Vertical pump motors are used in practically every industrial facility in the United States as well as Farms, and any other operations that need pumps to move water, or any other liquid.
So what do you need to know about them? They are a whole different animal than a horizontal AC electric motor. Vertical pump motors have a lot of aspects that should be understood.
Hollow Shaft or Solid Shaft
There are two kinds of shafts that a vertical pump motor typically has. The standard is a solid shaft which is comparable to most other motor shafts and couple to the pump's shaft with a keyed coupling. Very similar to most direct driven horizontal motors. A hollow shaft vertical motor works a bit differently. The pump shaft actually goes inside the motor's hollow shaft and couples at the top of the motor. These typically have an adjustment nut at the the top that allows for simple adjustment of impeller depth.
The thrust load must be factored in whenever evaluating an AC vertical pump motor. Normal thrust vertical motors are just that, normal and the thrust can be calculated out based on the horsepower and speed of the motor. High thrust is generally given in a percentage rating based on the normal thrust. For example, a high thrust motor may have a 200% multiple on the normal thrust road for the motor's rated horsepower and speed. Thrust rating comes from the thrust bearing (or bearings) in the motor's upper housing. The thrust bearing is generally a angular contact bearing, spherical roller bearing, or on larger motors a kingsbury (tilt pad) bearing.
Non-Reverse Ratchet (Anti-Rotate) Assembly
Vertical motors are many times equipped with a non-reverse ratchet, also known as an anti-rotation assembly. These can be designed with either ball or pin ratchet assemblies, depending on the motor manufacturer. These have a very simple purpose to prevent the motor from spinning backwards due to water flow hitting the impeller when the motor is off. These prevent it from spinning backwards and causing pump damage.
The two primary manufacturers of vertical pump motors, especially when you consider hollow shaft motors, are General Electric or GE (pictured above) and Nidec (U.S. Motors). However, most manufacturers have some form of a vertical motor that they make. HECO is a distributor for both GE and Nidec (U.S. Motors) as well as a variety of other manufacturers and can help you ensure that you get the correct motor for your application's demands.
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About the author:
Justin Hatfield is Vice President of Operations at HECO. He is responsible for Electric Motor & Drive Sales, Electric Motor & Generator Repairs, Spare Solutions, and Predictive Services. Justin was instrumental in developing HECO MAPPS (Motor and Powertrain Performance Systems) which focuses on “why” you have a motor problem instead of simply “What” product or service should be recommended. HECO is an EASA Accredited Service Center.