Shoken Shimizu

Analysis of death labour accidents relating with drag-shovels and investigation of the countermeasure for safety

In Japan, we have more than 600,000 drag-shovels and the death labour accidents relating with drag-shovels happened more than 70 per a year until 2006. So that we analysed the accidents relating with drag-shovels in details. As a result, there are 4 types of labour accidents: a drag-shovel falls down due to its unstable condition, a burden hanged hits a worker, slope or trench collapses due to excavation and weight of a drag-shovel, a drag-shovel drives backward or pivots and hits a worker. It is revealed that a drag-shovel becomes unstable condition due to dynamic operation such as driving forward or pivoting in a slope and that a drag-shovel and worker are working together within the maximum excavation radius of the drag-shovel. As the countermeasure for the safety, we recommend the use of a drag-shovel with ROPS (Roll-Over Protective Structure) and fastening a seat belt, to set the maximum stable grade considered with dynamic operation, the system alerting both an operator and worker to their approach. Language: ja

The Basic Consideration on Accident Prevention Strategy for the Operation Executed by Multiple Operators Cooperating in Large Scale Product Lines

This paper shows a new safety system to know the human existence in the machine moving area of large scale product lines. It is very difficult to create such a system because the operator can enter into the machine moving area without pulling out of the interlocking key, and there were not only nominated operators but also non-nominated operators. New concept of the risk management division (I : safe condition, II : uncertain condition, III : hazardous condition) was proposed to evaluate the risk reduction of such system. The risk reduction to the division I can be achieved by direct monitoring devices such as the laser scanning sensor. It can be achieved also by indirect monitoring devices such as the mechanical counter gate. On the other hand, the risk reduction to the division I cannot be achieved only by the plug, key-switch or movable guard.