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Document title:

Detailed hydraulic description

Knuckle boom crane

A 19-03-2015 Initial Issue TGR JPS JHA

Rev Date Description Prepared Checked Approved

KNUCKLE BOOM OFFSHORE CRANE 50t CT

1219200
Huisman

1219200-C-80-05A.doc
 Detailed Hydraulic description

1. General

Overview Hydraulic Appendices

Appendix Document or Supplier
HPU - Hydraulic Diagram 1219200-B-80-10
HPU - Part list 1219200-B-80-19
Crane - Hydraulic Diagram 1219200-B-80-20
Crane - Part list 1219200-B-80-29
Winches - Hydraulic Diagram 1219200-B-80-30
Winches - Part list 1219200-B-80-39

2. System desrciption

Specifications
Main pumps
Number of pieces 2 [-]
3
Maximum Displacement Variable 250 [cm /rev.]
Flow Per piece 415 [l/min]
Pressure 300 [bar]
Electrical power Per piece 235 [kW]
Voltage 690 [VAC]
Frequency 60 [Hz]
-1
Number of revolutions 1786 [min ]
Boost pumps
Number of pieces 2 [-]
3
Displacement Fixed [cm /rev.]
Flow Per piece 500 [l/min]
Pressure 20 [bar]
Electrical power Per piece 37 [kW]
Voltage 690 [VAC]
Frequency 60 [Hz]
-1
Number of revolutions 1775 [min ]
Filtration pump
Number of pieces 1 [-]
3
Displacement Fixed 10 [cm /rev.]
Flow 18 [l/min]
Pressure Maximum pressure 5 [bar]
Electrical power 0.37 [kW]
Voltage 690 [VAC]
Frequency 60 [Hz]
-1
Number of revolutions 1780 [min ]

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 Detailed Hydraulic description

Hydraulic reservoir
3
Tank capacity 4470 [dm ]
3
Maximum oil volume 4000 [dm ]
Used Oil ISO VG 68
Cylinders
Luffing cylinder 1219200-B-81-10
Number of pieces 2 [-]
Bore 400 [mm]
Rod 320 [mm]
Stroke 4700 [mm]
Knuckle cylinder 1219200-B-81-20
Number of pieces 2 [-]
Bore 300 [mm]
Rod 230 [mm]
Stroke 4500 [mm]
Hydraulic motors
Slewing motors
Number of pieces 4 [-]
Type Axial piston
Displacement 90 [cc/rev]
Main winch motors
Number of pieces 2 [-]
Type Axial piston
Displacement 500 [cc/rev]

The Knuckle Boom Crane is powered by one hydraulic system. This system can be divided
in 4 sub-systems:

• HP: High-pressure system, which is connected with the main pumps.

• LP: Low-pressure system, which is connected with the boost pumps.
• T: The return line is connected with the Reservoir via oil cooler and return filter.
• DR: The drain line is directly connected with the Reservoir. The pressure is below 2
[bar].

All systems and hydraulic reservoir are described in the chapters below.

2.1 Hydraulic reservoir and filtration

The hydraulic reservoir, item 0.01, can contain 4000 litre hydraulic oil. The reservoir is
divided in compartments. The return line enters the first so-called “dirt” compartment.
The boost pumps are supplied with oil from the so-called “clean” compartment. The suction
of the filtration pump is connected to the dirt compartment while the pressure side is
connected to the clean compartment.

Parts on the reservoir

The temperature is monitored and can be read from the electronic temperature switch, item
0.08.

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 Detailed Hydraulic description

The oil level is visual on the level gauges, items 0.06 and 0.07. Level gauges, items 0.06, are
a combination of a level switch and a gauge. The switches are used for the High Level, Low
Level and Too Low Level alarms.
Check valve, item 0.11, is mounted to prevent the reservoir for high pressure. The cracking
pressure of the check valve is 0.2 bar.
To prevent the reservoir from dirt in the air in the environment, tank breathers, item 0.04 will
filter the air. The breathers use a 3 µm element.
Draining the reservoir can be done with ball valves, items 0.13A and 0.13B. Two drain valves
are mouted, one for each compartment.

Offline-Filtration

The suction of off-line filter unit, item 1.90, is connected to the dirt compartment. This unit
contains a large 2 µm filter element and is used as the main filter of the system. It is
equipped with an optical and electrical dirt indicator. Clean oil out of the filter unit goes to the
clean compartment.
Ball valve, item 0.13C, must be closed for service activities.
Use sample point on the unit to take an oil sample for checking fluid cleanliness condition.

