Page 27025 Instruction Manual (Rev. 2) The piston almost touches the cylinder end at each stroke, regardless of thepre-set volume. This ensures that all air taken into the pump is expelled witheach stroke.Figure 1 “Linkage” The stroke volume knob can be adjusted either while the pump is running or ata standstill. Volume is clearly indicated on a stationary scale rather than on amobile slotted link or by graduation marks on the cylinder, either of whichleads to uncomfortable volume setting, the latter adjustable only when thepump is in motion. The mechanism does not incorporate the slotted link assembly found on otherventilators. The reciprocating motion is generated, adjusted and transmitted tothe piston by pivoting joints and rods only.This lack of sliding friction leads to:A. practically no wearB. no backlash, and hence silent operationC. exact stroke reproducibilityD. minimal maintenance requirements2.2 Cylinder/Piston & ValveFour different cylinder/piston assemblies are available: 1, 5, 10 and 30 ml.