Hydraulic System; Troubleshooting; Troubleshooting Aids; Troubleshooting Procedures - Manitowoc Grove CD3340B Service Manual

CD3340B/YB4411
push more oil into the system until the resistance is
overcome or the relief valve opens (fixed displacement
pumps) or the pump compensator setting is reached
(variable displacement pumps).
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 gallon per minute (gpm) or liter 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 kilopascals (kPa). There are four general types of
pressure.
1. High Pressure, which is normally the result of an
external load on the system.
2. Low Pressure, normally the result of the internal
resistance of the components in the system.
3. 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.
4. 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

There are four hydraulic systems on this machine.
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
GROVE
this section. The main hydraulic system gives hydraulic
power to:
1. The swing motor
2. The boom cylinders
3. The front and rear outrigger cylinders
4. 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

1. 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
unders tand the schematic is important to good
troubleshooting. The schematic can be found at the end
of this manual.
2. 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 gallon per minute (gpm) or liter
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 flow meter and
the use of the flowmeter are normally included with the
flowmeter.
3. Pressure Gauge - an instrument for measurement of
the pressure in the system. This indication is normally
given in pounds per square inch (psi) or kiloPascals
(kPa). On this machine, 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.
1. Check with the operator. Learn if there was a loss of
power (machine did not move the load) or a loss of
speed (slow cycle time).
2. Learn if the problem is common to all circuits or is found
in one or two circuits.
Published 04/07/2015 Control # 569-00

HYDRAULIC SYSTEM

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