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Internal gearings are commonly used in transmissions due to their advantages like high-power density. To ensure high efficiency, load-carrying capacity and good noise behavior, a profound knowledge of the local gear mesh is essential. The tooth contact of internal gears relates to a convex and concave surface that form a conformal contact. This is in contrast to external gears, where two convex surfaces form a contraformal contact. This paper aims at a better understanding of conformal contacts under elastohydrodynamic lubrication (EHL) to improve the design of internal gearings.

An existing numerical EHL model is used for studying the characteristic properties of a hard conformal EHL line contact. A hard contraformal EHL line contact is studied as reference. Non-Newtonian fluid behavior and thermal effects are considered. By taking into account the local contact conformity and kinematics, the effects and relevance of the curvature of the lubricant gap and micro-slip are analyzed. In a parameter study, scale effects of the contact radii on film thickness, temperature rise and friction are examined.

The curvature of the lubricant gap and effects of micro-slip are small in hard conformal EHL line contacts. For high micro-slip, it can be neglected. Hence, the modeling of conformal contacts using an equivalent geometry of the contact problem is reasonable. The parameter study shows beneficial tribological aspects of the conformal contact compared to the contraformal contact. Higher film thickness and lower fluid coefficient of friction are observed for conformal contacts, which can be attributed to lower pressures for the case of the same external normal force, or to a higher contact temperature rise for the case of equivalent contact pressure.

Despite its widespread existence, the local geometry and kinematics in hard conformal EHL line contacts like in internal gearings have been rarely studied. The findings help for a better understanding of local contact characteristics and its relevance. The quantified scale effects help to improve the efficiency and load-carrying capacity of machine elements with hard conformal EHL contacts, like internal gearings.

The peer review history for this article is available at: https://publons.com/publon/10.1108/ILT-12-2022-0366/

Skilled graduates delivered through vocational programmes are critical to ensure the future growth of emerging economies. This study explored students' reflections and experiences of online teaching and learning (T&L) during the COVID-19 pandemic in South Africa. The study specifically focused on the transferable skills students acquired and their relevance to working in the local retail and hospitality industries.

Following a case study research design, this study retrospectively delved into the multi-perspectives of students enrolled in vocational programmes. A total of 145 students completed reflective questions via a Qualtrics link regarding the topic in question. Student reflections were grouped and analysed for recurring themes using Atlas.ti. Through thematic analysis, two topical themes emerged related to transferable skills development and the usefulness of skills for future work.

The findings suggest that although students had to rely on online classes during the COVID-19 pandemic, they still developed vital transferable skills, including communication, teamwork, organisational, self-management, flexibility, technology, metacognition and problem-solving.

The findings offer valuable input into planning and developing student-centric online courses to facilitate the development of desired transferable skills. Findings could also guide best T&L practices regarding how education and training across digital platforms could be used to ensure that graduates are prepared to navigate the future complexities of working in ever-changing globalised industries.

This study provides new insights into the evolution of T&L and how unexpected situations could provide an opportunity to hone desired skills and prepare students for employment and the 21st century workplace.