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Service on request of the company LDPL Middle East Shipping LLC

Reason for service:
Bearing replacement due to failure after three years of service
Place of service: Dakar, Senegal
Customer order no: 632H-22-0116
Date of service: 13.09. – 13.10.2022

Vessel ALM LOURA / Boom conveyor
Drawing: B006302 (MacGregor Part No.) 133.40.4000.402.04.03F2 (XREB Drawing No.)
Serial no: 1903022112 (MacGregor Serial No.) A222159026 (XREB Serial No.)

Sumit Pundhir (LDPL / Superintendent; at times)
Vitaly Trofimov (LDPL / Captain; at times)
Zaied Marwen (LDPL / Chief Engineer; at times)
Anders Johansson (MPM Consultig / MacGregor; at times)
John Egholm Anderson (MPM Consultig / MacGregor; at times)
Nils Einar Narrman (MPM Consultig / MacGregor; at times)
Daniel Musshoff (thyssenkrupp rothe erde Germany GmbH, tkre DE)
Mohammad Lotfi (Ceeport Marine Service)

Date Activity / Result Commission Name 2019 Commissioning of Vessel ALM LOURA 09.2022
Bearing and installation inspection due to failure after 3 years of operation

Beams and the conveyor bench have to cut to be able to remove the boom on the turret from top. That means we have to lift the boom +/- 1,8 meter before coming out of the turret.   

So, it is meaning support the tripper on the temporary support!

But it was continue with removing the tripper drives, release the tripper belt pressure and remove the complete discharge end!


Parked in the service position, it is 60 bar in the luffing cylinders and 0,4 bar on the piston side giving about 65 tonnes in each cylinder which measured (port and stbd) to maintain the forces on pins.

The stbd luffing cylinder and connect the gauge. Reset all pull cords etc and try to start the HPU. When operating luffing down from the HMI, nothing happens. Manually could operate and after a while the piston starts to move and then stop the operation, checking there is a slight “under pressure” in cylinder!

The oil from the tripper drives open up and drain, still intend to heat up the hollow shaft and pull off the gearboxes from the drive pulley.

It has to be released the clamps or to lift up to take up in order to lift the drive free from the foundation.

With 2pcs M20 they can pull with 2×15 tonnes that is prepared to try with the PS drive.

Pulling with 35 tonnes, and heating on the hollow shaft but the hollow shaft doesn’t move bit! Job stops and gives up the idea. Now what to do?

Cutting the top frame and disconnect the Plummer blocks. Lift drives and drive pulley as one unit and park 3-4 meter aft on the tripper frame! Then remove the whole platform!

After while forth and back, the belt should be cut and remove the complete drive station including chute and platforms.( owner approval).

Meantime, removing cabling and the steel structure from the boom that has to be removed to lift off the boom from the turret are in progress!

The boom belt stoppers fixed properly and cut from top and bottom sides, it was transferred on deck.   

The boom conveyor driver brake clogged released and locked with spacers for both port and stbd side.


The boom streams (3pcs); diagonal (1pc) and lower part roller guide (1 pc) removed and transferred on deck.

The complete tripper drive station prepares lift off. The motors and foundation are already separated. The tripper belt cut. 

Continue disconnecting the boom cabling, the port and stbd side junction boxes and boom conveyor driver power and controllers for both side cables and wires marked as per installation manual. The wires and cables removed and lay down on the boom from port and stbd side.

The boom cylinder and hinges pin’s covers removed out (8 pcs), the rusted area chipping and subbing carried out on surface properly. WD-40 injected inside the hinges and cylinders pins for de-scaling.

Internal cleaning regarding grease, dirt etc inside the turret carried out. There should not be any slippery and dirt when disconnecting slew drives and turret later on.

Continue removing cables from the boom and the 8 idler frames and structures:

  • The remained tripper discharge area disconnected and transferred on deck.
  • Conveyor bench including 8 pcs idler frames dismantled and transferred on deck.
  • The boom’s electrical cables of port and stbd sides rapped and secured on top of turret
  • The boom’s hydraulic pipes and hoses disconnected and blanked properly. 
  • The booms’ mechanical parts removal carried out completely.

