Municipal Drive Units

Municipal Clarifier and Thickener Drive Units

Clarifier and thickener drive units provide the rotational force necessary to turn the rake arms in a circular basin. The rotating rake arms transport settled solids to the center of the tank for removal.

You can count on our clarifier and thickener drive units to provide the rotational force necessary to turn the rake arms that transport settled solids to the center of your circular basin for removal.

Customers have been coming to us for precision bearing drives since the 1970s, as part of the company’s high-quality process equipment offerings for liquid-solids separation. Our drives give you a flexible design, precision components, and strict quality control. We guarantee a long drive life and the best fit for your process equipment. We stand behind our equipment, which has a proven reputation for meeting the toughest requirements.

One of the unique advantages of premium WesTech drives is their great design flexibility. This flexibility allows the engineer to select a drive that best matches your environmental and mechanical requirements.

Because drive units are applied in municipal and industrial water and wastewater treatment plants, we have developed a premium drive unit for each application. WesTech drive units can be designed for torque requirements from 1,000 LBFT to 6,000,000 LBFT.

Our thorough design and meticulous component selection yields a strong, reliable, premium-quality drive that will provide a long service life with minimum maintenance. Your drive unit will be delivered to the job site completely assembled, shop tested, and ready for installation.

Retrofits and Upgrades

WesTech has unparalleled experience upgrading existing equipment and retrofitting our drives to mechanisms from any manufacturer. With every drive retrofit, we visit the site to inspect the existing equipment, thoroughly record connections and measurements, and plan for any special installation requirements.

Our line of replacement drives uses the same efficient components and quality manufacturing that our standard drives do. This means you get the single best clarifier drive available.

Want to know how well your existing drive unit is performing?

Request your free inspection and evaluation here

Drive Unit Types

WesTech offers two main drive types: the shaft drive and the cage drive. Drive-type selection depends on how the rotating mechanism will be supported in a given application.

Cage Drive: A cage drive unit rests on a stationary column mounted in the center of the tank. A half or full-span bridge then attaches to the robust housing of the drive unit. This column-mounted drive transmits power to the sludge collection system through a center cage mechanism.

Shaft Drive: A shaft drive works well in smaller-diameter tanks where the entire mechanism is supported by a full-span bridge. This bridge-mounted drive transmits power to the sludge collection system through a center drive shaft.

Drive Unit Options

Concentric Dual Drive: Dual drives are multi-tasking units that provide independent mixing in the feedwell, while the rakes transport settled solids along the floor. Supplied in both shaft and cage designs, dual drives are commonly used in WesTech’s Solids CONTACT CLARIFIERS™ and Flocculating Clarifiers. Two distinct motor/reducer assemblies are combined into one unit, which allows for independent speed control of the mixer/flocculator and the rake arms.

D25 Gearless Shaft Drive: The D25 drive has the motor and speed reducer assembly directly mounted on the precision bearing for low-torque applications. The precision bearing eliminates the need for a submerged bearing, which is common with other gearless drives and some strip-liner drives. In these low-torque applications, the main gear-to-pinion reduction is not needed.

Direct Shaft Drive: For light-duty applications, WesTech provides a drive unit that connects the center drive shaft directly to the output of the cycloidal speed reducer.

Peripheral Drive: Rim drives travel along the periphery of a concrete tank and pivot the sludge collection system around the center support column. For large-diameter tanks, rim drives can provide both mechanical and cost advantages.

Precision Bearing Drive

We offer precision bearings in our drive units, a better choice when compared to the primitive strip-liner bearings of other units.

Drive Precision Bearing

Precision Manufacturing Tolerances: The precision bearings WesTech uses in its drive units are ideal for high-load, high-speed applications and are manufactured by recognized bearing companies. The use of these precision bearings is widespread among larger and more heavily-loaded clarifier and thickener mechanisms common to the metallurgical industries, in addition to overhead cranes, gun turrets, and track hoes.

