The ZE III has the same function as the ZE I, but is designed primarily for the LMB mine, which cannot accomodate the ZE I. It is a 200-day clock driven by two small springs wound by a small 9-volt motor. The clock consists of three main parts; the wind-ing system, the clockwork and switches, and the safety mechanism. This clock can be set from 45 to 200 days by turning the setting dial clockwise past zero to the desired position. Termination of the UES run connects a 9-12-volt battery across terminals 7 and 8, starting the clock motor. After a run of 10 to 15 seconds, contacts 1-2 and 3-4 close, and the motor continues to run for 40 to 50 seconds until both springs are wound. The safety spring winder, which is driven by a notches disc, automatically cuts off the motor current for 30 minutes when initial winding is completed. After a delay of 30 minutes, the motor starts, again rewinding the spring. This process contiunes until the ZE III reaches its preset period, at which time contacts 1-2, 3-4, and 7-8 are opened and contacts 1-3, and 5-6 close.

If a mechanical failure occurs after the clock starts, the independent safety system operates. From 60 to 70 minutes after the failure, all contacts are made in the same manner as through the clock had completed its run.

Figure 273 – ZE III

Figure 274 – ZE III

Figure 275 – ZE III Switches before the UES has run off

Figure 276 – ZE III Switches 10 to 15 seconds after ZE Start

Figure 277 – ZE III Switches after Run-off of Pre-Set Time