Safety Adaptability of Engine Retarder (Jacobs) on Long Downhill of Expressways

Abstract

In order to solve the problem that the truck should spray water to cool its brake during run the long downhill on mountain highway in winter, which can lead to icy road and cause traffic accidents. We specially selected the straight truck (6 × 4) which installs the engine brake (Jacobs), carrying out safety tests on Yaxi highway downhill sections in winter. The tests showed that 30% of vehicle overloading conditions, without the engine brake (Jacobs), relying on the service brake to control downhill speed, when the elevation drop of about 300m, the truck’s highest brake drum temperature will rise to a hot recession critical failure temperature (260 °C) above. If you continue driving, it will lead to break failure and loss of control. When the truck going downhill and open the engine brake (Jacobs), due to the brake load is greatly reduced, the brake drum temperature of the truck maintained at 150 °C or less to maintain a good braking performance, and the truck can pass the 51km gap between 1500m long downhill safely. The results of field test show that, when a straight truck goes down a long downhill slope and opens the engine braking (Jacobs), the brake maintains a safe speed without spraying water, and keeps good braking performance. So it can solve the straight truck pass the long downhill sections of mountain highway fundamentally and the brake is not tricking.