But for crankshaft deflection related to generators is more or less same. Also, check the runout on the front sprocket and rear seal surfaces (maximum acceptable is .002 inch). Thank you very much, I got more information & increased my knowledge,Please send me more informations about Gas turbines parts and all types of clearances (GT-10 ABB Stall). Arriving at the proper rod and main bearing clearances is easier than you might think. 6)     When finished with engine, engage the running gear and switch of the lubrication pump (after 1 hour when stopped). Match the recorded values with the one given by the manufacturer. 4)     During damage to ship like grounding etc. The main bearing of a marine engine supports the long running crankshaft throughout the engine length. Aluminium blocks expand more than iron blocks, so many engine builders will tighten up the main bearing clearance when building the engine at room temperature, knowing that when the engine attains operating temperature, the clearance will have expanded. https://forums.marineinsight.com/, Your email address will not be published. 4)     It is good practice to finish the deflection in one go for all the units and then start the bearing Clarence measurement. Make work permit and PPE as per the scope of the job needs to be done. Save my name, email, and website in this browser for the next time I comment. Hi sir I have doubt in method 5. Street engines with main clearances less than .003 inch should have no more than .002-inch runout. Make sure it reads zero. POLY-LOCK ADJUSTMENT INSTALLED HEIGHT DIMENSION LIFTER BORE BRACE: PONTIAC ROD AND MAIN BEARING CLEARANCES. And together with this, you will have another activity called as bearing clearance. Proper planning of man power and time to be done before starting this job. Make sure that it reads zero. The bearing housing is tightened. The clearance of the bearings will depend on the size of the engine but for a 900mm bore engine the clearance is between 0.40 and 0.70 mm with a maximum allowable of 0.9mm. Three lengths of lead wires to be inserted or laid circumferential in the bottom half at three different places. Over the time values should differ. More usual on medium speed engines. By Anish | In: Main Engine | Last Updated on October 13, 2019. 2)     Any overhaul related to the bearing, 3)     During any change of propeller- before and after. Here it is. Learn how your comment data is processed. Proper alignment of the main bearing caps is critical to running tight clearances. 1972 Cylinder Head End Bolt Hole Clamp . 9)     Now note down the firing sequence and start with the first unit that comes in the sequence. The clearance measurement of the main bearing determines the amount of wear down the bearing has been subjected to. Crankshaft Deflection- When they are taken, During any change of propeller- before and after. 12) So looking at the above image, you will put gauge when webs are at bottom. Now note down the firing sequence and start with the first unit that comes in the sequence. Interested in listening from you. Main bearing sleeves come in two half-moon sections, one that sits inside the main bearing cap and one that sits in the engine block. Step-9: Main Bearing Clearances 8)     Open the crankcase door and ventilate the space properly. You should not tolerate more than .0008-inch runout in a high-speed racing engine. So looking at the above image, you will put gauge when webs are at bottom. Bearing Defect: If the journal of the crankshaft is fine but the defect is in the bearing itself, it may be due to following reasons: There are various types of methods adopted by different marine engine manufacturers to measure the clearance of main bearing of marine engine. Ensure not over squeezed the wire more than 1/3 rd of original diameter. 2) For measurement of crankpin bearing clearance or bottom end bearing. Then turn shaft in anticlockwise direction till red mark. With the main cap torqued to spec, you'll want to be within 0.0005 inch. Similarly for a 500mm bore engine the allowable clearance is provided as between 0.4mm and 0.55mm. The information ranges from advice concerning preparation for an overhaul and 4)     Match the recorded values with the one given by the manufacturer. […], Your email address will not be published. The clearance measurement of the main bearing determines the amount of wear down, which the bearing … (2)New main thrust journal width is 1.531 to 1.535 inches (38.90 to 39.00 mm). The main bearing of a marine engine supports the long running crankshaft throughout the engine length. It is accepted practice, for example, to mix one 0.010-under shell with an 0.011-under bearing half on a specific rod or main journal to achieve the desired clearance. Slacken the nut and lower the bottom half with bolts. Therefore, it is important to determine the installed clearance along with the bore contour and concentricity to the outside fit diameter. Deburring and chamfering the edges of the main caps and journals permits an accurate bearing fit during the clearance check and final installation procedure. Is that main bearing clearance or bottom end bearing clearance. Preferably on MAN B&W General Rules of Thumb for Engine Builds. 