Traction drive system design considerations for a lunar roving vehicle
Optimum design considerations of traction drive for lunar roving vehicle
Doran, B. J.↗
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Traction drive system design considerations for a lunar roving vehicle
Optimal traction drive system design for lunar roving vehicle, considering weight, energy consumption, operational flexibility, power supply, motor and power train
Doran, B. J.↗
An investigation of traction in elastohydrodynamic point contacts using optical interferometry
An optical EHD machine is described which will measure the thickness of elastohydrodynamic lubricant films in rolling/sliding contacts while a traction force is applied to the film. A convenient way of plotting friction coefficient against slide/roll ratio is proposed. For 13 pure fluids with well-established physical properties, the value of the peak friction coefficient was found to lie between 0.011 and 0.09.
Gentle, C. R.↗
Traction Characteristics of a 30 by 11.5-14.5, Type 8, Aircraft Tire on Dry, Wet and Flooded Surfaces
A limited test program was conducted to extend and supplement the braking and cornering data on a 30 x 11.5-14.5, type VIII, aircraft tire to refine the tire/runway friction model for use in the development of an aircraft ground performance simulation. Tire traction data were obtained on dry, wet and flooded runway surfaces at ground speeds ranging from 5 to 100 knots and at yaw angles extending up to 12 deg. These friction coefficients are presented as a function of slip characteristics, namely, the maximum and skidding drag coefficients and the maximum cornering coefficients are presented as a function of both ground speed and yaw angle to extend existing data on that tire size. Tire braking and cornering capabilities were shown to be affected by vehicle ground speed, wheel yaw attitude and the extent of surface wetness.
Yager, T. J.↗
A study of various synthetic routes to produce a halogen-labeled traction fluid
Several synthetic routes were studied for the synthesis of the compound 1, 1, 3-trimethyl-1, 3-dicyclohexyl-2 chloropropane. This halogen-labeled fluid would be of use in the study of high traction lubricants under elastohydrodynamic lubrication conditions using infrared emission spectroscopy. The synthetic routes included: dimerization of alpha-methylstyrene, methanol addition to alpha-methylstyrene, a Wittig reaction, and an organometallic approach. Because of steric hindrance and competing reactions, none of these routes were successful.
Jones, W. R., Jr.↗
Design considerations for attaining 200-knot test velocities at the aircraft landing loads and traction facility
Design studies are presented which consider the important parameters in providing 200 knot test velocities at the landing loads and traction facility. Two major components of this facility, the hydraulic jet catapult and the test carriage structure, are considered. Suitable factors are determined to correlate analytical data for characteristics of the hydraulic jet catapult with data measured from the existing catapult system. The resulting equations are used to calculate test velocities for a range of jet nozzle diameters and carriage masses with both the current 122 m and an increased 183 m catapult stroke. Using the catapult characteristics, a target design point is selected and a carriage structure is sized to meet the target point strength requirements.
Giles, G. L.↗
Traction studies of northeast corridor rail passenger service: Executive summary
The enabling legislation of 1976 for improvement of service in the Northeast corridor (NEC) requires a schedule of 2 h 40 min between Washington and New York City by 1981 and 3 h 40 min between NYC and Boston, when the electrification is completed. Various options of the NEC operation that may satisfy the legislation were investigated, particularly in terms of travel time and energy consumption. NEC operations were compared with overseas systems and practices. The emerging new technology of AC traction was also evaluated.
Macie, T. W.↗
Spectroscopic study of the effect on an EHD contact of trichloroethane addition to a traction fluid
Addition of trichloroethane to a traction fluid was studied in a ball/diamond plate EHD apparatus by infrared emission spectroscopy of the radiation transmitted through the plate. Small concentrations of an organic chloride at first increased infrared radiance, then decreased it. Large concentrations caused a rapid decrease. During running, the infrared spectrum showed an increase of aromatics and olefins. A polymeric deposit formed on the plate. X-ray examination of the ball surface showed the presence of chlorine. Reuse of the same ball with fresh fluid resulted in similar chain of events, indicating that adsorbed chloride could promote fluid deterioration.
Lauer, J. L.↗
Electric vehicle traction motors - The development of an advanced motor concept
An axial-field permanent magnet traction motor is described, similar to several advanced motors that are being developed in the United States. This type of machine has several advantages over conventional dc motors, particularly in the electric vehicle application. The rapidly changing cost of magnetic materials, particularly cobalt, makes it important to study the utilization of permanent magnet materials in such machines. The impact of different magnets on machine design is evaluated, and the advantages of using iron powder composites in the armature are assessed.
