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The hydrostatic transmission offers several advantages in construction machinery: delivery of variable output speed from a constant input speed, stepless speed change, delivery of constant output speed from variable input speed, maximum torque output from minimum power input, and production of maximum torque while stalled. This paper discusses the application of such transmissions to a trailer-mounted transit concrete mixer, the hydraulic powered Autograde, and a hydraulic excavator.

Not everyone has the time required to learn enough about elastomers to specify and select them properly. There are many performance requirements which defy reduction to a material specification. This paper suggests ways in which the designer can provide improved guidance to prospective vendors, or their “in house” materials group, to insure proper material selection. Included in the discussion environmental considerations (exposure to temperature, fluids, weather, sunlight) and functional considerations (electrical and wear resistance, vibration isolation). Testing methods and durability evaluation are also covered.

The selection of a filter is based on a knowledge of engine requirements and filter performance. This paper describes some of the newer concepts in filtration theory, particularly as it relates to lubricating oil filters. Data are included to show that filter “life” should be based on the ability to prevent engine wear rather than pressure drop. These data also show the importance of oil quality. Comparisons are made between filter papers having different micron ratings, after it is shown that micron ratings can be misleading unless they are clearly defined. Comparisons are also made between surface type and depth type filters, indicating that it is what the engine needs that really governs filter selection.

The vane type hydraulic pump has been a major source of accessory power for mobile equipment over the past 10–20 years. Developments in machine power requirements have been paced by pump developments as construction equipment, in particular, has become larger, more powerful, and more sophisticated. Discussed in this paper are fundamental design aspects of vane pumps and the designs primarily utilized in present-day mobile applications. Construction, configuration, ratings and efficiencies are covered. The trend toward higher operating pressures is also considered.

Recent developments in instrumentation have made the art of measurement, data accumulation, and analysis faster, more reliable, and while costly, more meaningful in terms of product improvement. This paper will discuss some of the more up-to-date instrumentation and data gathering techniques in various appropriate fields.

Higher speeds, smaller engine displacement, and increasing turbocharging pressures are placing continually greater demands on injection equipment being used in diesel engines. A description and the application of current injection equipment in use is presented. Some items mentioned and analyzed are multiplunger pumps, distributor pumps, and both high pressure metering and low pressure metering injectors. Another important element in the injection system is the filtering technique utilized, as the prevention of wear and scuffing and the removal of water is of utmost importance. The author mentions that with increased speeds and pressures erosion from fuel impingement and cavitationin pumps, lines, and nozzles as well as increased metal wear are problems that have to be overcome.

The hydraulic system is of utmost importance in the overall performance of earthmoving machines. The heart of any hydraulic system is the pump. The modern gear pump is available in a wide range of flow rates and pressure ratings. This paper will deal with the major factors to be considered in the selection of a pump, including capacities and pressure ranges available, life, fluid compatability, efficiency, cleanliness requirements, etc. A brief look at the future will show that gear pump technology is in a position to keep pace with the rapid advance in flow and pressure requirements of the earthmoving industry.

The paper describes the development of the design and the fabrication procedures required to replace an existing aluminum section of wing structure with a part made of boron-epoxy. The wing box extension was selected as a significant aircraft demonstration component for boron-epoxy because it incorporates many of the problems associated with aircraft structures such as access covers, control surface mountings, contoured surfaces, and fuel pressurization; and because of the variety of loads and environmental conditions involved. Although the existing aluminum design is unpressurized, the demonstration component has been designed to include a pressurized cell in order to demonstrate the feasibility of building an integral fuel tank. Representative test data and specimens, design allowable philosophy used, and specific weight-strength comparisons with typical aircraft materials are presented. Process techniques used in boron laminate fabrication are discussed.

Advantages of filament-reinforced epoxy structures are discussed in comparison with metal structures commonly used for helicopter rotor blades, while test data on various fiber-reinforced epoxy materials are compared. Development test results demonstrating structural adequacy of reinforced-epoxy full size rotor blade segments are presented as well as quality assurance techniques. Economic considerations on cost of materials versus component performance improvement are discussed in a cost effectiveness summary.

An aircraft systems complex under development shows considerable promise as a means of supplying aircraft systems power remote from the propulsive engines. It is shown that when compared with conventional drives, an improved standard of reliability can be obtained with less redundancy than in orthodox systems. The extensive use of pneumatic power as considered replaces hydraulics and to some extent electrics, in an economical manner. Considerable simplification and weight saving in the propulsion engines are envisaged as a result, together with minimal power off-takes and improved operational effectiveness.

To realize the value of filamentary composite materials the establishment of an entirely new design and fabrication philosophy is required. The new design philosopies which are to be established must have as their prime objectives lower cost fabrication techniques and the application of directional properties. The greater freedom provided the aircraft structures design engineer with filamentary composite materials requires the establishment of an entirely new design cycle. The development of just such new design concepts and techniques for an aircraft lifting surface is the subject of this paper.