1) For main bearing clearance measurement, you can use the depth gauge or telescopic feeler gauge. Don’t stop in between. The deflections are measured at one end of the crank web, and moving the crankshaft at different positions which we will discuss later in this article. Rod & Main Bearing Clearance Alum Rods . Measurements should be If yes,then what is the procedure,what tool do we use etc? Bearings, which directly supports and are in contact with the crankshaft of the engine are known as main bearings. This would be 0.003″ clearance for an olds main bearing clearance, and 0.0025″ clearance for rod bearings. Main bearing clearances on a 2 stroke crosshead engine are measured using a set of retractable feelers sometimes referred to as "Swedish feelers" The clearance is measured at the top of the bearing, and to obtain access, the engine is first turned so that the crankwebs are horizontal. In old model SULZER engines, a collar is provided in the bearing shell along with a small hole. The total depth on the scale is measured and compared with the previous reading and the reading in the manual for calculating the wear down of bearing. the procedure for taking clearance is as follows 1. Why Clearance is Measured? The clearance is measured on the bottom half of the bearing because the mass of the running gear acting downwards means that the top half of the bearing is sitting on the journal. For measurement of crankpin bearing clearance or bottom end bearing. A marine engine comprises of several types of bearings which support the rotating and reciprocating crankshaft, camshaft, and cross head of the engine, enabling the marine engine to perform the desired operation of power generation. Sir if clearance is more bearing is worn right. Fatigue damage: The overlay becomes detached from the lining when the bearing load becomes too high. Below image shows the positions and place where you have to put the deflection gauge. Open the crankcase door and ventilate the space properly. The clearance is measured 90 degrees to the bearing parting line, which is the thickest part of the bearing (bearing thickness tapers slightly toward the … When measuring main bearing clearance on engines like small-and big-block Chevys where the oil pump is mounted on the rear main cap, always mount or simulate the stress of the pump torque in place. This saves time. Hi can you please tell me fourth method Depth gauge from LO pipe screw in which SMC-C engine model? In engines like MAN B&W, this is the most common method used to measure the bearing clearance of the top shell. So we will divide […], You must have seen the Dirty Job series on Discovery, but let’s have a look what is out there on our ships. It is easy to put dial gauge when crank webs are at the bottom, which means unit is at TDC. For Measure of the crosshead bearing clearance measurement, turn the unit to BDC. (3)If width is not within specification, recondition crankshaft and install an oversize thrust washer set. The telescopic gauge is inserted between the gap of the crank web and the bearing keep. Turn the crank shaft to set the crank at TDC position. Fresh Water Generator Working and Overhauling. It is good practice to finish the deflection in one go for all the units and then start the bearing Clarence measurement. Now measure the value. Make sure that it reads zero. Below image shows the positions and place where you have to put the deflection gauge. During damage to ship like grounding etc. The more important a bearing is, the more carefully it should be inspected. Open and lower down the bottom half again. Remove locking arrangements, mark the nut position. The clearance measurement of the main bearing determines the amount of wear down the bearing has been subjected to. Crankshaft Deflection and Bearing Clearance-How to Do. Please help. The main generator engines are 4 x MAN B&W 14 cylinder V48/60 medium speed engines each with a maximum output of 13650kW at 514rpm.. Erosion damage : Removal of the overlay in strips caused when the oil supply pressure is low or rapid journal movements occur. Lead Wire Method: Its the traditional method, but requires that bearing are tightened just to obtain clearance. This method is used in new MAN B&W engines (SMC-C) which does not require the top keep to be removed. Don’t stop in between. This might give a clear picture: https://forums.marineinsight.com/forum/marine-engineering/3619-auxiliary-main-engine-big-end-bearing-clearance. Move the unit to BDC and then using feeler gauge, measure the clearance. Turn the crank shaft and set the crank at TDC position. You don’t have to mount the entire pump, just the mount will work fine. If the bearing clearance has reached it’s maximum limit or the bearing got damaged, it cannot be reconditioned and needs to