Lesson 3:

Northern Pump Components

Lesson 3: Northern Pump Components

Northern® PumpDivision of McNally Industries

Lesson 3:

Northern Pump Components

Drive Gear

Driven Gear

Driven Shaft

Drive Shaft

Gears & Shafts –The gears are the heart of the positive displacement gear pump. They consist of a drive gear and a driven gear. They are installed the drive and driven shaft using a press fit. In Some pumps, the gears are “floating” which means they are allowed move freely on both the shafts. The drive shaft has a keyway installed to help drive the gear. Nearly all of the Northern gears are helical design, and all feature heat treated construction. All gears have the profile ground into them which offer significant life cycle advantages.

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Lesson 3:

Northern Pump ComponentsPump Cylinder

This component is the part of the housing that the gears rotate within. The clearances around the outside diameter of the cylinder are tightly controlled based on desired volumetric efficiency and performance. The clearance can be increased for higher viscosities to reduce horsepower required, or decreased to improve flow. Cylinders are available with flanged connections, NPT connections, or “blind” on pumps with gears too narrow for a piping connection to mount directly. Northern has many different configurations available.

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FlangedBlind

Lesson 3:

Northern Pump ComponentsPump Liner Plates

These components are located on both sides of the cylinder for pumps that require them. They are typically used when the bearing plate wear surface is not acceptable for the gear to rotate against, or in situations where the liquid being pumped is extremely abrasive. Northern Pump offers several options for materials of construction, most of which are very hard. An extremely valuable benefit of the liner plates is the ability to replace them during an overhaul, thus, reducing maintenance and life cycle costs.

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Lesson 3:

Northern Pump ComponentsPump Bearing Plates

These components are located on both sides of the cylinder, or outside the liner plates on pumps that are liner plate equipped. Their main purpose is to hold the main shaft bearings. They also provide a wear surface for pumps without liner plates. As a result, Northern Pump bearing plates are available in many materials of construction, and with special inlayed materials.

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Inlayed Wear Surface

Lesson 3:

Northern Pump ComponentsPump Shaft Bearings

Bearing design and configuration is arguably the most important factor in estimating and assessing the life cycle of a gear pump. Northern pump bearings are lubricated by the liquid being pumped, and as a result are available in a wide variety of types and configurations. The most common type of bearings for liquids with reasonable lubricity is our 52100 alloy steel roller type. Northern Shafts are specially designed to be the inner bearing race. Another common design incorporates sleeve type bearings of a variety of materials. Is some cases, the bearing plate itself in designed to have an integral bearing surface.

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Lesson 3:

Northern Pump ComponentsPacking Plate, Suction & Discharge Plate, Seal Adapter Plate

This plate is typically located on the front of the pump. This plate can be configured in hundreds of ways, based on the type of shaft seal, piping connections, or pump design. Packing plates are designed for use on pumps that use packing rings for shaft sealing. Suction & Discharge plates have pipe connections installed, or flanges welded on. These plates are typically used with mechanical seals for shaft sealing. The are configured to hold the seal seat and also the seal housing. For flanged cylinders, Seal adapter and packing plates are used as there is no connection needed in this plate.

Seal Adapter Plate Weldment w/ Flanges

Blind Seal Adapter Plate

Lesson 3:

Northern Pump ComponentsSeal Housing or Packing Gland

The seal housing holds the mechanical seal and seat for pumps that are in this configuration. The have a weep hole to identify when a seal failure has occurred, and are usually sealed with a gasket and O-Rings. Depending on the seal type, it may hold either, both components. They also have a roller bearing that is greased externally. This bearing helps stabilize the shaft which extends seal life. For pumps equipped with packing, a gland located on two studs provides for the ability to tighten the packing to contain leakage.

Seal Support Bearings

Lesson 3:

Northern Pump ComponentsPump Mounting Brackets

The mounting brackets are located on both the front and rear of the pump. The allow the pump to be bolted and aligned with virtually any size motor or driver. Northern Pump customizes these brackets to fit the pump “Drop” to the motor “Drop”. This is the established distance from the center of the shaft to the bottom of the feet for both.

Pump Drop

Motor Drop

Lesson 3:

Northern Pump ComponentsPump End Plate

This plate is located on the rear of the pump on pumps with packing or a single mechanical seal. The only purpose for this plate is to “cap” the end of the pump off. End plates may contain special grooves to help move liquid through the pump, or NPT connections for pumps designed with internal heating ports.

Pump design with internalHeating connections. NPT connections are installed

in the end plate

Lesson 3:

Northern Pump ComponentsMechanical Shaft Seals and Packing

The drive shaft is constantly exposed to the equivalent of the suction pressure on the pump. I cases where it is less than 5 PSI, packing may be an acceptable means of sealing the shaft. However, in many cases, processors want a more reliable sealing mechanism. Northern Pump offers several different types of Mechanical seals. In cases where the suction pressure exceeds 25 PSI, we add the hydraulic balance option which places an additional mechanical seal at the rear end of the pump.

Type 21

Type 8-1, 8B-1, Type 9

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Lesson 3:

Northern Pump ComponentsPump Unit Assembly

Northern Pump is a full service gear pump manufacturer. We frequently build and assemble pump unit assemblies, or “Skids” as they are sometimes called. They typically consist of a Northern Heavy Duty Gear Pump, Electric motor, Shaft Coupling, and Coupling Guard, mounted on a Unit Base. We configure the mounting holes to match the application and install lifting hooks to safely move the unit.

Unit Base

Electric Motor

Northern Heavy Duty Gear Pump

Shaft Coupling

Coupling Guard