，伺服阀的主阀是靠前置级阀的输出压力来控制的，而前置级阀的压力则来自于伺服阀的入口p，假如p口的压力不足，前置级阀就不能输出足够的压力来推动主阀芯动作。
伺服阀其实缺点极多：能耗浪费大、容易出故障、抗污染能力差、价格昂贵等等等等，好处只有一个：动态性能是所有液压阀中最gao的。就凭着这一个优点，在很多对动态特性要求高的场合不得不使用伺服阀，如飞机火箭的舵机控制、汽轮机调速等等。动态要求低一点的，基本上都是比例阀的天下了。MOOG伺服阀：
J761-001
J761-003
J072-110
J072-056
J761-004
JA
JA
D
D
D
DA
D
DS16JOQA6USX2-A
DS10JXQB6VSX2-B
DS25JOQB6VSS2-B
D791Z140B-6 /S16JXQOFVSB0
D
D
D
D
D661 G45HOAA4VSX2HA
DP60HAAM7NSX2-A
D
DC /G35JOAA5VSX2HA
DC /G35JOAA5VSX2HA
DC
DC/G35JOAA4VSX2HA
D661-XXXX(4551)/G30HOAA5VSD2HO
D661-XXXX/G30HOAA5VSD2HO
DG35JOAA6VSX2HA)
DG35
DG35JOAA6VSX2HA)
Dnbsp;
DC
DC
D
DP80FAA-04NEM2-0
DC
D
D
D661-P80HABF6VSX2-B
DC
DEG60H0CA5VSX2HA
DEG35H0CA5VSX2HA
DE
DC
DC
DC
DC/G60JOAA6VSX2HA
D
DAG75HOA06VSP2HA
D
D
D
DP60HAAF6VSX2B
D661—4627A G75HOAO6VSP2H.A
DC
DP30HAAD6VSX2-B
DCG45JOAB6VSX2HA
DC
DA
DE
D
D
DC/G75JOAA6VSX2HA
D661-431D-5
D
D
D
D662-P01JAMF6VSX2-A
D
D
DE
D662Z4310K/P02JXMF6VSX2-A
D
D
D
DK
D
D
D
D
DK
D
D
D
D633-317B
D633-308B
D633-302B
D
D633-471B
D633-525B
D633-204
D633-333B
D633-375B
D
D633-R16KO1MOVSS2
D633-498B
D633-509B
D633-303B R02KO1M0NSM2
D633-317B R04KO1M0NSM2
D633-308B R08KO1M0NSM2
D633-313B R16KO1M0NSM2
D633-312B/R08K01MONSS2
D633-442B-RO2KO1FONSS2
D633-526B/R02KO1DONSP2
D633-419B/R16KO1FONSP2
D633-473B/R08K01F0VSX2
D633-500B/R02K01MOVSX2
D633-314A/E02K01M0NSP2
D633-333B-R16KO1FONSS2
D633-442B-R16KO1DOVSS2
D633-R04KO1MOVSS2
D633-D2500B/RXXKX1FONSS2
D633-D2501B/R04KD1MONSM2
D633-362B/R16KO1F0NSM2
D633-318B
D633-399B
D633-447B
D633-455B
D633-545B
D
D634-319C/R40KO2M0NSP2
D634-301C
Dnbsp;
D634-501A
D634-501A
D634-341C/R40KO2M0NSS2
D634-538A
D634-543A
D634-528A
D634-314C
D634-346C
D634-383C/R24K02MONSX2
D634-371C
D634-341C
D634-Z510
D634-391C
D
D
D663-333BR16K01FONSS2
DLO3HABF6VSX2-A
DLO3HABD6VSX2-A
D663-Z4307K/P02HONF6VSX2-A
D
DE
D662Z4336KP01JXMF6VSX2-A
D663Z4323K /PO3JONF6VSX2-A
DLO5HABF6VSX2-A
D664-Z4306K/P05JXNF6VSX2-A
D
G
G
GB
GB
G
G
G
G
G
G
