Vit and Super Vit

MAN B&W - VIT and Super VIT, Forum Post, Marine Talk, Equipment...1 of 6 Technical Discussions MAN B&W - VIT and Super VIT All dates are given in mm/dd/yyyy format. http://www.marinetalk.com/forum-post.asp?thread_id=T73255 MarineTalk Discussion Forums Technical Discussions MAN B&W - VIT and Super VIT Post Reply Member: Ritinkar Sen MarineTalk Site Search: Featured Companies WONDERMAR c/o BALance Technology Consulting GmbH WONDERMAR, an open user group in the maritime sector, coordinates activities of European projects with a main focus on reviewing the state of the art and identifying new developments in the information technology area. Germany Centre for Coastal and Marine Science CCMS is a public sector research organisation, carrying out R&D in oceanography. Our science is carried out in 6 Core Strategic Research Programmes, see http://www.ccms.ac.uk/ccms.htm for details. United Kingdom Tomasello & Weitz Tomasello & Weitz is a law firm that in addition to its important experience in the field of shipping, is able to advice its clients in a wide range of legal, commercial, financial, and real estate matters. Chile Post Date: 1/26/2003 Modern large slow speed MAN B&W 2-stroke engines have Super VIT mechanism fitted to advance fuel injection at lower loads for increasing maximum firing pressure resulting better fuel economy. Details of Super VIT are available in the engine manuals. Why use the term "Super"? was there an "ordinary" VIT earlier, which has been changed to Super VIT? If yes, can I have a brief description of how the ordinary (non-Super) VIT worked? Reply | Email Member: Lars G. Jacobsen Edit/Delete Post Date: 1/27/2003 Before the Super VIT was introduced variable injection timing was obtained by means of a special profile on the fuel pump plunger. Hence there was a fixed relationship between the injection timing and the fuel index. Thus it was not possible to adjust the fuel index of the individual pumps without also altering the injection timing. For this reason the Super VIT was introduced, where it is possible to adjust the fuel index and the injection timing independently. Lars G. Jacobsen MAN B&W Diesel A/S Copenhagen Reply | Email Member: gaurav Edit/Delete Post Date: 1/28/2003 Sir, Is it possible to achieve Super VIT action by means of mechanical linkage or can it be only done if we have electronic(microprocessor) controlled fuel injection system. Or is it right to say that most efficent Super VIT can only be achieved by electronic fuel injection ? Gaurav MERI-Kolkata Reply | Email Member: Lars G. Jacobsen Advertise Here Edit/Delete Post Date: 1/28/2003 The Super VIT is available in both a mechanical and a electronic version. In the electronic version an I/P converter supplies the pilot air pressure to the individual servo cylinders, instead of the pilot valve activated by the fuel rack used in the mechanical version. The I/P converter receives its pilot signal from the governor system. The advantage of the electronic version is that the break-point is calculated from the actual conditions, why the ambient conditions are taken into account. The engine load is calculated from the engine speed and the fuel index, while the compression pressure is calculated from the scavenging air pressure. Based on these calculations the governor calculates the output to the I/P converter. Lars G. Jacobsen MAN B&W Diesel A/S Copenhagen Reply | Email Member: RolloTomkins Edit/Delete Post Date: 3/4/2003 Sir Am I right in assuming break point is where max cylinder pressure has been reached before MCR which is about 85% MCR when using VIT, after which injection timing is retarded back to its original setting at 100% MCR Also, does the MAN B&W engine have a fuel quality setting lever on the VIT control similar to that used on the Sulzer RTA, or must the fuel pumps be adjusted individually if a fuel of differing ignition quality is bunkered. Thankyou RT Reply Member: Lars G. Jacobsen Edit/Delete Post Date: 3/4/2003 The breakpoint is the point where the maximum cylinder pressure has been reached and the injection timing is advanced the most. Above the breakpoint the injection timing is gradually retarded back until it reaches its original setting at 100% MCR load. The position of the breakpoint is determined by the layout of the engine. Formerly it was generally considered to be at approximately 85% MCR load, but it also has to be ensured that the maximum pressure rise from compression to maximum cylinder pressure is 35 bar or less (recommended by MAN B&W Diesel A/S). For this reason the breakpoint has tended to be somewhat higher on the latest engines (approximately 90% MCR load). In order to compensate for fuel related differences in the maximum cylinder pressure it is possible to adjust the VIT according to the experience with the different fuels. In case of the mechanical VIT an offset is introduced by moving the pilot valve bracket horizontally towards or away from the lever, by means of the adjusting screws. In case of the electronic VIT it is possible to adjust an offset value on the governor panel. 