LamaLo Technology Inc.
Z-Drive Propulsion
Shafting
Click here to obtaion a LamaLo Technology Inc. paper
presented at ICMES 2003 - pdf file
Example Shaft
Arrangement for Z-Drive Thrusters
Working on Stub Shaft Checking Alignment
MV Seabulk Angola – Ocean-Going Anchor Handling Tug (2 x 2375 HP): The MV Seabulk Angola is a 165' (50 m)
anchor handling tug (AHT), constructed in Indonesia. The propulsion system has two Z-Drive
thrusters (port and starboard). Each
thruster is driven by a diesel engine, with a rating of 4,000 HP (2,970 kW) at
750 RPM. Each lineshaft is approximately
42' (12 m) long and is supported by four cylindrical roller bearings, with one
bearing “fixed” to prevent axial motion of the shaft. There is a stub shaft that connects the main
engine to the lineshaft, which is about 60" (1.5 m) long and is supported
by two roller bearings, with the aft bearing also being a “fixed” bearing. All the fixed bearings over-heated on the
propulsion shafting both during sea trials and transit. During the first week in June on voyage to
MV Energy Hercules Class – Thruster Tug (2
x 1838 HP): The Seabulk MV Energy
Hercules Class vessels are 96' Thruster Tugs constructed at
MV Brewster Tide Class
250' OSV (2 x 2575 HP): Three (3) 250' Offshore
Supply Vessels (OSVs) were constructed at Leevac Industries, LLC in
Louisiana. The propulsion systems have
two Z-Drive thrusters (port and starboard).
Each thruster is driven by a diesel engine, with a rating of 2575 HP at
1600 RPM. Each lineshaft is
approximately 5.0 m (17') long and is supported by 4 roller bearings. The second bearing from the forward end also
acts as a fixed bearing, to carry axial loads on the shaftline. The forward end of the lineshaft connects
directly to a torsional coupling supported in a flange housing complete with a
double spherical fixed roller bearing.
LamaLo Technology Inc. was contracted to ensure that the propulsion
shaftline design and installed alignment condition would be satisfactory for
all modes of operation. This was
accomplished by a combination of theoretical modeling, design review and
assessment, and on-site measurements.
The last vessel was delivered in 2008.
All vessels have operated without incident.
Kilgore Marine 216' OSV (2
x 1575 HP): A 216' Offshore Supply Vessel
(OSV) was constructed at Leevac Industries, LLC in Louisiana. The propulsion system has two Steerprop SP14
Z-Drive thrusters (port and starboard).
Each thruster is driven by a diesel engine with a rating of 1,575 HP at
1600 RPM. Each lineshaft is
approximately 3.65 m (12') long and is supported by 4 roller bearings. The forward end of the lineshaft connects
directly to a torsional coupling supported in a flange housing complete with a
double spherical fixed roller bearing. LamaLo Technology Inc. was contracted to
ensure that the propulsion shaftline design and installed alignment condition
would be satisfactory for all modes of operation. This was accomplished by a combination of
theoretical modeling, design review and assessment, and on-site measurements. The vessel was delivered in 2007 and has
operated without incident.
MV Beesecker 150' Push Boat (2 x 1520 kW): The
MV Beesecker, a 150' Push Boat, is under a major repair / retrofit, which
includes the installation of a new propulsion system at
Tidewater Class
207' Offshore Supply Vessels (2 x 2375 HP): Four Tidewater Class and three
The primary objective of this
work was to ensure that the propulsion shaftline installed alignment condition
was satisfactory for all modes of operation.
This was accomplished by a combination of theoretical modeling, design
review and assessment, and on-site measurements. Theoretical alignment and whirling vibration
analyses were conducted prior to the installation of the shafting system, and
an alignment procedure was produced and followed. The strain gauge technique
was used to conduct the final alignment of the lineshaft bearings. Using this technique the bearings were
positioned within ± 0.004" of their prescribed locations. The maximum static bending stress on the
shaft was measured to be less than 700 psi.
The last of the vessels was
delivered in 2004. The alignment
performance of the shafting has been reported to be acceptable.
MV
The primary objective of this
work was to ensure that the propulsion shaftline installed alignment condition
was satisfactory for all modes of operation.
This was accomplished by a combination of theoretical modeling, design
review and assessment, and on-site measurements. Theoretical alignment and whirling vibration
analyses were conducted prior to the installation of the shafting system, and
an alignment procedure was produced and followed. The strain gauge technique
was used to conduct the final alignment of the lineshaft bearings. Using this technique the bearings were
positioned within ± 0.004" of their prescribed locations. The maximum static bending stress on the
shaft was measured to be less than 700 psi.
The vessel was delivered in
2003. The alignment performance of the
shafting has been reported to be excellent.
MV Point Clear – Tractor Tug (2 x 2500 HP): The MV Point Clear is a 98.5' foot
state-of-the-art 5000 HP “tractor tug” with a bollard pull of 75 tons. The vessel works in the Mississippi River. The propulsion system consists of twin
Z-Drives with nozzled propellers, each driven by a diesel engine rated at 2500
HP at 1000 RPM. The lineshaft is support
by three Cooper split roller bearings and there is a stub shaft aft the main
engine with two support bearings.
LamaLo Technology Inc. was contracted to
determine a least-cost solution to repeated lineshaft bearing failures. Work focused on determining the shafting
system alignment and vibration characteristics, and isolating the source of the
higher temperatures. This was
accomplished by a combination of theoretical modeling, design review and
assessment, and on-site measurements and observations.
