large vintage brass face bezel Ashcroft Locomotive industrial gauge steampunk

Description

A large vintage brass face gauge with brass bezel ring made by  Ashcroft New York and is marked Locomotive Auxiliary Spring towards the bottom of the face.
The very outside of the ring  is apr. 7 3/8 inches and  the inside of the ring it is apr. 5 3/4 inches in diameter.
The bezel ring, the gauge face and the needle / dial hand are all made of brass ( a magnet does not stick to them )
The edge of the bezel ring has some light dings, etc.
There is No glass.
The numbers and the markings on the brass face are all deeply stamped in the brass.
Looking at the face of the gauge at apr. the 4 o'clock position,  there is a brass screw that comes out, at the seven o ' clock there is a threaded hole but no screw and at the 12 o'clock position there is the threaded part of a screw but no screw head.
I am not sure how to take the dial / hand off to see what the inside looks like
The body is cast iron or steel.
The overall thickness is apr. 2 1/8 inches.