10
When the pressure on the brake valve (10) drops below 100 bars, the indicator
lamp on the instrument panel lights. This lamp is controlled by controlling the power
switch. The pump is switched by brake service switch.
When pressing down the brake valve (10), pressure oil in the accumulator circuit
flows to the wheel-side brake (12). At the same time, the brake lights are switched on
by the brake light switch.
6.1.4 Hydraulic operating system and hydraulic steering system
a. Hydraulic operating system
This hydraulic operating system is composed of double pumps and double circuits
(Fig.9). It is made up of closed oil tank (4), a two-gang gear pump (1), two five-gang
multi-way reversing valves (Refer to 14, 15), hydraulic cylinders for operating
apparatuses, motor and hydraulic lines. Each system has its own hydraulic pump, but
the hydraulic oil is supplied from the same oil tank (4). The hydraulic oil from oil
tank (4) is pumped by a two-gang pump (1) into two circuits. Among them, oil flows
are equal. When multi-way reversing valves (14, 15) are in central position, the
hydraulic oil, passing through returning lines and the filter (6), returns to oil tank (4).
When moving one or two operating levers, hydraulic oil pushes one-way valve in
reversing valve to flow into hydraulic cylinders and motor. The action of one-way
valve prevents the oil in working apparatus from return oil tank (4).
It can insure that hydraulic system in correct working condition. The double
direction hydraulic lock (16) mounted on the returning lines for titling and lifting the
blade can guard against moving due to their own weight and the load to insure safety
running and operating accuracy of the blade.
Because of the supplying oil in the equal flow, double lift cylinders for up and
down operation in the simultaneous and same speed to raise operating performance of
the grader. System pressure is controlled by the throttle valve in reversing valve (14,
15) .The pressure value is16Mpa and system flow: 65L/min.
b. Steering system
When the hydraulic steering-gear (8) needs the oil, the oil from the oil tank (4) is
intaken by the steering pump and delivered. When turning the steering wheel, the oil
enters into two steering cylinders to make double front wheels steering. Double front
wheels are connected by a common pulling lever.
With safety valve (7), the oil pressure of steering system is limited in 150 bars to
guard steering system. Double safety valves (13) prevent hydraulic steering system
from over pressure. For example, because of the overload caused by road dump, it can
be transmitted from front wheels to steering system.
The oil tank (4) is equipped with pre-pressure air filter that can prevent the air
with dusts from entering into the oil tank and contaminate the hydraulic system.
If the return filter (6) is blocked and the oil cannot flow, the filter valve (5) allows
the oil over the filter from by pass-way and therefore it eliminates the block action of
the filter element. The micro- measuring coupler in the system allows gauge to be
fitted at various positions in the system to adjust the pressure.
Summary of Contents for PY180H
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