A pump or a fan is the equipment, and an electric motor drives it. The same kind of fault can start in either one, so it helps to know what each part does. Choose an example to see how it is put together.
This page used to show a submersible borehole (well) pump. It now shows asubmersible drainage pump instead, which is a different machine: it is lowered into a pit or sump to pump water out. The change reflects the kind of equipment PERS wants to show. It does not mean borehole pump motors cannot be repaired.
These examples are for learning. PERS repairs all kinds of industrial electric motors, including the motors inside equipment like this. For repairs to the pump or fan parts themselves, ask the shopabout your equipment. All content on this page is awaiting review by the PERS technical team.
Moves clean water from one place to another, or raises its pressure, for example from a tank into a building’s pipework.
Close-coupled, single-stage, end-suction centrifugal pump
A standard electric motor is joined to the pump by a rigid coupling inside an adapter (motor stool). The pump has no bearings of its own, so the motor’s bearings carry the impeller. Water comes in along the line of the shaft (axial inlet) and leaves at the top (radial outlet) through a spiral casing called a volute. A single mechanical shaft seal stops water escaping along the shaft.
Tap a part, or a name below, to see what it does.
Electric motor
A standard induction motor that turns the pump. In this design its bearings also carry the impeller. More about the electric motor
Motor bearings
The motor’s two bearings support the rotating shaft and, in a close-coupled pump, the impeller as well. More about the motor bearings
Shaft and rigid coupling
The pump shaft is clamped to the motor shaft by a rigid coupling, held by set screws and covered by a coupling guard. More about the shaft and rigid coupling
Adapter (motor stool)
The open frame that joins the motor flange to the pump and surrounds the coupling. More about the adapter (motor stool)
Mechanical shaft seal
Two precision seal faces, one turning with the shaft and one fixed, pressed together to keep water in. More about the mechanical shaft seal
Pump cover
The plate that closes the back of the pump housing around the shaft. More about the pump cover
Impeller
The spinning part with curved vanes that flings water outward from its centre. More about the impeller
Wear ring
A replaceable ring in the housing next to the impeller’s inlet. More about the wear ring
Pump housing (volute casing)
The spiral casing that collects water from the impeller and turns its speed into pressure. More about the pump housing (volute casing)
Simplified 3D model of a close-coupled end-suction pump. Not a specific product and not to scale. It is a simplified model for learning, not a manufacturer’s design or a repair guide. Pending review by the PERS technical team.
The pump is the equipment, and a standard induction motor drives it. A pump fault (a worn impeller, a leaking seal) and a motor fault (a winding, a bearing) can cause similar signs, such as noise or the protection tripping, so both are checked.
A standard motor provides the turning force. Its own parts (stator, windings, rotor, fan) are explained in the Motor explorer.
Sources:Grundfos NB/NBG instructions, §10.3 p. 34; §12 p. 36.
In a close-coupled pump the motor and pump are joined rigidly, so the motor bearings also carry the impeller and its loads. Long-coupled pumps differ: there, the motor and pump have separate bearings.
Sources:Grundfos Pump Handbook, §1.1.4 p. 12; Grundfos NB/NBG instructions, §10.4 p. 34; §12 p. 36; ABB installation and maintenance manual, §7.1 p. 19.
Passes the motor’s turning force to the impeller. The shaft also runs through the mechanical seal, so its surface matters for sealing.
Sources:Grundfos NB/NBG instructions, §4.1 p. 14; §12 p. 36; Grundfos Pump Handbook, §1.1.9 p. 16.
Holds the motor and pump in line. The opening around the coupling is closed by the coupling guard.
General description: not all of this is matched to a listed source yet.
Sources:Grundfos NB/NBG instructions, §4.1 p. 14.
The rotating part is fixed on the shaft; the stationary part sits in the pump. A spring and the water pressure press the two faces together, and a thin film of liquid between them lubricates the seal. Secondary seals, such as O-rings, stop leaks around the seal parts.
