Displacement Pump Service
STAINLESS STEEL DISPLACEMENT
PUMPS, with rubber packings
This procedure covers the following displacement
pumps. Refer to the parts drawings on the indicated
pages for an illustration of your pump.
Model 220–440
page 33.
Model 220–439
page 34.
Before You Start
1. Disconnect the displacement pump from the air
motor as explained on page 11.
2. Be sure you have all the necessary repair parts on
hand to reduce downtime.
3. Repair Kit 218–112 is available. For best results,
use all the new parts in the kit even if the old parts
look good.
Intake Valve
1. Unscrew the intake valve housing (23) from the
cylinder (13), using a strap wrench. Disassemble
the valve and clean and inspect all parts.
2. Inspect the ball (28) and seat in the housing (23)
for wear or nicks.
3. Replace parts as necessary. Reassemble as
shown in the applicable parts drawing.
Piston Valve
1. Using a strap wrench, grip the cylinder (13) near
the outlet housing (6) and unscrew it from the
housing. Pull the cylinder down off the piston.
Check the inner surface of the cylinder for scoring
or wear by running a finger over the surface or
holding the part up to the light at an angle.
2.
On Model 220–440, loosen the lower nut (16) and
unscrew the valve housing (18) from the connect-
ing rod (17). Unscrew the piston stud (22).
On Model 220–439, remove the cotter pins (29)
from the ball stop pin (30). Remove the ball stop
pin and unscrew the piston stud (22) from the dis-
placement rod (15). Be careful not to drop the ball
(25).
3. Clean and inspect all piston parts. Be sure to in-
spect the ball (25) and its seat on the piston stud
(22) for wear or nicks. Replace parts as necessary.
Reassemble the piston parts as shown,
being sure
that the lips of the u-cup packing (21) are facing
up. Torque as specified on the applicable illustra-
tion.
NOTE:
On Model 220–440, when reassembling the
piston to the connecting rod (17), screw the connecting
rod all the way into the displacement rod (15). Tighten
the upper nut (16) against the displacement rod and
torque to 33 N.m (24 ft–lb). Adjust the lower nut (16) to
allow 3.1 mm (0.125 in.) free travel for the ball (25).
Throat Packings
1. Remove the cylinder (13) and piston as explained
previously. Remove the packing nut (1) and pull
the displacement rod (15) out of the top of the out-
let housing (6). Inspect the outer surface of the
displacement rod for scoring or wear by running a
finger over the surface or holding it up to the light
at an angle.
2. Remove the throat packings from the outlet hous-
ing (6).
3. Clean and inspect the parts for wear or damage.
Lubricate the packings before reassembly. Install
the parts one at a time, in the same position as
before.
The lips of the u-cup must face down
against fluid pressure.
4. Leave the packing nut (1) loose until the displace-
ment rod (15) has been installed.
CAUTION
Insert the displacement rod from the top of the out-
let housing to prevent shearing of the packings.
5. Tighten the packing nut just enough to prevent
leaking. Overtightening can damage the packings.
6. Reconnect the displacement pump to the air motor
as explained on page 11.
