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Duringclutchoperation,thereisslips,whichisdeterminedbytheformula:
s
±
n
1
n
-
2
n
2
|
100%
,
where:n
1-pumpshaftspeedinrpm,n
2-turbineshaftspeedinrpm.
(1)
Whenthereisastator(3)betweenthepumpandtheturbine,thenthesystem
isahydrokinetictransmission,commonlycalledatorqueconverterbyoperators
ofworkingmachinery,(Fig.1b,c).Ahydrokinetictransmissiontransfersconstant
power,butvariabletorque.
Thecharacteristicsofthegearboxaredefinedbytheformula:
Mn
2
n
±
const
,
(2)
where:M-transmittedtorque,n
2-speedofthedrivenside,η-efficiencyofthe
transmission.
Asinthehydrokineticclutch,thereisalsoaslightslippageinthehydrokinetic
transmissiontomaintainoilcirculation.Inmachines,itiseliminatedbytheuseof
alockingclutch,whichmechanicallyconnectsthepumprotortotheturbinerotor
whiledisconnectingthehydrokineticdrive.
TheprincipleofhydrostaticpropulsionisbasedonPascal’slaw,concerning
theprincipleofuniformpropagationofpressureinalldirectionsinaliquidcon-
tainedinaclosedvessel.Adiagramofanexamplehydrostaticsystemisshown
inFigure2.Aweightlesspistonmovingwithoutfrictionunderidealconditions
inacylinderisloadedwithaforceF.Thecylinder(3)isconnectedtothepump
(1)throughthedirectionalcontrolvalve(2).Withthepositionofthevalveasin
Figure2betweenthepistonandthepump,thepressureiscausedbytheforce
Factingonthecylinderrod.Takingthebottomofthetankasareferencelevel,
Bernoulli’sequationcanbewrittenforpointsAandB,
p
A
+
h
A
p
g
+
p
2
v
2
A
±
p
B
+
h
B
p
g
+
p
v
2
B
2
(3)
where:p
A,p
B-arepressuresatpointsAandB,ρ-densityofthemedium,g-accel-
erationoftheearth,V
A,V
B-flowvelocityattheconsideredpoint,h
A,h
B-heights.
Assumingasmalldifferenceinheighth
Aandh
Bandasmalloilflowvelocity,
wecanassumethat:
p
A
±
p
B
±
p
.
(4)
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