| 摘要 |
PROBLEM TO BE SOLVED: To provide a blocking prevention device, optimized to meet subject material to be fed or construction site by securely sending a reverse rotation instruction for reverse rotation when pressure rises due to blocking to reach the reverse rotation start pressure or more. SOLUTION: This device is provided with a controller 58 to input a signal from a main pressure sensor 42 to detect pressure when concrete is normally fed under pressure. The controller 58 stores maximum pressure for pressure-feeding under consideration of the mixing ratio of concrete being fed, the length, gradient, of a transport tube to transport concrete, etc. In the controller 58, a setting value for reverse rotation start pressure can be preliminarily set. When the feeding pressure reaching or exceeding the set reverse rotation start pressure is determined in the controller, the reverse rotation instruction is outputted, and solenoids SOL 2 and SOL 3 of an electromagnetic change-over valve for switching to reverse operation are excited to switch a hydraulic circuit to reverse rotation. COPYRIGHT: (C)2007,JPO&INPIT
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