FIST 2-1 Flashcards
The rotating weight of the unit is transferred through the thrust bearing, through the upper bridge, and through the ___ ____ to the foundation
Stator frame
On an umbrella unit, the thrust bearing is located
Below the rotor
The three typical types of thrust bearings are
adjustable shoe, self equalizing and spring loaded
The adjustable shoe thrust bearing uses a ___ under each of the shoes for adjusting the height and loading of the shoes.
Jack screw
To install the thrust block, it is heated to a predetermined temperature and lowered over the shaft, again with the unit on jacks. The block is set on the ____ ____
the rigging removed,
and the radial keys and keeper installed.
Thrust shoes
With the thrust block still hot and installed on the shaft, the jacks are released to:
allow the full weight of the unit to set the block in place against the keys
Using the thrust bearing high pressure lubrication system, allows for both ___ and ___ movement required during the alignment process.
Rotational; lateral
As alignment deviates, loading on the guide bearings will increase as will ___ levels
Vibration
Any increase in vibration from misalignment will decrease the ____ factor of operation in severe conditions
Safely
The concentricity of the stationary components can be checked by:
hanging a single tight wire to check plumb reference
The tolerance for plumb of center of shaft run-out is _____ multiplied by the length of the shaft
from the highest plumb reading to the lowest plumb reading in inches.
0.000025
The tolerance for shaft straightness should not be more than _____ inch from a straight line connecting the top and bottom reading point.
0.003
The parallel misalignment between two shafts that occurs at the coupling between the generator and turbine shaft is called
Offset
Shaft dogleg is
angular misalignment of the turbine and generator shafts
Plumb wires should be hung ___ apart.
90°
The first preliminary check during the alignment process, is to loosen the mounting bolts on each leg of the upper bridge to check for:
Soft foot
One of the most important things to check before taking alignment readings is to make sure the:
Shaft is free
The procedure that is particularly useful during major overhauls is to temporarily install the upper and lower bridges and the head cover to check the concentricity of the stationary components with a single plumb wire and a(n):
Electric micrometer
When the unit is centered the concentricity can be checked by taking ____ readings at the turbine guide bearings, seal rings, generator air gap, etc.
Clearance
Correcting dogleg between the generator and turbine shafts requires installing a shim pack between the:
Coupling faces
The second method used for aligning Hydrounits with Adjustable Shoe Thrust Beanngs is using the adjustable feature of the shoes only to achieve equal:
Loaded
On Self Equalizing Thrust Bearings, one step in the procedure is to center the shaft in the ____ ____ housing and move the ____ of the shaft to make plumb
turbine bearing; top
The final step in the alignment process is the installation and adjustment of the _____ _____
Guide bearings
To make the generator guide bearings concentric to the turbine guide bearing, the ____ is used as a reference
Shaft
When installing the turbine bearing, several ____ are used to prevent lateral movement
Dowels