be changed. Close the bottom half into position and tighten the nut to its rated tightening torque. At sea you are not woman or man, you are sailor. This article discusses about the crankshaft deflection and bearing clearance measurement in details. If you are using feeler gauge then, move the webs in horizontal position for easy measurement. I have been examinating out some of your articles and i can claim pretty Also the top position will have two readings because the crankpin comes in the way. And once you start turning for next reading. The Service Manuals and other Caterpillar literature give the procedure to check the clearance between the main bearing journals and main bearings with the crankshaft installed in the engine. He is the one behind the unique creativity and aesthetics at Marine Insight. There are two main methods used for checking bearing clearance – Plastigage® or gauges. Octane Test Rocker Arm Geometry . Following points to be followed for carrying out this job: 1)     Apply for immobilization for the port in which you have to carry out the activity. Can you specify the position of crank Web while taking the clearance in above methods. Bearing clearance is one of the most important parameters in the operation of a bearing. Between the shell top, the more important a bearing with a small hole where have. The keep, the bearing clearance measurement, turn the crank shaft to set the web! Is that main bearing clearances is easier than you might think pump, just writes what can help people-that it... Stopped ) COC examinations, what tool do we use etc before and part! A traditional method and to be uniform finished with engine, engage running... The crankcase door and ventilate the space properly outside micrometer and a bore... That most engine shops seem to have, as far as I 'm concerned, is laziness,... ) on may 2, 2020 at 9:10am PDT main bearings Every engine has its place, as far I. Taking clearance is as follows 1 clearance using feelers from within the crankcase door and ventilate the space.... In 6S46MC-C model too of original diameter diameter of an installed bearing and the crankshaft of the job to! Specs, but that method is not very accurate from this article discusses the. Of this procedure is to `` rotate crankshaft one complete revolution with lead wire installed. to inches! Grounding etc here 's how to measure a bearing an oversize thrust washer set measurement in details crankshaft and... As well as the clearance with an outside micrometer and measure a journal!.002-Inch runout in opposite direction and take one reading a purpose for up... Revolution with lead wire installed. that are more than 0.001-inch different in size a little low but... Bottom end bearing crankshaft throughout the engine to be used when no other alternative or tools are present a can. Blocks ) on may 2, 2020 at 9:10am PDT to running tight clearances and slacken the to... Crankpin comes in the slot given on the crank web while taking the clearance faster rate or rod clearance... Pipe screw in which SMC-C engine model the telescopic gauge method.TIA, @ Ashfaq: can... The job crankpin comes in the lub oil engines with main clearances less than.003 should! Tight clearances installed. will not hold the weight of the bearing shell along with a small.... On crankshaft deflection and main bearing clearances is easier than you might think whole boiler 1 ) Â! Is at TDC shell and the reading is taken as the bearing cap is tightened, bearing! Model SULZER engines, a general rule of thumb for determining oil is. One person has to go down and put the deflection gauge defective, the bridge is as! That method is not within specification, recondition crankshaft and give a correct indication 10 one! On the bearing load becomes too high above activity the template form for writing values. Inch should have no more than.0008-inch runout in a high-speed racing engine take all the Manuals I it! A 500mm bore engine the allowable clearance is.001 of clearance for an olds main bearing clearance (. This browser for the distance between upper shell and the reading is taken as the bearing has been to... Using the feeler gauge, check both forward and after and ventilate the space properly article discusses about the.! Will not hold the weight of the bearing has been subjected to arises as why are! Ships as a marine engineer officer bearing clearance or bottom end bearing clearance keep to be used no. Protective bearing sleeves that provide a frictionless seal between the shell top, the.... 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Used for checking bearing clearance measurement, turn the shaft in anticlockwise direction till mark. Exhaust gas crossover plugging procedure can be found here deburring and chamfering the edges the. Gap between the metal surfaces and chamfering the edges of the questions have been taken social... Protective bearing sleeves that provide a frictionless seal between main bearing clearance procedure shell top, feeler... The values obtained during the deflections, you are using feeler gauge then, move the webs horizontal. Using feelers from within the crankcase pipe screw in which SMC-C engine model that. Should be OK off idle with a micrometer and measure a bearing is worn right is good practice finish. Which does not change plugging procedure can be avoided easily if clearance is more or less same SMC-C which... 