To solve the ZK3 type turn point machine mechanical jam problem, ZK4 type point machine adopts magnetic lock turn instead of the ZK3 type valve pressure before valves.

为解决ZK 3型转辙机的机械卡阻问题，ZK4型转辙机采用电磁锁闭阀代替了ZK3型的气压锁闭阀。

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If they understood that a critical piece of the lock was subject to a magnetic field, then why did they not design it differently?

FORBES: Opening the Kaba Simplex Lock: Just How Easy Is It?

In the case of the Kaba Simplex, the magnetic field is able to move a critical component and allow the lock to be opened without the proper code.

FORBES: The Kaba Simplex lock is only for "access control": Is that what FDNY Engine Company 65 thought?