15-600 Page 25
B 76904
FIGURE 26 – INSTALLATION OF PUSH RODS
CROSSHEADS
- Crossheads are one-piece
construction and run on replaceable bronze slides
bolted in the frame. Crossheads are made of ductile
iron.
Procedure For Removal
1.
Remove oil stop head assemblies, crosshead pins
and push rods as described above.
2.
Slide the crossheads through the oil stop
openings in the frame and lift them clear. Be
careful to protect the shoe surfaces from damage.
CROSSHEAD SLIDES
- The crosshead slides are cast
of tough bearing bronze. Top and bottom slides are
interchangeable and are bolted into the frame. Slides
are also interchangeable end for end.
The operating load is carried on the lower shoe and
slide when pump is run in prescribed direction.
It is unlikely that upper slides will even require
replacement unless damaged by accident.
It is necessary to remove the jackshaft in order to
reach the cap screws which hold the upper crosshead
slides to the frame on early models. Later models are
provided with openings on the outside of the frame to
reach and remove these cap screws and nuts.
Lower slides may eventually need to be replaced after
long wear or if damaged. It is advisable to remove the
crossheads as described above in order to reach the
countersunk head cap screws which secure the slides
to the frame. The nuts are on the outside and
underneath the frame.
Use of shims between the crosshead slides and the
frame is not recommended as they may fret through.
Use new slides instead of shimming.
Slides can be removed through oil stop head openings
in frame, or through crosshead inspection openings.
OIL STOP HEADS
- Oil stop heads keep the
crankcase oil within the frame. They also keep mud
and liner washing fluids from entering the crankcase.
Oil stop packing consists of two identical seals
mounted in adaptors. They are not adjustable.
The inner seal lip is pointed inward toward the
crankcase to strip oil from the push rod. The outer seal
lip points outward toward liner to strip mud and/or
water from the push rod. Be certain seals are properly
installed.
The seal adaptors, with seals in them, can be slipped
off and on the push rods by removing the clamp
holding piston rods against the push rods and
separating the two flanges. Do not use a screwdriver or
drift to separate the push rod and piston rod flanges.
Turn the pump slightly.
It is essential that oil stop head seals be replaced at
the first indication of leakage. Oil leakage will be
indicated by oil collecting on top of the liner washing
water in the reservoir. If rig water is used for washing
and run to a waste area, it is difficult to check the
above method.
If oil leakage is serious it will show up in a lower oil
level in the crankcase. In this case oil must be added
to the crankcase as required until new oil stop seals
can be installed.
Leakage of mud and water into the crankcase will be
indicated by a milky appearance of the crankcase oil.
Mud will also be seen below oil stop heads on inside of
crankcase through crosshead inspection plate
openings.
When mud is found in crankcase, oil should be
changed. Drain and clean out crankcase before putting
in the new oil. Replace seals in oil stop heads before
running pump.
It is recommended that oil stop head seals be changed
every six months of operation, even though leakage is
not evident.
VALVE CHAMBERS
- The PZ series and PXL pumps
are equipped with individual valve chambers
(cylinders).
Valve chambers are secured to frame with high tensile
strength studs. It is important that nuts on these studs
be checked occasionally for tightness. A loose nut will
eventually cause a stud to break under pulsating load.
These connecting studs extend through the liner clamp
flanges. Liner clamps are clamped by means of above
studs against the liner flanges and serve to clamp
liners tightly against valve chambers. A square rubber
