scholarly journals Influence of oxidation of automatic transmission fluids (ATFs) and sliding distance on friction coefficients of a wet clutch in the running-in stage

Friction ◽  
2020 ◽  
Vol 9 (2) ◽  
pp. 401-414
Author(s):  
Leonardo Israel Farfan-Cabrera ◽  
Ezequiel Alberto Gallardo-Hernández ◽  
Manuel Vite-Torres ◽  
Jesús Gilberto Godínez-Salcedo
Keyword(s):  
Automatic Transmission ◽  
Viscosity Index ◽  
Composite Plates ◽  
Friction Material ◽  
Friction Coefficients ◽  
Surface Flattening ◽  
Wet Clutch ◽  
Torque Capacity ◽  
Pin On Disk ◽  
Sliding Distance

AbstractIn this paper, the influence of oxidation of automatic transmission fluids (ATFs) and sliding distance on the friction coefficients of a wet clutch in approached running-in conditions was investigated. The ATFs were oxidized by a laboratory process approaching oxidation occurred in actual ATFs. Oxidation was evaluated by means of increase in carbonyl compounds and depletion of zinc dialkyldithiophosphates (ZDDPs) additives. Also, the changes in kinematic viscosity and viscosity index were evaluated. Pin-on-disk tests were conducted to replicate the actual sliding contact in a wet clutch. The pin specimens were cut from friction material composite plates and the disks were actual steel separators both from an automotive wet clutch. Friction coefficient, μ, was measured at progressive sliding velocity, ν, to obtain μ-ν curves at 26 and 100 ΰC. Three μ-ν tests were consecutively run using the same pair of specimens and oil. The cumulative sliding distance for each μ-ν test generated surface flattening using the oils. The friction coefficients of the wet clutch increased due to the ATFs oxidation meanwhile the dμ/dυ values decreased in most cases. It suggests that ATF oxidation can enhance torque capacity of the wet clutch, but it could reduce anti-shudder property. Progressive sliding distance improved the slopes in the μ-ν results using fresh ATFs meanwhile it generated a slope decrease by using aged ATFs.

scholarly journals Evaluation of thermo-oxidized Jatropha bio-oil in lubrication of actual wet clutch materials

2020 ◽  
pp. 135065012098146
Author(s):  
Leonardo I Farfan-Cabrera ◽  
Ezequiel A Gallardo-Hernández ◽  
José Pérez-González ◽  
Benjamín M Marín-Santibáñez ◽  
Roger Lewis ◽  
...  
Keyword(s):  
Automatic Transmission ◽  
Viscosity Index ◽  
Jatropha Oil ◽  
Oxidative Aging ◽  
Lubrication Regime ◽  
Viscosity Increase ◽  
Bio Oil ◽  
Wet Clutch ◽  
Transmission Fluid ◽  
Pin On Disk

In this work, an assessment of the performance of thermo-oxidated Jatropha oil as a lubricant for actual wet clutch materials was performed and compared with a commercial automatic transmission fluid. For this, Jatropha oil, a commercial automatic transmission fluid and a blend of 20 vol% Jatropha oil–80 vol% automatic transmission fluid were subjected to thermo-oxidative aging at 26 °C and 100 °C, followed by a pin-on-disk testing with disk samples from an actual wet clutch. Evaluation of the film thickness at the sliding interface resulted in a boundary lubrication regime for all the tests. The changes in oxidation, viscosity, and a viscosity index of the samples were evaluated along with friction coefficients at various sliding speeds. Jatropha oil was the most sensitive to thermo-oxidation. Jatropha oil and the blend showed a higher viscosity increase than automatic transmission fluid with thermo-oxidation, while the viscosity index of all oils was decreased considerably, Jatropha oil and the blend being the most reduced. Finally, the anti-shudder property, as measured by the change in the friction coefficient with a sliding speed, of Jatropha oil and automatic transmission fluid was improved by thermo-oxidation at 26 °C but worsened at 100 °C, meanwhile it was barely affected in the blend. Therefore, these results indicate that using pure Jatropha oil as automatic transmission fluid would be unsuitable, but blending it with automatic transmission fluids in specific proportions may be apposite for improving the friction properties of wet clutches even under thermo-oxidative conditions.