Sources:Grundfos Pump Handbook, §1.3–1.3.1 pp. 28–29; Grundfos NB/NBG instructions, §2.2.2 p. 9; §10.2 p. 34; §12 p. 36.
Closes the pump housing on the motor side and holds the stationary part of the shaft seal. O-rings seal it to the housing.
General description: not all of this is matched to a listed source yet.
Sources:Grundfos NB/NBG instructions, §2.2.2 pp. 8–9; §12 p. 36.
Water enters at the impeller’s centre (the eye) and the vanes fling it toward the outside, adding energy. The impeller’s diameter is part of the pump’s specification.
Sources:Grundfos Pump Handbook, §1.1.1 p. 8; Grundfos NB/NBG instructions, §2.2.2 pp. 6–8; §12 pp. 35–36.
Sits at the narrow gap between the impeller and the housing, where water could leak back from the high-pressure side to the inlet. Being a separate ring, it can be replaced when that gap wears.
General description: not all of this is matched to a listed source yet.
Sources:Grundfos NB/NBG instructions, §2.2.2 pp. 8, 10; §12 p. 36.
Water enters through the inlet on the shaft line and leaves through the outlet at the top. The spiral (volute) shape gathers the water from around the impeller and slows it, raising its pressure. In this design the housing has the feet that support the pump.
Sources:Grundfos NB/NBG instructions, §2.1 p. 5; §2.2.2 p. 7; §12 pp. 35–36; Grundfos Pump Handbook, §1.1.4 p. 12; §1.1.6 p. 15.
Each problem can have several causes, some outside the equipment itself. This is not a diagnosis. Switch faulty equipment off and have it checked by a qualified person.
Sources:Grundfos NB/NBG instructions, §12 item 1, p. 35.
Sources:Grundfos NB/NBG instructions, §12 item 2, p. 36.
Sources:Grundfos NB/NBG instructions, §12 item 3, p. 36.
Sources:Grundfos NB/NBG instructions, §12 item 4, p. 36.
Send a photo of the nameplate, describe what is happening, and say what the equipment is. Bearing or seal numbers help only if you already know them. Please don’t take equipment apart to get a quote.
Pricing & pickup: what pricing depends on, and pickup and delivery by arrangement.
Sources:Grundfos NB/NBG instructions, §2.1, §4.1, §10, §12; Grundfos Pump Handbook, §1.1, §1.3.
Pumps water out of flooded pits, sumps, excavations and construction sites. Tsurumi lists construction, mining and general drainage among the uses for this series.
Top-discharge submersible drainage pump with a dry motor and two mechanical seals in an oil chamber
Based on the Tsurumi KTZ series, using the 1.5 kW model (about 650 mm tall) for proportions. A dry three-phase motor sits in a sealed cast-iron housing. Below it, an oil chamber holds two mechanical seals. At the bottom, a semi-open impeller draws water in through a strainer and pushes it up a passage beside the motor and out of the top. Tsurumi says this flow helps cool the motor.
Tap a part, or a name below, to see what it does.
Top outlet and side passage
Where the pumped water leaves. It rises through a passage beside the motor and out of the top. More about the top outlet and side passage
Cable entry
Where the power cable enters the sealed motor. More about the cable entry
Motor housing and head cover
The sealed cast-iron shell around the motor. In this design the motor inside is dry (air-filled). More about the motor housing and head cover
Motor protector
A built-in device that switches the motor off if it gets too hot or draws too much current. More about the motor protector
Stator and windings
The fixed part of the motor: an iron core wound with copper wire. This is the part a rewinding shop rewinds. More about the stator and windings
Rotor
The turning part inside the stator, fixed on the shaft. More about the rotor
Shaft
A stainless steel shaft that carries the rotor and, at its lower end, the impeller. More about the shaft
Bearings (upper and lower)
Two ball bearings, one above and one below the motor, keep the shaft centred. More about the bearings (upper and lower)
Oil chamber
A sealed chamber of oil between the pump and the motor. Both mechanical seals run in it. More about the oil chamber
Mechanical seals
Two seals on the shaft that stop water getting into the motor. More about the mechanical seals
Impeller
The spinning part that pushes the water. More about the impeller
Pump casing and wear plate
The shell around the impeller, and the replaceable plate under it. More about the pump casing and wear plate
Strainer
The screen at the bottom where water enters. More about the strainer
Simplified 3D model of a top-discharge drainage pump, based on the layout of the Tsurumi KTZ series. The heights of the inside parts are estimates. Not a specific product and not to scale. It is a simplified model for learning, not a manufacturer’s design or a repair guide. Pending review by the PERS technical team.
