Document 57.4402.8200 - 1
st
Edition 03/2007
INDEX
GYRO 4020 - 4518
INTRODUCTION
The circuit of pump (
4
) is protected by a pressure relief
valve
33
) calibrated to 160 bar.
The suction lines of the open-loop pumps (
3
-
4
) and the
power-driven emergency pump (
48
) are not protected by
filters and are conveyed to a single port on the hydraulic
fluid tank (
32
).
Between this port and the suction lines of the aforesaid
pumps, there is a gate valve (
31
) that allows to perform
important maintenance interventions on the oil-pressure
circuit of the machine without emptying the oil tank. This
tank has a capacity of 230 litres.
On the contrary, the drive pump (
2
) is protected by a
special filter (
45
), placed on the discharge line of pumps
(
3
-
4
). This filter purifies the oil from the open circuits of
the machine (boom-turntable control circuit and service
and parking brake feeding circuit) and allows to have
an additional oil port for the drive suction line with a
minimum pressure of 0.5 bar.
This construction feature of the filter guarantees
significant advantages in terms of absence of cavitation
in the drive suction line, especially when the machine is
started from cold.
The one-way valve (
34
) set to 1.5 bar protects the
pump housing against high pressures and guarantees
a certain circulation of the drain oil to the hydrostatic
motor reducing, in this way, the temperature.
From port “X” of the drive pump (
2
) low-pressure oil
is taken (25-30 bar). This oil is first conveyed to the
undercarriage through port 11 of the hydraulic rotary
joint (
9
), and then used for the two-speed mechanical
gearbox circuit (
51
), for the adjustment of the hydrostatic
drive motor (
50
) and for the differential anti-slip circuit
through the mechanism placed inside the front axle
(
57
).
The hydraulic energy produced by the drive pump (
2
)
and conveyed to the undercarriage through ports n.1
and n.2 of the hydraulic rotary joint (
9
), is converted into
mechanical power by a closed-loop hydrostatic motor,
model Linde HMV 75-02E112V (
50
) equipped with an
electroproportional adjustment valve and with a flush
valve for reducing the max temperatures inside the
drive circuit.
In addition to the high-pressure connections with pump
(
2
) throughj ports n. 1 and n. 2 of the hydraulic rotary
joint (
9
), the motor (
50
) is hydraulically connected to the
turntable through port n.12 of the aforesaid joint from
which it receives the flow from the drain circuit of the
drive pump (
2
), through port n. 7, to which it conveys
all the drain flow, and through port n. 11, from which it
takes the low pressure needed for its adjustment.
The electroproportional valves of pump (
2
) and motor
(
50
) are controlled by a dedicated electronic control
unit (Linde) which is connected to the remaining control
devices of the machine through the digital network.
