Search Results

Two-stroke cycle direct injection engines can achieve adequate stability at idle with stratified combustion at very lean overall air-fuel ratio, but exhaust temperature is very low. A rotary valve system was designed to spill charge from the cylinder into the intake tract during the compression stroke, in order to allow stable operation at lower engine delivery ratio and thereby increase exhaust temperature. Reduction of the engine delivery ratio was not achieved due to the poor scavenging characteristics of the swirl liners used, which resulted in high content of exhaust residual gas in the spill recirculation flow. Although the concept objective of higher exhaust temperature was not realized, the results indicate that the concept may be feasible if high purity of the spill recirculation flow can be achieved in conjunction with high trapping efficiency.

The pneumatic air brake system for heavy commercial trucks is composed by a large number of components, aiming its proper work and compliance with rigorous criteria of vehicular safety. One of those components, present along the whole vehicle, is the air brake tube, ducts which feed valves and reservoirs with compressed air, carrying signals for acting or releasing the brake system. In 2011, due to a lack of butadiene in a global scale, the manufacturing of these tubes was compromised; as this is an important raw material present on the polymer used so far, PA12. This article introduces the methodology of selecting, developing and validating in vehicle an alternative polymer for this application. For this purpose, acceptance criteria have been established through global material specifications, as well as bench tests and vehicular validation requirements.

Discussion of four factors pertinent to any overall ride evaluation. These factors are frame beaming, fifth wheel location, special body mountings, and variable loading conditions on tandem truck and tractor ride. The methodology for measuring the characteristics of these factors is reviewed and practical solutions for improved ride are given.

The salt spray test has been an industry wide standard corrosion test since its conception in 1914. A literary review of its history shows that it has· always been thought of as inconsistent and unreliable but, for a variety of reasons, has continued to be used. A study of more than 55 salt spray cabinets was performed using a controlled lot of parts and questionnaires on cabinet operation. Although the tested parts varied from mildly corroded to extremely rusted no factor could be found to account for the differences. Although the test has its uses it should be studied by an industry formed committee which should make recommendations as to further standardization and corrections to the test. A lengthy chronological bibliography aids the reader in further study and reference.