Owner's manual

SECTION VIII.
8-1. OVERVIEW. The options for the PP405TR power
positioner covered in this section include an air lock,
electric position bansmitter, and heater/thermostat.
8-2. AIR LOCK.
a. Descrtpticm. The air lock, Figure 8-1,
automatically locks the power positioner piston
and shaft assembly when there is a loss of supply
air. when supply air pressure falls below a set
value, the air lock diaphragm collapses causing a
spring to move the lock lever. This clamps the
friction plate and locks the piston and shaft
assembly. Upon loss of supply air pressure, the
automatic lock can be overridden by mming the
air lock release handle fully clockwise. The
operator must then open the bypass valve,
manually position the output shaft, and lock the
output shaft by turning the air lock release handle
fully counterclockwise.
b. Adjustment.
WARNING
Before performing any maintenance or
repair action on power positioner, shut off
supply air and signal air, and disconnect
any ekcttical supply or electronic signals to
power positioner. Isolate power positioner
from all systems connected to power
positioner. Severe tnjury or death may
dt from large torque power positioner is
capable of producing, or from electrical
ShOCk.
1. Remove power positioner from service, close
supply air shut off valve. Disconnect
electrical power to power positioner.
2. Turn the air lock release handle, Figure 8-1,
clockwise until the lock lever (1, Figure 8-2)
brake shoe is clear of the sector.
Figure 8-1. Air Lock