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Parts 28 & 29: Contrate Wheels
The term 'contrate wheel' is a fairly unusual synonym for what is more often known as a crown wheel (because its appearance is similar to a crown). For the first few years, Hornby referred to this as a "contrite wheel" (sic), but at least that was corrected. The word 'contrate' is probably only still used today because of its inclusion in the Meccano system.
| 28 | Contrate wheel, 1½'' 50t | 1902 | - | 3 | 2 | 2 | N°8 | |
| 29 | Contrate wheel, ¾'' 25t | 1902 | - | 4 | 2 | 2 | N°8 | |
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The parts
Two very early parts in the Meccano system, designed to transmit drive when the axles are at 90 degrees. Later on, bevel gears were introduced to do the job better, but contrates were by that time stamped out from sheet brass and thus much cheaper to make. Although they were only included in outfits from 8 upwards in the 1937-on sets, they were included in the Gears outfit and thus are very common parts.They are also used as clutches, since a pair of equal size mesh perfectly and only take a fraction of
a revolution to do so (unlike the dog clutch, which can take up to half a revolution). The 50-tooth
part 28 also meshes perfectly with a 50-tooth gear part 27. Since the large contrate is a common part
with 8 holes it is often used as the crown wheel on a differential, and the smaller contrates used inside
the differential instead of bevels. Sadly, part 28 was never made with six
holes and therefore cannot be easily used to make a spur differential.
Chronological variations
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Clive Weston
The first contrate wheels were milled from solid brass, before the invention of the patent boss in 1911. The photo
to the right of three different solid small contrate wheels shows the variation in size of these early
contrates.
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Please do not download or copy it for any purpose. It has been
kindly provided for use on this site by the image owner,
Richard Payn
With the introduction of the plastic gears in 1979, the same variations are seen with the boss as happen with the
spur and pinion gears parts 26 and 27. Initial
UK-produced parts have a slightly longer boss than the later ones. Parts marked Meccano
England have a long boss, but some are known with a shorter boss. These may have been parts manufactured
in France in the early 80's. Later French parts (with the stamping just Meccano)
have shorter bosses, as do the 1990's versions in black.
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Michael Conduit
Variations and oddities
Here's a strange duck – a nickel-plated contrate. The stamping appears to be late pre-war (about mid-30's), but it is nickel plated as you can see by the brass one next to it. The tappings are brass internally, showing that it appears to have been nickel plated before it was tapped. Perhaps it was dropped in the nickel tank by mistake, says Michael Conduit?
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webmasters, and you may copy it for your personal use, or for a non-
commercial website - if you credit the source. All other rights reserved.
Richard Payn (and others on Spanner) describe a way of reversing the boss on the plastic contrate wheels. One way
of doing this using common Meccano parts is shown to the left. A long bolt is placed through the boss
of the contrate, and on the other side a pair of double brackets and a large washer complete the "boss puller".
Tighten the nut slowly and the boss will come out cleanly. You can then press it in the other side, as shown on the example to the right. This is a very useful space-saving part, and might even pass as "genuine Meccano" depending upon how strictly you interpret the rules!
