© Mike Dennis 2003



The gears described and illustrated were purchased from SHG Model supplies

They are inexpensive, made from injection moulded Nylon 6, and Red in colour. They are also impervious to cellulose thinners and most other generally available solvents.

The use of Nylon and "Delrin" (Acetal copolymer 150) gears is advantageous in that both materials have a low co-efficient of friction, need little or no lubrication, are hard wearing and allow nearly silent running.  Both types of plastic have been in use in the engineering and manufacturing industries for well over half a century.  The SHG spur gears are all 6mm face width and all types are available with either Brass bosses, bored 4mm and fitted with M3 grub screws, or without bosses, the centre holes being a press fit to suit 4mm rods.  Bosses are Ø 10mm.

Some in the range comply with Meccano spacing.  The full range covers 12,15 & 18T pinions plus 30, 38, 45 & 58T spur gears, plus 20T 1:1 bossed bevel gears.

Note: The hole pitch dimensions for 2:1 and 3:1 ratio using 15T pinions with 30 and 45T gears do not comply with any standard linear, offset or 45º diagonal Meccano hole references. They can, however, be used in conjunction with Meccano slotted parts fitted with Mecarep moveable bosses. The part was developed in the mid 1990ís by me for use with non standard axle spacing.

Mecarep moveable boss

NON MECCANO SHAFT CENTRES ? Dimensions in brackets : Metric and Imperial
2:1 Ratio 15 and 30T (22.5mm = 0.886") -
3:1 Ratio 15 and 45 (30mm =1.181")

MECCANO COMPLIANCE (Dimensions in brackets)
Number of holes required, Linear, diagonal 45º pitch and other offsets as stated

1:1 ratio options                    2 x 12T pinions    (2h L)
                                                 2 x 18T pinions    (2h x 45º)
                                                 2 x 38T Gears      (4h L)
                                                 2 x 58T Gears      (5h L x 3h offset)

Other established ratios    15T - 18T   1.2:1    (2h x 45º)        12T -15T   1.25:1  (2h L )
                                                30T - 45T  1:5:1    (4h L)               18T - 38T  2.11:1  (3h L +1h offset)
                                                12T - 38T  3.16:1  (3h L)               12T - 45T  3.75:1  (3hL x 1h offset
                                                15T - 58T  3.86:1   (3h x 45º         18T - 58T  3.22 :1  (4h L)

Standard range as supplied:
Left, top to bottom: 15T  30T  45T
Centre: top 12T  Below it, 18T
Right: top 38T, bottom 58T
Far right:  Worm

NOTE:  These are the same as supplied by Frizinghall but at less expense from SHG


The double gears shown below are my developments and have been fitted with Meccano type bosses.

Left, top to bottom: 15/30T, 30/45T
Centre: 12/38T, 14/18T slide gear, 18/38T
Right: 12/58T, 18/58T