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Cylinder wear in railroad diesel engines

Cylinder wear in railroad diesel engines cylinde r wear in railroa d diesel engines COM E interesting facts came to light concerning Freight trains tend to idle on downgrades more the optimum Viscosity Index of oils used for than passenger diesels, with resulting increase in railroad diesel engines in the U.S.A. in a paper given wear rates. by R. McBrian and L. C. Atchison, of the Denver and Low Operating Temperatures Cause Wear. Rio Grande Western Railroad Co., and read at an Field experience confirmed the usual opinion that SAE National Diesel Engine Meeting at St. Louis. engines operating below 140°F. show excessive wear rates. The authors stated that they made every Mediu m VI Oils gave best results. effort to maintain engine temperatures as near to The authors gave seven principal reasons for 180°F. as possible. They could not go far above this engine wear, and these are outlined below. In in view of the mountain territory which' had to be addition, however, they remarked that their experi­ negotiated and which caused boiling to occur, but ence with diesel-electric freight locomotives, using they found that wear rates decreased slowly as good fuel and when well maintained, showed that temperatures increased above 140°F. medium VI oils gave lower rates of metal pick-up than lower or higher VI oils. Spectrographic High Sulphur Fuels and Poor Filters. analysis of the lubricating oil ash from units at High sulphur fuels were again stated to cause high various mileages showed that oils having a VI of wear rates, as also were the installation of poor type 50 to 65 have lower rates of pick-up than 20 VI or filters. Although some filter manufacturers had 80 VI oils. stated that dirt particles of less than three microns were harmless, the authors stated that they had not The following figures were quoted by the authors found this proved. as typical total amounts of metal contamination from starting such a medium VI oil in use, with no oil- Importance of Correct Rings. change, to 300,000 miles :— The overcoming of excessive piston ring and groove Silver — below 0.0015 mg. per 20 gm. oil sample. wear, in one case was of interest. The 6-cylinder four- Copper — below 0.2 mg. per 20 gm. oil sample. stroke engine was rebuilt using three different ring Iron — below 0.2 mg. per 20 gm. oil sample. tensions in the top ring grooves, these were 8 lb., Lead and Tin — only traces. 13 lb., and 25 lb. respectively. After 65,000 miles I t was noticed that metal pick-up is highest the pistons were removed, when the 25 lb. ring immediately after an oil change. Operating con­ showed no wear, and neither was there any measure- ditions in the engine quickly create essential com­ able liner wear with this ring. Groove wear with binations in the oil which form protective films, this ring was also very small. The other rings prevent corrosion, and give good detergency. caused varying degrees of wear. The 25 lb. rings are We wonder if vehicle manufacturers, and oil claimed to have reduced groove wear to one-third of companies, who insist on frequent changing of the its former rate after installation in a complete group sump oil, always consider this latter important fact ? of engines. The principal factors stated to cause diesel engine wear on railroads were as follows. Increased Output Shortens Bearing Life. The authors stated tha t engines delivering 1,350 h.p. would average 1,000,000 to 1,500,000 miles before renewal of the main bearings. If this output was increased to 1,500 however, and making no other change, this bearing life dropped to 400,000 to 600,000 miles. These results were obtained by spectrographic analysis of the lubricating oil ash. Copper, tin, lead, silver, and iron were estimated and totalled to represent bearing and engine wear. Engine Idling Causes Wear. Each engine has a certain output at which its wear rate is lowest. Engines permitted to idle for several hours per day will show the same or higher wear as those that operate at full output all the time, and this will be greater than if operating at the optimum load at all times. 26 Scientific LUBRICATION September, 1950 http://www.deepdyve.com/assets/images/DeepDyve-Logo-lg.png Industrial Lubrication and Tribology Emerald Publishing

Cylinder wear in railroad diesel engines

Industrial Lubrication and Tribology , Volume 2 (9): 1 – Sep 1, 1950

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Publisher
Emerald Publishing
Copyright
Copyright © Emerald Group Publishing Limited
ISSN
0036-8792
DOI
10.1108/eb052076
Publisher site
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Abstract

cylinde r wear in railroa d diesel engines COM E interesting facts came to light concerning Freight trains tend to idle on downgrades more the optimum Viscosity Index of oils used for than passenger diesels, with resulting increase in railroad diesel engines in the U.S.A. in a paper given wear rates. by R. McBrian and L. C. Atchison, of the Denver and Low Operating Temperatures Cause Wear. Rio Grande Western Railroad Co., and read at an Field experience confirmed the usual opinion that SAE National Diesel Engine Meeting at St. Louis. engines operating below 140°F. show excessive wear rates. The authors stated that they made every Mediu m VI Oils gave best results. effort to maintain engine temperatures as near to The authors gave seven principal reasons for 180°F. as possible. They could not go far above this engine wear, and these are outlined below. In in view of the mountain territory which' had to be addition, however, they remarked that their experi­ negotiated and which caused boiling to occur, but ence with diesel-electric freight locomotives, using they found that wear rates decreased slowly as good fuel and when well maintained, showed that temperatures increased above 140°F. medium VI oils gave lower rates of metal pick-up than lower or higher VI oils. Spectrographic High Sulphur Fuels and Poor Filters. analysis of the lubricating oil ash from units at High sulphur fuels were again stated to cause high various mileages showed that oils having a VI of wear rates, as also were the installation of poor type 50 to 65 have lower rates of pick-up than 20 VI or filters. Although some filter manufacturers had 80 VI oils. stated that dirt particles of less than three microns were harmless, the authors stated that they had not The following figures were quoted by the authors found this proved. as typical total amounts of metal contamination from starting such a medium VI oil in use, with no oil- Importance of Correct Rings. change, to 300,000 miles :— The overcoming of excessive piston ring and groove Silver — below 0.0015 mg. per 20 gm. oil sample. wear, in one case was of interest. The 6-cylinder four- Copper — below 0.2 mg. per 20 gm. oil sample. stroke engine was rebuilt using three different ring Iron — below 0.2 mg. per 20 gm. oil sample. tensions in the top ring grooves, these were 8 lb., Lead and Tin — only traces. 13 lb., and 25 lb. respectively. After 65,000 miles I t was noticed that metal pick-up is highest the pistons were removed, when the 25 lb. ring immediately after an oil change. Operating con­ showed no wear, and neither was there any measure- ditions in the engine quickly create essential com­ able liner wear with this ring. Groove wear with binations in the oil which form protective films, this ring was also very small. The other rings prevent corrosion, and give good detergency. caused varying degrees of wear. The 25 lb. rings are We wonder if vehicle manufacturers, and oil claimed to have reduced groove wear to one-third of companies, who insist on frequent changing of the its former rate after installation in a complete group sump oil, always consider this latter important fact ? of engines. The principal factors stated to cause diesel engine wear on railroads were as follows. Increased Output Shortens Bearing Life. The authors stated tha t engines delivering 1,350 h.p. would average 1,000,000 to 1,500,000 miles before renewal of the main bearings. If this output was increased to 1,500 however, and making no other change, this bearing life dropped to 400,000 to 600,000 miles. These results were obtained by spectrographic analysis of the lubricating oil ash. Copper, tin, lead, silver, and iron were estimated and totalled to represent bearing and engine wear. Engine Idling Causes Wear. Each engine has a certain output at which its wear rate is lowest. Engines permitted to idle for several hours per day will show the same or higher wear as those that operate at full output all the time, and this will be greater than if operating at the optimum load at all times. 26 Scientific LUBRICATION September, 1950

Journal

Industrial Lubrication and TribologyEmerald Publishing

Published: Sep 1, 1950

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