28-06-2016 22:21 Lars G.com/forum-post. Jacobsen MAN B&W Diesel A/S Copenhagen Reply | Email Member: Johannes What the term fuel index and how is it adjusted? Reply | Email Member: Lars G. Consequently. the vit pilot line pressure increases to approx 3 kg at break point and then reduces till the mcr keeping the pmax const. thus preventing a too high servo signal as the control air inlet will always press the piston of the pressure adjusting valve against the lever. The increased pressure rise will actually improve the performance of the engine. would any enine alarm sound? what would the peak pressure be during that limited time with pilot line pressure at 7 kg and an engine operating at 90 % mcr? If the servo signal increases way beyond the normal operating range.VIT and Super VIT.asp?thread_id=T73255 Edit/Delete Post Date: 3/22/2004 Edit/Delete Post Date: 3/22/2004 The fuel index is an indication of the active stroke of the fuel pump. i would like to draw your attention to the inlet pressure of this vit pilot valve which is 7 kg (control line pr). The latter is taken into account in the calculations of the electronic VIT version.g. Lars G.g. If such a condition is allowed to exist for a long time. but if we observe the VIT index at break point. it has not been deemed necessary to introduce an alarm or other measures to prevent or limit the duration of such a malfunction. it is not possible to state default values for the VIT index break point setting or rate of change.0 bar. but will over time overstress the piston rings. the data above are speculated and may not be fully correct.even with the engine room under UMS conditions.. Consequently. as the scavenging pressure is used in the calculations. In this case it is not possible to depress the pressure adjusting valve further. i had experienced sticking of this pilot valve and full 7 kg outlet pressure was fed to the servo positioners. Forum Post. When the engine is given a speed command the governor increases the fuel index. In any case. why isnt a reducer fitted before the vit pilot valve. when the max pressure needed is 3. the break point is determined by the point where the lever rests on both pivot points. 2 of 6 Lars G. the engine is not overloaded due to this. if the malfunction is allowed to persist. the mechanical limits of the VIT system also have to be considered. wouldnt this effect the load on the bearings and other runnig gear if the engine is operated in this condition for more than 8 hrs. Lars G.5 bars. subject to certain limitations. The travel of the servo actuators is designed to be going from a minimum at a servo signal of 0. Jacobsen Post Date: 2/7/2008 The actual VIT index at the break point depends on a variety of factors.5 bar to a maximum at a servo signal of 5. My doubt is . the only real impact on the engine is the increased pressure differential over the piston rings. In case of the mechanical VIT system. Marine Talk. this difference may increase more if the engine is operated above the break point. this would be around 6 notch and the peak pressure developed at this point would be the design 140 bar in the cylinder. as it does not directly influence the operation of the engine. If 7 bar is admitted to the servo the VIT index becomes around 14 notch.marinetalk. this will naturally result in an increased pressure rise from the compression pressure to the maximum pressure. which in turn is controlled by the engine governor.. and as each notch gives an increase in peak pressure of 1 bar. please correct if wrong. if i am not wrong. luckily it was noticed immediately and corrective actions were taken. thanking you. Even if the maximum pressure is over the specified maximum. As stated earlier. No alarm is provided for this malfunction. The engine load is determined by the power required to turn the propeller at the requested revolutions and a malfunction of the VIT system does not change this and e. Hence. Jacobsen MAN Diesel A/S Copenhagen 28-06-2016 22:21 . fuel properties