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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 parts

Part 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.

When first introduced in 1919, part 31 had 40 teeth.  These were only made for a couple of years, and are highly sought-after gears useful for making odd ratios in orreries and gearboxes.

Chronological variations

Other 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.

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 numbers

Part 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).

Description	from	31
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
		ALL

Please send us pictures of missing parts! Hints and tips for pictures
Take a picture of the part in very good light, preferably on a plain yellow background, without a flash but with a tripod.
Ideally, trim the picture to about 150 pixels per inch of the Meccano part (unless the part is particularly big or small), save it as a reasonably good quality jpg file with a filename of exactly the part number, for example 19b.ni1.jpg, and email it to us by clicking on 'Contact us' at the top of the page. Thanks!

• A greyed-out box shows that no part exists for that colour combination.
• Part number codes with a green background have an attached picture of the part, just click once on the code to show a photograph of that part in a separate window.
• Parts marked "†" were temporary or economy parts, or existed only within specific themed outfits. The previous part continued throughout or afterwards.

Further information

Total number of messages on this page: 9.  This is page 1 of 2.   

Brian Maunder      (at 11:04am, Thu 10th Sep, 20)

I have a double tapped 40 tooth gear.

Staffan Kjellin      (at 3:11pm, Sun 1st Feb, 15)

Look at: http://www.nzmeccano.com/image-85413 Mekanik no. 62 compared to Meccano no. 31 gear wheel 1"

Peter Bentley      (at 7:55am, Sat 22nd Nov, 14)

Hi Richard thanks for your prompt reply. My dad stopped buying Meccano in the 1950's so can't think where they came from.I think you bought stuff off me a couple of years ago and gave me a lot of information. If you give me your address I would willingly let you have these free of charge. You can e-mail me at peteb912@gmail.com Regards Pete

Richard Payn      (at 7:39am, Sat 22nd Nov, 14)

Hi Peter, They sound like either repro gears or poorly manufactured ones from the 1970s as they weren't stamped.

Peter Bentley      (at 6:15am, Sat 22nd Nov, 14)

Hi, sorry to bother you again, but I am clearing out my Dads meccano and have found two part no 31 that are totally different from the ones you describe. They are solid brass and mesh with 38 tooth wheel. They have no stampings on them and only have one side flanged, the other side is flat. The boss is double tapped. The rim is slightly narrower than the standard wheel.Hope you can enlighten me,

Andy Knox      (at 12:26pm, Thu 15th Jul, 10)

The 1" gear also meshes perfectly with the 15 tooth pinion (26c) on diagonally adjacent holes.

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