Early Taycols seem to have been wound with two coils connected either side of the brushes. Later Taycols often had a pair connected at one side only, as indicated below, though they still kept the multiple terminator bolts. For later drawings I will only show one 'logical' coil to make the images simpler!
Taycol Model Marine Electric Motors
After from the weight and the open-frame nature of the motors, the next thing that surprises new owners of a Taycol is the mass of connection points on the paxolin back plate. Modern motors have two connectors – these have at least three main ones, and often six or more (with some pairs joined together by a brass strip). What is going on?
Usually it is pretty obvious that two of the connectors are the main ones (if you're not sure, look at the instruction leaflet elsewhere on this site). Where there are three connectors, there is one common post and two others – one for forwards and one for reverse. But if our new owner connects the motor up to a 6v supply the next surprise occurs - the motor rotates the same way whichever polarity the battery is connected.
The drawings here illustrate the problem. You can see that a 'normal' permanent magnet motor changes armature polarity when the battery polarity is changed, but the magnet polarity stays the same. The motor then reverses.
By contrast, in a DC field motor the magnetic force is generated by the field windings, so when you reverse the polarity it reverses the magnetic field on both the armature AND the magnet. Reversing BOTH forces means the motor continues to spin in the same direction...
If you can switch round the coil polarity WITHOUT switching the armature brushes (or vice versa) this will reverse the engine. This is what the early instruction manuals asked users to do, using a double-pole double-throw switch:
Taycol initially addressed the requirement to obtain reverse by allowing the user to re-wire the connectors between the field and armature coils – this could be done by removing the jumper strips of brass so that the field and brush connectors were seperate, then wiring up a two-pole switch as a crossover. That is why the paxolin backplate is full of bolt connectors – they are the termination points and jumper positions for two sets of coils and the armature brushes.
Let us look at the typical wiring for a Taycol:
Modern engineering practice would condemn this approach as wasteful in materials, though it had some advantages for a vehicle application. The 'reverse' coil had fewer winds, so that when reverse was selected the motor automatically went at half-speed. This would also be useful for boats, cars and railway engines, though less so for static models...
Taycol brought out motors with the 'reverse coil' on them by altering pre-existing models. This can cause some confusion! Taycol seem to have added larger paxolin bobbins to all the motors, and then either wound one coil onto this (the original design) or a main coil and a reversing coil. They then named the varient differently. Later motors without reversing coils can be recognised by their half-empty bobbins...
The 'renamed' motors seem to be:
Rewiring the motors for reverse operation like this was seen as a complicated and technical process for most users, and Taycol must have fielded a lot of letters on the subject. In the final Taycol range, the problem was addressed by providing an extra completely separate reverse field winding – adding to the weight and build cost of the motor, but making reverse a simple matter of switching between the two different coils with a single-pole switch. On some motors this is simplified by providing a brass strip which swings between the two connectors, so it is easy to mechanically switch the engine.
Here is how the later 'wasted coil' reverse wiring works:
Motor without reversing coil
Same motor with reversing coil
As far as I know, the 'Standard' and the 'Double Special' were only available with the reversing coils fitted, and have no earlier equivalent. The 'Supermarine' is interesting – I believe there was an earlier motor called the 'Marine' which had conventional 'drum' type brush gear rather than the 'disk' type which all the other motors had. The 'Marine' motor is very rare – I have not seen an example – but it may be that the Marine became the Supermarine with the brush gear change, and the Supermarine Special with the reversing coil.