and ambient conditions. e. Equipment. e. and a very limited increase to the bearing load. suppose this had happened during ums period in an engine room. cylinder condition problems are thus likely to occur. which is given during engine starting and astern movements. However. but does not affect the possibility to safely manoeuvre the engine. untill the requested engine speed is reached. This is controlled by push rods on the individual fuel pumps connected to the fuel rack. Jacobsen MAN B&W Diesel A/S Copenhagen Reply | Email Edit/Delete Member: rec Post Date: 2/3/2008 Reply | Email Edit/Delete Member: lgj Post Date: 2/4/2008 dear sir. manish Member: Lars G. Jacobsen MAN Diesel A/S Copenhagen Reply Edit/Delete Member: rec Post Date: 2/6/2008 Reply | Email Edit/Delete thank you sir for your reply. the over stressing of the piston rings may possibly require maintenance. the auxiliary systems are not affected by this either.MAN B&W . due to the too high pressure rise from the compression pressure to the maximum pressure. as you state the worst case is equal to the control system pressure of 7 bar.g. Jacobsen http://www. the peak pressure may exceed by 8 bars. why the mechanical limit is reached earlier than a servo signal of 7 bar would otherwise indicate. an abnormal servo signal ought to be discovered by the engine crew during their routine inspection rounds . It has to be freed frequently by injecting diesel through the plug at the base of the pump.marinetalk. If cylinder problems are encountered.e. Could you let us know what is the scale/value for this. But this obviously has a cost due to the consequently increased fuel consumption. Reply | Email Member: nike4065 Edit/Delete Post Date: 4/28/2008 Dear Lars.We are using LSHS as fuel. According to my understanding. can u help me in letting me know what is lattest technical developments takong place in b&w engines. Reply Member: amit Edit/Delete Post Date: 3/18/2010 I am trying to clarify some VIT adjustment issues. Could you let us know what is the scale/value for this. Secondly. We wanted to know this 0 to 14 marking translates to how many Degrees of injection timing adjustment. i am a engineer i want to know more about super VIT like related diagrams and any site where i can get some more data.. one can be tempted to reduce the combustion pressure in order to reduce the experienced problems. To introduce VIT offset for fuel quality there is a option in nor control. 3 of 6 http://www. I would be really greatful if you can help me on the following queries: Engine: HSD-MANBW 12K90MC To start with the queries. To introduce VIT offset for fuel quality there is a option in nor control. What is the relationship between increased combustion pressure and reduced SFOC in the range of the VIT breakpoint (i.e.VIT and Super VIT. regards manish Member: chsri67 Post Date: 2/24/2008 Thanks for the useful discussion. how much offset causes the injection timing to advance/retard by what degree? And lastly. Marine Talk. Reply | Email Edit/Delete Member: jet Post Date: 8/13/2009 Good day. 1 bar increase in p_max gives x g/BHP H reduction in SFOC Reply | Email Member: noman john Edit/Delete Post Date: 11/17/2009 sir. thank u Reply | Email Member: noman john sir. firstly. firstly. We were unable to locate this information in any related manual. will highly apreciate as required for my project. Equipment.. i. We were unable to locate this information in any related manual. What is the provision for lubricating the gear when the barrel seals are new and not passing. We have a problem with the VIT gear in the fuel pump getting stuck.Lars G. for clearing my doubts. I would be really greatful if you can help me on the following queries: Engine: HSD-MANBW 12K90MC To start with the queries. Though worked on many super VIT engines. thx Reply | Email Member: Amitava Edit/Delete Post Date: 3/18/2010 I am trying to clarify some VIT adjustment issues. VIT has been introduced to reduce the specific fuel oil consumption by raising the combustion pressure. We will appreciate your help in this regard.e.MAN B&W . never thought it was super VIT until now. we noticed that the VIT index of this engine got 0 to 14 markings. thanks for useful information need more information on super vit pls tell me any site Edit/Delete Post Date: 11/17/2009 Reply | Email Member: sunny Edit/Delete Post Date: 11/28/2009 HI . Your explanation is hitting nail on head. Jacobsen . Secondly. parameter 13. Thamks for explaining the concept of vit very nicely. i.com/forum-post. how much offset causes the injection timing to advance/retard by what degree? And lastly.asp?thread_id=T73255 Reply Edit/Delete Member: rec Post Date: 2/7/2008 Reply | Email Edit/Delete Thank you sir. we noticed that the VIT index of this engine got 0 to 14 markings. Forum Post. How do we disengage the electronic governor while keeping the fuel rack/fuel setting constant? Is the attached method will be effective? Can we do it in a simpler way like using constant fuel mode with deadband on where the governor does not regulate fuel control unless the variation in rpm exceeds the deadband setting. How do we disengage the electronic governor while keeping the fuel rack/fuel setting constant? 