Return filtration

The Return filter, item 4.15, is mounted between the cooler and the reservoir.
A 10 µm filter used. It is equipped with an electrical dirt indicator.
Check valve, item 0.05, make it possible to replace the filter element, draining the piping
system can be done by ball valve, item 4.18, mounted at the filter.

2.2 Low Pressure system and cooling

The low pressure system (LP) or boost system is used to maintain a constant pressure of 20
bar in the low pressure sides of the pumps and motors.

Boost pumps

The boost pumps, items 1.55, are screw pumps, which are mounted vertical inside the tank.
Only the electric motors are mounted outside and on top of the tank. In operation both boost
pumps are running.
The pressure of the LP system is monitored at the “MLP” connection on item 3.01.
Two 20 µm filters, item 1.60, are mounted in the LP system to prevent the system from
contamination in case of an unexpected large amount of dirty oil in the reservoir. This filter
has an electrical dirt indicator and a by-pass valve.
Check valves, item 1.70, make it possible to replace the filter element without draining the
piping system.
A low pressure accumulator, item 4.50 (dwg 80-20), will maintain the pressure in the LP
system in case of a sudden short extreme flow demand.

Boost pressure

The pressure of the LP system is adjusted with a pressure relief valve, item 3.12, mounted
on the control cover, item 3.11. This is the pilot valve of the cartridge, item 3.10. Pressure
relief valve, item 3.15, is mounted for smooth operation of the main relief valve. These valves
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 Detailed Hydraulic description

are mounted on manifold, item 3.00. This manifold is located in the top of the HPU frame.
The LP system can be drained for maintenance by needle valve, item 3.02A.

Cooling

The oil / fresh water cooler, item 4.10, is mounted below the reservoir. Thermostatic valve,
item 4.11 will bypass the cooler if the temperature of the oil is below 120F/49°C. Aqua
sensor, item 4.12, is mounted for monitoring the water content in oil.
This aqua sensor makes it unnecessary to check for water in the reservoir.

2.3 High Pressure system

Main Pumps

Two axial piston pumps with variable displacement, items 1.05, are used for the HP system.
The pumps use a pressure control to achieve a constant pressure of 300 bar in the high-
pressure circuit. This pressure is set by pressure relief valve, item 2.03.
Pressure of the HP system is monitored with electronic pressure sensors, item 1.10. Check
valves, item 1.20, prevent the pumps to be driven by the HP system.
Pressure enable valves, item 2.02, will not activated during the start up of the pump. When
this valve is not activated a minimum pressure in the displacement control will be maintained.
The pump will operate in the minimum displacement at a low pressure level.
When the electric motor is switched from star to delta, the pressure enable valve will be
activated and the pump feeds the system with 300 bar.
The pumps and electric motors are mounted vertical, above the hydraulic reservoir.
The case of the pump is flushed with oil from the LP system, through a restriction, item 1.06.
Case pressure can be read by connecting a pressure gauge on the minimess connection on
the T-port.

The system safety

The system safety is a cartridge valve, item 3.20, mounted in manifold, item 3.01. The
maximum system pressure is adjusted with a pressure relief valve mounted in control cover,
item 3.22. This pressure will not be reached in the normal operating mode. This valve limits
the pressure in case of a failure of the pressure control of the pump, or a too high system
pressure. Pressure relief valve, item 3.25, is mounted for smooth operation of the main relief
valve. The HP system can be drained for maintenance by needle valve, item 3.02B.

Accumulator system

The accumulator, item 4.55, is with connected to the HP line, to maintain pressure during a
period when more oil is necessary than the pumps can deliver and to smooth pressure dips
or peaks. The manifold, item 6.41, is mounted at the oil side of the accumulator. The
accumulator can be isolated with a cartridge valve, item 6.42, controlled by pilot valve, item
6.44. The oil from the accumulator can be drained with needle valve, item 6.45. A pressure
sensor, item 5.58B, is mounted to check the nitrogen pressure. The pressure relief valve,
item 6.45, limits the pressure when the accumulator is isolated. For emergency lowering
manriding a pressure connection from the accumulator to one of the secundair units is made
at port A2 of the manifold.

Slewing/Luffing/Knuckle Control

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 Detailed Hydraulic description

In the base frame a valve bank, item 5.50, is mounted. This valve bank has three
proportional control valve sections, slewing/luffing/knuckle/slewing. All functions are mounted
behind enable-valve item 5.55 / 5.56. When not activated, the pressure line is blocked to all
functions. When activated, pressure is measured at the pressure transmitters, item 5.58A,
used as an input in the control system. The valve bank can be isolated from the HP system
by closing ball valve, item 4.31A. To prevent back flow in the return line, check valve, item
4.13, is mounted.

