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Part 31: Gear wheel 1''
|31||Gear wheel, 1'' 38 tooth||1919||-||4||4||2||N°10||40 tooth until 1921|
The partsPart 31 is a lovely heavy solid brass gear, only ever supplied in the largest outfits (outfit 7, L, and 10). They provide a 1:1 drive when paired together at 1'' spacing, and although they can be used with other gears at odd spacings this is unusual. Since they are normally used in pairs, they can often be substituted by the multipurpose gear part 27f, introduced in 1970.
Both of these gears have 38 teeth, though.
Chronological variationsOther than the change from 40 teeth to 38 after the first two years of production, the main difference between different versions of these gears is in the outside diameter. Initially 27mm (to fit the 40 teeth round), the gears stayed this size when the number of teeth were dropped to 38, leaving the gear effectively oversized. In 1927, the outside diameter was dropped to 26mm, but this was a bit overzealous, and these pre-war gears don't mesh together very well. The photo above shows the largest (1921-26) and smallest (1927-41) versions of part 31.
The post-war variations increased in size a little to an intermediate size, around 26.5mm, making them work better together as pairs. Almost all of these gears are stamped Meccano, although the stamping ceased in the mid-70's.
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Variations and oddities
A real oddity on the stamping front is supplied by Ed Barclay. This 1'' gear wheel is from a collection of 1930's Meccano, and is stamped on the face MFEA. However, on the end of the boss we can clearly see Made in England. This is a very unusual stamping, particularly for a pre-war part.
And now, Chris Mothershaw describes a very unexpected use for part 31:
Dealer spare parts boxes
Individual part numbersPart numbers for the parts on this page are as follows: Unique part numbers
For identification, each variation has been given a suffix to the main Meccano part number. These suffixes consist of a two-character code for the colour, and if there are many variations, a further number and sometimes letter code to identify each variation. See the bottom of the 'Parts' page for further details.
You don't need to worry what the codes are, just click on any one for a photograph.
The button above turns on and off the display of DMS numbers (where they are known). The DMS (Development of the Meccano System, Hauton and Hindemarsh) published in 1972 and added to in 75 and 82, suggested part numbers for every variation of every Meccano part. These numbers aren't perfect, but they are recognised and also referenced in the EMP (Encyclopedia of Meccano Parts, Don Blakeborough).
|40 tooth, ¼'' face, 27mm o/a diameter||19||.br1|
|38 tooth, ¼'' face, 27mm o/a diameter||21||.br2|
|38 tooth, ¼'' face, 26mm o/a diameter||27||.br3|
|38 tooth, ¼'' face, 26mm o/a diameter, double-tapped||29||.br4|
|38 tooth, ¼'' face, 26.5mm o/a diameter, double-tapped||46||.br|
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The Infamous Chris Mothershaw (at 11:23am, Thu 5th Mar, 09)
Hi - I've a pair of the '.br4' variant of this part that are nickel plated, though clearly brass underneath. I've not come across this before. Is it common?
Harley Carter (at 2:09am, Tue 25th Sep, 07)
The 1'' gear wheel also meshes perfectly with a 3'' diam rack segment, part 129. I was under the impression that this was its original purpose. I think both these parts were introduced at the same time, but the rack segment was discontinued. Part 31 also meshes diagonally with a 15 tooth pinion and with a 95 tooth gear wheel, and of course it will mesh with a worm. It is a very handy part to have.