TRIBOLOGICAL ANALYSIS ON PALM FATTY ACID DISTILLATE (PFAD) AS ALTERNATIVE TRANSMISSION FLUID FOR CLUTCH APPLICATION

2017 ◽  
Vol 79 (7-4) ◽  
Author(s):  
M. A. A. Salleh ◽  
M. K. Abdul Hamid ◽  
Z. H. Che Daud ◽  
A. R. Abu Bakar ◽  
S. A. Abu Bakar
Keyword(s):  
Fatty Acid ◽  
Automatic Transmission ◽  
Viscosity Index ◽  
Tribological Behaviour ◽  
Low Viscosity ◽  
Palm Fatty Acid Distillate ◽  
Wet Clutch ◽  
Transmission Fluid ◽  
Tribological Analysis ◽  
Fatty Acid Distillate

Typically, a mineral based oil from petroleum refining has been widely used as automatic transmission fluid (ATF) in the wet clutch application. However, it has two major disadvantages: (1) It causes pollution to the environment and (2) It is a non-renewable source. Thus, Palm Fatty Acid Distillate (PFAD) is explored as an alternative lubricant for the wet clutch application. In present study, tribological behaviour of PFAD is first sought using a pin on disk tribo-tester and then its behavior will be compared with the behavior obtained in the commercial ATF. It is found in the friction analysis that PFAD has good anti friction ability at low speeds. In addition, PFAD generates almost identical dynamic friction coefficients obtained in the commercial ATF at velocity of 0.4m/s to 0.9 m/s. A slight positive slope in the friction coefficient–velocity graph indicates that PFAD has tendency to have anti-shudder properties, which can improve engaging quality of the wet clutch. However, PFAD has two weaknesses; low viscosity index and less anti wear ability. Some additives should be added into PFAD so that it can give better friction level and less wear rate. 

Frictional Behavior of a Wet Clutch Using Blends of Automatic Transmission Fluid (ATF) and Biolubricant (JatrophaOil) in a Pin-on-Disk Tester

2015 ◽  
Vol 58 (5) ◽  
pp. 941-946 ◽  
Author(s):  
Leonardo Israel Farfán-Cabrera ◽  
Ezequiel Alberto Gallardo-Hernández ◽  
Manuel Vite-Torres ◽  
Juan Rodrigo Laguna-Camacho
Keyword(s):  
Automatic Transmission ◽  
Frictional Behavior ◽  
Wet Clutch ◽  
Transmission Fluid ◽  
Pin On Disk

Investigation of the Wear Behavior of AA6082 Against Different Counterparts

2021 ◽  
Author(s):  
Safiye İpek Ayvaz ◽  
Mehmet Ayvaz
Keyword(s):  
Wear Resistance ◽  
Aluminum Alloy ◽  
Wear Rate ◽  
Abrasive Wear ◽  
Wear Behavior ◽  
Specific Wear Rate ◽  
Pin On Disk ◽  
Disk Method ◽  
Sliding Distance ◽  
Oxidation Wear

In this study, the effect of different counterparts on the wear resistance of AA6082 aluminum alloy was investigated. In tests using pin-on-disk method, 6 mm diameter Al2O3, 100Cr6 and WC-6Co balls were used as counterparts. The tests were carried out using 500 m sliding distance and 5N load. The lowest specific wear rate was measured as 7.58x10-4 mm3/Nm in WC-6Co / AA6082 couple, and the highest value was measured as 9.71x10-4 mm3/Nm in 100Cr6/AA6082 couple. In the Al2O3/AA6082 couple, the specific wear rate of the AA6082-T6 sample was determined as 8.23x10-4 mm3/Nm.While it was observed that the dominant wear type in the 100Cr6/AA6082 pair was abrasive wear, oxidation wear and oxide tribofilm were detected in the WC-6Co/AA6082 and Al2O3/AA6082 couple besides the abrasive wear.

Experimental study on the friction stability of paper-based clutches concerning groove patterns

2019 ◽  
Vol 72 (4) ◽  
pp. 541-548 ◽  
Author(s):  
Liang Yu ◽  
Biao Ma ◽  
Man Chen ◽  
He Yan Li ◽  
Jikai Liu
Keyword(s):  
Experimental Study ◽  
Surface Temperature ◽  
Design Methodology ◽  
Automatic Transmission ◽  
Applied Pressure ◽  
Friction Torque ◽  
Content Type ◽  
Rotating Speed ◽  
Wet Clutch ◽  
Transmission Fluid

