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The manufacturing tolerances of off-highway machine linkages have an impact on linkage position during machine use. A study was undertaken to determine the extent of these tolerances on linkage position for standard machining tolerances of each linkage pin joint for a four wheel drive loader linkage. Linkage positions and distributions for each pin joint are shown in order to determine positional accuracy of the working tool connected to the linkage and impact to the machine loads. It is determined that the affect of the machining tolerances on this linkage have a very minor impact on the linkage position when the linkage is in new condition (before use) and the maximum variation in linkage actuation loads is less than 1% of nominal load.

The topic of condition monitoring has been an area of significant research in the last two decades. There are many reasons for the increased popularity of this research field. These reasons include the need to diagnose increasingly complex modern-day systems coupled with the continuous desire to provide better product reliability. Additionally, the dramatic improvement in digital computing speed and flexibility has enabled much of this technology to be feasibly implemented. The condition monitoring research area is quite diverse in both its applications and the approaches necessary for implementation. This paper will provide a survey of literature pertinent to condition monitoring applied to fluid power systems. In addition, some distinctions between various methodologies will be investigated.

It is not uncommon for complex engineering products to undergo several design iterations due to changing market expectations or inadequate performance. In such circumstances, a prototype is generally available that could be used for performance analysis before a revision to the design is made. The availability of a prototype can be an invaluable tool for the analysis of the impact of potential design changes on the system performance. In this paper, a process is proposed for the derivation of a physical model that could be used for design analysis. The process uses model identification for determination of model complexity and numerical optimization for estimation of model parameters. This process is applied to a new pneumatic fan clutch system that has been developed to improve the efficiency of engine temperature regulation in heavy-duty commercial vehicles. This system is currently in a prototype phase and its detailed physical model is required for design trade-off analysis

This paper introduces two new types of basic components (an Electro-Hydraulic Tube and a Hydraulic Tube) which when connected in an appropriate manner can control flow and pressure for many applications; in addition, one of the devices is readily interfacable to a microprocessor for external control. Some background information about the basic concept and the operation of the two components is introduced. Some of the experimental characteristics will be illustrated and several basic circuit examples will be presented to show how the concept can be implemented. The Electro-Hydraulic Integrated Block (EHIB) and Circuit (EHIC) will be introduced followed by a discussion of the advantages and potential of the EHIC concept.

The development of high precision flow divider/combiner valves has received considerable attention by the authors over the past decade. Several different valve designs for division and combination of flow have been designed which display small flow dividing/combining error (1-2%) when compared to conventional designs (2-10%). Recent studies have improved upon the design in order to reduce cost, weight and complexity of the valve. This paper will present the latest of the authors research into the development of a high precision, autoregulated flow divider/combiner valve with an integral shuttle valve. The autoregulator extends the operating range of the integrated flow divider/combiner valve (for errors less than 2 %) to 10-50 lpm compared to 30-50 lpm for the unregulated valve.

A flow divider valve is a device which allows a single stream of fluid to be split into two paths according to a predetermined ratio and independent of variations or differences in the load pressures. A flow combiner valve combines two paths of fluid into one stream such that the ratio of the flow rates coming into the valve remains independent of any variation or difference between the inlet pressures. This paper describes the design, operation and performance of an integrated flow divider/combiner valve. This design maintains the small flow dividing/combining error of high precision valves (less than 1.5% at rated flow) but incorporates the shuttle valve into the main spool system. This new design reduces the weight of the valve by 20% reducing the cost by approximately 10%. The new structure simplifies the construction of high precision valves and reduces a source of flow dividing/combining error (leakage).