<p><em>The increasing number of vehicles every year provides opportunities to vehicles service. Vehicle components that often serviced or overhaul is the valve mechanism. How to remove the valve from the cylinder head generally use a manual valve remove tool. The time required to remove the valve using the tools need a long time. Effort to overcome these problems is to modify the existing valve remove mechanism. The purpose of this research is to design and test the performance of valve remove using lever mechanism. Performance test was conducted to determine the press force value to remove the valve, the percentage increase performance and time to remove the valve. The main components of the valve remove tool using the lever mechanism is frame, table, pole support, locking, hand grips, hydraulic, lever pusher and shaft sled. Testing using the valve mechanism is contained in the cylinder head Toyota Kijang 4K. The valve remove tool design has a simple form, easy to make, cheap, but has very good performance. The smallest of the press force to remove the valve is 129 N obtained at a distance of lock and poles support as far as 22 cm. The valve remove tool using the lever mechanism was design can remove the valve from the cylinder head in time 26,17 seconds/valve or 418,67 seconds to remove 16 valves on the cylinder head. This tool is able to improve the performance of manual valve remove tool screw type by 76,28%, and can improve the performance valve remove tool the pneumatic system by 65,79%.</em></p>
AbstrakTujuan penelitian komposit adalah memperkuat serat Bundung (Scirpus Grossus) untuk mengetahui sifat mekanik komposit terhadap kekuatan tarik. Metode yang dilakukan pada serat Bundung diberi perlakuan dengan perendaman 5% NaOH selama 2 jam, kemudian dipanaskan dengan temperatur 70°C selama 4 jam. Penyusunan serat Bundung dengan gabungan orientasi sudut 0° dan 90° dengan resin polyester type 157 BTQN dengan variasi fraksi volume serat 20%, 30%, dan 40%. Hardener yang digunakan adalah MEKPO berkonsentrasi 1%. Komposit dibuat dengan metode hand lay up. Spesimen dan prosedur pengujian tarik mengacu pada standart ASTM D638-03. Hasil penelitian ini menunjukkan terjadi peningkatan kekuatan tarik pada penambahan fraksi volume sebesar 40% serat dengan perlakuan perendaman 5% NaOH selama 2 jam dengan pemanasan 70°C selama 4 jam. Kekuatan tarik tertinggi komposit serat bundung pada perlakuan perendaman 5% NaOH selama 2 jam dengan pemanasan 70°C selama 4 jam sebesar 67,56 N/mm 2 dibandingkan dengan kekuatan tarik pada perlakuan perendaman 5% NaOH selama 2 jam tanpa pemanasan yaitu sebesar 54,25 N/mm 2 .
<p><em>The purpose of this study was to determine the effect of solar panel circuits on current, voltage and power. This research is a true experiment. Dependent variables were current, voltage, and power. Independent variables were a series circuit of solar panels and a parallel circuit of solar panels. The sample numbers of studies were 12 for each group of independent variables. The data were analyzed using the t-test at the 5% signification level. The results showed that the electrical power produced by a series circuit of solar panels was, P = 4.81 watt, Sd = 0.24. The electrical power produced by a parallel circuit of solar panels was P = 4.69 watts, Sd = 0.13. The t-test showed that there was no difference in electrical power produced by the series circuit of solar panels and parallel circuit of solar panels, with t<sub>o</sub> = 1.525 < t<sub>α/2, v</sub> =2,074. The form of a circuit (series or parallel) has no significant effect on power but differs only in current and voltage. In series circuit, I<sub>1</sub> = I<sub>2</sub> = I<sub>Σ</sub> and V<sub>1</sub> +V<sub>2</sub> = V<sub>Σ</sub>. In parallel circuits V<sub>1</sub> = V<sub>2</sub> = V<sub>Σ</sub> and I<sub>1</sub> + I<sub>2</sub> = I<sub>Σ</sub>. This can be adjusted to our purpose of using solar panels circuit. If it requires a large current, the solar panels must assemble in a parallel circuit. But if it requires a large voltage, the solar panels must assemble in a series circuit.</em></p><p><strong><em>Keywords</em></strong><strong><em>:</em></strong><strong><em> </em></strong><strong><em>current, parallel, power, series, voltage</em></strong></p>
Pepper is one of Indonesia's leading agricultural products. However, post-harvest handling of pepper, such as the threshing process, is still done traditionally. Efforts to overcome these problems done by developing a mechanical threshing process, including by designing and construction a mesh thresher cylinder type of pepper threshing. Test results show, this pepper thresher has a weakness, namely low threshing efficiency so that it needs to developed. Based on these conditions, research is needed that aims to develop, modify and done performance tests on the pepper thresher. The modification was made by making the contact angle between the thresher cylinder and the threshing net is 60o and resulted length of the threshing contact field of about 5.23 cm. The independent variable was the thresher cylinder rotational speed varied into 540, 471, 451 and 352 rpm. The dependent variables were capacity, threshing efficiency and percentage pepper of damage. The results of the analysis showed that the rotational speed of the threshing mechanism had a very significant effect on the capacity, threshing efficiency and the percentage pepper of damage. Increasing the speed of the thresher cylinder can increase the capacity and percentage of damaged pepper, but reduce threshing efficiency. The threshing efficiency increase of the pepper thresher before and after modification was from 35.8% to 95.93% on the approaching treatment.
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