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Optimum design of gear systems for surface durability
SYSTEMATIC
ABSTRACTS
OF CURRENT
LITERATURE
sealing faces shows close correlation with the experimental data obtained. A few practical consequences are discussed. Viscoseal-pressure Generation and Friction Loss under Turbulent Conditions. J. G. Pape and W. J Vrakking, ASLE Trans., II (4) (1968) 310-320; 13 figs., 2 tables, 17 refs A new theory is developed that predicts the sealing coefficient and the friction factor of a viscoseal under turbulent flow conditions. It shows very satisfactory correlation with available experimental data. The results have been given in simplified formulae such that they are readily useable for design purposes. Existing theories on the turbulent behaviour of the viscoseal are briefly discussed. Optimum Design of Gear Systems for Surface Durability. A. Seirig and T. Conry, ASLE Trans., II (4) (1968) 321-329; 9 figs., 2 tables, 23 refS. The development of a design system for the evaluation of the significant parameters which optimise the performance of gear units for surface durability. A double reduction unit is considered for illustration. The results show the feasibility of automated design procedures for gear systems with regard to pitting, scoring and wear. Increasing the Contact Strength of Steel Gears by Electrolytic Polishing. A. D. Kornev et al. Russian Eng. J., 48 (I) (1968) 44-45; I fig., 6 refs. (English translation of Vestn. Mashinostr., 48 (I) (1968) 42-43. Test results show that the life of electropolished rollers is IO-15% higher than turned rollers. Electropolishing improves the surface finish of the working surface and considerably increases the contact strength: this suggests that the load-carrying capacity of the tooth surface in gear transmissions can be increased by applying this finishing process. The Development of SG Iron Piston Rings and Centrifugal Casting. R. R. Leitch, SAE Australasia 2, 28 (6) (1968) z15--220; 7 figs., 3 tables, 3 refs. The author discusses the advantages of spheroidal graphite iron as a new piston-ring material. From a practical aspect the higher elastic modulus and tensile strength suit ring designs demanding increased wall pressure and reduced section. They will not break during fitting, will withstand shock loading and have good wear resistance. Engine tests under extremely arduous conditions substantiate the superiority of spheroidal graphite iron piston rings where breakage in service has become a problem.
I39
Case Hardened Tooth Wheels. H. Rettig, V.D.I.-Z., III (4) (1969) 274-284; 16 figs., 3 tables, 14 refs. Case hardening is still the most reliable method for improving tooth-flank rolling strength, the dedendum strength and the wear resistance. High-quality case-hardening steel can be produced by vacuum melting, increased toughness can be obtained by the addition of nickel, chromium and molybdenum. Careful heat treatment, grinding, dimensional accuracy and surface finish as well as shot blasting of the roots of the flanks aid the attainment of high load capacities. Investigations on the Lubrication Film Development at Tooth Wheels. G. Lechner. V.D.I.-Z., III (4) (1969) 269-274; 19 figs., 8 refs. Measurements of the passage of electrical current allow a direct insight into the lubrication state of mating tooth wheels and confirm that these operate within the range of mixed friction. The share of liquid friction generally exceeds 60%. Seizure is preceded by a collapse of the oil film in the contact zone where film development occurs. A presumption for the collapse is that the oil film reaches a limiting temperature which is characteristic for each lubricant used. Poor film development has been found on austenitic steels. Driving Elements-Annual Survey. V.D.1:Z., III (4) (1969) 231-252. a. Seigfried, Gears and gear units, pp. 231-235; 123 refs. G. Stade, Worm gears, pp. 235-236; 9 refs. W. M. Capellen and R. Schraut, Transmissions with varying velocity ratio., pp. 236245; 284 refs. P. Schrimmer, Belts and belt drives, pp. 246-249; 84 refs. H. Korrenn, Slider and roller bearings., pp. 249-252; 80 refS. Hydrostatic Gears-Ratios of Torque, Speed and Power of Fully and Semi-hydrostatic Gears under Consideration of the Efficiencies. F. Jarchon, V.D.I-Z., III (4) (1969) 222-227; 8 figs., I table. The correct design and use of infinitely variable hydrostatic gears must be based on the knowledge of the ratios of torques, speed and efficiency at every operating point. It is possible to establish for all types a common equation each for the ratio of torque, speed and power under consideration of the efficiencies. Multi-layshaft Gears for Turbo-machinery. K. Ehrlenspiel, V.D.I.-Z., III (4) (1969) 218~221; 6 figs., 3 refs. Multi-layshaft gears are able to transmit more power than ordinary parallel shaft spur gears because of the power distribution on three Wea+‘. I3 (1969)
