Powertrain

Tribology has been an essential part of the development of improved powertrains for decades and - even with a growing shift to electrical vehicles - this continues to be the case today.

The powertrain of a vehicle encompasses every component that is involved in the conversion of power to movement. This is true for any sort of vehicle, from boats to planes and cars to bikes, although each of these will have very different requirements placed on powertrain components. However, one thing all will have in common is that they will consist of many moving parts that are in near-constant contact with other components. It is in these contacts – found in any powertrain – where tribological research has been focused to continually improve and optimise designs.

PCS’ range of instruments are used extensively by industry and academia to achieve this continual improvement. The MTM and ETM are key tools used for this work. Both have independently driven specimens which enable a wide range of contact conditions to be replicated, and together cover an impressive range of contact pressures from close to 0 to 3.5 GPa with standard specimens, and even more with non-standard specimens. This versatility means that researchers can use these instruments to investigate all the different contacts you would find in a whole host of powertrain applications, investigating wear, friction and film build up. The EHD is also extensively used in this area for investigating film thicknesses and traction coefficients of lubricants found in these systems; and the MPR is used to investigate how parts and lubricants will stand up to prolonged use over the years.

As an area of significant power wastage in vehicles, powertrains have always been of interest to tribologists. This interest will only continue to grow, as the frictional losses in the powertrains of electric vehicles are a larger portion of total losses than in internal combustion engines. As such, powertrain research and developments that tribology can bring are only going to become more important in the future.

Powertrain industry research areas include:

  • CV Joints
  • Gearboxes
  • Marine specific lubricants
  • Engine systems
  • Wind turbines
  • Bearings and gears

Powertrain Industry includes the following:

Agriculture

Agriculture

The powertrains in agricultural vehicles must regularly deal with high-stress forces, and be very reliable to prevent down-time. One way this reliability is improved is through the optimisation of tribological contacts.

Automotive

Automotive

Automotive powertrains are an area ripe for continual improvement through tribological study, and this study is important now more than ever as the industry adapts to more complicated systems incorporating electric power.

Aviation

Aviation

With reliability forming the cornerstone of the aviation industry, knowing how components in your powertrain will wear and fail is fundamentally important for knowing when they need to be inspected and replaced.

Machinery

Machinery

The requirements on powertrains in machinery are as varied as the jobs performed by the machines. Every one of them will need lubricating, and choosing the right lubricant comes down to knowing the tribology of the contacts involved.

Marine

Marine

Marine powertrains can be large or small, and some have to deal with as much as 80MW of power and 7.6MNm of torque. These conditions mean lubrication and part protection are critical to the longevity of an engine.

Mining

Mining

Facing constant high loads, harsh and dirty environments, and huge costs associated with downtime, the powertrains in mining vehicles have to be reliable even in the most adverse conditions. Tribological studies helps ensure this is the case.

Trains

Trains

Trains often now work by using a diesel engine to generate power, which is then converted to electrical power, which runs the motors to drive the train. These myriad components and processes are designed with tribology and lubrication in mind.

Wind Turbines

Wind Turbines

Wind power remains one of the most rapidly growing renewable power sources, so the tribological problems found in the powertrain - from the blades to the generator - are the focus of significant research.

Instruments for the Powertrain Industry

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Powertrain Industry Articles & Papers

Paper

Wear of Hydrogenated DLC in MoDTC-Containing Oils

This paper describes a study of the effect on MoDTC-promoted a-C:H DLC wear of adding various surface-active additives used in …

This paper describes a study of the effect on MoDTC-promoted a-C:H DLC wear of adding various surface-active additives used in engine lubricants, including ZDDP, an ashless EP additive, Ca detergents, dispersants, an OFM and a PAMA, to an MoDTC solution. Tribofilms formed on wear tracks on steel were analysed using SLIM, TEM, STEM-EDX, Raman spectroscopy and XPS. Relevant mechanisms by which these additives reduce the impact of MoDTC on DLC wear have also been suggested. DLC wear in PAO+Mo can be reduced by the presence of other surface-active additives in three ways. Firstly, asperity contact between DLC and steel can be mitigated by forming thick antiwear tribofilms. Secondly, other additives can increase the ratio of MoS2:MoO3, reducing the amount of wear-enhancing MoO3 in the tribofilm. Thirdly, the amount of MoDTC tribofilm including MoO3 can be reduced by the competitive adsorption of other surface-active additives. This study has practical implications for ways in which DLC surfaces can be protected by lubricant formulation.

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Paper

Experimental Investigation Into the Effects of Diesel Dilution on Engine Lubrication

The dilution of lubricant due to contamination with diesel fuel is an increasingly prevalent, potentially important and poorly understood issue. …

The dilution of lubricant due to contamination with diesel fuel is an increasingly prevalent, potentially important and poorly understood issue. This study addresses two fundamental questions: 1) How does the change in lubricant rheology due to diesel dilution affect engine lubrication? 2) How is the chemical performance of lubricant components (base oil and performance additives) impacted by diesel dilution under different lubrication regimes (boundary/full film, hydrodynamic/elastohydrodynamic). This is achieved by testing three lubricant samples: 1) neat fully formulated 0W-30 engine oil, 2) fully formulated 0W-30 oil diluted with diesel at a concentration of 15%, denoted “0W-30D”, and 3) neat, fully-formulated 0W-16, with the same base oil components and performance additives as the 0W-30, but blended to give a viscosity equal to that of the diluted an equivalent “0W-30D”. Tribometer tests, including 1) low pressure, low shear viscosity, 2) Ultra-high Shear Viscosity (USV), 3) elastohydrodynamic film thickness, 4) Stribeck friction and 5) boundary friction and wear, are then conducted. To further emulate engine lubrication conditions, Stribeck curve measurements are performed on the three lubricants using a journal bearing test rig, fitted with a connecting-rod and commercial diesel engine shells. Results suggest that diesel dilution only slightly affects chemical additive performance (with friction modifiers being more inhibited than anti-wear additives) but does reduce both viscosity and film thickness. However, care must be taken in using viscometrics to predict dilution behaviour because 1) the pressure viscosity coefficient is also affected by diesel dilution which has implications for elastohydrodynamically lubrication contacts, 2) shear thinning means that viscosity modifier additives effects lose their functions at high shear rates; whereas diesel contamination affects viscosity behaviour throughout the whole shear rate range.

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