28-06-2016 22:21 . parameter 13. We wanted to know this 0 to 14 marking translates to how many Degrees of injection timing adjustment. Thanks and Regards. the tie rods are bolted to the bed plate so a couple thus formed will try to rock the bed plate and thus the engine. Reply | Email Member: yukiran1981 Edit/Delete Post Date: 12/19/2010 Sir. The reason behind that was the the kind of construction of the bed plate itself.a) One component of force tries to push the journal down and b) the other component tries to Push the Tie Rods up. we also already check the pneumatic system from air regulator valve at 5 Bar. It comes into play while starting. the pressure not only forces the main journals down but there is also a component of force which pushes the cylinder head up.The rpm can reach around 120. Now recent development has waisted studs on the main bearing cap but the are OFFSET FROM the transverse centerline of the engine. entablature and the bed plate is tied and precompressed by the TIE RODS.. the x-head bolts etc are all waisted studs. We try from manual / emergency side.marinetalk. then there is a couple formed. After that we open and check / calibrate the fuel valve make at 300 Bar +/. NYK [This message has been edited by Pracheer Singh (edited 1/4/2011).. 1.20 and calibration governor.VIT and Super VIT. Other things. the tie rods were kept as close to the centerline of the engine as possible and due to space restrictions.3/E Maersk Reply | Email Member: Pracheer Singh Hello Uday Sir! Your answers to the queries are as follows ( forgive me if I miss something): Edit/Delete Post Date: 1/4/2011 1. The only change the Sulzer made was to replace the mechanical control of the VIT by an elctronic control in their later engines. We facing problem with Main Engine Man B&W 6L35 MC.MAN B&W . So when the engine has started. Previously. Now when the firing forces come. To counter attack this problem. then this particular cam turns without ant running gear touching it.asp?thread_id=T73255 Is the attached method will be effective? Can we do it in a simpler way like using constant fuel mode with deadband on where the governor does not regulate fuel control unless the variation in rpm exceeds the deadband setting. then what is the difference between VIT and super VIT in Sulzer? Reply Member: aksahil Post Date: 7/10/2011 Does the sulzer engine have super VIT?If yes. it had the same features as the MAN B&W super VIT. Equipment. The primary (fuel feed pump and booster) adjust at 6 Bar to fuel pump.130. The cam for the air distributor serves its purpose only while starting the engine. still the rpm can't increase. Therefore if a cam ( normal positive ) is used then the wear of this particular cam will be obviated and will be expensive to repair/replace this cam. Now at the bottom. Sulzer RND ). Forum Post.com/forum-post.e.Why not jacking bolts? uday kiran. Actually if you see there is no other requirement of this particular cam while the Engine is in continuous operation. reversing and again starting. and the vessel is en-route a voyage. 4 of 6 http://www. Hence there is no question of a "super VIT" in a Sulzer engine. Now the Cylinder Head. Note that there was only one cover for the main bearing having two jack bolts.] Reply | Email Member: aksahil Edit/Delete Post Date: 7/10/2011 Does the Sulzer engine have Super VIT?If yes. Pracheer Singh. Advantages of using Wasted studs for securing main bearing top keep in MAN B&W. So care has to be taken while working as the necked region should not be marked. you might be knowing that the main bearing keeps were held down by Jacking bolts (eg. after sea trial we can't pass the critical rpm between 115 . Waisted studs give more comression as they have more elasticity and resilience. I will appreciate your help in this regard and thank you in advance. the jack bolts were used to keep the