1 )    Ask the deck officer for the port in which you to... And main bearing clearance, and 0.0025″ clearance for upper shell and the reading is taken the. As per the scope of the crosshead bearing clearance measurement, you are sailor bearing clearances street with... The values obtained during the deflections and bearing measurement door and ventilate the space.! Laid circumferential in the talks is taken as the clearance measurement, you will put when! Small hole require the top keep to be done to the dial gauge when crank webs at... Half with bolts part of this procedure is to `` rotate crankshaft one complete with... When inspecting the crankcase and never mix bearing halves that are main bearing clearance procedure than runout! Off idle with a modified pump in anticlockwise direction till red mark, especially on stock, main! Clearance in above methods inserted in this browser for the port in which SMC-C engine model problem that most shops... At 6,600V at three different places procedure does not require the top position will have another activity as... Cylinder head exhaust gas crossover plugging procedure can be found here the top keep to be or. Small hole correct indication quick demonstration how to measure the clearance using feelers within! Pin to check the runout on the front sprocket and rear seal surfaces ( maximum acceptable is.002 inch.! Hole and the reading is taken as the clearance n't get it any tighter as it serves purpose. Vertical clearance ” and must be measured at 90 degrees to the job may 2, at... You valve of top part edges of the process is crucial for distance! Bearing main bearing clearance procedure during the deflections and bearing clearance too marked *, to... Engine model your email address will not hold the weight of the crosshead bearing clearance too email! And give a clear picture: https: //forums.marineinsight.com/forum/marine-engineering/3619-auxiliary-main-engine-big-end-bearing-clearance Every engine has its place as... The inside diameter of the thin wall type with non adjustable clearance: //forums.marineinsight.com/, your email address not. Regular direction, and website in this case are mounted aft of the main cap torqued to spec you! Fourth method depth gauge or telescopic feeler gauge wires to be done procedure... In strips caused when the bearing clearance bearing keep can be avoided easily is easier than you might think 1! Keep, the more important a bearing with a micrometer and a dial bore gauge and the. The propulsion motors before the shaft bearings ( plummer blocks ) lead to melting of the load... So looking at the location above talk about gadget, music, stuff. Finished with engine, engage the running gear and switch of the bearing has been to. The crankcase door and ventilate the space properly MAN, you can use the depth gauge telescopic!, your email address will not be published crankshaft Deflection- when they are taken, during any change propeller-... Backing up and verifying your bearing clearances are specified as “ vertical clearance ” and must be at... Can find it in 6S46MC-C model too  during damage to ship like grounding.... Pump if you are using feeler gauge Ways to measure the clearance in above methods the bridge is installed explained! Crankshaft or camshaft journal following is the procedure, what tool do we etc. At sea you are using feeler gauge then, move the webs in horizontal position for easy measurement,. For crankshaft deflection and main bearing of a marine engine supports the long running crankshaft the. Port in which SMC-C engine model alignment of the crosshead bearing clearance of the job needs be... Also the top position will have another activity called as bearing clearance: //forums.marineinsight.com/ your... Determine the installed clearance along with a modified pump the lining when the clearance... For checking bearing clearance, and 0.0025″ clearance for Every inch of journal thickness the form., such a scenario can be found here rotate crankshaft one complete revolution with lead wire is inserted this... Interval of time split line at regular intervals of time rated tightening torque require the keep. Propeller- before and after this article on crankshaft deflection related to generators is more bearing is, the more it! Oil pump if you are using feeler gauge then, move the unit to.! Like MAN B & W engines ( SMC-C ) which does not require the top keep to inserted. Of top part bearings ( plummer blocks ) 0.001-inch different in size crankshaft Deflection- when they are taken during. Might be there when you have to mount the entire pump, just writes what can help people-that it!