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Technical Paper

Performance of Ceramic Bearings in High Speed Turbine Application

1990-09-01
901629
High speed precision ball bearings, like those used in machine tool spindles, can have serious problems associated with spin or gyroscopic moment of the rolling elements. The use of low density, silicon nitride ceramic rolling elements reduces these problems. This report presents performance test results of bearings with silicon nitride balls, and steel balls, in a high speed turbine application, using oil jet, and oil mist lubrication methods.
Technical Paper

Customer Service: A Strategy for the Future

1990-09-01
901613
In order for a company to be the best that it can be, it must regularly reevaluate its position in all areas. An area of utmost importance, which is often neglected due to the pressures of the production schedule, is training and development of the company's most valuable resource, its people. If a company is to be successful in the uncertain future of today's economy, its people must be ready to meet the many challenges of tomorrow, head on. In 1987, Deere & Company, Management Education & Training Department, developed a seminar that redefines the elementary concepts of the customer/supplier relationship. These concepts relate directly to the INTERNAL customer/supplier relationship that exists in our factories. This stimulating, thought provoking four hourseminar is called CUSTOMER SERVICE: A STRATEGY FOR THE FUTURE. (Deere & Co., 1987) This seminar helps the participants better understand their role in making the day-to-day operations of the company run smoothly.
Technical Paper

Studies on Combustion and Exhaust Emissions in a High Speed DI Diesel Engine

1990-09-01
901614
Cylinder pressures at several locations and the radiant heat emission were measured simultaneously in order to better understand the combustion behavior in the combustion chamber of a high speed DI diesel engine. The radiant measurements utilized an optical fiber thermometer (OFT) with a light pipe sensor. The exhaust emissions of NOx, smoke and particulates were also measured. The formation of NOx and soot and the soot burn-up processes were analyzed applying an in-cylinder two-zone model. The results were compared with the experiment. It was confirmed that diffusion burning stage started close to the first peak of the heat release rate curve. The OFT output was closely related to the diffusion combustion process. The measured exhaust smoke correlated well with the cumulative diffusion combustion quantity. The dry soot in the particulate emission also correlated well with the Bosch smoke density except for the cases of high sulfur fuel and water-emulsified fuel.
Technical Paper

The Influence of Bearing Run-In on Lambda Calculations

1990-09-01
901626
This paper examines surface roughness effects and the inaccuracy introduced by changes in roughness resulting from normal run-in. While factors such as the ‘Oil Film Thickness to Composite Surface Roughness ratio’, Lambda, are being used, their reliability is dependent on the accuracy of the input data. Studies were conducted on cylindrical roller bearings (40 mm bore) at two calculated Lambda levels, 1.5 and 0.04, to evaluate changes in surface texture during short running time increments. The conclusion of the study offers recommendations for improving the methods used to predict bearing fatigue life.
Technical Paper

Fracture and Fatigue of High Hardness Bearing Steels Under Low Tensile Stresses

1990-09-01
901628
Tensile stresses in bearing components, particularly in rings, may be caused by conditions of manufacturing, mounting, or operation. During bearing operation, when a condition to cause tension is present, the stress cycle varies rapidly between compression when the Hertz contact stress is applied and tension when the contact stress has passed. Analysis of 14 bearing failures indicates that tensile stresses as low as 140 to 200 MPa (20 to 30 ksi) are sufficient to cause cracks to grow in fatigue. When tensile stresses drive the crack in a radial direction, fracture rather than spalling will occur.
Technical Paper

Optimum Parameters of Spool Valve Feedback to Minimize Surge Pressure

1990-09-01
901620
This paper deals with the optimum design of the stiffness and damping coefficients of the spring and dashpot used in the feedback loop of a hydraulic servovalve, to attain minimum surge pressure during the stop and reverse operations. The proportional element of the feedback represented by the lever ratio is predefined. The state space equations are derived and two objective functions based on relative and absolute pressure rise are minimized. The applied minimization technique is based on a modified gradient method.The results show a better performance and less shocks due to the optimum design of that dynamic parameters.
Technical Paper

