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Drop-In for Marley - Double Reduction "A" Series 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.



  *Provide Amarillo Gear Company with dimensions of input and output shafts for possible interchange modifications to the Amarillo “A” series model selected. Please note that in some instances Marley® offers up to 4 different output shaft choices per model.

Ratio Selection and Gear Drive Ratings

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.


Length of taper (D)_________________Keyway size (F)______________________

Small end diameter (E1)____________ Keyway parallel to centerline or taper___

Large end diameter (E2)____________ Overall Height (C)____________________






















Other Options to Consider

Upon request, Amarillo Gear Company can equip your Amarillo “A” Series gear drive with non-reverse backstop, low oil level switch, oil heaters & thermostat, synthetic oil, drain valves, etc.

Limited Warranty

Unless otherwise provided with the particular Goods, Seller warrants to Buyer that the Amarillo Right Angle Fan Drive, Amarillo Parallel Shaft Gear Drive, and the Amarillo Gear Composite Drive Shaft (whether new or renewed) will be free from defects in material and workmanship for a period ending on the earlier to occur twelve months from the date of installation or eighteen months from the date of shipment from Seller’s factory. Seller warrants to Buyer that the Amarillo Right Angle Pump Drive (new) will be free from defects in material and workmanship for a period ending on the earlier to occur of twenty four months from date of installation or thirty months from date of shipment from Seller’s factory. All other products will be free from defects in material and workmanship for a period ending 12 months from ship date. This Limited Warranty shall be void if the Goods are not installed, operated, serviced and maintained in accordance with Seller’s published instructions for the Goods in effect from time to time or if transmitted loads are not within the published limits for the Goods. In addition, this Limited Warranty shall be void if the Goods are is in any way subjected to: (i) improper storage; (ii) accident, damage, abuse or misuse; (iii) abnormal operating conditions or applications; or (iv) repair or modification by Buyer or any third party without the prior written consent of Seller. Any contract created between the Seller and Buyer is subject to the specific condition that Seller is not obligated to provide insurance, defend and/or indemnify any person or entity other than as provided in Section 12 (Amarillo Gear Company LLC Terms and Conditions of Sale) and that there are no flow-downs from the federal government that become part of the contract.

With respect to any defect in material or workmanship covered by this Limited Warranty, if Buyer notifies Seller of such defect in writing within the warranty period, Seller will, at its sole option, (i) with respect to New Goods, either repair or replace any such defective Goods or part thereof, or (ii) with respect to Renewed Goods, repair or re-perform the defective services or part thereof. This shall be Buyer’s exclusive remedy. Any claims not made within the warranty period are deemed waived by Buyer. Before returning any Goods or part hereunder, Buyer must contact Seller for a Return Goods Authorization number and to arrange for transportation. Seller will not pay any transportation costs incurred without its prior written approval.

In no event will Seller be liable, whether in tort, contract or otherwise, for any bodily injury, death, or property damage resulting from or in any way arising out of any Goods or their sale, use, renewal or manufacture. Seller shall not be liable for any costs for removal, shipping or re-installation of the Goods. IN NO EVENT SHALL SELLER BE LIABLE FOR ANY INCIDENTAL, CONSEQUENTIAL, OR PUNITIVE DAMAGES, OR ANY OTHER LOSSES OR EXPENSES.

No change in any provision in this Limited Warranty may be made without the prior written agreement of an authorized officer of Seller.


Amarillo "A" Series Model Replaces
Series 38
Series 32
Series 34
Series 36
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