Welcome to another Model T Ford interactive technical animation.
Below you will find a simplified explanation of the Model T Ford Generator and an interactive animation to show the different steps.
This page assumes you already have a basic understanding of the principles of electricity, magnetism and generators. If not, read the generator theory here.
Explanation and Instructions for use
So having covered all the theory, lets look at it in practise.
There are 5 main steps in the animation.
Choose your country (to get the vehicle controls right)
Review the magnetism and field poles
The cut out closes
Speed up the charge rate
First step, choose your country! The US flag is for left hand drivers and the Aussie flag, for right hand drivers. This will change the controls. Click on the flag next to the battery to change the controls.
Review the Magnetism and field poles
The generator cut out is designed to disconnect the storage battery from the generator circuit. Note how the current, with the engine stationary, runs back through the wiring, but is stopped at the cut out switch which is open. This stops the battery from being drained flat. If it wasn't there, it would continue to try and "drive" the generator as an electrical motor.
As we know, the field coils, when electrified, create a magnetic field. So once the generator spins, it starts to produce current immediately, albeit at low levels. Some of this current is fed to the field coils, in turn, increasing the magnetic field that the armature is spinning in.
Click the accelerator level once to increase the "engine" speed.
The above reaction, increases the output until sufficient current is produced and passed through the brushes to the generator cut out and field poles.
As the cut out is an electro magnetic switch, the current from the generator entering the cut out's coil, creates a small magnetic field which pulls the switch contact closed, allowing the generator current to continue its path, through the vehicle's wiring, through the ammeter to the car battery.
Click the "resume" button above the throttle control to see the cut out close and current continue. NOTE: The cutout closes automatically as engine revs rise and the generator output increases. It is necessary to click resume here to see this, only so that you can read and review at your own pace.
Unlike a modern vehicle system, where the charging current is increased, decreased or stopped depending on the charge state of the battery, the charge rate of the Model T Ford Generator as discussed earlier, is permanently set by the third brush position. Whilst the engine is running at a sufficient speed, the battery is constantly charged.
Click the accelerator again. The engine speed will increase again.
The increased engine speed will turn the generator at the optimum generating speed, the charge rate predetermined by the third brush. Once the maximum charge rate is reached, increasing the engine speed further will not increase the charge rate any more.