Waukesha Bearings CQ Tilting Pad Thrust Bearings - Manual (Page 5)

- 5 -
Note: No excessive force should be necessary to bring the two cage ring joint faces into
contact when correct engagement has occurred.
The final operation is to rotate the complete ring until the stop pin rests on the casing
joint face (or groove). In all standard bearings the stop pin is at the right hand side when
looking on the face of the thrust pads.
After the above operations, the upper casing is placed in position ensuring the stop pin
engages with the hole or recess in the casing top. This closure should be as soon as
possible to exclude dirt and other foreign bodies. Before finally closing the bearing
however, all surfaces should be liberally smeared with clean oil.
When dismantling the bearings the above operations should be reversed.
Note that, as the thrust rings are trapped into position, when the casing top is lifted,
there is no danger of the half rings being lifted with it and, subsequently, falling with
the risk of damage to the pad or collar faces.
Note: The bearings as supplied, including any protective coating of oil, can be installed
directly into the machine.
6.4.Axial clearance
Some axial clearance, or end play, is essential to give room for the formation of the oil
film between the collar and the thrust pads and also to allow for expansion of the parts
as the bearing warms up to its operating temperature. In the case of double thrust
bearings, allowance must be made for the oil films on both sides of the collar, noting
that the idle, or non-loaded side will have a thicker oil film than the working, or load-
carrying face.
The total minimum axial clearance required is given in the contract drawing.
If the clearance is too small, excessive pressures will be built up in the oil films causing
a high bearing temperature and excessive power loss; end even, in extreme cases,
leading to bearing damage.
A clearance larger than necessary will not cause any harm to the bearing.
The clearance must be checked at erection and this must be done with all surfaces
wiped clean and dry or a false figure will result. Never use feelers between the face and
collar since this will tend to give false readings, apart from the risk of damaging the pad
faces. The simplest method of checking the clearance will depend largely upon the
individual machine, but the most reliable method is to jack the rotor axially in each
direction and measure the total movement.
Alternatively, the rotor may be pushed against one face and the clearance measured by
feelers between the back of the opposite thrust ring and the casing.
Note: In order to overcome lever/assembly settlement, it is recommended that a
reasonable load be applied to the bearing when taking these measurements (see contract
drawing).
If the thrust bearings are supplied with a machining allowance on the external face of
the spacer plate (item 8), it is important that they should be laid on a flat horizontal
surface (taking care to protect the whitemetal faces) with the spacer plate (item 8)