an irregularity that might otherwise be present in the flow characteristic of the system is cured by damping the motion of the armature of the cps valve in two ways . one way comprises incorporating a &# 34 ; step &# 34 ; into the confronting faces of the armature and stator at their interface across the air gap . the other way comprises guiding the armature motion by means of a brass tube with sufficiently small running clearance such that pneumatic damping occurs .