Exceptional Long Life and Load Capacities: Instead of applying the bearing load in four points on the bearing balls as with the old-style strip-lined bearings, the precision bearing uses a full-band contact race with hardness equal to that of the strip liners. Calculated bearing life is at least five times that of strip liners with the same ball size and diameter. The superior service life eliminates the need for splitting gears and housings.

Overturning Load Capacity: Strip-lined bearings have no inherent overturning load capacity and must rely on the mechanism weight alone to hold the bearing race together. This capacity of the precision bearing makes possible tank settling, misalignment, and lack of precision leveling of the drive during installation and operation a far less of a determining factor in premature bearing failure.

Even Load Distribution: The rotating turntable of the strip-liner can easily separate from its stationary base and cause a point load on one or two bearing balls. This separation can occur with the simple action of a skimmer riding over a scum box. The locked ring design of the precision bearing eliminates damaging point loads by equally transferring any unbalanced load to the entire group of bearing balls.

Main Bearing Protection: WesTech gear housings protect the bearings from dirt and contamination using designed neoprene seals and gaskets, whereas strip-lined bearings typically only use a loose felt seal. WesTech precision gears also allow the bearing to run in a separate, sealed grease cavity, which achieves additional protection from contamination.

Benefits and Features

  • Pinion Shaft and Main Bearing tooth configuration
  • Wide range of speed reduction ratios available
  • Optimal corrosion resistance
  • Paint system is a three-step application of epoxy/polyurethane enamel
  • Precision Main Gear and Bearing in a WesTech drive has a calculated L-10 service life exceeding 100 years. The alloy steel gear teeth are hardened to 285-321 BHN for exceptional gear life. A modified-addendum main gear tooth geometry increases load distribution among gear teeth, reduces gear wear, and prevents tooth breakage. The tight bearing tolerances maintain a proper gear-to-pinion alignment.
  • Cycloidal Speed Reducer can withstand momentary shock loads exceeding 500% of its rated continuous torque. At least two-thirds of the speed reducer teeth are engaged at any one time. The rolling action of the main lobes and pins reduces heat buildup and wear, while increasing efficiency to 95% per stage.
  • Direct Coupling of motors, speed reducers, and shafts eliminates drive chains, belts, and an oily mess around the drive. This design improves safety, reduces maintenance requirements, and provides a neat and clean space-saving design.
  • Torkmatic™ Overload Protection accurately senses the torque from the pinion shaft and displays it on the torque indicator. On every new drive, the electromechanical switches are factory set for high-torque alarm and high-torque motor cutout to protect the mechanism from damage. These settings can also be confirmed by field tests during start-up. Other options include rake arm lift, remote monitoring, redundant motor cutout, and explosion-proof torque boxes. An electronic load cell type torque protection is also available for use on new and existing drives.
  • Pinion Bearings eliminate overhung loads on the output bearing of the speed reducer. The upper and lower pinion bearings keep the pinion shaft in precise alignment with the main gear.
  • Heavy-duty Gear and Bearing Housings are available in mild steel, stainless steel, or cast iron. The steel and stainless steel designs use box construction to provide the strongest drive base on the market. Now you can select your preferred material of construction and combine it with the best drive mechanism design available.
  • Lubrication Options: While oil lubrication has been the standard for many years, WesTech also supplies an all-grease lubricated drive. Grease lubrication eliminates the need for periodic condensate draining and messy oil changes, as well as the threat of potential oil spills. Both systems of lubrication have been successfully used for years and help ensure a long bearing life.


  • Primary Clarifiers
  • Secondary Clarifiers
  • Tertiary Contact Clarifiers
  • Gravity Sludge Thickeners
  • DAF Thickeners


  • Sedimentation Clarifiers
  • Contact Clarifiers
  • Flocculating Clarifiers
  • Filter Backwash Clarifiers

Industrial and Minerals

Visit our industrial drive unit page for more information.

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