Pitch Change Assembly

T-34C AIRCRAFT SYSTEMS FAMILIARIZATION

CHAPTER SEVEN

WORKBOOK

Figure 7-2 The Three Basic Blade Angle Stops

Blade angle directly affects the speed of the propeller. A high blade angle causes low prop speed.

Conversely, a low blade angle causes high prop speed.

In event of engine failure it is desirable that the blades go toward feather or low drag position in

order to maximize glide distance.

Pitch Change Assembly

Change of blade angle is accomplished through the pitch change assembly. The feathering spring,

located inside the hollow prop shaft, moves the blades to high blade angle. The counterweights,

attached to the base of each blade, assist the feathering spring in setting high blade angle when the

propeller is rotating. Low blade angle results when the servo piston is moved forward by high-

pressure oil. Connecting links, between the piston and the base of each blade, transmit the fore and

aft motion of the piston to rotate the blades. The beta feedback ring assists in controlling blade angle

from 17.5 to 5 degrees.

PROPELLER 7-3