Amarillo Gear Company LLC

- Model A Series - Double Reduction Gear Drive


The Double Reduction “A” Series Gear Drives for cooling towers from Amarillo Gear Company are designed as direct replacements for the Marley right angle gear boxes. Since there are no differences in the critical mounting dimensions, the “A” Series will make Marley gear box replacements easy. Gear housing foot patterns are identical, eliminating expensive gear drive mechanical support modifications. The input shaft diameters and keyways are the same, so existing couplings and drive shafts do not have to be replaced. All service ports are also easily accessible. Reduction ratios are within ± 2% of the Marley® gear box ratios, eliminating the need to make costly fan pitch adjustments.


All ratios shown in the catalog are reducing and defined as the ratio of the input speed to the output speed. Ratios shown are exact within ±2%. For your particular model and ratio, please contact the factory to confirm selection and availability.


AGMA and CTI recommend a minimum service factor of 2.0 for gear drives in cooling tower fan service when driven by electric motors or steam turbines. All ratings are service ratings and include a 2.0 service factor unless otherwise noted. Ratings listed in the catalog are for 60 cycle electric motor speeds. Ratings for speeds less than 1,750 rpm are proportional to the rated speed. Contact the factory for recommendations when the driver speed exceeds 1,800 rpm or falls below 450 rpm.

Direction of Rotation

Normal rotation is both shafts clockwise as shown in the illustrations in the catalog. Occasional use with both shafts rotating counterclockwise is permissible (unless the gear drive is equipped with Amarillo Gear’s optional non-reverse backstop).

Straight Output Shaft Information

All Amarillo “A” Series gear drives cooling tower drives may be furnished, upon request, with a cylindrical output shaft (no-taper). Please contact factory for pricing and availability.

Other Output Shaft Selections

Marley® has offered numerous output shaft lengths and at least 2 tapers (1/2” per foot and 3-1/2” per foot) on their double reduction models. If you do not know which output shaft your gear drive has, please complete the worksheet below and contact Amarillo Gear Company for proper selection or provide a certified dimensional print of your existing gear drive. A dimensional print of an Amarillo “A” Series gear drive with proper output and input shaft dimensions can be provided before ordering if requested.

Customer reviews

No reviews were found for Amarillo Marley - Model A Series - Double Reduction Gear Drive. Be the first to review!