HA40A6B212 by Danaher

The HA40A6B212 is an electromechanical interval timer manufactured by Danaher for the Timers and Controllers series. Designed for panel mounting in automated assembly lines, it sequences auxiliary loads by closing or opening internal relay contacts after a fixed delay. The device couples a synchronous drive to a calibrated front dial, allowing operators to adjust process dwell times without making program changes. Its predictable mechanical countdown coordinates secondary actuators with the main PLC cycle in material-handling and packaging equipment.

During operation, the drive section uses a synchronous motor that rotates in step with the line frequency for consistent timing. The gear train has a dial advance ratio of 20:1, allowing the pointer to provide precise adjustment for short intervals. The translucent scale measures 4 inches across, providing clear visibility inside crowded control cabinets. At its upper limit, the mechanism supports a programmed interval of 20 seconds before energizing the switching contacts. Power is supplied directly from a 120 VAC, 60 Hz source, allowing the unit to share a common control transformer with other panel devices while remaining isolated from high-power loads.

Switching is provided by three Form C relays that can carry up to 15 A each. Their contact surfaces are plated with silver to minimize electrical resistance during repetitive operating cycles. The timer provides three independent changeover circuits, enabling simultaneous control of coils, pilot lights, or solenoid valves after the preset delay elapses. A solenoid-operated clutch engages the timing train only when a start signal is issued, preventing unnecessary wear between cycles. After the sequence is complete, an electric reset mechanism returns the pointer to zero and prepares the timer for the next operating cycle.