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
Limit conditions for axial piston units
; T4 W% ]2 A1 k9 n1 D! ?) rMinimum storage temperature ___________________ - 50 C
Warm-up phase at low load ________________ as from -40C
Operation under load _____________________ as from -25C
8 Z  e3 q9 a9 @3 b1 D4 aGeneral
' t4 P' q0 S$ A) y( G6 E$ E• For applications at temperatures lower than -25C, we recommend
that the shaft seal be made of perbunan or PTFE1). However, in the
6 c0 v; ^& X; G8 Ecase of perbunan, please note that the maximum operating
4 ]5 E. J! e% {0 y! r- Qtemperature is reduced to 90C
: j/ a) s6 n8 H$ l# w/ Z  k• Moisture in the environment of the axial piston unit must be
. L$ n1 g' p( T7 j, [" Fprevented, because any moisture on the shaft seal can cause the
seal lip to freeze on the shaft while the machine is at standstill.
. d3 U: p4 Q/ h7 _& V/ XThen, on starting, the possibility of seal destruction cannot be
eliminated.
* p. p0 @5 o( u* l/ |2 L! p  ~# D• Viscosity must be maintained within the limits specified in the
0 {1 Y6 W+ a6 v( v1 p8 ~technical data of the axial piston machine by selecting a suitable
9 c" p  Z2 L1 L2 {; a, rhydraulic medium for the entire operating period, both in winter
7 a* E$ H+ j% ~' M7 v- pand in the hotter summer temperatures.
3 f, Y3 O4 A! \7 Y0 |' a2 o- _( s" WThe limiting values for viscosity are as follows:
+ `: |3 g' ~, C0 Pmin = 5 mm2/s
8 T" u0 u1 s. c2 Q* zshort term at a max. permissible temp. of tmax = 115C/90C.
7 H6 g, w1 u$ H. ]. x$ V, |Please note that the maximum temperature of 115C for the
# l# r- ?1 O  a3 I6 Y2 Mhydraulic medium (90C for perbunan) must never be exceeded,
even in specific locations, e.g. the bearing area.
+ T, ~; t4 h. W# `' X% Imax = 1600 mm2/s
1 E  s; g- ]4 a1 X' bshort term on cold start (n≤1000 rpm, tmin = -40C).
1 X: A8 f) I4 T' L# b3 i• Particular attention must be paid to the starting viscosity.
1 H4 Q8 M4 |/ I- j) gFor pumps in open circuit, there is also an acute danger of cavitation
when starting with highly viscous (“gelled”) media in the intake
( Q2 M8 O* g9 w- d& D' k) W1 b' eline, because this type of pump usually starts with the maximum
swivel angle.
• When installing new components, these components must first be
filled at higher temperatures, so that sufficient lubrication is ensured
in all zones.
• Measures for filters, cylinders, gears etc. must be agreed with the
manufacturers.
7 B$ E; b. l% x' `% [# I  {4 kSpecifications for electronic systems
5 ]: ]& Y% I: g- N• Control units, amplifiers, sensors, transducers and solenoids:
Minimum storage temperature ___________________ - 50C
( _3 [. ], _$ ^% M! w( E$ y/ f2 SInstallation and full operation _____________ as from -40C
' J% [" f7 s( F/ `• Devices with displays (unless otherwise specified)
Minimum storage temperature ___________________ - 20C
Installation and full operation _____________ as from -20C
) j% ]! B$ V9 t% rIn the case of switching- and proportional solenoids, possible
- Q6 T' s& g1 b* x. h' q' P! Pincreases in hysteresis or increased switching times must be
! \5 d, x3 T" t/ |, iexpected due to increasing viscosity of the hydraulic medium at
8 t" F7 Q: F  k7 C  [4 U& R; X* B/ Olower temperatures.
. ?7 ]* n: `0 ?3 rRE 90 300-03-B/11.01
Warm-up instructions
3 w3 L  p8 f3 e• Warm up all components to at least -40C.
* B$ K8 q$ h- E. O+ c, D• Start the drive engine.
• Warm-up phase for open hydraulic systems
- The pump starts up with the diesel engine and must be operated
for at least 10 minutes at the engine idling speed in order to
, G2 d" t$ a6 P* o5 @ensure self-lubrication.
4 \0 j) \2 ~8 b3 R* I* {- The pump must be in low-pressure circulation mode
! P1 |8 B8 _! G* d3 a(max. 50 bar and max. 50% oil flow).
- Generate a circulating pressure of approx. 50 bar at the pump by
; W* Y6 v. N0 i% d: Q* H  Sa separate pressure make up valve. This operating condition must
be maintained until the system reaches a temperature of -25C.
( r& H* a4 l9 n/ YThe speed of the diesel engine must not be increased during this
period.
- Then slowly operate all system functions several times at low load
in order to warm up the entire system as uniformly as possible.
) \0 @( U/ n6 P8 X( O6 e1 dDuring this period, the tank temperature must be monitored, since
it will drop due to the cold hydraulic medium returning to the
# J1 `5 p: I) w4 A6 ptank.
& h$ E% ~5 A8 \4 n' i" |) \• Warm-up phase for closed hydraulic systems
+ r* `! G5 V$ D2 Q/ Z7 F: h/ @- Set the pumps to neutral position without oil flow.
- The pump starts up with the diesel engine and must be operated
) O* w- e8 |: g' n# A, P7 vfor at least 10 minutes at engine idling speed.
- Then slowly swivel the pump outwards. All system functions must
be operated slowly several times at low load until the entire system
0 g0 |; S+ V" L' xreaches a temperature of -25C.
• Continuous flushing is necessary in all components in order to
$ n$ s* Z& `) o9 K$ L- x9 Gprevent temperature shocks. The temperature difference between
- |9 u8 w7 H% t2 |* f' M5 Ithe hydraulic medium and individual components must not exceed
( |' ~, D  q" T$ p. N6 _2 H: v20C.
( G% l" V* J/ ?1 J• The hydrostatic motors must be flushed transversely via the flushing
(U) and leakage oil ports (T). During this process, the permissible
housing pressures must be monitored. Flushing should remain active
during operation in order to ensure that motors operated only
occasionally are maintained at operating temperature.
! B5 V  V/ W- N5 B2 C  A# W' N& M• Our axial piston units can be operated under full load as from a
circuit temperature of -25C in the system.