A capsule
element
is a
unit
that
expands
and
contracts
axially
with
changes
in
pressure
Most capsule measuring devices have the pressure applied to the inside of the capsule
The capsule is spring-loaded (a spring opposes the capsule and thus prevents full expansion); limiting the expansion of the capsule protects and prolongs its life
Motion of the element is transmitted by linkages and gears to a dial pointer