135-143
ABSTRACTS
OF CURRENT
LITERATURE
sealing faces shows close correlation with the experimental data obtained. A few practical consequences are discussed. Viscoseal-pressure Generation and Friction Loss under Turbulent Conditions. J. G. Pape and W. J Vrakking, ASLE Trans., II (4) (1968) 310-320; 13 figs., 2 tables, 17 refs A new theory is developed that predicts the sealing coefficient and the friction factor of a viscoseal under turbulent flow conditions. It shows very satisfactory correlation with available experimental data. The results have been given in simplified formulae such that they are readily useable for design purposes. Existing theories on the turbulent behaviour of the viscoseal are briefly discussed. Optimum Design of Gear Systems for Surface Durability. A. Seirig and T. Conry, ASLE Trans., II (4) (1968) 321-329; 9 figs., 2 tables, 23 refS. The development of a design system for the evaluation of the significant parameters which optimise the performance of gear units for surface durability. A double reduction unit is considered for illustration. The results show the feasibility of automated design procedures for gear systems with regard to pitting, scoring and wear. Increasing the Contact Strength of Steel Gears by Electrolytic Polishing. A. D. Kornev et al. Russian Eng. J., 48 (I) (1968) 44-45; I fig., 6 refs. (English translation of Vestn. Mashinostr., 48 (I) (1968) 42-43. Test results show that the life of electropolished rollers is IO-15% higher than turned rollers. Electropolishing improves the surface finish of the working surface and considerably increases the contact strength: this suggests that the load-carrying capacity of the tooth surface in gear transmissions can be increased by applying this finishing process. The Development of SG Iron Piston Rings and Centrifugal Casting. R. R. Leitch, SAE Australasia 2, 28 (6) (1968) z15--220; 7 figs., 3 tables, 3 refs. The author discusses the advantages of spheroidal graphite iron as a new piston-ring material. From a practical aspect the higher elastic modulus and tensile strength suit ring designs demanding increased wall pressure and reduced section. They will not break during fitting, will withstand shock loading and have good wear resistance. Engine tests under extremely arduous conditions substantiate the superiority of spheroidal graphite iron piston rings where breakage in service has become a problem.
I39
Case Hardened Tooth Wheels. H. Rettig, V.D.I.-Z., III (4) (1969) 274-284; 16 figs., 3 tables, 14 refs. Case hardening is still the most reliable method for improving tooth-flank rolling strength, the dedendum strength and the wear resistance. High-quality case-hardening steel can be produced by vacuum melting, increased toughness can be obtained by the addition of nickel, chromium and molybdenum. Careful heat treatment, grinding, dimensional accuracy and surface finish as well as shot blasting of the roots of the flanks aid the attainment of high load capacities. Investigations on the Lubrication Film Development at Tooth Wheels. G. Lechner. V.D.I.-Z., III (4) (1969) 269-274; 19 figs., 8 refs. Measurements of the passage of electrical current allow a direct insight into the lubrication state of mating tooth wheels and confirm that these operate within the range of mixed friction. The share of liquid friction generally exceeds 60%. Seizure is preceded by a collapse of the oil film in the contact zone where film development occurs. A presumption for the collapse is that the oil film reaches a limiting temperature which is characteristic for each lubricant used. Poor film development has been found on austenitic steels. Driving Elements-Annual Survey. V.D.1:Z., III (4) (1969) 231-252. a. Seigfried, Gears and gear units, pp. 231-235; 123 refs. G. Stade, Worm gears, pp. 235-236; 9 refs. W. M. Capellen and R. Schraut, Transmissions with varying velocity ratio., pp. 236245; 284 refs. P. Schrimmer, Belts and belt drives, pp. 246-249; 84 refs. H. Korrenn, Slider and roller bearings., pp. 249-252; 80 refS. Hydrostatic Gears-Ratios of Torque, Speed and Power of Fully and Semi-hydrostatic Gears under Consideration of the Efficiencies. F. Jarchon, V.D.I-Z., III (4) (1969) 222-227; 8 figs., I table. The correct design and use of infinitely variable hydrostatic gears must be based on the knowledge of the ratios of torques, speed and efficiency at every operating point. It is possible to establish for all types a common equation each for the ratio of torque, speed and power under consideration of the efficiencies. Multi-layshaft Gears for Turbo-machinery. K. Ehrlenspiel, V.D.I.-Z., III (4) (1969) 218~221; 6 figs., 3 refs. Multi-layshaft gears are able to transmit more power than ordinary parallel shaft spur gears because of the power distribution on three Wea+‘. I3 (1969)
135-143