Here's how it works.
The 18A has a fully articulated, swash plate controlled, three-blade rotor system. It also has a manual hydraulic pump, operated by a handle next to the pilot's seat that looks like a collective control (it isn't a true collective, but it is used to change pitch). The hydraulic pressure can be re-directed by use of buttons (electrical switches) that act through solenoids.
To prepare for spin-up, a button is pushed on the panel, (labelled "DE-PITCH") to direct the hydraulic pressure to move the swash plate. When the pump handle is then stroked up and down a few times, the hydraulics will move the swash plate to pull all three blades into flat collective pitch, working against springs that urge them toward a positive pitch angle. When you reach max pressure for the pump (there's a gauge on the panel so you can tell) the blades will have zero collective pitch and the springs will have maximum displacement. The blades have a symmetrical airfoil, so flat pitch means no lift and minimum drag for the rotor during spin up. You are now sitting still on the runway, with the blades flat, brakes held, and the engine at low rpm (900 - 1100 on a Lycoming O-360 that goes to 2700), constant speed prop set for climb, and low prop thrust. Hydraulic pressure is maintained and opposes the springs and keeps the blades flat for the next step.
The pilot next selects the "CLUTCH" button. Further pumping of the handle will slowly engage a multi-plate clutch so that the engine drives the rotor blades and accelerates them. After the clutch is fully engaged, the throttle is advanced until the rotor reaches approximately 370 rpm in flat pitch. Most of the engine power is going into the rotor system rather than the prop at this point. Anti-torque during this spin up comes from the tires while you sit on the ground, with the pilot holding the brakes. This spin up is far in excess of the normal flight rpm of around 240, and that stores lots of excess energy in the heavy blades (50+ pounds each for three blades, diameter 35 feet).
When the blades are fully spun up, if the pilot wishes to do a jump takeoff, he pushes a small button on the top of the throttle. This disengages the clutch, puts in a one second delay, and releases the hydraulic pressure that was holding flat pitch. All engine power is now going to the prop. The rotor blades, responding to spring force on the swash plate, all pop up to about 8 degrees of pitch, while still spinning at about 370 rpm. In response, the aircraft will jump up (and slightly forward, the forward motion coming from the prop thrust), climbing helicopter-like while extracting the extra stored energy. No anti-torque is needed because the engine is de-clutched before you ever break ground.
As the aircraft climbs up in the jump, the rotor now carries the weight of the aircraft, some rpm is lost, and the blades start to cone upward. A delta-3 angle in the hinges provides pitch/cone coupling, so that the increased coning leads to a reduction in collective pitch. By the time the rotor has decayed down to normal flight rpm, the collective pitch is down several degrees from the initial 8, at a good autorotative pitch setting. The aircraft has also accelerated to adequate flight speed (thanks to the prop thrust) to permit climb out from there. You are now in flight as a gyroplane.
The pitch/cone coupling means that the pilot doesn't have to do any collective adjustment to go from the high pitch used for the helicopter-mode jump to the lower pitch autorotation-mode forward flight; it all happens automatically. All he needs to do is push the button and steer the aircraft.