Godtfred Kirk Christiansen´s firm belief in the LEGO® brick and the LEGO System in Play drives the company to search for a way to ensure just the right clutch power between the bricks. The LEGO System’s basic element needs improving in order to live up to the product idea and the company’s quality standard. All bricks up until this point are hollow, reducing the stability of constructed models and this generates complaints from the markets, and competitors are moving in. In the mid-1950s, an intensive search begins for the best possible clutch power (the ‘grip’ between interlocking elements) in both raw material and bricks.
After two years’ hard work, the company can present its new interlocking principle. A system that, with studs and tubes, create clutch power. Clutch power provides stability and endless possibilities for combining bricks. With the new stud and tube principle it is possible to combine six 2x4 bricks in 915.103.765 different ways. After inventing the tube solution, Godtfred Kirk is anxious. The ingenious interlocking principle has to be properly protected. On January 28, 1958 at 1:58 pm, the LEGO Group submits a patent application for “a toy building element”. Enclosed are drawings and physical bricks showing every conceivable interlocking option.