Purpose This paper aims to study and compare the friction stability of wet paper-based clutches with regard to the radial grooves (RG) and waffle grooves (WG). Design/methodology/approach This paper presents an experimental study of a wet clutch concerning the effect of groove patterns on the friction torque and surface temperature. The friction stabilities of RG and WG are investigated with the applied pressure, rotating speed and automatic transmission fluid (ATF) temperature taken into consideration. Findings The friction torque and surface temperature of WG are larger than those of RG under the same operating condition. The friction torque difference between RG and WG grows with the increase of applied pressure and narrows with the increase of ATF temperature. Additionally, their temperature difference expands via increasing the rotating speed and ATF temperature or reducing the applied pressure; in this way, not only the variable coefficient difference between RG and WG can be narrowed, but also the friction stability of the clutch can be improved dramatically. Originality/value This paper explains the thermodynamic differences between RG and WG; moreover, it is verified experimentally that WG has a better friction stability than RG.

scholarly journals Wear Properties of Sc-Bearing Zr-Based Composite BMG with Nano-CuZr2 under Lubrication

2020 ◽  
Vol 10 (14) ◽  
pp. 4909
Author(s):  
Shing-Hoa Wang ◽  
Chau-Chang Chou ◽  
Hsien-Hung Chung ◽  
Rong-Tan Huang ◽  
Horng-Yi Chang ◽  
...  
Keyword(s):  
Wear Rate ◽  
Wear Test ◽  
Surface Friction ◽  
Sample Surface ◽  
Optical Microscope ◽  
Wear Properties ◽  
Friction Coefficients ◽  
Adhesion Wear ◽  
Pin On Disk ◽  
New Phase

Lubricated sliding wear of amorphous (Zr55Cu30Ni10Al5)99.98Sc0.02/CuZr2 nanocrystal composite bulk metallic glasses (BMG) under various sliding velocities with a load of 20 N was investigated using the pin-on-disk test. After the wear test involving oil lubrication was performed, there was no wear induced new-phase transformation in the sample surface. Friction coefficients were within the range from 0.22 to approximately 0.29 under a 20-N load at different sliding velocities. Therefore, the calculated friction coefficients clearly indicated that the adhesion wear dominated from the experimental results. This deformation behavior resulted in a higher wear rate and wear coefficient. In addition, worn surfaces were characterized and examined under a scanning electron microscope (SEM) and optical microscope. The mechanism of high wear rate was clarified.

The influence of repeated high-energy engagements on the permeability of a paper-based wet clutch friction material

2017 ◽  
Vol 231 (12) ◽  
pp. 1574-1582
Author(s):  
Niklas Lingesten ◽  
Pär Marklund ◽  
Erik Höglund
Keyword(s):  
High Energy ◽  
Friction Material ◽  
Sliding Surface ◽  
Steel Core ◽  
Interface Surface ◽  
Clutch Engagement ◽  
Wet Clutch ◽  
Oil Flow ◽  
Contradictory Behavior ◽  
Test Cells

The behavior of a wet clutch during engagement is of great importance to the durability of the clutch and the drivability of a vehicle. While many different factors influence the engagement behavior, the focus of this paper is to investigate only one factor, the permeability of the wet clutch friction material. Two test cells for measuring the permeability of friction material mounted on clutch discs have been developed. The test cells were then used to examine the effect of clutch material ageing through clutch engagement on the permeability of the material. The tests were performed on full size friction discs including the steel core prior and subsequent to testing in a wet clutch engagement test rig. The ability of the friction material to allow for oil flow both through the sliding surface layer and the bulk of the material was measured. The results indicate that repeated clutch engagements will increase the bulk permeability. However, the repeated engagements will decrease the ability to pass fluid through the friction material sliding surface. This contradictory behavior could be explained by a combination of an increase in pore size through repeated compression and the surface glaze clogging of the friction interface surface pores.

On the Formation of Hot Spots in Wet Clutch Systems

2001 ◽  
Vol 124 (2) ◽  
pp. 336-345 ◽  
Author(s):  
J. Y. Jang ◽  
M. M. Khonsari
Keyword(s):  
Hot Spots ◽  
Friction Material ◽  
Mechanical Seal ◽  
Comprehensive Model ◽  
Governing Equations ◽  
Thermoelastic Instability ◽  
Wet Clutch ◽  
Special Case

A comprehensive model is developed for analyzing the onset of thermoelastic instability in a wet clutch. For this purpose, appropriate governing equations are derived that take into account the porosity and deformability of the friction material. The effect of the thickness of the separator disk and that of the friction material are also included. The model is general and can be used to describe TEI in a variety of other systems such as in a mechanical seal, as a special case. A series of simulations are presented that predict the thermoelastic behavior of a wet clutch from an instability viewpoint.

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