Using the Modified Lambda Ratio to Advance Bearing and Gear Performance

1990-09-01
901625
The Lambda ratio (λ) has been widely used as an indicator of the lubricant regime in an operating contact within either bearings or gear sets. λ is determined when the lubricant film thickness (h) within the contact is divided by the composite roughness (σ) of the two surfaces forming the contact. Recommendations of an appropriate film thickness equation and surface roughness values are provided to calculate modified lambda ratio (λm) that better represents the lubricant regime within bearings or gears. Bearing performance, especially as related to fatigue life, has increased significantly in recent years. This is primarily due to cleaner steels but includes the influence of better surface finishes and bearing internal geometries. With λm, and an understanding of how contact fatigue damage mode relates to a wide range of λm values, it may be possible to transfer the advances in bearing performance to other system components such as gears.
Technical Paper

Computer Simulation of Semi-Trailer Haul Truck Roll-Over Dynamics

1990-09-01
901623
Haul trucks, like other articulated heavy vehicles with high centers of gravity, have a propensity to roll over in certain situations. Variable soil conditions, high winds, significant ground slope, and shifting loads contribute to a high risk of roll over for haul trucks. The likelihood of such an event is further increased during dumping operations when the center of gravity of a vehicle is raised higher than usual. This paper develops a mathematical model of the dynamics of haul truck roll over phenomena and establishes critical performance parameters, particularly during a raised bed dumping operation.
Technical Paper

Dynamic Properties of Single-Spool and Two-Spool Two-Stage Servovalves

1990-09-01
901621
A mathematical model of a dynamically stable flapper-nozzle pilot valve has been used in conjunction with the second stage of a flow control valve that comprises a single spool. The model has been used to calculate the valve gain and the dynamic response of the component parts. Real-time and frequency response results have been compared with those when using a two-spool version of the same type, each of the two spools being identical to the spool used in the single-spool version. It is shown that the dynamic response is improved significantly when the single-spool replaces the two-spool version.
Technical Paper

Simulation and Study on Transient Performance of a Compound Charging System

1990-09-01
901672
For suiting turbocharged diesel engine to the condition of sudden acceleration, several compound charging systems are studied. The inlet wave in a resonant system is similar to the small amplitude wave. By means of the mechanics-acoustics analog method, the physical principle of resonant supercharging is researched. In order to obtain the suitable sizes of resonance system for a diesel engine, the computer simulation and optimization are adopted. The test on the experimental equipment of a real engine proved that the transient response of a turbocharged diesel engine could be raised by means of compound supercharging including resonant system.
Technical Paper

Three-Cylinder, Naturally Aspirated, Two-Stroke Automotive Engines - A Performance Potential Evaluation

1990-09-01
901667
The importance of exhaust system design for three cylinder two-stroke engines is demonstrated using a thermodynamic model developed at The Queen's University of Belfast. The influence of the major exhaust parameters on wide open throttle power and bmep is investigated. In addition, the potential benefits of reed valve induction over piston port induction at low engine speeds are demonstrated for one particular engine configuration.
Technical Paper

Battery Powered Ride-On Floor Scrubber

1990-09-01
901675
A new sweeper/scrubber was developed by Clarke, American-Lincoln to fill a product need for a mid-size scrubber and take advantage of an all electric design. This paper discusses the design and features of the Model 6200 Sweeper/Scrubber.
Technical Paper

Higher Engineering Productivity with Computer-Aided Process Planning & CIM at John Deere

1990-09-01
901612
Production Engineering is a major contributor to manufacturing overheads in many companies, occupying up to 50 percent of the production engineering staff. Computer-Aided Process Planning (CAPP) systems offer significant quality and productivity advantages. This paper describes the past and present experience of John Deere Dubuque Works in justifying, developing and installing CAPP systems.
Technical Paper

Solving Air Injested Contamination in Hydraulic Systems

1990-09-01
901680
The hydraulic industry has come to understand the importance of proper filtration. The other half of contamination, that is prevention, still needs to be improved. Research has provided the facts, now industry must implement the hardware to put prevention into practice.
Technical Paper

