McDonnell & Miller 302900 Cam

The McDonnell & Miller 302900 Cam, also identified by model number CO-106, is a critical mechanical component engineered for the precise actuation of bellows assemblies in Series 47, 51, 53, and 63 boiler controls. As a veteran-grade replacement part, this cam is essential for restoring the mechanical linkage between the float movement and the switch mechanism in low water cut-offs and combination water feeders. It is specifically designed for compatibility with bellows assemblies such as the SA47-4, SA47-104, SA51-4, and SA53-4, ensuring the burner circuit is interrupted at the exact calibrated water level. Technical field inspections often reveal that worn or pitted cams lead to erratic switch firing or failed burner shutdowns; replacing the 302900 restores the factory-standard mechanical switch actuation required for safe boiler operation. This heavy-duty assembly is built to withstand high-cycle industrial environments, maintaining tight tolerances within the head mechanism of steam and hot water systems.

• Broad Series Compatibility: Engineered to fit and function within McDonnell & Miller 47, 51, 53, and 63 Series units.
• Precise Switch Logic: Restores the intended timing for boiler low water cut-off and feeding sequences, preventing dry-fire conditions.
• Industrial Build Quality: High-tolerance construction minimizes mechanical play in the linkage, reducing the frequency of emergency service calls.
• Direct OEM Replacement: Replaces the CO-106 cam assembly without the need for field modifications to the bellows or switch bracket.

Which bellows assemblies are compatible with the CO-106 cam?
The CO-106 (302900) is the standard replacement for bellows assemblies BA-51-05, BA-53-05, SA47-4, SA47-104, and SA63-5 used in common M&M feeders.

Does this cam include the mounting screw and pin?
Yes, the 302900 is typically supplied as the cam assembly including the necessary screw and pin for securing it to the float linkage.

What are the signs that a 302900 cam needs replacement?
Technicians should look for visible rounding of the cam lobes or hesitation in the switch rocker movement, which often indicates the cam is no longer providing sufficient lift to actuate the No. 2 switch.

This item is not eligible for free shipping.

Disclaimer: While we strive for 100% accuracy, product data and specifications are subject to change. Please contact our team to confirm compatibility or technical details before purchasing.