Manitowoc Grove YB5515-2, Руководство по обслуживанию и ремонту

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HYDRAULIC SYSTEM CD5515-2/YB5515-2 SERVICE MANUAL
4-2
Published 1-20-2017, Control# 483-02
Valves are used to control the flow, pressure, direction, and
volume of the oil in the system. There are many different
types of valves. An explanation of the different valves used
on this machine is given in the description of each circuit.
Filters remove dirt and particles of foreign materials from the
oil in the system. The oil in the system must be kept clean to
inhibit damage to the pumps, cylinders, valves, and other
components of the system.
Motors and Cylinders are the actuators or working tools of
the system. In the motors and cylinders, hydraulic energy is
changed into mechanical force (rotary or straight line
movement).
The Hydraulic Oil Tank has three important functions:
storage, cooling, and supply of oil to the pumps. Because
piston rods take space in the cylinders, the level of the oil in
the tank will be higher when all the cylinders are retracted.
To understand how a hydraulic system works, it is important
to understand the following words:
Flow - The flow through the system is caused by the pump.
The amount of fluid which is sent to a circuit or actuator
generally controls the speed of that function. The flow is
measured in gallons per minute (gpm) or liters per minute (L/
min).
Pressure - is caused by any resistance to the flow of the oil.
Pressure is normally measured in pounds per square inch
(psi) or bar. There are four general types of pressure.
• High Pressure , which is normally the result of an
external load on the system.
• Low Pressure , normally the result of the internal
resistance of the components in the system.
• Static Pressure , where the oil is closed in a circuit
between two components. There is no movement of the
oil, but there is pressure on the oil, normally because
there is an external load on the circuit.
• Series Pressure , which is found where oil is confined
between two components in a series arrangement, for
example when the rod port of one cylinder is connected
to the base port of another cylinder. Movement of either
cylinder will cause movement in the other cylinder.
Hydraulic System
T h ere are fo ur h yd r a ul i c s y st em s o n th i s m a c hi ne .
Information on the hydraulic system for the transmission,
brakes, and steering is found in Sections 7, 9, and 10
respectively. Only the main hydraulic system is included in
this section. The main hydraulic system gives hydraulic
power to:
• The swing motor
• The boom cylinders; lift and telescope
• The front and rear outrigger cylinders
• The main hoist motor
The hydraulic components on the boom and mast are
connected to the hydraulic components on the lower
structure through a hydraulic swivel. The hydraulic swivel is
at the center of rotation of the mast. The design of the
hydraulic swivel permits operation of the hydraulic functions
through full rotation of the mast.
TROUBLESHOOTING
To find a problem in the hydraulic system with minimum loss
of time, use the following aids and procedures.
Troubleshooting Aids
• Hydraulic schematics — an exact illustration of the
arrangement of the system. The schematic shows all the
components in relation to the system. The ability to
u n d e r s ta n d t h e s c h e m a t i c i s i m p o r tan t t o g o o d
troubleshooting. The schematic can be found at the end
of this manual.
• Flowmeter — an instrument that can be connected into
the system to measure the flow of the oil in the system.
The flow is measured in gallons per minute (gpm) or
liters per minute (Lpm). Normally, the flowmeter is used
to check the output of the pump. The flowmeter can also
be used to find the location of leakage or restriction in
the system. Instructions for installation of the flowmeter
and the use of the flowmeter are normally included with
the flowmeter.
• Pressure Gauge — an instrument for measurement of
the pressure in the system. This indication is normally
given in pounds per square inch (psi) or bar. On this
crane, quick couplers are installed in the pressure lines
from the pumps. Pressure taken at these locations will
give an indication of operating pressure or relief
pressure.
Troubleshooting Procedures
For good troubleshooting, a step by step analysis of the
problem and the possible cause is necessary. First, find the
symptoms.
• Check with the operator. Learn if there was a loss of
power (crane did not move the load) or a loss of speed
(slow cycle time).
• Learn if the problem is common to all circuits or is found
in one or two circuits.
• Make a visual inspection. Look for a restriction in the
linkages, low level of hydraulic oil, bent tubes, collapsed
or ballooned hoses, leakage around the hydraulic
components, etc.
Reference Only