The motor and the pump are one sealed unit. The seals, the oil chamber and the cable entry keep water out of the motor. If water gets past them, the windings can fail. That is when rewinding may be needed.
Cost: Some submersible pump repairs also require seals, the specified oil, and checks for water entry. These can add to the repair cost. Pricing & pickup
The impeller pushes water into a passage that runs up the side of the motor housing to the outlet on top, where the hose connects. Tsurumi says this top-discharge, side-flow layout cools the motor, even when the pump is only partly under water. The handle on top is for lowering and lifting the pump. In the model, the passage is drawn as a single channel for clarity.
General description: not all of this is matched to a listed source yet.
Sources:Tsurumi KTZ product page, Features; Tsurumi KTZ datasheets, KTZBL-P1 feature 6; 60-SS-KTZ-01 §1; DM-KTZ-01.
The cable passes through a strain relief, a compression seal and a rubber cable boot on the head cover. These stop water getting into the motor along the cable. Tsurumi also describes a block that stops water creeping along the inside of a damaged cable, listed with its larger models.
General description: not all of this is matched to a listed source yet.
Sources:Tsurumi KTZ datasheets, 60-SS-KTZ-01 §5; SEC-KTZ-01 item 1.
Keeps water away from the motor. In this design only the separate chamber below holds oil. Some other submersible pumps have oil-filled motors instead.
General description: not all of this is matched to a listed source yet.
Sources:Tsurumi KTZ datasheets, KTZBL-P1 feature 3; 60-SS-KTZ-01 §4; SEC-KTZ-01 items 50, 64.
It sits against the windings. Tsurumi says it also responds to a missing phase (single phasing), when one of the three supply lines is lost.
General description: not all of this is matched to a listed source yet.
Sources:Tsurumi KTZ datasheets, KTZBL-P1 feature 4; SEC-KTZ-01 item 53.
Current in the copper windings makes a turning magnetic field, and that field turns the rotor. If water gets into the motor, or the motor overheats, the insulation on the windings can break down.
General description: not all of this is matched to a listed source yet.
Sources:Tsurumi KTZ datasheets, 60-SS-KTZ-01 §4; SEC-KTZ-01 item 56; Tsurumi LB/HS manual, Maintenance, item (e).
An iron core with metal bars. The stator’s magnetic field makes it turn.
General description: not all of this is matched to a listed source yet.
Sources:Tsurumi KTZ datasheets, SEC-KTZ-01 item 55.
Runs from the motor down through the bearings and seals to the impeller. A replaceable sleeve protects it where the lip seal runs.
Sources:Tsurumi KTZ datasheets, SEC-KTZ-01 items 54, 71.
The upper bearing sits under the head cover. The lower one sits just above the oil chamber. Both are sealed ball bearings.
General description: not all of this is matched to a listed source yet.
Sources:Tsurumi KTZ datasheets, 60-SS-KTZ-01 §4; SEC-KTZ-01 items 52A, 52B.
In this design the oil lubricates and cools the seal faces, and keeps them out of the dirty water being pumped. Tsurumi’s “Oil Lifter”, a small part in the chamber, lifts oil to the upper seal if the level drops. The manufacturer states the oil type and amount for each model.
Sources:Tsurumi KTZ datasheets, 60-SS-KTZ-01 §3; SEC-KTZ-01 item 35; Tsurumi product technology, Oil Lifter; Tsurumi LB/HS manual, Maintenance, item (e); Mining Report, Tsurumi oil check, Oil check.
