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Types and Construction of Vertical Motors

Vertical Hollow Shaft (VHS)

HOLLOSHAFT® motors were designed and patented by U.S. Electrical Motors in 1932. Their primary use has been with deep well pumps. However, development of the turbine pump for industrial purposes has led to a more versatile design.

Weather Protected Type I Enclosure (NEMA MG1-1, 1.25.8.1) is specifically designed to minimize the entrance of rain and dust. These units are normally applied outside rather than indoors. Screens have been added to prevent entrance of debris and rodents. The mesh is 4 per inch. This enclosure is a U.S. standard for all high thrust machines.

Weather Protected Type II Enclosure (NEMA MG1-1, 1.25.8.2) is available on 449 frame and larger. This enclosure is designed with 3 abrupt changes in entrance path of ventilation air so that airborne particles will be discharged without entering the electric parts of the machine. In addition, air velocity is below 600 feet per minute to further minimize the possibility of moisture or dirt being carried into the electric parts of the motor.

It is highly recommended that this enclosure be used whenever premium protection is required. Thrust bearings run at cooler temperatures in this enclosure rather than the TEFC because air is raked over the thrust chamber. As noted in the Modified Vertical Motors Catalog , TEFC carries lower thrust loads per frame and horsepower. This is directly related to cooling methods.

All WP-II motors are given full CORRO-DUTY® treatment inside and out. All metal surfaces are primed and coated with a long-lasting epoxy paint. Space heaters are not charged for when specified at time of order.

Totally Enclosed Motors (NEMA MG1-1.26) are designed for external cooling of the motor by dissipation of the heat by fans blowing over the end shields and through ribbed frames. It is recommended that these be used in locations that are classified as hostile environments. They do afford excellent protection to the winding and other interior parts, but have two areas that must be given consideration:

  1. High ambient conditions further restrict cooling of thrust bearing.
  2. Operation in moist environments cause additional moisture to be sucked in from the outside air as the motor cools (condensation). Space heaters and possible drains are recommended.

When CORRO-DUTY® is specified on Enclosed motors, the following treatments are standard:

  1. Cast Iron construction.
  2. Class F insulation, non-hygroscopic with non-wicking leads.
  3. Neoprene slinger on take-off shaft.
  4. Cadmium plated or epoxy coated screw stock.
  5. Epoxy painted enclosure.

Hazardous Location motors are designed for Class I Group D hazardous areas and bear the Underwriters Laboratory label.

These motors have special features of long metal fits at brackets, bearing caps and leads are sealed to conform to detail specifically approved by Underwriters. Certain electrical and mechanical modifications may not be made without written approval. Some of these are:

  1. Space heaters - cartridge type - made of Chromalox.
  2. Thermostats - Klixon - 1200C trip temperature.
  3. Bearing temperature detectors, 360 frame and larger - RTD company or Minco.
  4. Thermistors.
  5. Extra conduit box for accessories - Krouse Hinds GUPB14.
  6. Oversized outlet box must be "refer to office".
  7. Bolted coupling for VHS motors. Self release is not approved since disengagement can cause sparking. Customers may specify certain features that Underwriters refuse to approve. It is good practice to review with the factory before quoting other than previously listed.

High Thrust Solid Shaft

These motors are similar to the HOLLOSHAFT in design and features except the shaft is solid. Shafts are designed to NEMA MG1-18.590 through 445 frame and industry standards above 445.

This type motor is supplied with annular keyway to withstand up and downthrust and a sled key to transmit torque. An adjustable coupling is offered in limited sizes.

On high thrust, 3600 RPM motors, 440 frame and larger, provision has been made for continuous up and downthrust as standard. When extra heavy downthrust is required, the same upthrust as in the standard will prevail.

Example: 4000 lb. downthrust standard and 4000 upthrust

7000 lb. downthrust extra heavy and 4000 upthrust.

This feature is provided because most applications requiring 3600 RPM have upthrust larger than 30 seconds. In order to protect against bearing failure, the extra upthrust is provided as standard.