If this alignment goes too much haywire it could result in problems. Crankshaft deflection and bearing clearance measurement. Five measuring points are taken tdc, 90 either side of tdc and 30 either side of bdc. Vessel in afloat condition engine in sagged condition piano wire verification. There the marine engineers need to keep them under limits. Hence there is a good maintenance requirement of measuring the crankshaft deflections at regular intervals to ensure that the alignment of the shaft remains within permissible limits and those deflections can be measured as described in the next sections. Carrying out the deflection measurement this deflection measurement is carried out by placing a springloaded dial gauge in the crank throw, opposite the crankpin, in axial direction, and at the. Crankshaft web deflection gauge baker gauges india pvt. Crankshaft position alignment is made under static conditions while the crankshaft lies at the bottom of its bearings. When deflections of the crankshaft occur at same vibrational or resonant frequency as another engine part, the. Crankshaft bending breakage may also result from excessive crankshaft deflection and which is usually caused by an improper alignment between the driven unit and the engine and can result in a broken or bent shaft along with considerable other. Crankshaft deflection crankshaft deflections are measured to detect. When taking crankshaft deflection, keep the deflection gauge over the engine for sometime so that it adjusts to the surrouding temperature of the main engine. Simple explanation of crankshaft deflections, measurement.
How to make sense of the deflection readings taken from. Th e crankshaft of the marine diesel engine is a huge bulky component which should remain as straight as possible during operation, otherwise it could lead to serious damage to the engine and the vessel. Strain deflection gauge a strain or deflection gauge is used to check the crankshaft alignment on large diesel engines. Crankshaft design, materials, loads and manufacturing, by. Instantaneous crankshaft torsional deformation during turbocharged diesel engine operation article pdf available in international journal of vehicle design 543 october 2010 with 2,615 reads. Crankshaft deflection occurs over time, during the repeated and continuous use of the crankshaft. Overspeeding an engine may also cause excessive crankshaft deflection. Recommended blowdown procedure for boiler level instruments duration. Crankshaft deflections will not reveal any problems with the crankshaft or the bearings. But to one degree or another, all parts behave like springs in response to a load.
That is to control the crankshaft deflection of the last unit and the engine aft end static load. The deflection is recorded by using dial deflection gauge which is fitted between the webs of the crankshaft in each unit. As you may know, the engine crankshaft comprises of the journal, crank pin, and crank webs. Crankshaft deflection must be taken twice before starting the dcarb and after completion of dcarb. The crank shaft of a main engine is held in place by main bearings but if due to any reason these bearings go up or down from their orginal positions then this is called deflection of shaftit. The entire chemical process that takes place inside the cylinder of the internal combustion marine diesel engine is materialized by transforming into mechanical work on crankshaft and further on the propulsin plants propeller. Excessive web deflection is dangerous for the engine. It is a process that occurs in the background as the engine operates and, though it cant be seen without a detection instrument, it causes significant damage to. Wireless sensor connectivity test information editing sensor measuring crankshaft rotating angle and indicator showing test positions. Checking crankshafts and crankshaft bearings of motors for defectiveness. The slope deflection method is used for analysis of statically indeterminate structures such as beams and frames. This comparison will then show whether or not the crankshaft concerned is dimensioned adequately.
Simple explanation of crankshaft deflections, measurement procedure, readings,curves. Crank web vertical and horizontal deflections are automatically calculated once 5 readings are collected. At present man diesel recommended procedure prior to chocking is. The cause may be faulty or damaged crankshaft, damaged bearing, poor bearing alignment, excessive bearing clearance or slackness, faulty flanging to transmission, flywheel or vee belt pulley, etc. A second visit was made to determine if the shims were remaining effective. The electronic pdf version of this document, available free of charge. The procedure is repeated for each unit and measurements are. Products solutions for checking check crankshafts and. Cause may be a faulty or damaged crankshaft, damaged bearings, poor bearing alignment, excessive. Guide on how to take crankshaft deflection marine and. Crankshaft deflections are directly related to engine roughness. The study includes measurements made by the crew of the ship and related graphics recording the crank web deflections evolution depending on the number of engine operation hours. The ultimate strength of a material is a measure of the stress level which can be applied to a.