It
is concluded that the failures were likely due to an excessive misalignment of
the bearing pedestal to the cartridge. The bearing pedestal was realigned to be
parallel to the cartridge. Since this
work was conducted, in March 2004, the alignment performance of the shafting
has been reported to be excellent.
MV Ensco Captain, Commander, Navigator and Admiral
231'
Offshore Supply Vessels (2 x 1,500 HP)
MV Ensco Captain: A number of damages occurred
to the propulsion shaftline bearings after delivery. An investigation was conducted to determine
the source(s) of failure and an optimum solution. It involved a combination of theoretical
modeling, design review and assessment, and on-site measurements. The
investigation concluded that the failures were due to a lineshaft misalignment
condition that resulted in a top-loaded lineshaft bearing, excessive shaft
bending stresses, and excessive lineshaft bearing offsets. A realignment of the shafting system (January
2002) resulted in acceptable vibrations, and no further failures have occurred.
MV Ensco Commander and Navigator : As a result of the experiences on the MV
Ensco Captain, it was recommended that subsequent vessels include the strain
gauge alignment technique as part of the alignment procedures. The shaftlines were aligned in 2002. Since then, the alignment and vibration
performance of the propulsion shaftlines have since been reported to be
excellent.
MV Ensco Admiral: The vessel was delivered in
early 2001. In January 2003 all the
lineshaft bearings over-heated and were damaged. Experience with similar failures in January
2002 on the MV Ensco Captain, which is the same class of vessel, showed that
the root cause of failures was misalignment of the lineshaft bearings. The shaftline was realigned in January 2003.
Since then, the alignment and vibration performance of the propulsion shaftline
has since been reported to be excellent.
MV Mathew K – Tug Boat (2 x 2,150 HP):
An investigation was conducted to determine the source(s) of vibration and an
optimum solution. It involved a
combination of theoretical modeling, design review and assessment, and on-site
measurements. The investigation concluded that the excessive shaftline
component vibration amplitudes were due to a lineshaft misalignment condition
that resulted in a top-loaded lineshaft bearing, excessive shaft bending
stresses, and excessive lineshaft bearing offsets. A realignment of the shafting system (August
2002) resulted in acceptable vibrations.
MV Skeena Queen – Passenger Ferry (4 x 1,394 HP):
Propulsion System Failure Investigation to determine cause of failure of
machinery components and recommendations for a complete solution. The recommendations were carried out in the
spring of 2000. Subsequent operations
resulted in a re-occurring failure due to a “design flaw” which was previously
noted by LLT. New main engines better
suited to the vessel’s operational profile were installed in the spring of
2002. A complete realignment of the shaftlines
was conducted in the fall of 2002.
Vibration measurements taken by LLT during sea trials were acceptable,
and the performance of the vessels machinery and shaftline bearings have since
been reported to be acceptable.
MV Lynn Marie and Marshall Foss - Enhanced ASD Thruster-Tugs (2 x
3,020 HP): The
vessels have two Z-Drive type thrusters (port and starboard), each driven by a
diesel engine with a continuous rating of 2,328 HP at 1800 rpm. Each propulsion shaftline is approximately 32
feet long and is supported by 7 lineshaft bearings. The MV Lynn Marie was completed in the spring
of 2001, after which a number of damages occurred to the propulsion shaftline
bearings. An investigation was conducted
to determine the source(s) of failure and an optimum solution. It involved a combination of theoretical
modeling, design review and assessment, and on-site measurements. The
investigation concluded that the failures were due to a lineshaft misalignment
condition, and improper type of bearing lubrication. A realignment of the shafting system, and
modification to the lubrication system on one lineshaft bearing resulted in
acceptable bearing performance (November-January 2001). Further bearing failures occurred in
2004. Visual inspection and measurements
of the bearing parts, support structure, chocking, assembly and disassembly was
conducted. It was determined that the
bearings housings were significantly distorted due to a non-uniform chocking
support across the base of the bearing pedestal. This distortion was considered to be the
cause of the recent bearing failures.
Both shaftlines and all bearings were disassembled and re-aligned using
the strain gauge technique, damaged bearings were replaced on each shaft, and
all bearings were re-chocked. The vessel
returned to service in July 2004 and has since reported excellent shafting
vibration and alignment characteristics.
As
a result of the experiences on the MV Lynn Marie, it was recommended that
subsequent vessels include the strain gauge alignment technique as part of the
alignment procedures for the sister vessel the MV Marshall Foss. The shaftlines were aligned prior to delivery
in December 2001. Similar to the sister
vessel MV Lynn Marie, modifications were conducted to one of the lubrication
system on a lineshaft bearing shortly after delivery. As of the summer of 2004 the alignment and
vibration performance of the propulsion shaftline has since been reported to be
excellent.
MV Delta Mariner - RO-RO Vessel: (2 x 4,000 HP):
Shaft alignment and vibration analysis and measurements during construction and
delivery. Responsible for ensuring the shafting system was aligned
properly. This involved conducting a
theoretical analysis, determining alignment criteria, producing shafting
installation procedures, and measuring the installed alignment condition. The vessel was delivered in the summer of
2000. The bearings on the stub shaft
from the main engine over-heated during long transits. This problem was rectified and the alignment
and vibration performance of the propulsion shaftline has since been reported
to be acceptable.