แป้นรองเครื่องขัดกระดาษทราย (ชนิดหลังกาว) In gauges meant to perception compact pressures or tension dissimilarities, or require that an complete pressure be calculated, the gear teach and needle could possibly be driven by an enclosed and sealed bellows chamber, named an aneroid, which means "without the need of liquid". (Early barometers applied http://pressuregauge25677.targetblogs.com/10600354/the-ultimate-guide-to-pressuregauge