Meccano Gears - 3 - More Simple Gearing

 Meccano Gears - 3

Even More Simple Gearing.

This post in this series on spur and pinion gears features the largest standard Meccano gear, and a couple of unusual ratios.

The holes in the plate are ½" pitch, so you can see the left pair of gears mesh at 1" (25.4mm) centres, the centre pair diagonally at 0.7" (√2 /2) (18mm) and the right hand pair of gears mesh at 2" (50.8mm) centres.

The left hand pair of gears give a 1.92:1 ratio - the upper pinion (Part 26r) you will find in the standard Meccano number 1 clockwork motor, and has 13 teeth; whilst the lower pinion is the familiar part 25, with 25 teeth. 25/13 = 1.92. This gives a similar ratio to the standard 50 tooth spur gear and 25 tooth pinion, but in a much smaller space.

The centre pair of gears give a 2.53:1 ratio. The lower gear is Part 31, with 38 teeth, and the upper gear part 26c with 15 teeth. 38/15 = 2.53.  This ratio falls between the standard 2:1 and 3:1 ratios, but additionally allows one axle to be offset.

The right hand pair of gears have a larger size difference, but also a wider pitch at 2". These are the familiar 19 tooth pinion (Part 26) and the large 133 tooth spur gear (Part 27b). These give a ratio of 7:1 (133/19 = 5). The 133 tooth part is the largest standard gear in the Meccano system.