Cylinder Head Temperature Indicator, Type B-7, US Army Air Corps Pre-WWII
This is a pre-WWII Type B-7 Cylinder Head Temperature Indicator as used in aircraft of the US Army Air Corps before and during WWII. The indicator measures the temperature of the cylinder head via thermocouple from a single engine, from 0-350 deg C. The B-7 indicator had an integral light source in the upper right corner, although the bulb is missing from this example. Made by Weston, part number 86884, with a serial number prefix of AC-39, evidence of a manufacturing year of 1939. The serial number, type number, and AC US ARMY are imprinted on its face.
According to the US Army Air Force Maintenance Interchangeability Cross Reference Chart dated Dec 1943, this indicator was used in fighter P-47 Thunderbolt (see photo of P-47 instrument panel from its flight manual dated 1945), light bombers A-20 Havoc, A-25 Shrike, A-28/29 Hudson, A-35 Vengeance, and A-36 Apache, and trainers AT-6 Texan, AT-17 Bobcat, BT-12 Sophomore, BT-13 Valiant, and BT-14 Yale. See spec sheet in photo gallery.
Measures 3.25 inches diameter and ~ 2 inches deep. It is in decent condition for it age. The glass and markings are clear and case are intact.