Search Results for Gear boxes

This chapter describes an investigation that was conducted to determine why quill shafts were failing prematurely in gear boxes on aircraft engines. The investigation focused on the splines in a splined bore. Visual examination showed that the splines were heavily worn and covered with red powder on one end. Investigators also observed blueing, an effect of overheating. Based on these observations and the results of SEM imaging, it was concluded that the splines in the spline bore were wearing out for lack of lubrication.

A driven gear in the gear box of an aircraft engine fractured after a 40 h test run. The driving gear and gear shaft were also damaged. Based on the results of fractography, chemical analysis, metallography, and hardness testing, the fracture was caused by a fatigue crack initiating at the corner of the inner rim near an inclusion. The report recommends the use of a cleaner material and more carefully controlling case hardening process.

The quill shaft in an aircraft engine was found in two pieces following a flameout. One piece was short, straight, and otherwise undamaged; the other piece was bent in several places as was the sleeve that covered it. The facture surface, as viewed under optical and scanning electron microscopes, was flat and shiny with deformation marks and dimples, typical of torsional overload, and signs of severe rubbing on the periphery. Based on their observations, investigators concluded that the quill shaft failed by torsional overload, the source of which could not be determined.

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.

Prior to forging, it is often necessary to preform billet stock to achieve adequate material distribution. This chapter discusses the equipment used for such operations, including transverse rolling machines, electric upsetters, ring-rolling mills, horizontal presses, and rotary (orbital) and radial forging machines. It describes their basic operating principles as well as advantages and disadvantages.

Several limitations in achieving optimal gear performance with conventional nitriding have led researchers to work on a variety of novel and improved nitriding processes. Of these, ion/plasma nitriding offers some promising results, which are reviewed in this chapter. The chapter concludes with a case history describing the application of ion nitriding to an internal ring gear of an epicyclic gearbox.

Ductile iron has far superior mechanical properties compared to gray iron as well as significantly improved castability and attractive cost savings compared to cast steel. This chapter begins with information on graphite morphology and matrix type. It then discusses the advantages and applications of ductile iron. Next, the effects of various factors on the grades, chemistry, matrix, and mechanical properties of ductile iron are covered. This is followed by a section detailing the ductile iron treatment methods and the quality control methods used. Guidelines for gating and feeder design are then provided. Further, the chapter addresses the technology of ductile iron castings, including the performance and geometric attributes, molding and core-making processes used, material grades, mechanical properties, and chemical compositions of a few applications. Finally, it describes ductile iron casting defects and presents practical cases of problem-solving.

The gravity permanent mold (GPM) process produces castings of high strength and integrity with good surface finish and consistent dimensions. This chapter lists castings produced using GPM and semipermanent mold (SPM). It illustrates the basic elements of a conventional tilt pour machine. The chapter also provides an overview of the high-volume rotary table, high-volume production rotary manufacturing cell, cycle time planning, sizes of tilt pour machine and table, and improvement of turntable uptime. It also presents some of the common semipermanent molded castings.

This chapter focuses on high-pressure cold spray applications pertaining to repair and refurbishment in the aerospace, oil and gas, and power-generation industries, the last specifically involving repair of gas turbine components. Advantages of cold spray coating in the repair and refurbishment of structural engineering components are also discussed.

High-pressure cold spray repair process has been used on a number of different applications in the defense industry. This chapter describes various applications for cold spray systems that have operating pressures greater than 2.4 MPa (350 psi) and operating temperatures greater than 500 deg C (930 deg F).

This chapter provides an overview of aluminum die casting and the equipment used. It discusses the advantages and limitations of the die casting process and the design and operation of hot- and cold-chamber die casting machines. It also discusses clamping systems and forces and the factors affecting die life, including die materials, metal injection cycles, and lubrication. A typical die casting cell layout is also provided.

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