Each seal has two very flat rings, one turning with the shaft and one fixed, pressed together by a spring. A thin film of oil between them seals and lubricates. In this design both seals sit in the oil chamber, and their faces are silicon carbide. A lip seal on a shaft sleeve below them adds another barrier against the pumped water.
Sources:Tsurumi product technology, Oil Lifter: mechanical seal; Tsurumi KTZ datasheets, KTZBL-P1 feature 2; SEC-KTZ-01 items 25, 26, 71; Mining Report, Tsurumi oil check, Oil check.
A semi-open impeller (its vanes are open on one side), made of high-chrome cast iron to resist wear from sand and grit. It throws water outward into the casing.
General description: not all of this is matched to a listed source yet.
Sources:Tsurumi KTZ product page, Features; Tsurumi KTZ datasheets, 60-SS-KTZ-01 §2; SEC-KTZ-01 item 21; Tsurumi KTZ catalogue, Features.
The casing guides water from the impeller into the side passage. The wear plate (suction cover) sits just below the impeller. It can be adjusted and replaced as it wears.
General description: not all of this is matched to a listed source yet.
Sources:Tsurumi KTZ datasheets, 60-SS-KTZ-01 §2; SEC-KTZ-01 items 20, 22; Tsurumi KTZ catalogue, Features.
Keeps larger solids out of the impeller. The pump stands on it.
General description: not all of this is matched to a listed source yet.
Sources:Tsurumi KTZ datasheets, SEC-KTZ-01 item 23.
Each problem can have several causes, some outside the equipment itself. This is not a diagnosis. Switch faulty equipment off and have it checked by a qualified person.
Sources:Tsurumi LB/HS manual, Maintenance, item (e); Mining Report, Tsurumi oil check, Oil check.
Partly general: not all causes are matched to a listed source.
Sources:
Partly general: not all causes are matched to a listed source.
Sources:
Partly general: not all causes are matched to a listed source.
Sources:Tsurumi KTZ datasheets, KTZBL-P1 feature 4.
Send a photo of the nameplate, describe what is happening, and say what the equipment is. Bearing or seal numbers help only if you already know them. Please don’t take equipment apart to get a quote.
Pricing & pickup: what pricing depends on, and pickup and delivery by arrangement.
Sources:Tsurumi KTZ product page, Product page; Tsurumi KTZ datasheets, KTZBL-P1, DM-KTZ-01, SEC-KTZ-01, 60-SS-KTZ-01; Tsurumi product technology, Oil Lifter; Tsurumi LB/HS manual, Maintenance.
Moves outdoor air through the condenser coil so the air-conditioning unit can get rid of heat.
PSC condenser fan motor (totally enclosed air-over) with a riveted propeller blade
A single-phase permanent split capacitor (PSC) motor with ball bearings. The air stream from the fan it drives also keeps it cool. It needs a run capacitor, which is mounted separately in the unit. A propeller-type fan with riveted blades is fixed on the motor shaft, behind the unit’s fan guard.
Tap a part, or a name below, to see what it does.
Fan guard
Part of the outdoor unit: the grille that keeps hands and objects away from the blade. More about the fan guard
Fan blade
Angled (pitched) blades riveted to a steel centre plate (spider), with a hub that fits on the motor shaft. More about the fan blade
Shaft
The motor shaft that carries the fan blade. In the example motor it is 1/2 in. with a double flat. More about the shaft
Ball bearings
Two ball bearings support the shaft. Some other condenser fan motors use sleeve bearings instead. More about the ball bearings
Shell and end shields
The closed motor body. It has no fan of its own and is cooled by the air stream from the blade. More about the shell and end shields
Stator windings
The main and auxiliary windings of a single-phase PSC motor. More about the stator windings
Rotor
The squirrel-cage rotor that the windings’ field turns. More about the rotor
Thermal protector
A built-in device that switches the motor off if it overheats and, in this example, resets by itself. More about the thermal protector
Mounting studs and belly band
Studs at both ends of the motor, or a band around its body, fix it in the unit. More about the mounting studs and belly band
Run capacitor (mounted separately)
Required by the PSC motor, but mounted in the unit rather than on the motor. More about the run capacitor (mounted separately)
Simplified 3D model, shown with the shaft horizontal for clarity. Outdoor units mount the motor in different orientations. Not a specific product and not to scale. It is a simplified model for learning, not a manufacturer’s design or a repair guide. Pending review by the PERS technical team.
