Printed from www.nzmeccano.com
Two varieties of 2 inch pulley
I've just noticed that the 2" Pulley, part 20a, has two variations of the common stamped 'quartered' version. This difference is beyond the obvious difference in the width and size of the groove. The difference follows a change in the 3" Pulley, 19b, when the tooling was changed around 1927 so that the two stampings could be made from the same tooling. The left version (both sides shown, and stamped "Meccano" three times around the boss on one side) has four plunged holes on one side, fitting in four oversize holes in the other side. The plunged holes produce short tubes, which then are 'riveted' over to hold the two plates together. In the version on the right (each side marked "Meccano" and "Made in England"), each plate has two plunged holes, and two oversize holes, making the two plates identical.
Timothy Edwards' site has the drawing of this part, with a 1933 revision describing this change.
All of the pulleys here are tapped 5/32" BSW; the ones on the left are single tapped, and those on the right are double tapped.
The tools either side are home made for checking 5/32" BSW and #7-32 threads.
Log in to the gallery
NP (at 8:03pm, Thu 1st Oct, 20)
There are nickel plated 2" pulleys (with the regular narrow V) which have the same method of holding the plates together as the black ones.