water levels are indented and these indentations make the water level useless.
In many cases, the work piece to be aligned can only be brought into the correct position by means of a tool, for example, a hammer. If the water level is not to be damaged, it must always be removed from the workpiece and then subsequently must be placed on the workpiece once again. This is cumbersome and time-consuming.
In many fields of application it is necessary that the water level remains always placed against the workpiece even when the alignment is carried out by means of a hammer, so that a precise and fast result of the operation can be achieved. Typical examples are tile layers and brick layers. In these fields, impact-sensitive materials are being used increasingly today, for example, porous clay bricks, autoclaved aerated concrete blocks, tiles and plates. These materials are not placed in mortar, but are placed in thin beds of adhesive and are tapped with soft rubber hammers. This always makes it necessary to change the tool, which, in turn, makes the operation cumbersome. In that situation, it is better to press the brick or block into the adhesive bed by lightly tapping on the water level. The upper side of the water level is the only useful surface where tapping with a hammer can be performed. Since conventional hollow sections of light metal would be damaged by impacts from a hammer, in these fields of applications water levels are still used today with a base body of wood, although wood, as is well known, is less suitable for the manufacture of water levels.
SUMMARY OF THE INVENTION
Therefore, it is the primary object of the present invention to provide a water level in which the disadvantages described above are eliminated, and to further develop conventional water levels in such a way that impacts with a tool do not lead to damage.
In accordance with the present invention, a protective cap of an elastic, impact-proof material is placed on the upper side of the metal section and the protective cap is placed on the metal section in such a way that an impact energy introduced at a single point-like location is distributed over a larger surface of the metal section.
The protective cap according to the present invention distributes the concentrated impact energy produced by tools such as hammers, axes, mason's trowels, etc., over a wide surface area on the upper side of the metal section, so that the level is no longer damaged, indented, etc. Nevertheless, sufficient energy is still transmitted to the workpiece to be aligned. The water level no longer has to be removed from the workpiece, so that it is immediately apparent whether the work piece has reached the desired horizontal or vertical position.
In accordance with an advantageous further development of the invention, the protective cap is constructed in such a way that the impact energy is preferably introduced into the side walls of the metal section. This is of particular advantage if the metal section is of light metal.
In accordance with an advantageous feature, the protective cap is removably placed on the metal section. Consequently, the protective cap can be manufactured in a separate work step, can be cut to length and then slid onto the metal section of the water level. This also makes it possible to replace the protective cap when necessary.
For improving the support of the protective cap on the metal section, the metal section preferably has at least one key and the protective cap a corresponding groove or vice versa.
Suitable materials for manufacturing the protective cap are all impact-proof and still elastic materials. The preferred material is rubber, however, synthetic materials or wood can also be used.
In accordance with a preferred further development of the invention, the protective cap is of a composite material, wherein the inner layers are relatively soft and the outer layers are relatively hard.
The various features of novelty which characterize the invention are pointed out with particularity in the claims annexed to and forming a part of the disclosure. For a better understanding of the invention, its operating advantages, specific objects attained by its use, reference should be had to the drawing and descriptive matter in which there are illustrated and described preferred embodiments of the invention.
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Friedrich Kueffner
Fulton Christopher W.
Stabila-Messgerate Gustav Ullrich GmbH & Co. KG
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