The cable/pipe bulkheads are closed with concrete; they are difficult to break through without damaging the cables. Continue breaking the cement in the turret bulkhead and figure out how the cylinder pins can be moved.


The  preliminary schedule based on the key-items Tensioning tool arrival, last cable is out of the slew bearing, arrival of the slew bearing and arrival of the 90+90 bolts. It is obvious there will be re-commissioning in the middle of October.


It has been summarized which bolts that has to be ordered for the installation.

The camera Ethernet cable cut and marked!

Summary of bolts have been given which needed for the assembly. Also added the seals V-500A for the hinges and the V-250 for the luffing cylinders.

Start removing the counterweights. Our very tight holes make it go slow.

Charged the cylinder pin with about 60 tonnes spread into the 6 pcs M24 (each stud capacity 20 tonnes) threaded bar via double end plates. (Notice the flange could not open up, with a good hit with the sledgehammer on the outer), the pin and sleeve start coming out! Only one sleeve gets out.

Prepare on the port side pin too! Start pressing

On stbd pin, the outer sleeve followed the pin. The inner sleeve stayed very tight in the flange. The remained sleeve split with a cutting disc, now it became possible to take it out.

Start arranging to support the hubs and to start check if it is possible to get the hinge pins moving with 100 tonnes jack! Getting the stbd hinge pin moved about 12 mm.

Some more jacks are requested to deliver, both push and pull on the hinge pins needed.

Applied the grease injected to the port and stbd hinges.

Connecting the hydraulic jacks to the PS hinge pin, only with pushing 70 ton cylinder, no movement.

Calculate weight if we remove the cylinders and the both drives! It had installed 2 x 40 ton jacks pulling and a 70 ton pushing on the port hinge pin. After it came loose, it was rather easy to move it. The pin totally removed and let the hub rest on the jack.

On the other hand the boom stbd side hinge, half the length of the pin was drawn by using 4 hydraulic jacks, one 100 tons jack which used on outer side to push (600 bars applied pumped), and the inner side as pulling used two 30 tons hydraulic jacks (600 bars applied on pump) and one 70 tons jack used under the hinge (220 bars applied on pump) for releasing the weight of the boom finally it move over to the stbd hinge and try to pull it out 50%.

Whole pin will be removed when shore cranes arrange to hold the boom and transfer it to land. 

Check the availability of used belt to use as weather protection on the new bearing.

Two pins and two sleeves rings of port and stbd hydraulic jack cleaned by chipping and brushing.

The encoder of slew bearing hydraulic motor removed and secured properly. 


Turret hydraulic pipes and hoses measured to prepare the plugs.

One 300 t , and one 250 + 200 t cranes are available, however it is expected to be a typhoon that day!

The motors/brakes removed from the slew drives. It recognises there is an unknown torque on the drives from parking and it decide to delay that until after removing the turret.

15 meter length of the used boom belt made skirting of the new slew bearing.

Continue labelling the cables and individual wires. The plan is to get all down into the gantry.


The manufacturing drwgs of drive lifting support and the three guide pins arranged.

The list is given either stainless A4-80 OR 8.8 bolts!

Start manually removing 2/3 of the slew bearing inner ring bolts.

All turret hydraulic pipes and hoses disconnected and blanked properly.

Start removing the outer ring bolt caps and clean.the turret inner slow bearing studs nuts also removed 30 pieces more (2/3). 60 pieces removed totally.

All cables got down into the gantry. The turret top side electrical junction boxes (port and stbd) marked the wires and the cables and whole cable clamps removed and transferred inside the turret.


The rest turret inner slow bearing studs nuts removed 30 pieces more (3/3). 90 pieces removed totally.

Three cranes prepared with counterweights and boom supports prepared at 3,4 meters separation. Platforms will almost touch the ship side. It is planned to burn off the paint and MPI test the lifting lugs.MPI is done just before lunch.


All cranes are connected, the hinge pin is out and the boom is in the air on the way down to the jetty! The cranes can lift about 102 tonnes!


Starts removing the last 30 bolts for the turret.

