Pump and Fluid Systems
Chapter 3: Operations
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24
MP-16 2-Piece 5000 psi January 2013
3.3.3
Knocking in the Power End
Even in cases where the knocking
appears to be coming from the power
end of the pump, it is much more likely
that they are caused by conditions in
the drilling fluid than by the actions of
the power end equipment. Therefore,
before checking the power end for
potential causes, you should consult
3.3.2: Knocking in the Fluid end and
follow the procedure outlined there.
If the problem is not in the fluid end,
then check for slop in the wrist pins.
The wrist pins should have a clearance
of no more than 0.002” between the
wrist pin and the crosshead. Insert a
0.002” feeler gauge and see if it will fit
through all 360.
Next, check the clearance of the
crossheads,
which
should
have
between 0.014
” and 0.030” between
them and the guides. Also check the
crankpin insert bearings, which should
be tight in the frame, and can cause
knocking when loose. Finally, check
the crosshead guides for upsets, as
these can also cause knocking.
If none of the above is the case,
you will need to disassemble the power
end so you can access the wrist pin
(see 5.2: Power End Maintenance
Procedures). Remove the outer
screws in the retaining plate and bump
the pin lightly. If it moves easily in the
crosshead, then the pin and bearing
should be removed and reinstalled or
replaced if damaged (as per 5.3.5:
Installing the Wrist Pin Bearing).
If none of these solutions help,
contact a Weatherford professional.
