b.
Place the six release springs (3) in position in the machined counterbored holes in the hub-and-back plate.
c.
Install a driving plate (4), center plate (5), driving plate (6), center plate (7), and driving plate (8), onto the hub-
and-back plate. Index the center plates to align with the springs and hub-and-back plate.
d.
Insert six rollpins (10) into the holes provided in the pressure plate (9). Install the insulator plate (11) onto the
rollpins of the pressure plate, and use a rubber mallet to firmly set the insulator plate on the rollpins.
e.
Install the pressure and insulator plate assembly onto the hub-and-back plate, making certain to align the bores
in the pressure plate with the release springs. After placing the pressure plate in position, center the springs by
inserting a drift pin or suitable tool through the holes in the pressure plate.
f.
Install the diaphragm assembly (12) against the insulator plate on the hub-and-back plate.
g.
Install the front cover plate (13) against the diaphragm assembly hub side down, aligning the hub splines and the
air hose connections on the diaphragm assembly.
NOTE
The air inlet holes must be assembled within 7-1/2 degrees of the keyway in the hub-and-back
plate.
h.
Clamp the front cover plate down, and secure it with the special nut (14). Tighten the nut until it bottoms, then
unscrew the nut until a setscrew hole in the nut is aligned with the slot in the hub-and-back plate. Secure the
special nut to the huband-back plate with the setscrew (15).
i.
If replacement is necessary, place the nameplate (16) in position on the front plate, and secure it with two
drivescrews (17).
4-5 MAINTENANCE OF THE MUD PUMP.
4-5.1 Mud Pump Fluid End. (Figure 4-8).
4-5.1.1 Replacing Valves.
a.
Remove nuts (1), cover (2) and gasket (3). Lift out spring (4) and valve assembly (5).
b.
Examine the valve assembly for wear. If the rubber insert (8) is worn it may be replaced.
c.
Remove the screw (6), washer (7), insert (8) from valve (9).
d.
Examine the valve seat (10) in the fluid cylinder. If it has been damaged by wear, it will need to be replaced. Do
not remove the seat (10) unless replacement is required.
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