Rate of Climb / Vertical Speed Indicator, 6,000 Ft/Min, US Navy WWII, SB2C Helldiver Piasecki The gauge indicates pressure differential

The gauge indicates pressure differential up to 1 kg per square cm

according to their WWII-era flight manuals (see images of relevant pages from these manuals in photo gallery)

and "МАСЛО ОПАСНО"  means Oil

The glass has a small crack at  ~7pm on its face

and the knob rotates stiffly

Rate of Climb / Vertical Speed Indicator, 6,000 Ft/Min, US Navy WWII, SB2C Helldiver Piasecki The gauge indicates pressure differentialThis is a nice example of the US Navy's Vertical Speed Indicator R 88 I 750 as used in the SB2C Helldiver Dive Bomber of WWII, indicating vertical speed up to 6,000 Ft Min. It has the alternating Munsell Green lettering common on US Navy aircraft of that era. Made by Kollsman, part number 731KN 02. It is in good shape for its age. The glass and case are intact and the lettering is bright and distinct. The knob adjusts the pointer clockwise or counter