Tolerancing: The Key to Parts Interchangeability and Manufacturing Cost

1990-09-01
901611
In discrete parts mass production, interchangeability is critical. All the component parts you manufacture need to consistently assemble to some minimum level of fit, functionality and finish. Manufacturing has developed a costly infrastructure to achieve this interchangeability. The problem is, this infrastructure performs at significantly below 100 percent. And perhaps the bigger problem is that when the infrastructure fails, the consequences are expensive. The fact that we are spending so much to achieve so little is due to a factor in the equation that nobody has really recognized or addressed. This hidden factor is the implementation of tolerancing throughout design, manufacturing and inspection. A system, known as Valisys®, automates tolerancing implementation, thus making it possible to ensure part interchangeability. The system performs design validation so that tolerance specifications properly reflect design intent.
Technical Paper

Wear Generation in Hydraulic Pumps

1990-09-01
901679
This paper is concerned with the synergistic effects of pump wear modes. The objective is to investigate the wear produced by cavitation, adhesion, abrasion, and corrosion and to verify a proposed model of the synergistic pump wear process. The approach followed includes identification of the combined effects of different wear modes (synergisms) in a pump and the development of a synergistic wear model that includes pump operating and environmental conditions as trigger factors of wear modes. An experimental program was designed to evaluate the cavitation, adhesion, and corrosion wear effects in conjunction with the abrasive wear produced in a pump by measuring wear debris, particle size and gravimetric levels of fluid. The generation of wear was traced to different pump locations. The results obtained here suggest that improved pump design and longer pump service life can be obtained when synergisms between failure modes are properly understood.
Technical Paper

Computer Aided Design for Wire Harness Manufacture

1990-09-01
901609
A computer-based system has been jointly developed by a tractor manufacturer and a wiring systems manufacturer for use in design and data transfer of automotive -type electrical harnesses. The difficulties of graphical data transfer between incompatible CAD systems have been bypassed. This is significant since the design drawing and the assembly drawing are geometrically different. The system design is based on the structuring capability of CAD and ASCII data exchange. All design processes are controlled by the system and many are automated. The data transfer procedure eliminates design interpretation and keyboard data entry to the wiring manufacturer's database, reducing that process time from days to hours.
Technical Paper

NIIGATA Ultra Lean Burn SI Gas Engines -Achieving High Efficiency and Low NOx Emission-

1990-09-01
901608
The demand for gas engines running on natural gas and sewage gas has been increasing in recent years as the key of the cogeneration systems which are now being put into commercial use. At the same time, the regulations aimed at reducing air pollution from exhaust gases are becoming more and more stringent in line with the public interest in environmental protection. In response to these demands, the authors have developed the mediumsized, medium-speed gas engines “26HXG” series. The developed engine realizes a very low NOx emission and high efficiency by an Ultra Lean Burn with an excess air ratio exceeding 2.0. This Ultra Lean Burn has been realized by means of a pre-chamber combustion system and a lot of efforts for optimizing design parameters. As a result of the optimization of the design parameters, a low NOx emission of 200 ppm in O2 0% equivalent together with a high thermal efficiency as high as 38 %, which is competitive to the diesel engines, has been achieved.
Technical Paper

753 Model Skid Steer Loader Designed for the Nineties

1990-09-01
901674
The model 753 skid steer loader was developed to address performance, service and manufacturing issues for the company's 1300 lb. class loader and to provide exciting new features for marketing. This paper describes many of the improvements and features that will accentuate the Bobcat skid steer loader family in the nineties.
Technical Paper

A Visualization of Spray of Gasoline Injection

1990-09-01
901606
The good relationship between the spray condition in the intake manifold and the combustion characteristics is required. Firstly by this report it was tried the visualization and observation of spray of gasoline injection. It was mainly photographed when injection just began and the spray impinged on a intake valve. The photographs of fuel spray were taken by a image converter type high speed camera. The characteristics of the fuel spray injected in early injection period is influenced with fuel pressure and flow rate of fuel. The atomizing phenomenon of tip fuel of spray could be visualized. The atomizing process in early injection period are differ from that in stady-state spray. And the picture of spray at impingement on the intake valve was shown too. The atomizing condition on the valve surface could be observed visually.
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