Service
Reassembling the Displacement Pump
NOTE:
When thread sealant is specified, use low
strength (blue) Loctite
r
.
1. Place the two halves of the piston (16) around the
packing (15*) and snap them together. See Fig.
10.
2. Apply thread sealant to the piston rod (17) threads.
Screw the rod through the piston and packings and
into the special piston nut (12). Torque the nut to
68–81 N
S
m (50–60 ft-lb).
3. With the lower pump housing (11) turned upside
down, install the balls (5). Install the seats; place
the vented seat (32) in the left side as viewed in
Fig. 9 (housing has a label to identify the correct
side), and the non-vented seat (6) in the right side.
Install the gaskets (7*).
NOTE:
The seats (6 and 32) are not reversible; the
chamfered side must face the ball.
4. Place the intake housing (10) on the lower pump
housing (11). Install the lockwashers (8) and
capscrews (9). Torque to 34–40 N
S
m (25–30 ft-lb).
See Fig. 10.
5. Place the intake housing (10) in a vise. Place one
o-ring (2*)
in each side of the lower pump
housing (11)
where the tubes (3) sit. Place anoth-
er o-ring (2*)
in the grooves at each end of the
tubes.
Place a gasket (18*) in both the upper and
lower housings (1 and 11). Position the tubes and
cylinder (4) in the lower housing (11).
6. Lubricate the inside of the cylinder (4). Slide the
piston assembly into the cylinder.
7.
Lubricate the throat packings and glands.
Install them one at a time in the throat of the upper
pump housing (1). Make sure the lips of the v-
packings face down into the housing, and use a
finger to seat the parts: the male gland (19
{
), one
UHMWPE packing (20
{
), one leather packing
(25
{
), UHMWPE, leather, UHMWPE, and the
female gland (26
{
). Install the packing nut (21)
finger-tight.
NOTE:
Model 237–220 and 237–221 displacement
pumps use 5 PTFE v-packings in the throat, instead of
3 UHMWPE (20) and 2 leather (25).
8. Install the upper pump housing (1). It may not seat
well on the tubes and cylinder. Apply thread sea-
lant to the threads of the three tie bolts (13). Install
the bolts and lockwashers (14) from the lower
pump housing (11). As you tighten the bolts into
the upper housing (1), they will draw the housings
firmly onto the tubes and cylinders. Tighten the
bolts uniformly and torque to 34–40 N
S
m (25–30
ft-lb).
9. Torque the packing nut (21) to 68–74 N
S
m (50–55
ft-lb).
10. Place a ball (23), seat (24) and gasket (7*) in each
side of the outlet housing (22). Install the outlet
housing on the upper pump housing (1). Note that
the flatter side of the housing faces the
outside
edge of the pump. Install the lockwashers (8) and
screws (9), and torque to 34–40 N
S
m (25–30 ft-lb).
CAUTION
When installing the outlet adapters in the pump, be
sure to hold the flats of both parts with wrenches.
Overtightening the pump adapter into the outlet
housing adapter may crack the housing.
11. Reconnect the displacement pump to the motor as
explained on page 18.
