Abstract: A gate valve includes a valve plate that opens and closes a gate opening, a valve shaft that is fixed to the valve plate, an air cylinder that includes a drive rod, and a valve moving mechanism that causes, by expanding and contracting movements of the drive rod, the valve plate to move between a hermetically closed position at which the gate opening is hermetically closed by the valve plate and a full open position at which the gate opening is fully opened. A cylinder housing of the air cylinder is provided with a locking mechanism that locks the valve plate that has moved to the hermetically closed position and a lock detection unit that detects a locked state of the valve plate. The locking mechanism includes a lock piston that is capable of advancing and retreating with respect to the cylinder housing. A cam frame that is fixed to the drive rod has an engagement hole. The lock detection unit detects whether the lock piston is in a state of being engaged in the engagement hole.

Abstract: A gate valve includes a valve plate that opens and closes a gate opening, a valve shaft that is fixed to the valve plate, an air cylinder that includes a drive rod, and a valve moving mechanism that causes, by expanding and contracting movements of the drive rod, the valve plate to move between a hermetically closed position at which the gate opening is hermetically closed by the valve plate and a full open position at which the gate opening is fully opened. A cylinder housing of the air cylinder is provided with a locking mechanism that locks the valve plate that has moved to the hermetically closed position and a lock detection unit that detects a locked state of the valve plate. The locking mechanism includes a lock piston that is capable of advancing and retreating with respect to the cylinder housing. A cam frame that is fixed to the drive rod has an engagement hole. The lock detection unit detects whether the lock piston is in a state of being engaged in the engagement hole.