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The present paper is a continuation of engineering efforts devoted mathematical modeling and computer simulation presented in [1]. The modeling and study is extended on starting a vehicle with use of a throttle. The basic mathematical model utilized in [1] has had to be modified because clutch engagement with throttle make investigators consider new human factors contributing strongly to starting conditions. In particular, not only the clutch release but also the accelerator pedal are controlled by a vehicle operator. This has made the authors modify the definition of an ideal engagement and incorporate both the throttle level and the throttle lead time to the mathematical model. Moreover, the model has been adjusted to consolidate dissimilar low range characteristics for diesel and gas engines.

It is common for difficult shifting to occur in synchronized transmissions. High shift effort is recognized as a basic performance malfunction that takes place during synchronization. This paper examines shift quality in vehicles with synchronized transmissions. The present study is working on three categories: a mathematical model and computer simulation of transmission shifts, an experimental verification of the model and program, and an engineering method for rating shift quality. The mathematical model in this study is a refinement of a model from an earlier paper [1]. With experience, this model has seen revisions that allow the results to be more accurate than the previous ones. The model takes into considerations many elements that affect the synchronizing process such as: synchronizing torque, inertia of both clutch disc(s) and transmission components, clutch drag, viscous drag in the transmission, shifting RPM's, etc.

Designing highly loaded spur and helical gears for truck transmissions that are both strong and quiet requires an analysis method that can easily be implemented and also provides information on bending stress, load distribution, and transmission error. The finite element method is capable of providing this information, but the time needed to create such a model is very great. In order to reduce the modeling time, a preprocessor program that creates the geometry needed for a finite element analysis has been developed. While requiring a minimum of user input, the program generates a three-dimensional model of contacting spur or helical gears using eight node brick elements. Gap elements are used to model the contact that normally occurs between meshing gear teeth as well as the contact that may occur off the line of action due to the teeth deflecting under load.

Heat generated in hydraulic systems can be responsible for reduced life of equipment. Current Industry trends look to load-sensing variable-displacement pumps and closed-center valves to combat the problem. A comparison is made between the load-sensing variable-displacement pump with closed-center control valves and the fixed-displacement pump (both wet and dry valve types) with open-center control valves, to determine the heat generation tradeoffs. The use of tanks, lines and cylinders as a heat radiator is considered. Heat generated by high-pressure leakage of driven members is addressed. The primary focus of this paper is on packer and body hydraulics of refuse trucks.

In today's global fluid power industry, successful hydraulic component manufacturers must utilize technical resources to maintain a competitive edge. When designing new products, past practice required an understanding of engineering theory and reliable and accurate lab and field testing of new products, but today's designers have a new tool at their disposal. Personal computer based software can be used to model and simulate individual hydraulic components or entire systems before prototypes are available for design and performance evaluation. This paper discusses the design of a hydraulic safety valve and how PC simulation was used to design and analyze valve performance during the design process.