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Parts 30-30c: Bevel gears

The first bevel gears were introduced in 1920, adding a much-needed and elegant alternative to the use of contrate wheels for transferring drive through right-angles.  In 1927, the range was extended, showing yet again the complete lack of engineering skill at Meccano despite their lofty claims for the system. Three new sizes of bevel gears were announced in the October 1927 issue of Meccano Magazine, along with the note that they "will enable several different speed ratios to be obtained" and describing how to mesh completely inappropriate gear combinations.

Very soon after their launch, someone pointed out to Meccano that bevel gears only mesh correctly when their cone angles meet and coincide with where the lines of their axles meet.  Part 30b, the ¾'' bevel gear, was discontinued and the parts 30a and 30c were re-cut to the correct angles and supplied as matching pairs.

30	Bevel gear, 7/8'' 26t	1920	-	4	4	8	N°10
30a	Bevel gear, ½'' 16t	1927	-	2	2	1	N°9
30b	Bevel gear, ¾'' 24t	1927	1927	n/a	n/a	n/a
30c	Bevel gear, 1½'' 48t	1927	-	2	2	1	N°9

The parts

The three standard bevels are shown in the picture to the right.  As explained above, bevels can only mesh when the teeth are cut correctly.  Because of this, the 45° bevel part 30 (left of the picture) only meshes with another part 30, and the 30a and 30c pair can only work together as a pair.

Chronological variations

The first bevel gear, part 30, existed on its own to begin with.  In 1927, the three other varieties were introduced.  As shown in this photograph, these gears were all incorrectly cut with their teeth at 45 degrees, and were advertised as being able to mesh with each other or with themselves.  They do mesh correctly with themselves.  The pair of 30a's to the left of this photo work well, but the combination to the right doesn't.  The part 30b was dropped only months afterwards.

The second phase of gears has the teeth correctly angled, but cut in a point like the left-hand one in this picture -- that is, they were wider at the outside of the gear than at the inside (not just wider at the bottom of the tooth than the top).  The easiest way to spot this is to look at the end of the part, particularly the small 30a.  In the earlier parts, the teeth are almost triangular at this end.  Later versions have differently cut teeth: clearly involute and they have the same profile along their entire length, as per the middle gear above.  Post-war gears have flat tops, as shown on the right-hand gear above.

The post-war part 30 had flats on the teeth, as per the left-hand part in this photo.  Later on (anyone know a date?) the teeth became slightly thinner, as you can see from the right-hand part.

There were variations on the depth of recess in the face of part number 30.  It is difficult to date these, although it is agreed that the non-recessed versions are early.  Examples of this non-recessed version can be found both single-tapped and double-tapped, implying that it was current around 1927/28.  A slightly recessed version with heavier teeth profiles is shown in the table below, single-tapped, and it is assumed that this part was earlier (because it has not been found in a double-tapped variant).  These classifications are very tenuous, but have been divided into non-recessed, recessed, and heavily recessed.  "Heavily recessed" is where the depth of recess below the bottom of the teeth is greater than the height of the tooth.

John Nuttall has pointed out differences in the tooth width of pre-war part 30c's, as shown by the two examples in this photograph.  It is not yet known whether these are two distinct types of gear or whether there are just slight differences in each batch, nor what dates these gears are from.

The Meccano builder needs to be aware of the variations in the teeth, as pairs of bevel gears do not mate satisfactorily unless they have the same tooth type.  I try to make sure I use exactly matching pairs, although some combinations do work.

Variations and oddities

None known

Dealer spare parts boxes

The pair of 45° bevels part 30 to the left are early post-war, probably 1950-53.  They are shown with a picture of the pre-war parts without flats on the teeth.  Misleading pictures like these are quite common on spare parts boxes. The 30a and 30c bevel gear pair were sold as a set in a single box, as shown by the later 1960's box to the right.

Above we can see two different box labels for the bevel gear pair 30a and 30c.  To the right, a later (probably 70's) plastic bag containing bevel gears part 30. 

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	30	30a	30b	30c
Centre slightly recessed, heavy pointed teeth	20	.br2
Incorrectly cut 45° teeth, single-tapped, no holes	27		.br2	.br	.br2
Centre not recessed, pointed teeth, single-tapped	27	.br3	.br3
Centre not recessed, correct teeth, double-tapped	27	.br4	.br4		.br4
Centre recessed, double-tapped	??	.br4a
Deeply recessed (> tooth size), double-tapped	??	.br4b
Flats on teeth, double-tapped post-war stamping	47	.br	.br		.br
Flats on teeth, teeth slightly narrower	??	.br1
Sintered brass, double-tapped	71		.br1		.br1
		ALL	ALL	ALL	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: 10.  This is page 1 of 2.   

NP      (at 9:47am, Wed 8th Feb, 23)

Hi Michael - please show some pictures of this in the forum

Michael Hewitt      (at 10:30pm, Tue 7th Feb, 23)

I have a single-tapped, Meccano-stamped, deeply-recessed part 30.

Michael Hewitt      (at 10:00pm, Tue 7th Feb, 23)

I have a single-tapped, Meccano-stamped, deeply-recessed part 30.

NP      (at 9:21pm, Tue 4th Jul, 17)

The tolerances on the early 45 degree cut bevels were such that the small and large gears work quite acceptably well together, even if the cut is not to 'engineering standards'. A contrate / pinion and worm / pinion combination all deviate from good practice in their tooth forms as well, but are perfectly acceptable for Meccano modelling. Moreover, four of the small 45 degree bevel can be built into the best all-bevel differential the system allows. I think it's a shame they dropped them!

Richard Payn      (at 10:07am, Mon 24th Jun, 13)

Yes - part 30 produced during the 1970s weren't stamped.

Andrew      (at 4:10am, Mon 24th Jun, 13)

Hi does anyone know if there were ever any unstamped bevels part 30 that came out of Binns Road? Thanks

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