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Power Balancing Of Engines

For economy and efficient running of an engine equal power should be produced from each cylinder, it may be necessary to make minor adjustments to achieve this. Power produced is related to quantity of fuel injected and balancing is carried out by small adjustments to individual fuel pump controls. These adjustments should be limited to make sure that individual units are not overloaded, exhaust temperatures are not excessive and that the pump controls will still cut off when brought to stop. Fuel pump rack positions, exhaust and cooling water return temperatures from each cylinder should be noted. Equal exhaust temperatures for each cylinder on their own do not show an accurate balance, particularly in turbo charged engines. Figures do tend to follow a path of a given engine and this may give some indication. Power balancing may be checked by measurements from indicator diagrams. For these engines if electronic combustion monitoring is not fitted, power in the engine may be related to the peak or maximum pressure in the cylinder.

If an engine operates in an unbalanced condition some bearings and running gear may be overloaded, this may cause overheating and bearing failure. Overloading cylinders may cause piston blow past with the corresponding dangers of overheated or seized pistons. Unbalance will also set up vibrations which if allowed for prolonged periods will cause fatigue. This may in turn lead to fatigue cracking of metal in bearings, fracture of bearing studs or bolts, cracks in the crankshaft and slackening or failure of the holding down bolts. A watchkeeper may ascertain that the running conditions are normal by observation of the relevant temperature and pressures particularly exhaust and cooling return temperatures, lubricating oil and turbo charger pressures. The exhaust should be clear of smoke and there should be no unusual noise or vibration The turbochargers should run smoothly with no panting or surging. Fuel injection equipment is particularly important and fuel pump settings, clearances and timings must be checked and maintained during periods when the engine is out of service. Fuel injectors must be changed regularly, cleaned and tested to ensure trouble free operation. The injector is the most likely part of the system to be subject to faults in service. A fault in one injector may cause loss in power in the affected cylinder but may also mean that other cylinders are subject to overload as the engine governor attempts to maintain normal total power or speed. It is important that regular and correct maintenance is carried out on the engine and that any deviation from normal running is noted, investigated and corrected at the earliest opportunity