Pioneer KEH-M5500 UC Service Manual page 85

(2) Direction change operation
Fig. 12
The direction is changed by pressing FF and REW levers
simultaneously. The DC arm turns along a cam groove of
FF and REW levers to turn the FR lock arm. As the FR
lever applies force from above downward, the FR cam gear
turns and the notch meshes with the sensing gear.
As aresult, the FR lever moves downward.
When FF and REW levers are kept pressed, the lock arm
contacts the outside of the FR cam gear to prevent
changeover between FWD and REV. Pressing FF and
REW levers also cause the mute switch to be turned ON.
In other words, muting is valid while FF and REW levers
are pressed. (Fig.12)
(3) REV play operation
Fig. 13
Moving the NR lever up and down causes changeover
among the pinch roller, FR switch, and play idler gear. With
FF and REW levers having been returned, the FR lock arm
returns to the normal lock position and locks the gear when
the FR gear completes an one-half turn. The mute arm
also returns to turn OFF the mute switch. The reverse piay
state is thus obtained. (The same applies to changeover
from REV to FWD.)