The turret support planed to be on hatch, and to use four counterweights to spread the load. Finally The support was on hatch #2 and it realizes the support is “dancing”, it is not stabile at all longitudinally! Present a solution to stabilize the support.

All obstacles have been removed out around turret like projectors; scaffolding, area cleaned and tools have been shifted etc.

The turret lift and land on the jetty.

Start up by the reinforcement of the turret support structure. Then decided to put the turret on temporarily block support on the jetty and make some height estimations.

Meantime the boom checked for cutting more of the “aft” conveyor bench to make it easier to install the boom. Also present about having welded supports for the boom hinge when installing the pins.

Start loosening the outer ring bolts, still no hydraulic tensioner on board. When loosening and removing the bolts manually, the water came out from all holes! Also start loosening the bolts for the drives expect two on each.

It was observed the top seal filled with dust and the inner ring is only 6-9 mm above the outer, nominal 10 mm!

All the grease connections have been disconnected around the bearings (27 pcs).

The slew bearing bolts removed (90 pcs) totally and lifted up by two hydraulic jacks, finally transferred on deck and the bearing dismantled and removed top and bottom rings.


The bearing is removed and surveyor from Thyssenkrupp checks the flatness of the flanges. 

Backlash of teeth: tkre specification: 0.03 – 0.04 x module; module 24; backlash of teeth at least 0.72 mm; to be adjusted at the three green marked teeth. 

The backlash of teeth were measured with feeler gauge (no rotation possible / 4 random points on circumference): Backlash of teeth drive 1 = 1.40 mm  Backlash of teeth drive 2 = 1.90 mm  Backlash of teeth drive 3 = 1.40 mm  Backlash of teeth drive 4 = 1.10 mm  

The drive pinions do not have any tip edge radius. We recommend using pinions with adequate tip edge radii. An inadequate tip edge radius results in increased wear and damage on the tooth flanks.

The measured evenness deviation at the contact surface is 0.26 mm (turret) and 0.33 (gantry). This value is within our specifications (due to the measurement conditions tkre DE allows in this case a deviation of 10%). Installation could be continued without any delay. 

Measuring device: Laser No.410  


According to Thyssenkrupp company, the turret flange is very flat, only some light corrosion in one area. The turret flatness result are:

They were 0,26 mm on the turret and 0,34 on the gantry flange. Both good and accepted, no machining required.

The cause of the bearing failure is probably composed of the following factors:

  • Bolt pre-tensioning force not adequate  
  • Sealing system not adequate 
  • bearing was mounted upside down 
  • Re-greasing quantity and greasing intervals  
  • No outer protection covers 
  • Possible overloads


The bearing tried to split for surveyor to inspect.What find inside the bearing is Bauxite and destroyed rollers!


On dismantling of the old slewing bearing the following abnormalities were found on the companion structures and bearing environment: 

  • Corrosion on the complete circumference of the upper and lower companion structure 
  • Fretting corrosion in some areas (main load / upper and lower companion structure) 
  • Bearing was assembled 180° upside down to drawing position 
  • High amount of dirt contamination and no protection plates around the bearing upper gap

The dismantled slewing was assessed, Following abnormalities:

  • corrosion on connecting surfaces and between retaining and supporting ring 
  • Outer contours completely corroded 
  • Inner contours completely corroded 
  • Upper sealing was destroyed in direction “boom” 
  • Chipped edges of the raceways in the main load areas (corresponding to load cases) 
  • High amount of water and dirt inside the raceway system 
  • High amount of broken rollers and spacers of retaining – and supporting –  raceway

Concentrate on lowering the slew drives, cleaning of all the flanges and bushings related to hinge pins and luffing cylinders. 

Four hydraulic drives motors and brakes and get down.

Four slew drives get down. There are some oil in the slew drives:

PA abt 20 litres, not easy to rotate. Stbd F about 0,5 litres, rather easy to rotate.

Preassemble the tripper drives down on jetty and replacement and splicing of the new boom belt.

The pins and brackets for hinges and cylinder cleaned.

90 pieces studs and nuts of bearing inner side cleaned properly.

The bearing flanges on pedestal and turret polished properly.

