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The development of the economy and the associated growth in trade both within the country and international transport, the associated construction and development of transport routes using elements of intelligent transport systems constantly require increasing the efficiency of trunk transportation. In addition, the development of new economic regions with an undeveloped road network is impossible without high-capacity motor vehicles and cross-country ability. To achieve these goals, the creation of active road trains, including multi-link ones, based on non-traditional technical solutions, is required. The idea of using multi-link trains in the system of intercity and international transportation is not new. However, at the present stage of development of automotive technology requires rethinking and use of new achievements of science and technology.

A ball screw regenerative shock absorber was designed for the relief of the vehicle vibration and the energy recovery of the vehicle vibration. The effect of its main parameters on the suspension system was numerically analyzed. According to the principle of the ball screw regenerative suspension system, a mathematical model of the ball screw regenerative shock absorber was established regarding the ball screw rotational inertia, the motor rotational inertia, the screw lead and the radius of the screw nut. A suspension dynamic model based on the ball screw regenerative shock absorber was developed combining the road model and the two-degrees-of-freedom suspension dynamic model.

In the past few years, maintenance costs have risen only about half as fast as the other components of operating cost. The evolution of maintenance philosophy and maintainability concepts are prime factors which have permitted this degree of control of maintenance costs, in spite of rising wages and material prices. This paper explains the maintenance philosophy at Douglas Aircraft and gives examples relating to the DC-8, DC-9, and DC-10. The three methods of maintenance control-Hard Time, On Condition, and Condition Monitoring-are described, and statistics of Delta Air Lines maintenance provided to illustrate their effectiveness.

The Boeing SST design incorporates a variable-geometry wing. Some of the wing-pivot-joint and actuation-system configurations considered during the development of the SST variable-geometry design are discussed herein. In addition, the selected SST design is described, and detailed maintainability and maintenance requirements are reviewed.

Maintainability Control in Design can be achieved by means of a formal procedure which utilizes all relevant talents available within a corporation. The procedure must have management support and proper funding. Effective maintenance engineering analysis is a primary element in maintainability control. The plan for use and the plan to maintain are key factors for consideration as is the maintenance capability of the customer. Examples of effective results are used to demonstrate maintainability control in action.

Although the requirement for a quantitative maintainability demonstration has been in existence since the inception of the Air Force Specification MIL-M-26512. “Maintainability Requirements for Weapon Systems and Subsystems,” dated 18 June 1959, there are very few results of such tests reported in the literature. All major DOD contracts presently require such demonstrations in accordance with the new DOD MIL-STD-471, “Maintainability Demonstration,” dated 15 February 1966. Since 1961, sixteen separate maintainability demonstrations have been conducted by Philco-Ford WDL under various Air Force contracts in accordance with MIL-M-26512A, B&C. All demonstrations were conducted on installed equipments in their final operating locations and environments. The purpose of each demonstration was to determine whether a given subsystem of electronic ground equipment satisfied maintainability time-to-restore requirements imposed in design and procurement specifications.

On the wing repair is a new concept in jet engine management, rapidly spreading throughout the airline industry. This new approach now requires that maintainability be moved high on the list of design considerations on engines of tomorrow. Some specific maintainability design features are now clearly needed to permit expanding this concept beyond the scope of work now being accomplished. The next commercial engine must have these features.

The procedure followed for the conduct of the Maintainability Design Review of the AN/SQS-26CX Sonar System is discussed. Esoteric Techniques utilized are presented, pitfalls to be avoided are emphasized, and solutions to design review problems are given. The paper presents a fundamental test point optimization technique and discusses modifications necessary to apply a standard Maintainability Prediction Technique to a modern complex system in order to utilize it as a design review tool.

THIS PAPER covers recent advancements in the maintainability measurement and prediction art, and it describes the Martin Company activity devoted to this effort under the Air Force (AFBSD) Titan II contract AF04(647)-576. The application of two significant techniques established for the military services for measuring and predicting maintainability in terms of inherent maintenance downtime are covered. The prediction technique developed by RCA Service Company under Air Force (RADC) contract AF30(602)-2057 was derived from field data on Air Force ground electronic equipment in the SAGE system. This technique involves the use of an analytical model relating numerically scored qualitative characteristics to system maintenance downtime. The maintainability prediction technique developed by Federal Electric Corporation under Navy (BUSHIPS) contract Nobsr75376 was derived from fleet electronic data.

Use of the analytical maintenance model to perform maintainability risk analyses is described. The procedure developed can be useful for the prediction, assessment, and validation of maintainability. The method presented uses the gamma distribution because of its relative algebraic simplicity. The rationale for this approach is described.

This paper consolidates the functional and data flow requirements of a quantitative maintainability program and contrasts these requirements against existent DOD maintainability specifications. An analysis is made of the results so far achieved in the field of maintainability and indicates the number of projects which have quantitative maintainability requirements. In conclusion, the paper suggests the establishment of a data bank for the recording and exchanging of critical maintainability data so that maintainability programs can be implemented effectively.

