Hartzell HC-D2MV20-3 Series Owner's Manual And Logbook page 44

Propeller Owner's Manual
140
(5) A manually controlled propeller assembly consists of a
central steel hub (Figure 2-1) that mounts on the engine
splined shaft. Blades are attached to the hub and are
retained by two piece blade clamps and thrust bearing
assemblies. A hydraulic unit consisting of a cylinder,
piston, and pitch change linkage is attached to the
face of the engine case encircling the splined engine
shaft and propeller. A valve assembly is attached to the
hydraulic unit and supplies oil to the piston and cylinder.
Oil supplied from the engine, or governor for a constant
speed propeller, through the valve assembly is pumped
into a cavity defined by the engine mounted cylinder
and piston. The piston and cylinder do not rotate with
the propeller. They remain fixed to the engine, although
the piston will move linearly in response to the changing
volume of oil. This linear movement is transmitted through
a thrust bearing to a jack plate unit that is also part of the
hydraulic unit. The thrust bearing allows the non-rotating
piston to be linked to the jack plate unit that rotates with
the propeller. The jack plate unit acts as the linkage
between piston linear movement and blade pitch change.
The jack plate unit is attached to knobs on the inboard
side of each blade retention clamp and translates the
linear piston motion into rotational movement of the blade
clamp and blade. This results in blade pitch change while
the propeller assembly is rotating.
APS2063A
Steel Hub
Figure 2-1
Page 2-4
61-00-40
DESCRIPTION AND OPERATION
Nov/02