Fabricated a handle for rotating the slew gears 

Due to torch cutting in total 8 bolts M20 x 240 10.9 was destroyed. I suggest these will be replaced.

Drwg. 8017299

Item 3, 8 pcs sleeve drwg A 583091, φ 32/20 l= 130, 

Item 9, 8 pcs bolts M20x 240, 10.9

Item 11, 8 pcs Nuts M20, class 10.

Item 13, 16 pcs washers 21/37 x 3, 200 HV

Due to damages when manually loosening, we should have in total 40 bolts, nuts, sleeves and 80 washers.

The template of boom’s hub support has been made according to drwg. We adjust the length to have space for a lifting lug in each end.

The hydraulic bolt tensioners and the hydraulic wrenches from both Germany and China arrives. 

The obstacle structures polished properly and put primer as well.

Now cleaning bolts and areas for the washers.


A new template 50 mm thick plate has made to support the boom hinge when reinstalling the boom. 

Only the point is that the pins should be frozen during the day!

The Chinese hydraulic bolt tensioner tested and operated. In fact the equipment is manufactured in Thane, outside Mumbai!

The tripper drives checked.

The boom hubs measure and make sure are some mm smaller than the turret flange and that our support will work.

The new bearing received and started to offload! Due to too small crane, deck crane #3 had to assist! It was landed on the flange. Now plan is to install the slew drives, 90 pieces nuts of outer bearing have been tighten at 700 bar on pump and 390KN (70%) on two tensioning tools successfully.

Surprisingly, the holes in the outer ring upper and lower flange didn’t match that well. The 38.5 mm pins did not go through the 39 mm holes! Continue finishing off the first round with 700 bar. 

The handles received for the slew drives with U-bolts and fixed with gear from hyd. motor!

90 pieces nuts of outer bearing have been tighten at 975 bar on pump and 485KN (100%) on two tensioning tools.

Plan is lifting the slew drives, Four hydraulic drives fixed back and adjusted backlash between rim and pinion (0.75mm to 0.95mm) on the green marks individually. 

  1. The new slew bearing received, the surfaces cleaned and put on the gantry flange properly. 90 pieces nuts of outer bearing have been tighten at 700 bar on pump and 390KN (70%) on two tensioning tools successfully.

The soft spot of new bearing set on aft side of pedestal as per manual.

How to use tensioning tool specially in this crane M36:

  • The tensioning jack, pump, flexible hose and ratchet to be prepared.
  • The tensioning table and graph specification should be available.
  • The electrical connection to be connected to the pump (220 volt)
  • Pressure set nub and by pass nub to be released in unti-clock wise
  • Close the bypass valve clock wise
  • Adjust the set pressure of the pump and lock (should be refer to manufacture manual commissioning list) equally refer to pump specification graph. For example 700 bar in the pump is equal to 390 KN 

(First round tightening adjustment should be 70% then second round 100% final tighten). 

  • Again release the pressure
  • The flexible hose to be connected between jack and pump.
  • The nuts of the stud should be tighten manually with spanner first, not use any hammer or pipe to excessive titening.
  •   The jack should fit on the stud with ratchet on top side clock wise. The important attention is the bottom part of jack should be turn around until inside spanner goes through the nut by spring with clicking sound.
  • The bypass valve close clockwise
  • The pump start with remote control the pressure will reach to the set point (the pressure will be constant on set point even the motor continue running. 
  • The nut should be tightening with ratchet in below side of jack.
  • The pressure release with bypass valve open unti clock wise.
  • The Jack should be removed by ratchet on top side unti clock wise.

And the stud should be marked and test by spanner and hammering the tightness.

Four hydraulic drives fixed back in the place properly and adjusted backlash between rim and pinion (0.75mm to 0.95mm) on the green marks individually. (The point has been chosen between minimum and maximum spaces of ellipse).

The inner bearing soft spot adjusted to the STBD side of pedestal as per manufacture manual required.

First start pulling the all the slew gear bolts (except one missing) with 975 bars. 

The slew drives installed with green teeth back lash (module 24 recommended 0,72-0,96):

Stbd fwd 0,75 / Stbd aft 0,95 / PS aft 0,90 / PS fwd 0,85

The slew bearing upper nipples lubricate to see if grease coming out from the lip seal.