The fan is the equipment, and a small PSC induction motor drives it. An air-over motor relies on the fan’s air stream to stay cool, so a damaged blade or blocked airflow can make a healthy motor overheat.
Guards the turning blade. In many units it also carries the motor mounting.
General description: not all of this is matched to a listed source yet.
Moves air through the condenser coil. Blades are chosen to suit the unit’s airflow, by diameter and blade design.
General description: not all of this is matched to a listed source yet.
Sources:Revcor condenser fan blades, product page; Regal Rexnord FASCO D7907 data, key features.
Passes the motor’s turning force to the blade. Flats on the shaft give the blade’s hub screws a firm seat.
Sources:Regal Rexnord FASCO D7907 data, key features; rain shield accessories.
Support the rotor and the overhung fan blade, and keep the rotor centred in the stator.
Sources:Regal Rexnord FASCO D7907 data, key features; SKF Bearing damage and failure analysis, p. 6.
Totally enclosed: the shell and the end shields close the motor. The end shields hold the bearings. Cooling comes from the air the fan moves over the shell.
Sources:Regal Rexnord motor definitions, Air-over; End shield; Regal Rexnord FASCO D7907 data, key features.
A PSC motor has two windings: a main winding and an auxiliary winding. The run capacitor is connected permanently with the auxiliary winding. It shifts that winding’s current in time, so the motor can start and run on a single-phase supply.
General description: not all of this is matched to a listed source yet.
Sources:Regal Rexnord motor definitions, single-phase motor types; Regal Rexnord FASCO D7907 data, key features.
As in other induction motors, a rotor made of thin steel sheets with cast metal bars, fixed to the shaft.
Sources:ABB Motor guide, §5.1 p. 59.
Senses current and heat and protects the motor against overheating from overload or failure to start. An automatic-reset protector can restart the motor without warning once it cools.
Sources:Regal Rexnord motor definitions, Thermal protector; Regal Rexnord FASCO D7907 data, nameplate: thermal protection automatic.
The example motor has extended studs at the shaft end and lead end, and can also be held by a belly band (supplied separately).
Sources:Regal Rexnord FASCO D7907 data, key features.
Stays connected while the motor runs. The example motor requires a 10 µF, 370 V capacitor that is not supplied with the motor.
Sources:Regal Rexnord FASCO D7907 data, key features.
Each problem can have several causes, some outside the equipment itself. This is not a diagnosis. Switch faulty equipment off and have it checked by a qualified person.
Partly general: not all causes are matched to a listed source.
Sources:Regal Rexnord motor definitions, Thermal protector; Regal Rexnord FASCO D7907 data, capacitor required.
Partly general: not all causes are matched to a listed source.
Sources:Regal Rexnord motor definitions, Thermal protector.
Partly general: not all causes are matched to a listed source.
Sources:SKF Bearing damage and failure analysis, p. 8.
Partly general: not all causes are matched to a listed source.
Sources:Regal Rexnord motor definitions, Air-over.
Send a photo of the nameplate, describe what is happening, and say what the equipment is. Bearing or seal numbers help only if you already know them. Please don’t take equipment apart to get a quote.
Pricing & pickup: what pricing depends on, and pickup and delivery by arrangement.
Sources:Regal Rexnord FASCO D7907 data, key features, nameplate; Regal Rexnord motor definitions, definitions; Revcor condenser fan blades, product page.
