AN ELECTRICALLY OPERATED HYDRAULIC CONTROL VALVE 



733 



The lower light area is oil in the annular groove of the plunger. The oil 

 is flowing from top to bottom. It will be noted that the flow on the 

 downstream side of the orifice hugs the radial surface of the plunger, 

 as discussed above and depicted in Fig. 13. The crosshair and the comb- 

 like scale are a part of the microscope. 



Fig. 16 shows two views of a subsecjuent trial model quite similar to 

 that shown in Fig. 14. Here, the bottom shadow is the insert and the top 

 is the plunger. The flow is from bottom left to top right. This particular 

 design reduced the Bernoulli force but resulted in a serious reduction in 

 flow. This reduction was caused by the large cavitation bubble visible 

 in the right view. This bubble was the result of rapid rotation of oil in 

 the chamber. It prevented the orderly release of the oil through the in- 

 ternal passage to the actuating cylinder (not visible in pictures) , 



Fig. 17 shows a trial model similar to the J-7. The left illustration 



520 



480 



440 



400 



< 



o 



360 



cc 



UJ 



O 320 



D 

 _l 

 Q. 

 2- 280 



O 

 oi 

 U 240 



O 



IL 



_l 

 < 



z 



Q 



h; 

 O 



z 

 o 



200 



1 60 



120 



80 



40 



2 3 4 5 6 7 



VALVE POSITION IN LINEAR MILS 



Fig. 18 — Force on plunger of J-7 valve due to Bernoulli effect. 



