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Masoneilan 37/38 Actuator Instruction Manual | 5
Air-to-Retract Actuators (Type 38)
Diaphragm Replacement
The procedure is the same as for air-to-extend
actuators except that the entire upper case
assembly (including spring barrel (71), spring
(22), spring seats (33 and 34), nut (30) and
diaphragm plate (40) must be removed to
release the diaphragm. Install a new diaphragm
and reassembly the above parts.
Spring Adjustment
The procedure is identical with that for air-to-
extend actuators except that supply air is piped
to the 1/4" port in the yoke.
Packing Box
The packing box is subject to low air pressure
only and requires minimum maintenance.
The packing rings have a square section and are
made of carbon core with braided PTFE jacket.
The packing may be added to or completely
replaced without disassembling either the
actuator or the mechanism (or valve) to which it
is attached. Be sure to tighten packing nut (20)
lightly. Over-tightening will cause excessive
friction, resulting in sluggish performance.
