I built this demonstration model of the Schmidt offset coupling following postings on the ”Spanner" internet mailing list back in 1998. Meccano enthusiast Edmundo Veiga from Brazil visited a now defunct web site called "Puzzling Gears", an illustration from which is shown on the left. This lead to the eventual construction of my model. Part of the correspondence is produced below.

The mechanism is fascinating to watch. I have altered the original IsoMec version (see illustration below) to show both vertical and horizontal movements but have used the same coupling mechanism. I believe the mechanism is used in offset litho printing machines to move the printing rollers away from the printing plates whilst the machine continues to run.

Dear Spanners, In the message below, Edmundo drew our attention to some very interesting creations. One of the mechanisms, the Schmidt coupling, has been beautifully drawn using the IsoMec clip art program for Meccano construction, the details were published in the July 1998 issue of the Johannesburg Meccano Hobbyists Newsletter. The accompanying text said, with little else: ”We put it together and it works" ! This type of coupling would be used to transmit a drive between parallel, but offset, shafts. It is, in fact, a link version of the double slider coupling, but would be able to cope with a much greater offset, particularly under load.

Well, having this perfect IsoMec drawing in front of me(shown above), I put it together, concocted a suitable framework to hold the input and output shafts - offset by about an inch and a half - then away we went .... what a beauty! I must say this mechanism is a delight - its motion is a treat to behold, it operates smoothly, and it would transmit all the torque you could possibly wish - at least until the joints began to wear excessively. Graham Jost, Melbourne, Australia.

Page revised April 28 2015

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