Structural Design and Friction Performance Test of a New Conical Groove Friction Disks in Wet Clutch

Wet clutch transmits its power by the friction torque between friction and separate disks. Conical groove friction disk is a new attempt in Wet clutch. Its configurations allow significant enhancement of torque delivery performances, compared with the traditional plane friction disk. In order to study the frictional performances of the conical groove friction configuration, the friction coefficient calculation model of conical groove friction disk was established, and experimental investigation was used to measure the friction coefficient under sliding velocity conditions. The influence of configuration parameters: cone heights and angles on friction coefficients were evaluated in a typical variable speed test. The results indicated that configuration parameters can affect friction performance in a constant speed period. The equivalent radius can directly describe the friction region of a conical groove friction disk. The constant speed test can be a useful method.

Effects of operating and material parameters on the thermal characteristics of a wet clutch

Based on the frictional mechanism of a wet clutch, frictional models of wet clutch engagement were established using the modified Reynolds equation and the elastic contact model between frictional pairs. Then, the heat flux models for the viscous shear and asperity friction were built, and the two-dimensional transient thermal models for the separator plate, friction disk, and ATF heat convection model were deduced based on the heat transfer theory and conservation law of energy. Finally, the Runge–Kutta numerical method was used to solve the frictional and thermal models. The average temperature of the separator plate, friction disk, and ATF were calculated. The effects of operating and material parameters, such as applied pressure, initial angular velocity, friction lining permeability, surface combined roughness RMS, equivalent elastic modulus, and ATF flow, on the thermal characteristics of friction pairs and ATF during engagement, were studied. The simulation results show that the temperature characteristics of the separator plate, friction disk, and ATF depend mainly on the viscous shear and asperity friction heat flux, and that the operating and material parameters of the wet clutch also have significant impacts on the overall variation trend of the thermal characteristics of the separator plate, friction disk, and ATF.

Development of Technological Bases for Manufacturing Blanks of Friction Disks with Molybdenum Gas-Thermal Coating for Working in Oil in Units of Transport Machines

This article is dedicated to the questions of development of technological bases for the manufacturing blanks of friction disks with molybdenum gas-thermal coating applied by plasma spraying, for working in oil in the transmission units of transport machines. For ensure high performance indicators, there is has been offered a technological scheme for manufacturing friction disk blanks: short blasting preparation of the surface of the disk’s steel base, applying a molybdenum coating, that characterized by high adhesion to the ferrous metals, mechanical processing of the coating by grinding, monitoring the coating’s quality. The developed technological bases for manufacturing blanks of friction disks with molybdenum gas-thermal coating, applied by plasma spraying, for working in oil in transmission units of transport machines are contributed to the creation of efficient products with enhanced performance indicators for friction coefficient, wear resistance, reliability in modern conditions at the enterprises.

Dynamic Temperature Rise Mechanism and Some Controlling Factors of Wet Clutch Engagement

The friction transmission model of wet clutch is established to analyze the friction transmission mechanism of its engagement. The model is developed by applying both the average flow model and the elastic contact model between the friction disk and separator plate. The key components during wet clutch engagement are the separator plate, friction disk, and lubricant. The one-dimension transient models of heat transfer in radial direction for the three components are built on the basis of the heat transfer theory and the conservation law of energy. The friction transmission model and transient heat transfer models are coupled and solved by using the Runge-Kutta numerical method, and the radial temperature distribution and their detailed parametric study for the three components are conducted separately. The simulation results show that the radial temperature for the three components rises with the increase of radius in engagement. The changes in engagement pressure, lubricant viscosity, friction lining permeability, combined surface roughness RMS, equivalent elasticity modulus, difference between dynamic and static friction coefficients, and lubricant flow have important influence on the temperature rise characteristics. The proposed models can get better understanding of the dynamic temperature rise characteristics of wet clutch engagement.

Research on Performance of the Cu-Based Friction Materials Repaired by Spark Plasma Sintering

The worn Cu-based friction disks were repaired and remanufactured by the spark plasma sintering (SPS) technology. The morphology and component of the repaired friction disk were analysed by SEM and EDS. The mechanical properties were characterized by microhardnessmeter and friction tester. The results indicated that the microstructure of the repaired areas combined closely with the worn areas and the components were well-distributed. The friction coefficient of the repaired materials is close to the unrepaired, but the hardness declined slightly.

Boron and carbon: Antagonistic or complementary? Proposal for a simple prototype of a molecular clutch or molecular switch

Boron and carbon, either in elemental form or when combined, are structurally very different. They are indeed complementary, and the weaknesses of one can be complemented by the strengths of the other, and vice versa. The structural complementarity can be readily observed in the shape of [XnHn]y– (X = C or B) compounds. One visualization of this complementarity can be found by comparing the most popular carbon and boron organometallic sandwich molecules, [Fe(C5H5)2] and [3,3'-Co(1,2-C2B9H11)2]–. Both obey the 18e– rule, and in both the metal is η5 coordinated by two pentagonal faces. However, for [Fe(C5H5)2], the first ring of atoms outside the pentagonal face is coplanar with the coordinating face, whereas for [3,3'-Co(1,2-C2B9H11)2]– the substituents are out of the coordinating face featuring a canopy shading the metal. Taking advantage of this feature, [3,3'-Co(1,2-C2B9H11)2]– can be a well-performing molecular clutch electrochemically driven. When it is engaged, the beams of the upper [7,8-C2B9H11]2– ligand in [3,3'-Co(1,2-C2B9H11)2]– mesh the beams of the lower [7,8-C2B9H11]2–. This occurs when the molecular friction disk, the Co, is as Co3+. When Co3+ is reduced to Co2+, its radius is elongated, and both sets of beams are unmeshed allowing for a more free rotation, or molecular clutch disengagement.