Dealer spare parts boxes
Individual part numbers
Part numbers for the parts on this page are as follows: Unique part numbersFor 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 | 28 | 29 |
|---|---|---|---|
| Milled from solid brass, squared profile, feather key | 02 | .mm | .mm |
| Milled from solid brass, squared profile, feather and tongue key | 07 | .mm1 | .mm1 |
| Milled from solid brass, squared profile, tongue key | 07 | .mm2 | .mm2 |
| Milled from solid brass, squared profile, tongue key, wide teeth | ?? | .mm2a | |
| Stamped out with square profile, 1911 boss, tongue key | ?? | .mm2b | |
| Brass with rounded profile, patent boss, tongue key | 11 | .mm3 | .mm3 |
| Brass with rounded profile, deep flange, 1911 boss, single-tapped | 12 | .br4 | |
| Brass with rounded profile, patent boss single-tapped | 12 | .br1 | .br1 |
| Brass with two holes, patent boss single-tapped | ?? | .br1a | |
| Brass with eight holes, patent boss single-tapped | ?? | .br1b | |
| Brass with standard boss, single-tapped | 21 | .br2 | .br2 |
| Brass with standard boss, double-tapped | 28 | .br3 | .br3 |
| Brass, post-war stamped, double-tapped | 45 | .br | .br |
| Yellow plastic, marked Meccano England, long brass pummel | 79 | .ye | |
| Yellow plastic, marked Meccano England, short brass pummel | 79 | .ye2 | |
| Yellow plastic, marked Meccano and bar, brass pummel | ?? | .ye1 | |
| Black plastic, brass pummel | 93 | .bk | |
| ALL | ALL |
, Milled from solid brass, squared profile, feather and tongue key.',296,236,'white')){kind=link}
, Milled from solid brass, squared profile, tongue key.',300,267,'white')){kind=link}
, Milled from solid brass, squared profile, tongue key.',250,251,'white')){kind=link}
, Milled from solid brass, squared profile, tongue key, wide teeth.',448,338,'white')){kind=link}
, Stamped out with square profile, 1911 boss, tongue key.',515,397,'white')){kind=link}
, Brass with rounded profile, patent boss, tongue key.',296,260,'white')){kind=link}
, Brass with rounded profile, deep flange, 1911 boss, single-tapped.',400,322,'white')){kind=link}
, Brass with rounded profile, patent boss single-tapped.',300,260,'white')){kind=link}
, Brass with rounded profile, patent boss single-tapped.',250,247,'white')){kind=link}
, Brass with two holes, patent boss single-tapped.',300,261,'white')){kind=link}
, Brass with eight holes, patent boss single-tapped.',300,257,'white')){kind=link}
, Brass with standard boss, single-tapped.',300,257,'white')){kind=link}
, Brass with standard boss, single-tapped.',288,254,'white')){kind=link}
, Brass with standard boss, double-tapped.',300,250,'white')){kind=link}
, Brass with standard boss, double-tapped.',250,241,'white')){kind=link}
, Brass, post-war stamped, double-tapped.',300,249,'white')){kind=link}
, Brass, post-war stamped, double-tapped.',250,231,'white')){kind=link}
, Yellow plastic, marked Meccano England, long brass pummel.',398,299,'white')){kind=link}
, Yellow plastic, marked Meccano England, short brass pummel.',391,306,'white')){kind=link}
, Yellow plastic, marked Meccano and bar, brass pummel.',300,253,'white')){kind=link}
, Black plastic, brass pummel.',300,243,'white')){kind=link}
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: 7. This is page 1 of 2. 
Richard Payn (at 11:30am, Fri 21st Nov, 14) |
Click on the ALL at the bottom of the 28 column and pictures of several large contrates with no holes will appear. |
Peter Bentley (at 10:33am, Fri 21st Nov, 14) |
I have a 1.5" contrate wheel with out the holes in it. Were they ever made like this? Be interesting to find out |
Nick Smith (at 6:27am, Fri 28th Feb, 14) |
It's not only plastic gears that have variable length bosses; I have one 28 from a gears A stamped 'MECCANO' 'MADE IN ENGLAND' on either side of short ¼" boss, and a pair stamped 'MECCANO' 'MADE IN ENGLAND' on either side of long 19/64" boss showing as a mirror image inside the crown, from an 8X (new in HK Spring 1981), and a spare bought because I couldn't find the 8X in 1979 in UK. Also a black plastic 28p, moulded (not stamped) "MECCANO" and bar (which doesn't quite obliterate 'ENGLAND'), '50' and '2' short ¼" brass pummel, Allen socket grub screw in a 1995 Evolution Set 2 with a 26n zinc 11 tooth pinion. Note that whereas only 27d of the brass gears has '60' as the No of teeth stamped on it, in my vast sample of 3 plastic gears, all 3 [27a @57, 27c @95 and this 28p @ 50] have the No of teeth moulded on. I suspect this is a multi-cavity mould and the moulded 2 is to distinguish which cavity it comes from for fault diagnosis. The 27a has a moulded A which I believe serves that purpose too. |
Michael Clark (at 2:54am, Tue 31st May, 11) |
Picked up 4 28's recently, 3 UK and 1 French and noticed the French 28 has a higher wall height on the circumference and tighter radius giving a flatter bottom to the gear. |
James Dell (at 1:39am, Sun 30th Jan, 11) |
I recently purchased on ebay a contrate gear from the UK. After close examination I find its stamped meccano (x2) and Paris. Is this genuine? |
russell hiscock (at 6:52am, Thu 11th Jun, 09) |
i also have a nickel part 28, mine is single tapped and stamped meccano x3. |