This attachment is used with CJA freight door interlocks CV-1, CV-2, HG-1 and HG-2 to prevent intentional tampering. For example, when the elevator door is in the raised position it is possible to physically close the interlock cam and contacts allowing the elevator to run with the doors open. The C-1 tamper proof attachment prevents intentional, physical closing of the interlock cam and contacts.

The HG-2 is an Elevator Door Interlock, retiring cam required device. Intended for use on single slide vertical rise freight doors. They are wired in series with all of the other door switches in the hoist-way and the electrical control circuit of the elevator so as to produce an overall electrical safety loop. In addition to this circuit closing system there is a mechanical latch which locks the door in the closed or down position. The HG-2 Interlock has two contacts and is used with a retiring cam. These two contacts are the door close contact and the door locked contact.

The C-1 tamper proof attachment consists of a cast iron “plug” which is affixed to the interlock, a rod with an offset, and rod guides for attaching the rod to the door. The “plug” is attached on the interlock opposite and parallel to the interlock cam. It rests on the straight section of the rod when the door is open holding the interlock cam and contacts in the open position. When the door is actually closed the “plug” drops into the offset of the rod permitting the interlock cam to close making the contacts. The tamper proof attachment may be ordered with the interlocks or as a field conversion kit for existing installations.