Roller drive materials performance

Roller traction performance basics, a test program to measure performance, and the need for and typical use of the information are outlined. A test rig was designed and fabricated to develop this information. Parametric conditions and specimen materials were chosen so that the resulting data will be valuable to the design and development of advanced, roller-driven space mechanisms, from precision positioning devices to telerobot joints

Microgravity mechanisms and robotics program

The primary goal of this program is to produce the motion control tools necessary to enhance and enable a particular NASA mission - space laboratory-based microgravity experiments. To that end, a spectrum of technology is being developed in the disciplines of precision mechanisms and robotics

Subsquares Approach - Simple Scheme for Solving Overdetermined Interval Linear Systems

In this work we present a new simple but efficient scheme - Subsquares approach - for development of algorithms for enclosing the solution set of overdetermined interval linear systems. We are going to show two algorithms based on this scheme and discuss their features. We start with a simple algorithm as a motivation, then we continue with a sequential algorithm. Both algorithms can be easily parallelized. The features of both algorithms will be discussed and numerically tested.Comment: submitted to PPAM 201

Efficiency testing of a helicopter transmission planetary reduction stage

A parametric study of the efficiency of a 310-kW (420-hp) helicopter transmission planetary test section (four planets) was performed. The purpose was to determine the planetary contribution to the overall transmission power loss. Test parameters varied were oil flow rate, oil inlet temperature, lubricant type, shaft speed, and applied torque. The measured efficiency over all the test variables ranged from 99.44 to 99.75 percent. These experimental results were compared with other experimental and computational results

An analysis of traction drive torsional stiffness

The tangential compliance of elastic bodies in concentrated contact applied to traction drive elements to determine their torsional stiffness was analyzed. Static loading and rotating conditions are considered. The effects of several design variables are shown. The theoretical torsional stiffness of a fixed ratio multiroller drive is computed and compared to experimental values. It is shown that the torsional compliance of the traction contacts themselves is a relatively small portion of the overall drive system compliance

Regression analysis of traction characteristics of traction fluids

Traction data for Santotrac 50 and TDF-88 over a wide range of operating conditions were analyzed. An eight term correlation equation to predict the maximum traction coefficient and a six term correlation equation to predict the initial slope of the traction curve were developed. The slope correlation was corrected for size effect considering the compliance of the disks. The effects of different operating conditions on the traction performance of each traction fluid were studied. Both fluids exhibited a loss in traction with increases in spin, but the losses with the TDF-88 fluid were not as severe as those with Santotrac 50. Overall, both fluids exhibited similar performance, showing an increase in traction with contact pressure up to about 2.0 GPa, and a reduction in traction with higher surface speeds up to about 100 m/sec. The apparent stiffness of the traction contact, that is, film disk combination, increases with contact pressure and decreases with speed

SAFE - Sustainability Assessment For Enterprises: Die Methodik. Ein Instrument zur Unterstützung einer zukunftsfähigen Unternehmens- und Organisationsentwicklung

-- In practice, questions of ecological company policy deal much more with technical questions than with organisational ones. In many guides for the implementation of an Environmental Management System the development of the organisation that first has to grow into this new task has not yet been fully planned, as has the participation of the employees. The deciding factors for this implementationinclude the improvement of information and communication within the company, the increase in employee motivation and the optimisation of the interfaces between economics, ecology and social aspects.Companies often show a great need for analysis and management instrumentswhich they themselves can organise and which, with the participation of the employees, help to find and to translate solutions quickly into action which show theway. Together with small and medium-sized companies (SMEs) of different branches, the SAFE - Sustainability Assessment For Enterprises instrument has been developed and tested.The instrument SAFE is used as a dialogue instrument in companies and serves as a lasting method of controlling success and of deriving new measures. The aimof the instrument is to motivate employees to become involved in change proc-esses and to cooperate in the shaping of the development of the enterprise in astreamlined procedure. They should know their participation possibilities as wellas learn how to use them. Altogether the viewpoint should be changed from anecological enterprise development to a lasting one and in doing this the develop-ment of ideas and strategies for the implementation of sustainability in the com-pany is to be supported.In a clear procedure the companies determine independently the ecological, economic and social aspects which are relevant for their enterprise's development and deduce potential for improvements and options for action for those aspects.The environmental control agents and/or quality control agents - and often alsothe managers - become qualified to use the instrument on their own. The imple-mentation of SAFE takes place together with employees from different levels inthe company who go through the procedure of several working phases in twodays. In these working phases a profile of the company's strengths/weaknesses will be drawn up as well as a list of organisational and technical suggestions forimprovement and qualification requirements. Afterwards, a plan of measures willbe deduced from those lists and suggestions. All these proceedings are based on the questionnaire Is your company fit for the future. The measures will be putinto action within a defined period of time by the persons who are responsible forthis implementation. The process will be repeated at regular intervals.In a test phase SAFE has until now been applied in approximately 40 companies for the first time and has been developed further. Its successful use shows that theinstrument can be applied to companies in all branches.Zukunftsfähige Unternehmen,Nachhaltigkeit,dreifache Gewinnstrategie,Indikatoren,Unternehmens-/Organisationsentwicklung,Kommunikation,Qualifizierung,Beteiligung,Umweltmanagementsysteme,Ressourcenproduktivität,Ressourcenmanagement,Lernendes Unternehmen,Kontinuierlicher Verbesserungsprozess (KVP),Wettbewerbsfähigkeit,Sustainable Enterprises,sustainability,triple-win-strategy,indicators,organizational learning,communication,qualification,participation,environmental management systems,resource productivity,resource management,the learning company,continious improvement,competitiveness

Traction behavior of two traction lubricants

In the analysis of rolling-sliding concentrated contacts, such as gears, bearings and traction drives, the traction characteristics of the lubricant are of prime importance. The elastic shear modulus and limiting shear stress properties of the lubricant dictate the traction/slip characteristics and power loss associated with an EHD contact undergoing slip and/or spin. These properties can be deducted directly from the initial slope m and maximum traction coefficient micron of an experimental traction curve. In this investigation, correlation equations are presented to predict m and micron for two modern traction fluids based on the regression analysis of 334 separate traction disk machine experiments. The effects of contact pressure, temperature, surface velocity, ellipticity ratio are examined. Problems in deducing lubricant shear moduli from disk machine tests are discussed

Sizing criterial for traction drives

A simplified traction drive fatigue analysis which was derived from the Lundberg-Palmgren theory is measured and the effects of rotational speed, multiplicity of contacts, and variation in the available traction coefficient on traction drive system life, size, and power capacity was investigated. Simplified equations are provided for determining the 90% survival life rating of steel traction drive contacts of arbitrary geometry. References to life modifying factors for material, lubrication, and traction will be made