Four hydraulic motors, item 6.10, drive the slewing bearing. Electric proportional flow
restriction valves, item 6.15, are mounted to protect the crane for load induced movement.
To prevent too high pressures at the motors, pressure relief valves, item 6.16, are mounted.
The pressure at both sides of the motors can be measured at MCA and MCB. The
mechanical brakes are controlled by directional valve, item 6.02. The brake pressure is
limited by pressure reducing valve, item 6.03. The time to apply the brakes can be set by
throttle and check valve, item 6.05.

At the luffing cylinders, item 6.20, counterbalance valves, item 6.23 and 6.27, are mounted to
protect the boom for load induced movement. To avoid load difference in both cylinders a
equalize line has been made. Hose rupture valves, item 6.25, are mounted to prevent
lowering of the boom in case of hose burst. All valves are mounted on manifold, item 6.22,
which is mounted at the bottom port of the cylinders.
In case of complete power shutdown each luffing cylinder is provide with two manual
operated valves, item 6.24 and 6.26 for lowering or luffing up the beam.
For luffing up the crane an external Powerpack must be connected at ball valve, item 6.26,
and needle valve 6.24 will function for controlling the movement.
This function is only to be used at reduced load due to the differential shortcut of the cylinder.

At the knuckle boom cylinders, item 6.30, counterbalance valves, item 6.33 and 6.34, are
mounted to protect the boom for load induced movement. To avoid load difference in both
cylinders a equalize line has been made. Hose rupture valves, item 6.35, are mounted to
prevent lowering of the boom in case of hose burst. All valve are mounted on manifold, item
6.32, which is mounted at the bottom port of the cylinders.

Main Winch

The hoist winch is controlled by two hydraulic motors. The motors, 500cc, item 7.02, are
secondary controlled in displacement.
Secondary controlled means that the displacement of the hydro motor is variable and that the
motor is directly connected to the constant pressure circuit. The delivered torque and speed
of the motor is controlled only with the displacement of the hydro motor. If the torque
delivered by the motor is greater than the needed torque for the load, the motor hoists the
load. If a higher speed is needed, the motor displacement is further increased so the drive
torque will increase also and the load will accelerate.
If the torque delivered by the motor is less than the torque needed for the load, the load is
lowered. For enlarge the lowering speed, the motor displacement is further decreased so the
drive torque will decrease also and the load will accelerate. To keep the load steady, the
torque from the motor is kept in balance with the torque of the load.

The motors are driven by the main pumps that maintain a constant pressure of 300bar at the
HP system. When the winch is hoisting the load, the pumps feed the HP system and thus the
hydraulic motors. In this situation the hydraulic motors work as a motor. When the winch is
lowering the load, the hydraulic motors are driven by the load and work as a pump feeding oil
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 Detailed Hydraulic description

from the LP system to the HP system. This causes a pressure rise in the high-pressure
circuit, higher than the set high pressure pump compensator pressure. In this situation, oil
flows from the motors (acting as pumps) into the HP system. The pressure will rise and
hydraulic energy is absorbed by the high pressure accumulator until the pressure becomes
more than 320 bar. At that moment the high pressure main relief valve, item 7.30, opens to
avoid to high pressures in the system. If after lowering the winch will hoist a load, the energy
absorbed in the high pressure accumulators will be used first until the pressure becomes
lower than 300 bar, at that moment the pumps begin to feed oil.

At standstill position the disk brake is applied and all valves are de-energized.
With the HPU running, HP and LP are available at the motor manifold block, items 7.10.
The motors B port are connected directly to the HP line, but are isolated from this line by
main logic valves, item 7.14, and the motors A port are connected to the LP line.
The LP and HP line are also directly connected to servo manifold, item 7.50, and to cylinder
release valves. The de-energized cylinder release valves, item 7.53A/B, and bypass valve,
item 7.53C, result that the cylinder controls of both motors put the displacement to a
maximum for hoisting. In this position the motor is set on maximum torque and provides a
hydraulic brake at the HP side of the motor.

