Pipe flow valve position indicator - has boss compensating automatically pitch difference between indicator and spindle thread

摘要

The flow indicator on a valve in a pipeline has a number plate (4), an indicator boss (6) and indicator (11) centrally arranged around a threaded spindle (3). The number plate (4) is screwed against a sealing bush (2), and the boss (6), union (7) can rotate freely but without axial play or displacement, in a recess at the rear. The boss (6) has an inner thread (8) to screw onto the indicator thread (9) which has a greater pitch than the thread (10) in the instrument housing. When the thread spindle (3) is rotated, the boss (6) compensates this pitch difference automatically by rotation on the indicator thread (9), and this appears by means of the indicator (11) in front of the fixed scale (5) as an analogue indication due to the cone position in the instrument between 'ON' and 'OFF' positions.