812671-A is referenced by 209 patents.
812,671. Flooring units. PIODI, R. May 24, 1957 [June 27, 1956], No. 16585/57. Class 87(1) A rubber &c. flooring unit has undercut tongues 2, Figs. 1, 6, on two adjacent sides and corresponding grooves 3 in the other two sides, each tongue having one end flush with the bottom of the adjacent groove and its other end spaced from the adjacent corner of the unit. The grooves may be closed at the ends remote from the tongues (Fig. 9, not shown). The tongues and grooves may be interrupted and spaced by gaps; in a rectangular unit, the groove in the longer side may be continuous to facilitate sliding engagement with an adjacent unit while the groove in the shorter side is interrupted and can be engaged with the spaced tongues on an adjacent unit by a "snap action".; An alternative form of tongue, Fig. 8, has a crosssection consisting of an arrow-head 12A connected to the unit by a stem 12B, the head 12A being slightly smaller than the part 13A of the groove while the stem 12B is slightly longer than the part 13B. The surfaces 15 above and below the tongue are inclined so that the angle c is less than 90 degrees. Intersecting grooves 5 are formed in the lower face of the unit and the upper edge may be rabbeted at 7, Fig. 6. The unit comprises an upper layer 1 of hard rubber and a lower layer 4 of softer, preferably spongy, rubber or a rubber mix with a cotton filler.