PRINCIPLES OF NAVAL ENGINEERING 



SECTOR GEAR 



CASE 



SEALED END 



BOURDON TUBE 

 HAIRSPRING 



CONNECTING 



LINK 



38.211AX 

 Figure 7-18.— Operating mechanism of simplex 

 Bourdon-tube pressure gage. 



FRAME 



POINTER SECTOR 



STAFF PIVOT ADJUSTMENT 

 POINT LEVER 



POST 



FRAME 



/ 



HAIRSPRING 



SECTOR 

 ADJUSTMENT 

 SCREW 



CONNECTING 

 LINK TO 

 BOURDON 

 TUBE Tl P 



38.211C 

 Figure 7-19.— Gear mechanism of simplex 

 Bourdon-tube pressure gage 



When a gage is designed to measure both vacu- 

 and pressure, it is called a compound gage 

 is marked off both in inches of mercurv 



um 



and is marked off both in inches of mercury 

 and in psig, as shown in figure 7-24. 



38.211FX 

 Figure 7-20.— Dial of a duplex Bourdon-tube 

 pressure gage. 



POINTER NO. 2 



POINTER NO. I 



BOURDON 

 TUBE NO. I 



THREADED 



PRESSURE 



CONNECTION NO. I 



THREADED 



PRESSURE 



CONNECTION NO. 2 



38.211G 

 Figure 7-21.— Two Bourdon tubes and operating 

 mechanism of duplex Bourdon-tube pressure 

 gage. 



140 



