Like the above post states, rotating the pitch trim knob slightly moves the swashplate up or down by moving all three servos at once. The throttle control on your radio does a few things together. It increases or decreases the power to the motor AND it moves the servos up or down together (through mixing). There are two different mixes on the AXE radio which are Idle up or normal. The normal mode increases power to the motor and increases blade pitch the higher it goes. Idle up causes the motor to have 80% power in the middle and 100% at top or bottom and blade pitch is full positive (10 degrees) at top and full negative (10 degrees) at bottom. In normal mode: Lets say you are at half throttle so the motor is getting half power and the pitch of the blades is at half (4 degrees) also, but you find that the motor is bogging down because half pitch is too much drag and causing a slow head speed. You can reduce the pitch of the blades (with pitch trim moving the swashplate up) which will require you to move the throttle to say 3/4 throttle for hover which will give 3/4 power to the motor and still end up with the same blade pitch angle (4 degrees) for hover resulting in higher head speed. If you didn't have pitch trim you would have to lenghthen all three servo linkages by the same number of turns which you would have to do a number of times before you get a satisfactory head speed.

It does the same thing in idle up, but here your goal is to get the blades to be at zero degrees pitch when the throttle is at mid stick or 50%. Again, instead of adjusting linkages, you can just spin a knob. My older Axe doesn't have the pitch trim knob, and even though all the parts are supposed to be the same size new or old, I have to go through this time consuming process every stinkin time I rebuild the head following a crash.

The trim slider next to the throttle makes changes to the power going to the motor and to the three servos. The pitch trim knob only changes the three servos.