York S1-028-12385-700 Sheave

The York S1-028-12385-700 Sheave is a professional-grade 1-groove variable pitch pulley engineered for precision air balancing in commercial and residential air handlers. Featuring a standard 7/8 inch bore, this adjustable component allows technicians to fine-tune blower speeds and system CFM by modifying the pitch diameter. As an OEM S1-028-12385-700 replacement, it ensures exact mechanical compatibility with Johnson Controls and York blower assemblies, maintaining the drive ratio required for optimal static pressure. The high-duty cast iron construction provides the dimensional stability necessary to prevent belt slippage and minimize vibration during high-torque startups. This adjustable blower sheave is a critical HVAC drive pulley for field adjustments where motor RPM must be translated into specific fan performance. Its rugged design facilitates long-term alignment, reducing lateral load on motor bearings and extending the life of the drive belt in demanding ventilation environments.

• Variable Pitch Versatility: Allows for precise field adjustments of blower RPM to meet specific airflow requirements without changing the motor.
• OEM Precision: Direct York variable pitch sheave replacement ensures perfect shaft fit and alignment for 7/8" motor spindles.
• Heavy-Duty Construction: Manufactured from high-grade iron to resist thermal expansion and bore wear under continuous operation.
• Improved Drive Efficiency: Maintains consistent belt tension and tracking, reducing mechanical noise and parasitic energy loss.

How do I adjust the pitch on this 7/8" bore pulley?
Loosen the set screw on the adjustable flange to thread the sheave inward or outward. This increases or decreases the effective pitch diameter, which directly alters the fan speed while the motor maintains constant RPM.

Is this sheave compatible with standard 5L or A-section V-belts?
Yes, this 7/8 inch bore sheave is designed to match standard industrial V-belt profiles commonly found in York and Johnson Controls air handling units.

Can this be used to troubleshoot low airflow issues?
Absolutely. If the motor is running at nameplate amps but CFM is low, adjusting this sheave to a larger pitch diameter can increase fan speed to overcome high static pressure in the ductwork.

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.