Ford Model T
Richard grapples with the planetary gearbox and comes up smelling of grease
Henry Ford and his design team decided on a two-speed planetary gearbox for the Ford Model T. This consisted of three drums with cotton-lined contracting bands, three triple gears (each gear consisting of three gears riveted together) and with the flywheel mounted central shaft, it drove through a wet multi-plate clutch. Confused? Well to cap it off, the two forward gears would be operated by the left clutch pedal, reverse by the central pedal and the transmission brake by the right pedal.
This whole amazing system allowed the car to be driven purely by using the two left pedals for forward and reverse, meaning there was no need for a gear lever and the impossibility of crunching gears. When I demonstrate this to enthusiasts they are astounded at how quickly the car can be driven from first to high gear while keeping hands on the steering wheel and by adjusting the hand throttle to get the car to 40mph, all in a matter of seconds. When cruising at 40mph there are no feet on any pedals, no gear lever in the way – all you do is steer and wave to passers-by.
Katy’s transmission was nice and oily. Just how we like to find them when stripping these units after 100 years. This meant that, like the engine, the components were in great condition and had escaped corrosion due to the oily residue left pretty much everywhere.
That genius Mr Ford also had the idea of allowing the car to generate its own electricity to power the four trembler coils for the ignition
system. Bolted to the block is a multi-wound coil plate or Stator Plate. The flywheel then has a number of horseshoe magnets bolted to it. When the flywheel spins next to the stator plate it creates a current to power all of the ignition coils.
Setting up the flywheel and stator plate is very time-consuming and is only achievable with the correct specialist tools to get maximum effect when running. The stator plate is bolted to the block and the gauge helps get an even distance from the crank face with the use of shims. The tool then reverses to allow the correct set-up of the flywheel plates. A gap of between 25 and 40thou is recommended.
So, in the workshop the transmission drums were cleaned and re-bushed as were the three triple gears mentioned earlier. The flywheel has to be re-magnetised and the test is to check each horseshoe magnet can hold the weight of an original Ford T iron piston. Be careful when doing this check because weak magnets means piston on foot!
Cleaned and ready to go
Once all the parts were cleaned, re-bushed and ready for assembly I begain to follow the very strict assembly sequence. It is best to turn the phone off, shut the door and systematically work through the list of actions ensuring no interruptions and that all components are lubricated as assembled, wired where necessary and split pinned when required.
Once I had emerged from the ‘process’ I grabbed another specialist tool which I used to set up and torque down the the large sump that goes over the cylinder block and transmission.
I made sure to use all-new fasteners to fit the sump along with new gaskets (highly recommended) and then I added the restored transmission cover – fitted with all-new lined bands.
Bands in a Ford Model T are quite a talking point. ‘Just nipping out to adjust the bands, love,’ or ‘Do we really need bands for a picnic?’ Numerous bums in the air is a common sight in the car park at T rallies while owners are adjusting the bands ready for the next leg of the rally. Many different linings have been tried over the years, from wood to Kevlar. Our Katy is being fitted with the traditional cotton webbing bands as fitted by the factory.
With Katy’s engine and transmission now assembled, pretty soon it’s going to be time to fit it to the lovely shiny chassis…
‘Numerous bums in the air is a common sight as T owners adjust their bands’