(2020-06-03, 20:59)Max Martin Richter Wrote: The half bush (4265) was changed in from a-variant to b-variant in 1993 and from b-variant to the smooth reduced axle hole version in 1998 (312123a) and again to the semi-reduced axle hole version (32123b) in 2008.Thanks. These are some great checks for OMR. I have introduced "phase in" as a concept in order to highlight the time where both versions of an element are in production and I have checked with Bricklink in order to ensure that the checks are not too strict. While I agree with your points (this is also how I remember sets), it seems that Bricklink has rather large periods of overlap. I have left these phase in periods lenient for now.
BTW I have two set from 1990 still containing the 4459 pin. :-)
Some sets from 1992 I own, still have the 4273a-version, but the b-version was introduced in this year. (Change to smooth version (32126) was in 1998.)
Only sets produced in 1994 contained the 6542a clutch gear in black (I know at least on 8880 set and one 8858 set, where it is black). The 1993 set 8824 and all sets produced after 1994 had them in dark grey only. (6542b was introduced in 2011.)
In 1996 the axle joiner 6538a (introduced 1993) was changed to 6538b. In 2008 it was replaced by the smooth version.
In 1997 the axle 2L (3704) was replaced by the notched version (32062). Furthermore the 24T gear (3648a) was replaced by 3648b.
In 2001 the 3L Pin without friction (32556) was introduced.
In 2003 the pneumatic system changed the first time to studless design (new cylinder and new valve)
In 2008 the U-Joint 4L was replaced by the U-Joint 3L.
In 2009 the Pin Joiner (75535) was replaced by the slotted version (62462).
In 2011 the 16T Gear (4019) was replaced by the reinforced version (95925).
In 2012 the technic triangle (2905) was replaced by 99773.
In 2013 the 8T Gear (3647) was replaced by 10928.
In 2015 the pneumatic valve (and all continued pneumativ parts) where changed to stepped outlet.
I'm not sure, when the small wedge belt wheel was changed (4185a/b) - I assume late 80s or very early 90s. I'm actually not sure when the Pneumatic T-Piece was changed from straight to reinforced version - I assume it was in 1993? And I have no idea when the 24T crown gear was changed through its versions. The Reinforced first appeared in a set from 1990 in my collection, but there was a change from version a to b, which I don't know.)
For anyone who would like to use the information, it is all hosted in this pli.js file and you can hotlink it without giving it a second thought
Bricklink doesn't distinguish some parts (such as crown gear type A and B) so I don't have proper timelines for those. I will add other parts, such as jumper plates, tiles, arches, etc. when I find time.