The analytical head is driven by the stepper motor that is connected to the drive shaft by a toothed belt. The drive nut on the spindle converts the circular movement of the spindle to linear motion. The drive nut pushes the sapphire piston against the tension of the spring into the analytical head. The base of the piston sits on the large bearing of the drive nut, which ensures the piston is always centered. A ceramic ring guides the movement of the piston in the analytical head. The home position of the piston is sensed by an optical sensor on the hydraulic unit board while the sample volume is determined by counting the number of steps from the home position. The backward movement of the piston (driven by the spring) draws sample from the vial.
base-id: 3714648971
id: 3714648971