Chairs of Adjustable Height for Use in Concrete Constructions

1. Field of the Invention

This invention relates to novel spacing devices, or chairs, as employed in the construction of concrete slabs, or beams. In particular, it relates to chairs of adjustable height for such usage.

2. Background

It is known to use various styles and forms of spacing elements for supporting and retaining concrete reinforcing materials, e.g., wire mesh, reinforcing rods, bars and the like, in elevated position while pouring and forming plastic, plastic-like and concrete forms, e.g., concrete slabs, or beams. Most are rigid members, constructed of plastic or metal; generally, iron or steel. These spacing elements, generally referred to as chairs, hold the wire mesh or rods above and away from the foundation or surface upon which the slab or beam is formed to enhance the strength of the finished slab, or beam. When the wet concrete is poured, the latter covers both the supports and the wire mesh or reinforcing rods; and all becomes a part of the finished slab, or beam, after the concrete has set.

It is particularly important to properly position the wire mesh or reinforcing rods within the slab or beam to enhance its strength. Most chairs sold in the marketplace are of rigid shape and of fixed height though the chairs are manufactured and sold in different specified heights. The mesh or reinforcing bar is held by a specified chair at a fixed preselected height above ground level. Since adjustment of the vertical height of a chair is not possible with devices of given height, it is thus necessary to use chairs of given preselected height for the slab poured at each jobsite; and since the thickness of poured concrete slabs are obviously not always the same this means that a supplier must furnish chairs of different heights for slab, or beam constructions of varying thicknesses. Obviously the thickness of a slab, or beam will vary from one jobsite to another; sometimes even at the same jobsite. For example, one manufacturer furnished "high chairs" made with fixed heights ranging, in one inch increments, from 2 inches to 18 inches; chairs of the same style and form having 17 different heights sized in one inch increments between 2" and 18". A special order is placed for high chairs of height greater than 18". This lack of standardization creates major problems for the supplier, not the least of which is that he must find storage space for all the different sizes of chair; albeit chairs of the same style and form. Moreover, chairs of the required height must be sent to the jobsite or the chairs cannot be used. Variations in the thicknesses of slabs, or beams at the same jobsite intensify the supply problem. Thus, there exists a need in the industry for greater standardization of these devices.

3. The Invention

The present invention accordingly, to meet this and other needs, relates to a novel chair of adjustable height which can be readily used in pouring plastic, plastic-like, and concrete forms, especially slab, or beam constructions, of different thicknesses.

The chair of this invention is constituted of three basic components, an upper cap, an intermediate member, or stem, and a base. The cap, upon which the mesh or reinforcing bar to be encapsulated into the cement is in direct physical contact, is constituted of a recessed, notched or slotted support surface in which is rested the mesh or reinforcing bar. The stem forms the connecting element between the cap and the base, a member which is most conveniently supplied at the jobsite suitably by cutting a concrete reinforcing rod into a length appropriate for the thickness of the slab or beam to be constructed. The base is constituted of a multileg member, suitably as a unitary structure the lower side of which is flat, or provided with projecting feet, and the upper side of which contains an opening or receptacle in which the lower terminal end of the stem can be inserted, secured, and supported. The cap is mounted upon the opposite terminal end of the stem. The height of the chair is determined by the sum-total of the height of the cap, the base, and by the stem which is cut at the jobsite to the length desired to adjust the chair to the desired height.

A supplier need only stock the caps and bases, as items of standard size. At the jobsite a chair of the height needed for the slab, or beam construction is prepared for use by a workman who cuts stems as needed of the desired length from an iron concrete reinforcing bar with shears or saw.

These and other characteristics of the chair of this invention will be better understood by reference to the following detailed description. In describing a preferred embodiment, reference is made to the drawing.

In the drawing:

FIG. 1 depicts an exploded view, in isometric form of the three components of the chair; inclusive of a stem which is located between the cap and base.

FIG. 2 depicts a section view of the chair as used in the support of a concrete reinforcing bar.

Referring generally to FIGS. 1 and 2 there is shown a cap 10, a stem 20 and base 30; these components, when assembled, constituting a complete chair. Cap 10 and base 30 are preferably molded shapes supplied in standard size to a jobsite, and stem 20 is produced at the jobsite.

The cap 10 embodies a tubular member having a lower opening formed by an enclosing side wall 11, and upper enclosing wall 12 providing a receptacle 13 within which the upper end of the stem 20 can be fitted, and held in place. The upper surface of the cap 10 is provided with a slot 14 within which a reinforcing bar 16 can be held in place, and supported (FIG. 2). A pair of ears 15.sub.1, 15.sub.2 are optionally, and preferably provided, for use in using wire to tie down the reinforcing bar 16, supported therein; if desired.

The base 30 constitutes the foundation, or bottom support for the cap 10, and stem 20. It is preferably constituted of a multilegged unitary structure at the center of which is located an upwardly opening tubular member formed by an enclosing side wall 32, and enclosing bottom wall 33 forming a receptacle 34 into which the lower terminal end of the stem 20 can be held, and supported. On one side the legs 35.sub.1, 35.sub.2, 35.sub.3, 35.sub.4 are secured to the receptacle portion 34 of the tubular member, and on the other by the encircling ring member 36 which creates the unitary structure. The bottom of the base 30 may be flat; or, optionally, both flat and arrayed with feet 37.sub.1, 37.sub.2, 37.sub.3, 37.sub.4 for supporting the chair upon a concrete form or other type of rigid foundation.

The external diameter of the stem 20 approximates the internal diameter of the receptacle portion of tubular member 34, and tubular opening 13 within the cap 10. The lower terminal end of the stem 20, conveniently a concrete reinforcing rod cut on the job to the desired length, rests in the receptacle portion, or upper opening of tubular member 34, and the upper end thereof is fitted within the opening within the cap 10. The height of the chair is determined by the height of the cap 10 and the base 30 which is fixed, and the readily adjustable height of the stem 20 which is controlled by the worker who cuts it to the desired length at the jobsite.

It is thus no longer necessary to supply the whole chair to a jobsite. A supplier need only supply standardized caps and bases. The height of the chair needed or a jobsite is there decided, and lengths of concrete reinforcing rod are cut to the length necessary to provide, with the caps and bases, chairs of the desired height.

Various changes, such as in absolute or relative dimensions of the parts, materials and the like, can be made without departing the spirit and scope of the invention, as will be apparent to those skilled in the art.