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NORA Oilheat Technicians Manual

10-8 Motors Excessive oil can also be a problem. Follow the recommended Figure 10-10 illustrates the types of bearings. Ball bearings consist of a ring of steel balls held in place around the rotor. As the rotor turns, the balls are free to roll, aided by lubricating grease. Because the rotor is attached to the inside ring of the ball bearing assembly, there is no end play (the fan wheel is not free to move away from the motor flange). The gap between the fan wheel and the housing is kept constant, minimizing air leakage and increasing the zero-flow static pressure by as much as .3 to .4 inches of water column, compared to sleeve bearing motors. Figure 10-10: Bearings Figure 10-9: Reversing rotation of burner motor wires lubrication procedure. Sleeve Bearing Ball Bearing Sleeve Bearing Filler Plug SShhaafftt Oil Wick Oil Well Bearings There are two basic types of bearings used on most of the motors in our industry: they are sleeve type and ball bearing type. Sleeve bearings, also called bushings or self-aligned bearings, are special metal sleeves around the rotor shaft. Oil is applied between the shaft and the sleeve; the thin film of oil lubricates the shaft and allows it to turn with little friction. Many modern sleeve bearings are permanently selflubricating and have a sponge like material that continually supplies oil as the rotor turns. Sleeve bearings require increased starting torque if they are contaminated by rust or dirt. Worn, dry, or tight bearings will cause motor overload and possible thermal overload lockout. Chapter 10 Motors


NORA Oilheat Technicians Manual
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