Learn about deflection in a crankshaft and how to keep the alignment within limits. Pdf instantaneous crankshaft torsional deformation. Failure of crankshaft was seen along the web between second journal and second crank pin. The first step is modeling and load preparation that includes mesh generation, calculation of internal static loads mass, external loads gas and inertia and torsional dynamic response due to. The slope deflection equations express the member end moments in terms of rotation angles and deflections. It is a specially adapted dial indicator that fits between the crank webs. Rules for classification and construction vi additional. This maximum load situation happens in all types of engines with a slight done on engines with more cylinders e. We take crankshaft deflection to make sure that the crank runs and maintain proper balance. The deflection when the crankshaft is approaching tdc will then go from its normal positive reading to zero and then to negative readings at which point the assembly is supporting the weight without the assistance from the lowered main bearing. Drawings and particulars to be submitted for the calculation of crankshafts, the documents and particulars listed in the following are to be submitted. This is a measurement done on engine crankshaft by placing a dial indicator gauge across the. View and download suzuki fa50 service manual online. The crank web of each unit is provided with a punch mark where the deflection gauge is to be set for measurement.
The crank webs are punch marked to ensure that the readings are taken in the same place each time. The strain gauge reads the flexing motion of the webs directly as the crankshaft. As it is wellknown, all crankshaft bending failures are usually related with the misalignment, aggravated by deterioration of the foundation. Application notes static and dynamic balancing of rigid. Cause may be a faulty or damaged crankshaft, damaged bearings, poor bearing alignment, excessive bearing clearance or slackness, faulty flanging to transmission, flywheel, or vee belt pulley, etc. The crankshaft is then rotated in one direction and readings are. In a marine installation, for example, the measurment is. Dnvglcg0037 calculation of crankshafts for reciprocating. Explain what deflection readings actually mean and suggest the action which taken 2nd classmust be by the should readings be outside motor examination questions values recommended engine manufacturer.
Mirmarine crankshaft procedures for inspection and. The deflection can be very small crankshaft, conrod, etc. This deflection occurs due to bending and twisting of the crankshaft. Shaft deflection, runout, vibration, and axial motion chapter d4 page 4 contact kalsi engineering search this handbook bearing internal and mounting clearances influence shaft runout side loads cause the shaft to articulate within mounting clearances, resulting in lateral shaft deflection at. Apart from that there could be web failure due to fatigue which is due to the presence of deflections which are beyond permissible limits and hence cause bending of the crankshaft causing fractures due to fatigue.
The crankshaft components are illustrated in figure 2. Some changes were made as there had been some bedding of the shims into the rough surface of the grout. The current industry approach to document crankshaft alignment is to measure static web deflections, see figure 1. Pdf in order to establish the proper functioning of a marine diesel engine. Crankshaft 1 support the crankshaft on a stand and apply a dial crankshaft deflection mm gauge to the crankshaft journal to measure assembly standard required repair level deflection. Every gauge carries a calibration certificate giving actual values crankshaft gauge measures the web deflection of a crankshaft. Engine type main engine measuring direction clockwise. An enginecompressor crankshaft has several places where rods to. Fatigue failure analysis of marine engine crankshaft. In our next article we will learn about the modes of crankshaft failure and points to be kept in mind during the maintenance of crankshafts so that they have a long life.
Crankshaft deflection when they are taken following conditions might be there when you have to measure the crankshaft deflection as well as. They will reveal a problem with the alignement of the main bearings, this can be caused by a failure of the chocking arrangements or distortion of the hull. Crankshaft deflection in a marine diesel engine occurs when the bearings which support the journals of the marine engine crankshafts are damaged and affect the alignment of the crankshaft which they support. We expect that our customers expect the best of the best. All members of the staff are extremely committed to maintain the good reputation that all products which are coming from prisma tibro, sweden have gained over the last decades. This is done to ascertain whether the crankshaft journal is deviated from the theoretical axis or not.
The presence of the beach mark shows fatigue fracture was produced along with a thin and hard zone. Scribd is the worlds largest social reading and publishing site. Measurements overhaul and control operations of crankshaft deflection are performed by the embarked crew on the merchant vessel during the performed international voyages. The cause of excessive crankshaft web deflection must be. Technically, its a long and heavy part which undergoes severe fluctuating loads because of the gas pressure generated in the combustion chamber and high bending and torsional loads from heavy moving objects piston, connecting rod etc. 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. We also recommended increasing the stretch length of the anchor bolts. Crankshaft deflection torque reaction the tendency of the engine to twist in the opposite direction of shaft. They should be taken in accordance with any planned maintenance system when an engine survey is conducted. Describe the procedure for taking crankshaft deflections, explaining all precautions that must be observed. A crankshaft will be approved when the calculation method as presented in this class guideline andor the. The crankshaft deflection gauge which is included in the set of. If the measurement exceeds the required repair level, repair or replace the crankshaft. Crankshaft deflection readings are an excellent method of determining engine to drive alignment and main bearing wear.