Campbell, P.↗
Traction drive for cryogenic boost pump
Two versions of a Nasvytis multiroller traction drive were tested in liquid oxygen for possible application as cryogenic boost pump speed reduction drives for advanced hydrogen-oxygen rocket engines. The roller drive, with a 10.8:1 reduction ratio, was successfully run at up to 70,000 rpm input speed and up to 14.9 kW (20 hp) input power level. Three drive assemblies were tested for a total of about three hours of which approximately one hour was at nominal full speed and full power conditions. Peak efficiency of 60 percent was determined. There was no evidence of slippage between rollers for any of the conditions tested. The ball drive, a version using balls instead of one row of rollers, and having a 3.25:1 reduction ratio, failed to perform satisfactorily.
Meyer, S.↗
Design study of a continuously variable roller cone traction CVT for electric vehicles
Continuously variable ratio transmissions (CVT) featuring cone and roller traction elements and computerized controls are studied. The CVT meets or exceeds all requirements set forth in the design criteria. Further, a scalability analysis indicates the basic concept is applicable to lower and higher power units, with upward scaling for increased power being more readily accomplished.
Mccoin, D. K.↗
Rolling-element fatigue life with traction fluids and automatic transmission fluid in a high-speed rolling-contact rig
Rolling-element fatigue tests were run in standard and high-speed rolling-contact rigs at bar speeds from 5000 to 50,000 rpm to determine the effects of speed and lubricant film parameter on rolling-element fatigue life. AISI 52100 test bars were tested at a maximum Hertz stress of 4.83 GPa (700,000 psi) with three traction fluids and an automatic transmission fluid. Rolling-element fatigue life increased with speed, with the greatest increases occurring from 10,000 to 50,000 rpm. The life data tended to follow published life-versus-lubricant-film-parameter data up to a film parameter of approximately 3.
Parker, R. J.↗
A historical perspective of traction drives and related technology
The evolution of traction-drive technology, in a limited sense, is traced from its early development to the efforts underway today.
Loewenthal, S. H.↗
Hybrid geared traction transmissions
The basic configuration of geared traction drives, geometric and structural factors to be considered in their construction, and current work on hybrid helicopter transmissions rated at 500 and 3000 hp are discussed.
Nasvytis, A. L.↗
Traction-drive, seven-degree-of-freedom telerobot arm: A concept for manipulaton in space
As man seeks to expand his dominion into new environments, the demand increases for machines that perform useful functions in remote locations. This new concept for manipulation in space is based on knowledge and experience gained from manipulator systems developed to meet the needs of remote nuclear applications. It merges the best characteristics of teleoperation and robotic technologies. The design goals for the telerobot, a mechanical description, and technology areas that must be addressed for successful implementation are presented and discussed. The concept incorporates mechanical traction drives, redundant kinematics, and modular arm subelements to provide a backlash-free manipulator capable of obstacle avoidance.
Kuban, D. P.↗
Traction-drive telerobot for space manipulation
The National Aeronautics and Space Administration (NASA) Space Station Program marks the begining of a new era in space utilization and habitation. Extensive use of remote manipulation and robotics to reduce astronaut extra-vehicular activity is expected. Emphasis on teleoperator technology in early Space Station phases, followed by growth of autonomous robotics capabilities, is planned. A new telerobot concept has been developed at Oak Ridge National Laboratory (ORNL) under NASA Langley Research Center sponsorship, to address the technical needs of both teleoperations and telerobotics for these future NASA programs. The concept is based on traction drives, redundant kinematics, modular construction, and a state-of-the-art distributed, hierarchical control system.
Herndon, J. N.↗
Drag or negative traction of geared-down supporting propellers in the downward vertical glide of a helicopter
Discussed here are computations of drag or negative traction of geared down supporting propellers in the downward vertical glide of a helicopter. By means of Frounde's Theory, the maximum value of the drag of a windmill is calculated. For wooden propellers, the author finds that the difference between the drag and the weight is proportional to the number of blades and is larger for propellers of small diameter; thus it is 25 kg. for a six blade propeller with a diameter of 2 m. 50. The author notes that if we are to adopt large propellers, we must have recourse to a different method of construction, resulting in large dimension propellers much lighter than those made of wood. In discussing insufficient drag, the author notes that the question of the drag of geared down supporting propellers can only be decided by experiment.
HELICOPTERS↗
A Conforming Multigrid Method for the Pure Traction Problem of Linear Elasticity: Mixed Formulation
A multigrid method using conforming P-1 finite element is developed for the two-dimensional pure traction boundary value problem of linear elasticity. The convergence is uniform even as the material becomes nearly incompressible. A heuristic argument for acceleration of the multigrid method is discussed as well. Numerical results with and without this acceleration as well as performance estimates on a parallel computer are included.
Lee, Chang-Ock↗