Tighten the available bolts on each drive (out of total 92).        

Meanwhile rotating the slew bearing, lubricate the top nipple and I lifted the lip and smeared out the grease to the whole seal lip circumference.  

One more set of the seals received.

Meantime, I find that a 20×20 seal rope (used onboard as shaft seals on pumps) might do the job! 

Start lifting the turret and get it in place by shore crane and start installing the bolts. 89 pieces nuts of inner bearings tight at 700 bar on pump and 390KN (70%) with one tensioning tool.The Chinese tools (manufactured in India) breaks down, and start using the German ITH tool.

When lifting off the boom, there was no real seal remaining! Taken just after lifting off the boom.

 Start the pulling the turret bolts (89 pieces nuts of inner bearing) to 975 bar on pump and 485KN (100%) 


The turret hydraulic pipes and hoses re-fixed properly and all internal supports of drives fixed back and tighten.


Think about how to lower the hubs into the turret without destroying the V-lips!

Turret direction has been adjusted precisely with turning drives by handle.

The hubs four V500 seals installed properly in the places

The V- block on port hinge grinded 2mm for appropriate space size.


Four breathing capsule drives brushed and painted properly  

The boom lifted up and fixed in the place as below procedure :

  • Turret direction re-adjusted again with turning slewing drives.
  • 8 V-seals fixed in hinges and hydraulic cylinders by guiding plates. (Fourth of them damaged due to swelling the vessel.
  • All four pins frozen by dry ice.
  • By the used of chain blocks, hydraulic jacks and V-block, the hinges adjusted.)  
  • First the port hinge pin installed then stbd hinge pin installed by pushing jack and lifting jack from below.
  • The V-blocks cut, removed out and transferred on deck 
  • The aft shore crane released
  • The front boom settle down on parking position and lift up cylinder pins on the turret. the both pins’ sleeves cut by grinder (disc 1 mm thick)
  • The stbd side cylinder sleeves, seals and pin fitted properly by using of one jack and three guiding chain blocks. 
  • The port cylinder sleeves, seals and pin fitted too. (The cylinder pressure released by used of the pressure gages’ hoses to moving up the cylinder for spherical bearings and sleeves alignment).      

Continue worked on boom mechanical structures installation such as streams (7 pcs), diagonal (1 pc), Conveyor bench idler frames (9 sets) and belt triangle plow (1 set), all transferred on places by ship’s crane and tighten properly.

4×25 liters gear oil drums Omala 220 transferred into the turret. 

Four hydraulic gears drives motors, brakes and breathers refitted back and filled the gear oil completely. (stbd forward drive the gear side leaking badly. There was nothing before any oil inside the box)

58 cables of turret and boom in port and stbd side lay down on trays for junction boxes (6 sets), conveyor drivers’ power and controllers and tighten with cable bands. Also all wirings connected to the terminals correctly. 

The leaking drive gear dismantled, found the o-ring damage, replaces the o-ring with new spare one and boxed up, filled 20 liters gear oil, not leakage anymore.

The remaining electrical equipment installed and connected into the system as below:

  • Two boom driver motors 
  • Two boom driver brakes
  • The boom angle transmitter basement repaired and installed in the place.
  • The camera cut wiring new jointed inside the junction box. 
  • Two limit switches installed and connected back in the places.
  • The drive encoder installed and connected in the place.

The boom hydraulic pipes and hoses connected back properly.

The remained tripper lower structure of discharge chute installed then put the top side in the place properly.

New boom belt replaced and jointed with three steps cutting of both surfaces and used the glue for sticking each other, the joint area heated up at 175 degree centigrade for 15 minutes and kept cool down for 3 hours.

Slew brings grease nipples fixed back in the system.

180 pieces of slew bearing nuts and studs put grease and covered back.

Commissioning of boom belt drive, luffing and slewing operation carried out successfully.      

If you have any questions do not hesitate to contact us. 

Best regards 

Mohammad Lotfi

For further information (sketches/procedures) we refer to:

For questions / scheduling please contact: 

Phone:  +971505583154 




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