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
$ R% H) v) E+ }. F6 `7 ELimit conditions for axial piston units
1 m% f$ n3 G" k6 YMinimum storage temperature ___________________ - 50 C
Warm-up phase at low load ________________ as from -40C
Operation under load _____________________ as from -25C
7 y+ U% X: K" t0 ?4 {3 `; a! x5 N# PGeneral
: E8 T- Q/ `0 k- o& \/ G( W• For applications at temperatures lower than -25C, we recommend
that the shaft seal be made of perbunan or PTFE1). However, in the
# g) P! e" T! P* H( T7 l5 pcase of perbunan, please note that the maximum operating
temperature is reduced to 90C
• Moisture in the environment of the axial piston unit must be
6 F  |0 r7 K; O# U' H! Kprevented, because any moisture on the shaft seal can cause the
seal lip to freeze on the shaft while the machine is at standstill.
4 g# Y5 h" ]+ xThen, 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
; D8 m3 v* o5 Z% x, F; N/ T# Xand in the hotter summer temperatures.
The limiting values for viscosity are as follows:
- f2 u$ V0 [. dmin = 5 mm2/s
short term at a max. permissible temp. of tmax = 115C/90C.
3 W) z( \: e/ V- c9 ?+ j6 JPlease note that the maximum temperature of 115C for the
hydraulic medium (90C for perbunan) must never be exceeded,
/ M3 l+ l8 ^* t( F% ceven in specific locations, e.g. the bearing area.
* n2 L4 c7 q) \! A& w# E, X/ A  Smax = 1600 mm2/s
3 v5 t. n& `, Mshort term on cold start (n≤1000 rpm, tmin = -40C).
, p, F( D0 m, ]• Particular attention must be paid to the starting viscosity.
For pumps in open circuit, there is also an acute danger of cavitation
! h" i# N. @# w2 d% s3 kwhen starting with highly viscous (“gelled”) media in the intake
% k5 u0 k/ O, R& Sline, because this type of pump usually starts with the maximum
! V0 \4 d% X4 eswivel angle.
( h7 V2 g9 q0 `+ U• When installing new components, these components must first be
filled at higher temperatures, so that sufficient lubrication is ensured
0 }$ ?- m- Z4 @in all zones.
- x( D: k% t/ S' ?6 w. O+ C+ H0 C• Measures for filters, cylinders, gears etc. must be agreed with the
manufacturers.
8 L+ F3 |+ ]8 z# p7 ISpecifications for electronic systems
• Control units, amplifiers, sensors, transducers and solenoids:
Minimum storage temperature ___________________ - 50C
: i  G" k; b% h/ L/ f- U$ ?: iInstallation and full operation _____________ as from -40C
6 Z  A8 A9 k- F0 |. R+ _• Devices with displays (unless otherwise specified)
0 s/ X, g& {6 W7 W7 vMinimum storage temperature ___________________ - 20C
Installation and full operation _____________ as from -20C
- k2 E* y8 S  K& ?3 RIn the case of switching- and proportional solenoids, possible
. V$ g) j+ B, ?6 ?increases in hysteresis or increased switching times must be
2 Q" L, |  k+ P4 }6 w" v# c- Aexpected due to increasing viscosity of the hydraulic medium at
lower temperatures.
9 [0 E9 g8 K! aRE 90 300-03-B/11.01
Warm-up instructions
• Warm up all components to at least -40C.
• Start the drive engine.
( ]8 B. I! \! u/ o4 Q& E7 y• Warm-up phase for open hydraulic systems
- The pump starts up with the diesel engine and must be operated
* g. k7 i) ?9 Q, N- `; [for at least 10 minutes at the engine idling speed in order to
ensure self-lubrication.
- K. u0 h  K& n- The pump must be in low-pressure circulation mode
(max. 50 bar and max. 50% oil flow).
- Generate a circulating pressure of approx. 50 bar at the pump by
a separate pressure make up valve. This operating condition must
3 W/ w  _. ^8 O6 ]3 }% Obe maintained until the system reaches a temperature of -25C.
: C; |. W) {8 [$ G' g5 E' r9 a" v* XThe speed of the diesel engine must not be increased during this
9 E, W) ]5 J! J% X  pperiod.
, P7 M9 @% c9 {3 z0 |2 z/ \  }2 y+ z- Then slowly operate all system functions several times at low load
8 r  y4 |# w( D' f2 U! E3 Ain order to warm up the entire system as uniformly as possible.
  ^7 E2 U9 v) @During this period, the tank temperature must be monitored, since
6 }6 N7 g: u: y3 N# P, Rit will drop due to the cold hydraulic medium returning to the
# L4 ^0 U5 b' E+ D, ?tank.
• Warm-up phase for closed hydraulic systems
8 i1 o4 R3 g0 C* _! ^+ U. n' I- Set the pumps to neutral position without oil flow.
- The pump starts up with the diesel engine and must be operated
' n5 f# T' v5 I, Q1 gfor at least 10 minutes at engine idling speed.
% F1 X& }: j; U1 T- 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
prevent temperature shocks. The temperature difference between
the hydraulic medium and individual components must not exceed
! U/ ^& a9 w  y" g8 F+ M; {( C20C.
8 ^! p% N) D# D' K7 {• 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
/ o+ R! h* v( y- y5 eduring operation in order to ensure that motors operated only
occasionally are maintained at operating temperature.
: Z( k5 ^2 K& X0 q+ X7 A1 L* f• Our axial piston units can be operated under full load as from a
% P; C/ @9 s) j$ [$ B- Bcircuit temperature of -25C in the system.