On the Shuttle Program, a great deal of effort is being expended toward the end of having a reuseable flight system with a minimum of expenditure of development dollars. Because of much of the hardware which is presently both space and man rated has achieved that status on programs with non-reuseable hardware, there are significant challenges to achieving a balance between development and production costs and those costs associated with supporting the deployed system. The maintainability analysis processes are described, as well as the various figures of merit associated with this support system and the maintenance characteristics of the flight and ground hardware. The interplay between hardware maintenance analysis and the derived design requirements, for both the flight and ground hardware, are described. A distinct relationship will be developed between the packaging and installation design approaches and the instrumentation and associated data system interface.

Extensive maintainability (M) and reliability (R) studies of a number of manned spacecraft missions indicate that the Environmental Control/Life Support System (EC/LSS) generally requires more scheduled and unscheduled maintenance than any other subsystem. This paper summarizes the EC/LSS M and R analyses performed on some of these studies. The expected redundancy and spares required to achieve a desired reliability is discussed. The requirements for scheduled and unscheduled maintenance are evaluated in terms of expected spares usage, maintenance time, and potential problem areas.

The role the FAA plays in promoting maintainability as an inherent characteristic of design is discussed. Some of the parameters used by FAA maintenance specialists in evaluating new designs are accessibility, inspectability, serviceability, replaceability, and reliability. Manufacturer's servicing and maintenance manuals are also reviewed. Advances in computer technology will bring about changes in maintenance concepts regarding business aircraft. Benefits derived will affect cost, reliability, and safety.

Phased planar array radars represent a class of equipment employing hundreds or thousands of individually steerable radiating and receiving elements. In the operation of such systems, it is necessary to keep continually ahead of an advancing failure accumulation through maintenance policies geared to replacement-while-in-operation concepts. Several practical maintenance polices are considered: Immediate maintenance Delayed maintenance Cyclic maintenance The effects of these policies on the outage availability are considered and it is shown that each has certain advantages. Immediate maintenance yields the highest system availability, but requires the continued presence of a moderate size maintenance force. Increasing the number of maintenance crews increases the availability of phased array systems, but the added contribution to satisfactory system states shrinks rapidly with the growth of crews.

Previous large liquid-rocket engine check-out and maintenance operations were mostly manual, time consuming, and costly. Using Saturn experience and guided by airline practice, the Space Shuttle Orbiter Main Engine has been designed for rapid turnaround and simple, low-cost maintenance. A streamlined operational concept and the addition of specific design features for easy maintenance were the prime factors in this accomplishment.

In order to address a Naval Fleet Logistics Support (VR) Wing Commander’s request to proactively uncover safety factors in VR maintenance operations, a prototype climate survey was taken by VR Wing maintainers in 13 squadrons. Nearly 800 surveys were tabulated, and the results were analyzed using a model for high reliability organizations. Overall, the preliminary analysis of the survey data pointed out some potential areas in the VR Wing and each of its aircraft communities for intervention.

How accurate are your thermal models? Few thermal analysts have the time and budget to test the convergence of their thermal models (e.g., SINDA models) as a function of mesh size. This paper presents guidelines for selecting mesh sizes and other simulation parameters to ensure accurate simulations. We considered the following aspects of thermal models: mesh size as determined by combined conduction, convection and radiation; perferred mesh geometries; treatment of boundaries and boundary conditions; and required time steps.

Multifunctional additives can compensate for lower quality diesel fuel. Performance and quality have been decreasing worldwide. This has resulted largely from increased use of heavier crude oils and more severe processing to achieve necessary fuel product mix. Fuel additives provide the refiner and marketer with an economic approach to restoring performance and quality. Additives can be formulated to solve many problems related to deposits and wear, which are major factors affecting engine power, economy, emissions and durability. They are of critical importance to the vehicle owner/ operator to maintain dependability and low operating cost. At the same time, the refiner benefits economically through the use of lower cost crudes, greater operational flexibility and ease of adjusting final fuel blends to meet specifications. Typical additive components include: detergent dispersants, inhibitors, stabilizers, cetane improvers, and flow improvers.

This paper addresses the special nature of the human-machine relationship during a trip to Mars. In particular, the potential for monotony and boredom during a long-duration space voyage and the effect on motivation and productivity can be important considerations to the health and welfare of the crew. On the voyage to Mars, there are likely to be extended periods of low-level activity for the crew during which it will be difficult to prevent monotony and boredom. These circumstances are different from those typically addressed in the human-machine designs which were concerned with reducing the human workload. For the voyage to Mars, we may be looking for a design that will purposefully maintain some level of workload for the crew as a preventive measure for the deterioration of productivity that comes with boredom.