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Understanding of concrete pump hydraulic system
Pumping Hydraulic system
Boom hydraulic system
Outrigger hydraulic system
Hydraulic system diagram
Daily check and maintenance of the hydraulic system
The functions of the truck mounted concrete pump, hydraulic system can be divided into pumping hydraulic system, boom hydraulic system, outrigger hydraulic system.
Pumping Hydraulic system Is divided into three parts: main pumping system, distribution and lubricating system, mixing and cooling and cleaning system.
Main pumping system
There are two hydraulic loops: open and close loop.
The Open loop: uses an A11VLO190 variable displacement of axial piston pump. It is fitted with a constant power control device, pressure cut-off valve and electrical stroke limiter with proportional solenoid. The constant power control device has been
set in the factory. The displacement can be adjusted from 0 to Maximum by turning the oil pump displacement potentiometer on the control panel from low to high.
Fig. 1 A11VLO 190
A，B Service port (without charging pump)      420 bar
S        Suction port (with charging pump) 35 bar
T1, T2  Air bleed, tank
R      Air bleed, oil drain
M1      Measuring point, regulating chamber
M      Measuring point, service port
G      Port for positioning pressure (controller) for version with stroke limiter (H.., U2), HD and EP with screwed fitting GE10 – PLM (otherwise port G closed)
controller翻译中文The other is the control line, which can change the flow direction and the displacement of main pump through constant power valve, proportional solenoid pressure reducing valve, directional control valve and servo valve of main pump.
The Closed loop: There is an auxiliary pump with relief valve that the setting pressure is 3.5Mpa in A4VG180. The auxiliary pump has two output ways. One is the charge oil line, which connects with suction line of main pump through the check valve in two pressure relief valves and add oil to main pump. At the same time excessive hydraulic oil return to oil tank through flushing valve and cooler to realize heat exchange for closed loop.
A, B Service line ports SAE 1 1/4", high pressure series 420 bar
T1 Case drain or filling port
T2 Case drain M33×2; 18 deep
M A, M B Pressure gauge - operating pressure A, B
R Air bleed
S Boost suction port
X1, X2Control pressure ports (before the orifice)
G Pressure port for auxiliary circuit
P S Control pressure supply
Fa Filter outlet
Fa1Filter outlet (filter assembly)
Fe Filter inlet M33×2; 18 deep
F S Port from filter to suction line (cold start)
M H Port for balanced high pressure
Y1, Y2Remote control ports (only for HD control)
Flushing valve
Used for closed loop to prevent excessive heat build-up in closed circuit operation. The setting pressure of flushing valve is 3.0MPa
Pressure reducing valve with proportional solenoid
Used for closed loop. The Output pressure is connected with the remote control port of main pump to control the displacement and is controlled by a proportional current signal and constant power valve. The displacement can be adjusted from 0 to Maximum by turning the displacement adjusting potentiometer.
Constant power valve
Used for closed loop. When the hydraulic system pressure is over the setting pressure, the valve works to reduce the output pressure of the pressure reducing valve and maintain the constant power.
Fig.3 Constant power valve
Main pump suction filter
Open loop: filtration fineness 100u.
Close loop: filtration fineness 20u.
When the indicator in the vacuum gauge exceeds the safe area or the electric signal instrument gives a warning, the cartridge may be blocked. It should be clean or replace filter cartridge promptly.
Filter filtration fineness is 20u in open loop. When the reading pressure of the vacuum gauge exceeds 0.35Mpa, the cartridge may be blocked. It should be clean or Return filter
replace filter cartridge promptly.
Filter filtration fineness is 10u in closed loop. When the electricity deliver reports to the police, the cartridge may be blocked, it should be clean or replace filter cartridge promptly.
Distribution and lubricating system
Constant pressure pump
Fig.4 Constant pressure pump
An A10VO28 constant pump is used for the distribution system of supply oil.
The setting of the pressure control valve of the pump is 16Mpa. Once the system pressure is reached, the bump will keep this pressure then decrease the displacement. There
is a pressure relief valve in the distribution circuit to act as a safety valve, which is set to 18Mpa.
Plate ball valve (shut-off valve)
Used to discharge the accumulator. It must be rotated the lever of shut-off valve anti-clockwise when the pumping finishes or stopped for maintenance, in order to discharge the pressure of theaccumulator. (Pressure gauge of distribution system is zero) Accumulator
Inflation pressure is 8-9Mpa. Use Only Nitrogen to fill the accumulator. Charging pressure should not exceed these figures.
Lubricating system
There are two types. One is reciprocating centralized lubrication that is driven by oil from the swing cylinders of distribution system includes lubricating single pump (or double pump), distributor, damper and filter. The other is automatic centralized lubrication that is driven by a D.C motor with an independent grease tank and independent from the hydraulic system. The interval time of lubrication is carried out in the factory. The lubrication system works automatically when pumping.
Mixing, cooling, cleaning system
Only the Mixing, cooling, cleaning system are driven by motor in open loop.
Gear pump
Gear pump supplies oil to the mixing, cooling, cleaning system.
Sandwich type relief valve
The pressure is set to 14Mpa.
Ressure relay
If the mixing blade is stuck, the system pressure will raise. When the pressure exceeds the setting value (usually 10Mpa), the pressure relay will give a warning. The Solenoid directional control valve changes direction to let the mixing motor to rotate anti-clockwise. After 6 second the solenoid valve will reset, and the mixing motor will rotate clockwise again.
Return filter
The filtration fineness is 10u in closed loop. The cartridge may be blocked when the electric alarm sounds. It should be replace promptly.
Boom hydraulic system

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