液压机械低温启动注意事项

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Instructions on the Use of Hydrostatic
Drives at Low Temperatures
6 \+ q" W% S, L  X) lLimit conditions for axial piston units
0 o8 `$ e. b2 x% C4 rMinimum storage temperature ___________________ - 50 C
Warm-up phase at low load ________________ as from -40C
Operation under load _____________________ as from -25C
General
7 \4 K2 f& V- L8 K( L• For applications at temperatures lower than -25C, we recommend
that the shaft seal be made of perbunan or PTFE1). However, in the
case of perbunan, please note that the maximum operating
temperature is reduced to 90C
! }- \" N) q& E2 z* K& @• Moisture in the environment of the axial piston unit must be
prevented, because any moisture on the shaft seal can cause the
/ y2 H& s" ^; p8 h" t0 Xseal lip to freeze on the shaft while the machine is at standstill.
  _6 y3 p/ j: j% f! F' A% H+ ^8 U* cThen, on starting, the possibility of seal destruction cannot be
eliminated.
• Viscosity must be maintained within the limits specified in the
technical data of the axial piston machine by selecting a suitable
hydraulic medium for the entire operating period, both in winter
and in the hotter summer temperatures.
The limiting values for viscosity are as follows:
min = 5 mm2/s
short term at a max. permissible temp. of tmax = 115C/90C.
Please note that the maximum temperature of 115C for the
hydraulic medium (90C for perbunan) must never be exceeded,
even in specific locations, e.g. the bearing area.
' ^0 a7 g0 I2 O# v3 ^max = 1600 mm2/s
% [9 Z) {' c. j* v7 sshort term on cold start (n≤1000 rpm, tmin = -40C).
• Particular attention must be paid to the starting viscosity.
For pumps in open circuit, there is also an acute danger of cavitation
when starting with highly viscous (“gelled”) media in the intake
line, because this type of pump usually starts with the maximum
swivel angle.
• When installing new components, these components must first be
% f6 D- X- W- g/ o, ~2 ?filled at higher temperatures, so that sufficient lubrication is ensured
in all zones.
• Measures for filters, cylinders, gears etc. must be agreed with the
8 }+ `& S# i8 ~0 f+ R7 smanufacturers.
/ W7 W: ~& q0 ~4 VSpecifications for electronic systems
• Control units, amplifiers, sensors, transducers and solenoids:
% c% m4 }, h" `4 v7 b3 mMinimum storage temperature ___________________ - 50C
% m3 r- V9 B1 M: m; A7 GInstallation and full operation _____________ as from -40C
• Devices with displays (unless otherwise specified)
9 Q" K( l4 q- T+ Q! x5 \Minimum storage temperature ___________________ - 20C
Installation and full operation _____________ as from -20C
- J, l5 e9 f% v1 L1 KIn the case of switching- and proportional solenoids, possible
increases in hysteresis or increased switching times must be
9 }  _0 T9 f) \: q. Vexpected due to increasing viscosity of the hydraulic medium at
lower temperatures.
3 ~5 F- N4 B% t3 xRE 90 300-03-B/11.01
/ @/ V% l7 H# l" {Warm-up instructions
7 @1 K- h7 i7 `/ ?5 Q3 f• Warm up all components to at least -40C.
• Start the drive engine.
9 S# ~/ }. D: r+ [7 t5 m• Warm-up phase for open hydraulic systems
; b6 \; N8 P" A3 v( z% T3 E- The pump starts up with the diesel engine and must be operated
/ E6 s- i' C( }, I' L* qfor at least 10 minutes at the engine idling speed in order to
ensure self-lubrication.
- The pump must be in low-pressure circulation mode
(max. 50 bar and max. 50% oil flow).
% Z. H: K" W4 F/ A' d+ x" K! S2 V: A- Generate a circulating pressure of approx. 50 bar at the pump by
% n+ S2 A0 @1 a! [. ia separate pressure make up valve. This operating condition must
be maintained until the system reaches a temperature of -25C.
The speed of the diesel engine must not be increased during this
period.
/ M, t$ M8 p. V% P% A- Then slowly operate all system functions several times at low load
/ F1 ~/ h! O8 `8 k8 |& Rin order to warm up the entire system as uniformly as possible.
During this period, the tank temperature must be monitored, since
it will drop due to the cold hydraulic medium returning to the
; k9 Q9 p) i, I+ H4 Rtank.
• Warm-up phase for closed hydraulic systems
- Set the pumps to neutral position without oil flow.
- The pump starts up with the diesel engine and must be operated
- Y4 {5 f7 }  c# H, Q5 gfor at least 10 minutes at engine idling speed.
' t, p6 x6 w4 d: s  G- [2 v- Then slowly swivel the pump outwards. All system functions must
be operated slowly several times at low load until the entire system
reaches a temperature of -25C.
• Continuous flushing is necessary in all components in order to
) _6 G! x: a0 W: s) S5 Fprevent temperature shocks. The temperature difference between
. T6 ]/ m  i3 x  b6 a1 vthe hydraulic medium and individual components must not exceed
' o- u: n4 c/ Z20C.
' n- V5 Y7 Y1 F, g7 c• The hydrostatic motors must be flushed transversely via the flushing
3 L# A- @2 J2 E& P5 y/ z3 g(U) and leakage oil ports (T). During this process, the permissible
housing pressures must be monitored. Flushing should remain active
0 Q3 C+ }, g' ]" aduring operation in order to ensure that motors operated only
occasionally are maintained at operating temperature.
• Our axial piston units can be operated under full load as from a
circuit temperature of -25C in the system.