Search Results for Roller bearings

This chapter documents the key findings of an investigation into the failure of an aircraft’s main wheel bearing housing. Using annotated images and a detailed SEM fractograph, it shows what investigators observed that led them to conclude that the flange on one of the hubs broke off due to a combination of fatigue, bending stresses, and wear. It also includes a recommendation to assess the structural integrity of the bearing housing after every 100 h of service using nondestructive techniques.

The wear caused by contact stress fatigue is the result of a wide variety of mechanical forces and environments. This chapter discusses the characteristics of four types of contact stress fatigue on mating metal surfaces: surface, subsurface, subcase, and cavitation. Features and corrective actions for these contact stress fatigue are discussed. The chapter also lists some possible ways to reduce the cavitation fatigue problem.

This chapter discusses the effect of friction in the context of design. It explains how friction coefficients are determined and how they are used to make sizing and selection decisions. It covers practical issues associated with rolling friction, the use of lubricants, and the tribology of metal, ceramic, and polymer surfaces in contact. It also discusses the nature of rolling friction and provides helpful design guidelines.

This chapter presents guidelines for reducing gearbox vibration, with an emphasis on design factors that play major roles in influencing vibration.

This chapter discusses the causes and effects of wear along with prevention methods. It covers abrasive, erosive, erosion-corrosion, grinding, gouging, adhesive, and fretting wear. It also discusses various forms of contact-stress fatigue, including subsurface-origin fatigue, surface-origin fatigue, subcase-origin fatigue (spalling fatigue), and cavitation fatigue.

This chapter focuses on the elements and functions of sand conditioning equipment which are critical to achieving good quality castings. The sand conditioning equipment include sand muller; core sand mixers; sand conveyors and bucket elevators; sand aerators; mold conveyors; shakeout units; magnetic separators; lump breakers and core crushers; screens; sand coolers; sand reclamation systems; and sand hoppers.

This chapter provides an overview of environmental factors when studying a gear failure. Environmental factors discussed are lubrication, temperature, and mechanical stability.

In the case of gearboxes, vibration is the primary mode of failure even at the mid-range of operating speeds. Avoiding such failures requires an understanding of gearbox design, vibration theory, and material properties. This chapter details sources and types of gearbox vibrations; characteristics of gearbox vibrations; fundamentals of periodic vibrations; and vibration theory. It provides housing design for single-stage offset parallel gearboxes, high-speed gearboxes, and epicyclic gearboxes. The chapter then provides an analysis and selection of design factors for vibration reduction. It presents five types of gear tooth geometry errors. The chapter also focuses on gear quality inspection and on bearing-induced vibrations.

The cyclic nature of gearbox vibration lends itself well to the analysis in the frequency domain where the effects of a gear mesh, bearing defects, and other sources of vibration are effectively set apart, making it much easier to identify and correct the underlying causes of vibration. This chapter presents spectral maps that show how gearbox vibrations change with the rotational speed of components. It then explains how to identify the sources of vibration in a high-speed gearbox. The chapter also discusses other errors including backlash, ghost frequencies, unbalance, misalignment, mechanical looseness, and index variation form errors. It also presents the calculation of gear frequencies on gearbox vibration spectra and the influence of operating conditions.

This chapter covers common types of erosion, including droplet, slurry, cavitation, liquid impingement, gas flow, and solid particle erosion, and major types of wear, including abrasive, adhesive, lubricated, rolling, and impact wear. It also covers special cases such as galling, fretting, scuffing, and spalling and introduces the concepts of tribocorrosion and biotribology.

This chapter discusses the processes and procedures involved in tribotesting, the significance of test parameters and conditions, and practical considerations including test metrics and measurements and the interpretation of wear damage. It also describes the different types of erosion tests in use and common approaches for adhesive wear and abrasion testing.

The technology of fabricating composite hardware and structures by filament winding has evolved empirically through the development and manufacturing of specific components. This chapter reviews areas of technology used in building composite parts and discusses the processes from which the current technology was derived. The discussion covers quality control requirements for composite fabrication technology and cleanliness standards in the workplace. It describes technology developed for specific components, including satellites struts, aircraft hydraulic cylinders, drill pipe, drive shafts, couplings, and cryogenic tubing.

This chapter reviews the types of friction that are of concern in tribological systems along with their associated causes and effects. It discusses some of the early discoveries that led to the development of friction laws and the understanding that friction is a system effect that can be analyzed based on energy dissipation. It describes the stick-slip behavior observed in wiper blades, the concept of asperities, and the significance of the shape, lay, roughness, and waviness of surfaces in sliding contact. It explains how friction forces are measured and how they are influenced by speed, load, and operating environment. It also covers rolling contact and fluid friction and the effect of lubrication.

This chapter presents the purpose, design, and function of a gear. It also presents the basic stresses applied to a gear tooth. The chapter provides an overview on the bending strength and characteristics of the gear tooth.