This instructional video from the track training team demonstrates the installation and crucial safety function of the "Hand Before 73" (HV 73) railway switch securing device. Developed decades ago, the HV 73 is a non-signaling physical locking mechanism used by rail personnel to secure switch points when their primary locking components are no longer effective. The video details the process of mounting the device onto the rail foot, tightening it, and securing it in the raised position with a wire and specialized lock. A key safety takeaway is the resulting speed restriction: operating the switch with the HV 73 unsecured restricts speed to 5 km/h, while securing it with the designated lock and key allows speeds up to 50 km/h.
Summarizing the Installation and Function of the HV 73 Switch Lock
0:06 Introduction to HV 73: The video discusses the "Hand Before 73" (HV 73) switch, a device introduced around the year '73, designed to manually secure railway switch points.
0:24 Primary Function: The HV 73 is used by railway employees to secure switches in position, typically when the normal locking mechanism is no longer effective. It is solely a physical securing device and does not establish any signal dependency (0:40).
0:48 Critical Safety Regulation: When a switch is secured using the HV 73 alone (unlocked), the speed limit over the switch is drastically reduced to only 5 km/h (0:51).
0:58 Enabling Higher Speed: To allow a train to drive over the switch at 50 km/h, the HV 73 must be fully secured using a specialized lock and key.
1:24 Assembly Demonstration: The video demonstrates installation. The user inserts the main component (talent compartment) onto the rail foot, ensuring the front tabs secure it in place (1:48).
2:20 Securing the Device: The device is tightened, then raised into the locking position (2:23). In the raised position, the mechanism prevents the moving switch tongue from crossing the rail (2:24).
2:29 Final Locking Steps: The secured position is initially fixed with a wire and then definitively locked using the specialized padlock (2:43).
3:00 Key Takeaway (Security): The lock ensures the switch is secured against being accidentally or manually switched against the jaw rail, maintaining the desired running position.
4:10 Speed and Access: The lock (and its key) grants the necessary security to allow the 50 km/h speed limit. The device cannot be removed until the correct key is used (4:21).