A: A function generator do just that output a function from any input. It can be as simple as sine wave, square wave, sawtooth, and ramp generator principle is to provide amplifiers that the output are gated to limits allows sum and subtract the input to provide the desired function. It looks more like an analogue computer when finished if it is very complex in design.

The AVR (automatic voltage regulator) can generally be set to maintain a constant output voltage or a constant power output. This device controls the field current; as field current increases, the back emf on the generator will cause it to slow down. At this point the generator's governor will open up some valves, increasing power to the prime mover (whatever is making the generator spin), which will keep the generator spinning at its' ideal speed. The exact opposite occurs when the field current is decreased. The AVR monitors terminal or system voltage, and makes decisions based on its' settings to ramp up, ramp down, or keep the field current constant.

By brushes, do you refer to the windshield wiper motor brushes, or the generator brushes?

If generator...just replace the generator, or ramp up to an alternator. It is cheaper and a lot less hassle.

If windshield wiper...well...that one is possible, but dreadfully difficult. Best to look for a replacement motor. I don't think they make the replacement brushes any longer.

One example of a ramp is a wheelchair ramp.

This is called an "entrance ramp" on "on-ramp" or simply a ramp, because the off-ramp is more typically called an exit.