Generic Marley Replacement Gear

Cooling Tower Gearboxes

“A” Series Cooling Tower Fan Drives

The “A” Series right angle gear drives for cooling towers from AMARILLO GEAR are designed as direct replacements for the Marley® Cooling Tower line of right angle drives. Since there are no differences in the critical mounting dimensions, the “A” Series will make gear drive replacements easy. Gear housing foot patterns are identical, eliminating expensive tower gear drive support modifications.

Cooling Tower Gearbox

New Product

Click to Download: Flyer – New AG RA Drives A Series

Operation & Maintenance Manuals

Click to Download: A Series

*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® reduction ratios, eliminating the need to make costly fan pitch adjustments.

"A" Series Cooling Tower Fan Drives
Marley® Model Amaeillo Model Horsepower Rating
Series 20 – All Models: 20.1, 20.2T, etc… A20 20 25 30 35
Series 22 – All Models: 22.1, 22.2 T, etc… A22 47 53 60 70
Series 27 – All Models: 27.1, 27.2T, etc… A27 40 60 75 80
Series 32 – All Models: 32.1, 32.2T, etc… A32 160
Series 34 – All Models: 34.1, 34.2T, etc… A34 180
Series 36 – All Models: 36.1, 36.2T, etc… A36 200 220 230 250
 Series 38 – All Models: 38.1, 38.2T, etc… A38 250

Ratio and Ratings


All ratios are reducing and defined as the ratio of input speed to output speed. Single and double reduction ratios shown are exact within +/- 2%. Ratios shown in blue in each table are normally stocked and drives ordered with these ratios can be shipped within our normal lead time. Check with the factory for availability of all model ratios not shaded.


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 are listed for 60 cycle electric motor speeds. Ratings for speeds less than 1750 rpm are proportional to the rating at 1750 rpm. Contact the factory for recommendations when the driver speed exceeds 1800 rpm.

Limited Warranty:

The Amarillo Right Angle Gear Drive is guaranteed against defects in workmanship and material for a period of one year after installation when operated under normal service at rated capacity. Within the above stated period, the manufacturer will replace the defective parts returned transportation prepaid. The buyer shall not be entitled to incidental or consequential damages, losses or expenses. The guarantee will not apply to repairs made outside the factory without the consent of the manufacturer or to drives that have been subject to abuse, accident, neglect or improper installation. No warranty is made in regard to bearings, trade accessories, machinery, or other articles or merchandise not manufactured by us. This warranty is expressly made in lieu of any warranties otherwise expressed or implied by law.

Direction of Rotation:

Normal rotation is both shafts clockwise as shown in the illustrations. Occasional use with both shafts rotating counterclockwise is permissible. Special bearing arrangements are used when the primary direction of rotation is counterclockwise and the gear drives should be ordered accordingly.

Rotational schemes with the shafts rotating in opposite directions are available on special order.

Straight Output Shaft Information:

All AMARILLO “A” series right angle cooling tower drives may be furnished, upon request, with a cylindrical output shaft. The most common cylindrical shaft diameter is shown in the following table, however, other shaft diameters can be supplied within engineering limits. When requesting a cylindrical shaft the following information must be provided before an order can be accepted.

Model Dia. Model Dia.
A20 2″ A32 4 1/2″
A22 2 5/8″ A34 5″
A27 3″ A36 5″
A38 5″

Length of shaft (D)_________________ Keyway size (F)____________________

Shaft diameter (E)_________________ Overall height (C)___________________

Cooling Tower Gear Box

Tapered Output Shaft Information:

All AMARILLO “A” Series right angle cooling tower drives may be furnished, as standard, with the tapered output shaft shown in the drawing. On rare occasions, the gear drive being replaced may have a different output shaft taper. Amarillo Gear Company will provide a matching shaft when the following information (or shaft drawing) is provided. This information is required before an order can be accepted.

Length of taper (D)________________ Keyway size (F)______________________

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

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

Weights and Shipping Dimensions:

Model Net Weight (lbs) Weight With Export Boxing (lbs) Export Box Dimensions (LxWxH) (in)
A20 200 240 29 x 19 x 27
A22 440 500 36 x 23 x 34
A27 840 940 36 x 40 x 30
A32 1575 1720 55 x 36 x 40
A34 2225 2405 58 x 46 x 40
A36 2245 2425 58 x 46 x 40
A38 2300 2480 58 x 46 x 40

Cooling Tower Gear Box

Cooling Tower Gearbox

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