Date: Pat. pend.

This site is about LEGO® from the period 1949 until 1974. Also called the 'pat pend period'. In 1949 the first plastic Automatic Binding Bricks are made, the predecessors of the modern LEGO. In 1974 the first LEGO Mom is made.

Until 1974 there were just bricks (and flags, trees, trains, etc) with which houses and cities could be build, but no people to live in these houses and cities. Beyond 1974 LEGO is developing enormously. With many different types of minifig and themes like pirates, space, technic, etc.

Pat pend

Pat pend stands for patent pending, or patent in request. In 1958 patent is requested on the stud-tube-technic which we see today in all the bricks. Because of this patent the specific gripsystem, with which the LEGO bricks stick together but can also be seperated again, it cannot be duplicated by others (read: competitors). This patent is granted in 1962.

Much parts until approximately 1974 has the words 'pat pend' printed on the plastic. That is why this period is also called the pat pend period.



Symbolical, pat pend stands for sets released in that period. These sets are (obviously) completely of partly build from 'pat pend' LEGO.

The exact boundary is not known. Set 393, the Norton Motorcylce, for example, is released in 1976 and contains at least 3 non'pat pend' LEGO parts. The arch 1 x 4 in black, and the two parts of the steering-hinge in red..

Others sets, like the 644, the Police Mobil Patrol, released in 1978 contained subtantially non-'pat pend' LEGO, but it did have pat pend (obscured) plates in black. (That is my personal version from back then.)

During this period-transfer, from pat pend to modern if you like, new produced (non pat pend) LEGO is used in combination with (probably) stock supplies of older pat pend LEGO. This supply was of course used and not thrown away.

Pat pend obscured

Some LEGO parts have a kind of stain printed, at the place where before 'pat pend' would be printed. As if the words 'pat pend' have been obscured. This is a distinguishing mark of LEGO in the transferperiod from pat pend to modern.

Moulding-pip

Not all old LEGO has the words 'pat pend' printed. Many parts simply did not have room for it. Nevertheless these parts from the pat pend period can be recognized. First because these parts are not produced any more, but in this period only.

Second because these parts have 'moulding-pip' on the side. A moulding-pip, is the place where the opening of the mould was. Modern bricks have the moudling-pip on one of the studs, a place where it does attract attention the least.

Older bricks have the moulding-pip on the side. By itself the moulding-pip has nothing to do with pat pend, these two things are completely seperated. However, modern bricks with the moulding-pip on a stud, are produced starting approximately 1974. At first very few parts but later on many more. Between 1974 and 1979 sets did have mixed bricks. Beyond 1980 sets did have modern bricks only.

Conclusion

Pat pend has to do with LEGO parts in the first place. It is almost always possible to tell if a part is from the pat pend period, because of these distinguishing marks. With sets this is not so easy. Sets until 1974 almost certain completely build with pat pend LEGO. Sets from 1974 until 1979 are partly or completely build from pat pend LEGO parts and / or pat pend obscured. Sets beyond 1980 are most likely build from moderne LEGO parts only.