HA40S172A6 by Danaher

The HA40S172A6 is a reset timer manufactured by Danaher for the Timers and Controllers series. Intended for panel installations that require short, repeatable delay cycles, the unit combines a synchronous-motor drive with a solenoid-released clutch to start or interrupt downstream processes on command. A calibrated dial linked to the internal gearing establishes the interval, while the reset knob returns the pointer to zero for the next cycle. This operating method supports timed batch processes, purge cycles, and safety interlocks in industrial automation systems without relying on a spring-wound mechanism.

Silver-alloy contact blades are rated for 15 A, allowing the timer to switch suitable motor or resistive loads without an external relay. The silver-alloy contact blades maintain low contact resistance during repeated operation. The switching stack contains three isolated contact sets, allowing independent control circuits to follow the same timing cycle. Output timing uses a 20:1 dial turn ratio, which provides fine adjustment across the available time range. One complete turn of the outer knob moves the internal cam through a small portion of its total travel, increasing the resolution available when selecting short delays. The synchronous motor maintains a steady timing rate by following the frequency of the electrical supply rather than changes in mechanical shaft torque.

When the clutch is energized, the timer provides a single-shot delay of up to 20 seconds before reset, making the available range suitable for dwell, purge, or safety-clearance intervals. The front dial measures 4 inches in diameter, providing enough scale length for closely spaced timing marks that remain easy to read during setup. Timing accuracy depends on a nominal 60 Hz supply frequency because the synchronous motor follows the electrical line frequency. The unit operates from a stable 120 V power source, and consistent input power helps the timer maintain repeatable intervals within the tolerance of its internal gearing and cam assembly. Its panel-oriented format keeps the dial accessible while the contact circuits and drive components remain enclosed behind the mounting surface.