To start a rotation a hydraulic reset has to be given to set the system standby for operation.
The control for the complete motor system from hydraulic reset to complete operation is
executed by the HMC (hydraulic motor control).
Before the reset is given the HMC checks a number of parameters and if found ok energizes
the bypass valves, item 7.54, thus enabling the main servo controls, that controls the
displacement to zero position.
If a hoist or lower command is given directional control valve, item 7.33, is energized and the
pilot line of main logic, item 7.14, is vented for the motor. The opening time for the motor can
be set with throttle/check valves, item 7.18. Main logic, item 7.14, is now opened, connecting
the HP line of the HPU to the motors B port. Now the main servo controls the displacement
control piston in such a way that the torque of the motor equals the torque of the load.
At the moment the signal from the torque balance proximity switches are given, the brake is
released by activating valve, item 7.20. The brake pressure is limited to 70 bar by pressure
reducing valve, item 7.19. The motor displacement is increased slightly until the desired
hoisting speed is reached or decreased slightly until the desired lowering speed is reached.
The HMC uses the signals given by the speed encoder (speed signal) and the LVDT
(displacement position indication), to control the servo valve, item 7.51, in such a way that
the desired speed output is continuously safeguarded.
If a stop signal is given (speed zero demand) the displacement is increased or decreased
until zero speed is reached (detected by the encoder) and the brake is applied by de-
energizing brake pilot valve, item 7.20. After approximately 30 seconds the logic pilot valve,
item 7.33, is de-energized bringing the system in the initial state after the hydraulic reset.
The maximum pressure at the HP side of the motor is limited by pressure relief valve, item
7.32, that opens cartridge, item 7.30, from HP to LP if the pressure exceeds 320 bar.
If the main servo, item 7.51A / B, fails because of a wire failure the cylinder release valves,
item 7.53A/B, are de-energised and the back-up servo, item 7.51C, takes over control (via
the by-pass valve, item 7.53C) and performs a controlled stop. The back-up servo is also
linked the other motor of the main winch motor via STA and STB on the servo manifold and
performs a controlled stop if the main servo of the other motor fails.

The motor housing is flushed with approximately 3 l/min taken from the LP line.

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 Detailed Hydraulic description

The drain of the motors is connected via a header tank, item 4.35 to the HPU reservoir. This
tank has level gauges, item 4.37. Anti-cavitation valves, item 4.38, are placed in the line
between header tank and LP line.

Ball valves, item 7.81, and handpump, item 7.61, are for releasing the mechanical brakes,
used in emergency hoisting or lowering procedures

Emergency controls winch.

EM hoisting:

Using hoisting ball valve’s 7.16B&D in combination with needle valves 7.17A&B A load can
be hoisted after lifting the brakes by means of the hand-pump. Oil is then led past the main
logics to feed the motors. HPU power is required.

EM lowering with load:

Using hoisting ball valve’s 7.16A&C in combination with needle valves 7.17A&B A load can
be lowered after lifting the brakes by means of the hand-pump. Oil is then led through the
needle valves back into the suction side of the motor. Leakage-oil is led into the header tank.
Lag of oil will then be refilled out of the header tank, through check-valves (0,1 bar) 8.03
back to suction side.

EM lowering without load:

Ball-valve 7.82 is used to isolate the line between the two servo controls (used by the back-
up servo). And the accumulator pressure is used to switch the swashplate of motor 2 to 15
degrees lowering. Ball-valve 7.80 is then used to feed accumulators oil into the motor, in
order to drive it.

Motor 1 is used to control the load. The difference in pressure (300 bar drive pressure from
accumulator on motor 2, against 320 bar relief pressure (7.31) on motor 1 makes that motor
1 is leading. However, this procedure should only be used in manriding / low load. Therefore
this procedure is to be followed only when the normal lowering procedure failed.
When lowering is completed, all valves are set to normal position and the HMC controller will
reset the swashplate after restart.

MOPS (Manual Overload Protection System)

This system, activated by the crane operator, protects the crane against overload and “over-
moment” by reducing the load-carrying capacity and allowing the hook to be pulled away
from the crane.

When activated, the load will be lowered uncontrolled, with a resulting tension of 10-25% of
the maximum rated capacity for platform lift.

This feature is controlled by the HMC controller. When activated, the controller positions the
swash plates of both motors in a position where the 10-25% resulting tension will be
maintained when the winch is driven. As soon as both swash plates are in position, the items
7.20A+B are activated to lift the mechanical brakes. When winch is driven, the energy will be
dissipated over the relief valve, item 3.20, set at 315 bar.

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 Detailed Hydraulic description

Since MOPS shall operate under all conditions, valve 7.69 is installed in an external feeding
line. If during a black-out, Emergency stop, or failure in the PLC, and the MOPS activation
button is pressed, this valve will be activated hardwired with usage of 24V battery supply.
Also the HMC controller is hardwired fed through these back-up batteries, and remain
energised when MOPS is activated during E-stop e.g. When activated, valve 7.69, leads oil
form the high pressure accumulator to both winch motors, allowing the HMC to control both
swash plates, and lift both brakes. The size of accumulator is sufficiently large, in order to
ensure MOPS can be activated at least 3 times in a row, at least for a 5 minute period.

Deactivating the MOPS function will result in applying the brakes (de-energizing item 7.20
A+B) and the HMC will make a transition to normal operation.

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