Projected increases in operating temperature for gas turbine engines for 1970-80 pose design challenges for increased operating speed and reduced size and weight for accessories. The Module Accessory Concept presents one approach to achieve a size match while addressing the logistics problem associated with sub-sonic aircraft and small utility helicopters for military service, particularly for relatively short duration missions. Key technology needs to implement the concept are identified and possible design approaches are suggested. The authors recommend early attention to the military operational problems of Maintainability-Training and Total Support Costs in new concepts as a response to the new demands of Life Cycle Costing.

This paper defines and evaluates auxiliary power systems for a self-sufficient 1975 fighter aircraft. The mission and auxiliary power requirements for a V/STOL fighter aircraft are used as a basis for this study. Candidate systems are identified and analyzed for their take-off gross weight penalty to the aircraft for missions requiring both short-time and long-time aircraft standby periods. The components of the various systems are evaluated as to their projected efficiency, weight, and size for use in the analysis. A recommended reference system is selected as the basis for an optimized system design. Specific areas of research and development are identified as required to obtain the advanced system components.

A new and unique variable speed constant frequency (VSCF) aircraft electrical power generating system has been developed by Lear Jet Industries. The LearVerter is a blend of the best features of proven existing systems, and new features which are inherently simple and reliable. The result is a system which has outstanding performance characteristics, meets the needs of both new and existing aircraft, yet is unusually simple and straightforward.

This paper describes a numerical method for solving three-dimensional incompressible flow problems and its use in predicting the aerodynamic characteristics of V/STOL aircraft. Arbitrary configuration and inlet geometry, fan inflow distributions, thrust vectoring, jet entrainment, angles of yaw, and flight speeds from hover through transition can be treated. Potential-flow solutions are obtained with the method of influence coefficients, using source and doublet panels distributed on the boundary surfaces. The results include pressure distributions, lift, induced drag and side force, and moments. Theoretical solutions are presented for clean lifting wings and for a NASA fan-in-wing model. Comparisons with the experimental NASA data demonstrate the validity of the approach and uncover the importance of viscous effects, fan inflow distribution, and jet entrainment.

V/STOL wind tunnel testing performed over the past several years has been guided largely by the well established practices of conventional low speed wind tunnel testing. Since this approach has not always been satisfactory, a recent investigation was made to determine the adequacy of current V/STOL testing methods. The study was particularly relevant to tests of a four-propeller tilt-wing airplane configuration, but the knowledge gained from this study is also applicable to other types of V/STOL airplanes. The principal result of the investigation was finding that some testing practices for conventional models are not adequate for V/STOL models. The key factors that separate conventional and V/STOL testing were found to be the balance interference tares, model power, and angle-of-attack range.

The term programmed engine and accessory testing systems implies a variety of design options that are available to the activity contemplating computer assisted test operations. Implementation of such systems may be restricted to one specific option or may be a combination of several options. Final design configuration will reflect the results of trade-off studies involving economics, reliability, and the functional nature of the individual test to be conducted. A total testing system complex pertaining to post-overhaul engine test cells and accessories test stands is selected and described.

The design of the power control and accessory systems of the GE4 engine for the United States supersonic transport strongly responds to airlines needs for ease in maintenance and overhaul. Next to safety, the first objective in design is long life and dependable, trouble-free operation. However, in commercial use the service periods will always continue to extend out to the maximum capability of the design, and maintainability for ease in component replacement will still be required as condition indicates. Moreover, designs favoring maintainability will receive better maintenance and thereby yield longer service before replacement. In this paper the integrated power control and the accessory systems of the GE4 are presented. The design reflects the efforts to understand the user's point of view.

Maintainability analysis incorporated into the initial design of the F-111 air inlet control system has achieved greater dispatch reliability for this aircraft. Experience from this program, together with knowledge gained from today’s commercial jet engine aircraft components, can be used for design and development guidance for the air inlet control for the Supersonic Transport (SST). Air inlet control experience on a supersonic military aircraft is reviewed and applicable commerical jet engine component maintainability data are presented.

The Olympus 593 supersonic engine uses a two-spool turbojet with a simple reheat system for thrust boost. Control of engine fuel flow, primary nozzle area, and reheat fuel flow is largely electronic and the paper briefly describes principles of system operation before examining the function, location, and mounting of the constituent line replacement units. Procedures and equipment for checkout and fault diagnosis are described. Maintenance philosophies and relevant test equipment were defined when the system performance requirements were specified and the case will be made that advances in maintainability techniques match the increased range of control system requirements, leading to utilization and “go” capability at least equal to best current experience.