Chapter 5 Hydraulic Control Valves (4)By the operating means:These valve cores may be operated by a difference of oil pressure on the spool,or manually. mechanically,electrically,or by a combination of these means. 3.The construction of spool or directional control valve The common configurations of spool or direction valves are shown in Tab.5-2.Their differences lie in the ways and positions they possess.Two or three-position valves mean that their valve cores have two or three different working positions; similarly,two,three or four way valves indicate that there are two,three,or four oil paths on the valve body which are separated from each other and connected with their independent oil lines.The function of the direction valves depend upon their ways and working positions. Homepage List Upwards Downward达 Return ExitChapter 5 Hydraulic Control Valves 15 3. The construction of spool or directional control valve The common configurations of spool or direction valves are shown in Tab.5-2. Their differences lie in the ways and positions they possess. Two or three-position valves mean that their valve cores have two or three different working positions; similarly, two, three or four way valves indicate that there are two, three, or four oil paths on the valve body which are separated from each other and connected with their independent oil lines. The function of the direction valves depend upon their ways and working positions. (4) By the operating means: These valve cores may be operated by a difference of oil pressure on the spool, or manually, mechanically, electrically, or by a combination of these means