MTS Series 249G2 Swivels - Manual (Page 26)

Series 249G2 Swivels 26
Checking for Swivel Bearing Backlash—Observation
Maintenance
Checking for Swivel Bearing Backlash—Observation Method
During system operation, you should examine the swivel assembly to determine
if there are any visible signs of backlash. If possible, this examination should be
performed immediately after system installation, so that you can better recognize
the “normal” appearance, sound, and feel of a properly adjusted swivel in case an
adjustment becomes necessary in the future.
Never allow any part of your body to get in the path of motion of any
hydraulic component or its associated fixturing. Never rely on your reflexes
to protect you from unexpected actuator movement.
Actuator and associated fixturing movement can injure personnel or
damage equipment it comes in contact with. Unexpected actuator
movement can happen much too quickly for you to get out of the way.
Touch or stand near hydraulic equipment only if you are not in the path of motion
of any actuator or its associated fixturing. If it is not possible to access the
equipment without crossing the path of motion, do not attempt to access the
equipment.
Swivel bearing backlash can produce an audible clicking noise from the spherical
bearing. This sound might be difficult or impossible to hear above the noise of
the other components in the testing system. Using a stethoscope can enable you
to hear the noise and determine if backlash is present.
When there is an excessive amount of backlash, there can be a visible separation
between the ball and race of the spherical bearing. This separation will be quite
small, and the position of the swivel can make it impossible to observe. Care
should be taken to differentiate between deflection and backlash. Deflection
appears as relative motion between the swivel eye and jaw. Some amount of
swivel deflection is normal. Backlash is distinguished from deflection by relative
motion between the ball and race of the spherical bearing.
Extreme care should be take before attempting to feel backlash.
An unexpected actuator motion could cause grave injuries to the person
checking the swivel.
Unless the swivel assembly can be accessed from a position that provides
adequate protection from unexpected actuator movement, you should not attempt
to “feel” the backlash in the system.
The presence of swivel bearing backlash can often be detected by the “feel” of
the swivel. If backlash is present, a mild thumping sensation can be felt when a
hand is placed on the surface of the swivel.