Mahdi Ajami, Hossein Jannat, Masoud Masih-Tehrani,
Volume 10, Issue 4 (12-2020)
Abstract
Braking test is one of the most important tests of a mechanized technical inspection line. In this study, the effect of tire pressure changes on the accuracy of the braking test results is investigated at technical inspection centers. This study is conducted in three stages. In the first step, the braking efficiency at different tire pressures is examined using a roller brake tester. In the second step, the tests at different pressures and velocities on the road are done. These tests are carried out in terms of stopping distance, to ensure the accuracy and reliability of the first step test results. The results of the first and second steps showed that the effect of tire pressure changes on the braking efficiency is significant. In the third step, the braking test results of a thousand vehicles that received technical inspection certificate are studied. Analysis of these results, considering the results of the first and second steps cleared that about 16% of vehicles that received technical inspection certificate have lower braking efficiency than the minimum acceptable efficiency. The obtained results specified the necessity of adjusting the pressure of tires before the braking test at vehicle technical inspection centers in Iran.
Ali Akbar Majidi-Jirandehi, Moslem Mohammadi Soleymani, Hossein Dehghani,
Volume 11, Issue 3 (9-2021)
Abstract
Today, many car manufacturers can achieve emission standards through catalytic converters. The goals of this research was in tow sections. Initially, the amount of pollutants was measured to determine the role of the catalytic converters in the reduction of pollutants for 3 types of vehicles and in 50 cases, in the two stages before and after the catalytic converter. Then, to achieve the useful life of the catalytic converter, out of 750 test vehicle emissions were tested. Data analysis was done by SPSS software, which shows that catalytic converters can reduce up to 80% of exhaust emissions. This is independent of the type of vehicle. The useful life of the catalytic converters is up to 36 months, so they should be replaced at least every three years. Also, the pollutant standards of the technical examination centers are reviewed. For this purpose, the pollutants have been measured in 2200 vehicles. Due to the huge difference in technology, cars are divided into two main categories of carburetor and injector and are analyzed statistically. Eventually, for each group of these vehicles, the values of HC, CO and O2 are obtained.
