A Meccano Triple Co-axial drive - The Hours Minutes Seconds device

Designed specifically for the clock builder, this device will incorporate nicely into any large clock where a compact mechanism is required.  The basic component is a standard Meccano size rod 6cm which is essentially a tube through which a 2.3mm rod can pass.  A second tube 6mm in diameter can be slid onto the Meccano rod.   A special adapter with an outside diameter of 4mm fits over the 2.3 mm rod.

These three components can be seen in fig 1. as well as the adapter.

Fig 1

A seconds hand can be attached at one end of the smallest rod.  Adjacent to it is the hours hand on the Meccano rod, and next to that is the minute hand on the largest tub.  Next is a bush wheel with a large boss drilled to 6mm which slides onto the largest tube, and then a specially adapted 60 tooth gear with large boss fixed on the same rod. Each of the hands has its own tiny set screw.

The various components are shown in Fig 2.

Fig. 2.

When the components are assembled (Fig. 3) it is possible to see how the system works. 

Fig. 3.

 It is fixed by the bush wheel into the front clock plate.  Behind the bush wheel, the minute hand is driven by the 60 tooth gear.  This gear has been chosen because it is part of the 60 : 1 reduction needed between hour and minute hand drive.  The hour hand is driven by a gear fixed to the Meccano size rod.  Finally, the second hand is driven by gear fixed on the adapter, which itself is fixed on the 2.3mm rod by a set screw, thus locking the series of rods in place. (Fig 3)

The assembled system is shown in a clock in Fig. 4.

The Triple Coaxial drive has a wider application in the Meccano system.  It can be used in the centre of a multi- drive from cab to chassis of a mobile crane, or used in a complex gearbox.  The parts are made of brass, and accurately machined.  As such, it represents a significant step forward in the components available to the Meccano builder and to clock enthusiasts.  

For further details of the triple coaxial drive system, contact mike@mecarep.freeserve.co.uk

Michael Adler - September 2002