| 摘要 |
PROBLEM TO BE SOLVED: To provide a tread cleaning device equipped with a detaining brake function. SOLUTION: When a vehicle is in the detaining brake condition, the pressure air being supplied via a high pressure passage 21 and a low pressure passage 22 is shut off. At the same time, the solenoid selector valve 21a/22a of either or both of the passages 21 and 22 is allowed to exert its release function to exhaust the pressure air from the supply/exhaust passage 23 side, which causes decompressin of inside the pressure chamber 3b of a cylinder 3. Thereby the spring force of a spring 2 is restored, whereby an abrasive element 1 is pressed to the tread W' so that the detaining brake condition is held.
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