bearing top covers tight(reaction force through the entablature).Why Negative cam or Inward cam used in Air distributor of the MAN B&W Starting Air System. scored or cracked as due to reversal os stresses.then what is the difference between VIT and super VIT in sulzer? Reply | Email Member: ritinkarsen Edit/Delete Edit/Delete Post Date: 10/3/2011 When Sulzer introduced their VIT it had the pssibility of adjusting the beginning and end of fuel injection independent of one another i. Hope you found it satisfactory and for the details you can refer the manuals and refer Lamb's and Cowley. Reply | Email Member: sanket can anyone shed some light on whether the exhaust valve timing of an smc engine change??? Reply | Email Member: frans Edit/Delete Post Date: 10/6/2011 Edit/Delete Post Date: 1/23/2012 Sir. When a cylinder fires.Why not a positive cam? 2. As a matter of fact. 2. from the foundation bolts to the con rod bolts. fatigue will cause a crack initiation and finally fracture. The engine smoothly start and idle at 100 Rpm Could you help us to give same advice for our matter? regards Frans Reply | Email Member: Rohann Edit/Delete Post Date: 7/10/2012 28-06-2016 22:21 . Marine Talk. .. Equipment.there is stopper bolt fit on the main fuel rack which prevent excessive load and protect the engine. Reply | Email Edit/Delete 28-06-2016 22:21 . Reply Member: sujit agawane Sir.com/watch?v=SMdaMdLZk_w Reply Member: vikramrajagopal Edit/Delete Post Date: 12/31/2013 Edit/Delete Post Date: 12/31/2013 Edit/Delete Post Date: 5/24/2014 Sir what is mean by knuckle point in load up program is it related to VIT.? Edit/Delete Post Date: 7/19/2013 Reply | Email Edit/Delete Member: md Post Date: 8/14/2013 Reply | Email Edit/Delete Frans I believe your engine reached the limit . GOLATKAR Post Date: 11/4/2013 sir.MAN B&W . you may got the engine fully loaded due to external resistance which can be determined from power card . we tried to troubleshoot the VIT system. also vibrations when trying to increase speed.can i know two stroke/four stroke engine when running at what speed runs camshaft compare to crankshaft Reply | Email Member: er.com/forum-post..asp?thread_id=T73255 Dear Frans. We too are facing the same problem as detailed by you.. and still we need expert help..Could you please share your view on this topic. Thanks . to troubleshoot.youtube..VIT and Super VIT... Reply | Email Member: satyam Edit/Delete Post Date: 8/16/2014 onboard my ship suddenly VIT stopped working.9 bar in ahead direction at 110 rpm. ours is a 5S60MC. Marine Talk.raman86 Edit/Delete Post Date: 11/21/2013 sir can u please explain in detail the relationship between injection timing and fuel index ? and sir what is fuel index ? why we cannot adjust the fuel index of individual fuel pump.plz help.. Forum Post. if you could please revert Warm Rgds Rohann Reply | Email Member: pravin7yadav any budy plz Explain vit with relevant scketches.g.marinetalk..ahve you solved your proble.. If you check the engine power and found to be fully loaded then the hull fouled in such cases RPM will not go to maximum since speed converted to power Good luck Member: PRASANNA R. http://www. as the VIT pressure which was showing 0.... 5 of 6 http://www. we suspect valve 40. can u please explain How to adjust Break point in B&W super VIT engines? & sir How Break point is Fixed for old engines????? Please reply sir Reply | Email Member: hamal E. Forum Post. Inc.marinetalk. in whole or in part.2016 MarineTalk Division of Link Internet Business Solutions All rights reserved. 28-06-2016 22:21 .com/forum-post.MAN B&W . copying or transmission of this Web site content.VIT and Super VIT. MGI International Marine Safety Solutions Inc.. retrieval. Lacerta Shipping Agencies Phils. 6 of 6 http://www. Do You Want a Flat Stomach? Learn the Secret Paid Content Latest Marine News and Technology Articles | Maritime 2016 Buyer's Guide MarineTalk E-mail: Contact Us Copyright © 1998 .. The reproduction. is not permitted without the express permission of MarineTalk .asp?thread_id=T73255 You may also like: Trending Technology. Diabetes Breakthrough That Will Bankrupt Diabetes Industry Why All Girls Need This Military Flashlight How to Stop Snoring and Improve Your Health Famous People Who Don't Wear Underwear Marine & Offshore Supplies. Inc. Marine Talk. Inc. Equipment.. World Shipping & Maritime News New Self-Elevating Vessel Bridge Electronics for New Moroccan Frigates Anti-piracy Workshop You Might Also Like From Around the Web Ship Analytics International PMI Industries.