Limiting Loads for Scoring and Coefficient of Friction on a Disk-Machine : Effects of Lubricating Oil, Specific Sliding and Sliding Velocity, in the Case of Steel/Steel

Prediction of friction-related power losses of hypoid gear pairs

“…The first group of studies focused on measuring power losses of gear pairs directly [8][9][10][11][12][13][14][15][16][17]. Several others measured µ values using roller test machines under conditions simulating a gear pair with the expectation that these measured µ values can be used to predict the efficiency of a gear pair [18][19][20][21][22][23][24][25][26][27][28][29][30][31][32]. Some of these studies resulted in well-known empirical µ formulae that are currently widely used in gear applications [18][19][20][21][22][23][24][25].…”

“…Several others measured µ values using roller test machines under conditions simulating a gear pair with the expectation that these measured µ values can be used to predict the efficiency of a gear pair [18][19][20][21][22][23][24][25][26][27][28][29][30][31][32]. Some of these studies resulted in well-known empirical µ formulae that are currently widely used in gear applications [18][19][20][21][22][23][24][25]. These empirical formulae indicate that µ is a function of a number of parameters including sliding and rolling velocities, radii of curvature of the surfaces in contact, load or contact pressure, surface roughness, and lubricant viscosity.…”

“…The tangential friction force in the sliding direction was computed by using this constant µ and the involute geometry, from which the amount of reduction of torque transmitted to the driven gear was calculated to determine the mechanical efficiency η of the spur gear pair. Although these models provided a qualitative understanding to the role of geometry on mechanical efficiency of spur gears, they were not accurate since a user-defined constant µ value must be used for every contacting point on the tooth surface, as other published experiments on contacts subjected to combined sliding and rolling indicate that many parameters might influence µ [18][19][20][21][22][23][24][25]. In addition, these models were two-dimensional (limited to spur gears with no lead corrections), and complicating effects of the tooth bending and contact deformations, tooth profile modifications, and manufacturing errors were not included.…”

Development of a Gear Oil Scuff Test (GOST) Procedure to Predict Adhesive Wear Resistance of Turbine Engine Lubricants

“…Blok derived an expression for the flash temperatt~re risr (AT) in rectangular moving contacts and for the general case of tn.o bodies made of different materials ( 8 ) . (35). M%en the two bodies are made of the same material, as in the Ryder test (ATR), Blok's equation may be simplified to read (36):…”

A new load-sharing-based approach to model mixed-lubrication contact of spur gears

“…34 A large number of studies have been published, especially within the past 40 years, on friction and efficiency of gear trains. 35–37 Some of these studies 10,38–45 resulted in well known and widely used empirical formulae for coefficient of friction. These empirical formulae state that coefficient of friction is a function of a number of parameters such as sliding and rolling velocities, radii of curvature of the surfaces in contact, load related parameters (unit load or contact pressure), amount of surface roughness, and the lubricant viscosity.…”