Displacement pump – Hitachi EM 490 User Manual
Page 17
307-735
17
DISPLACEMENT PUMP
Reassembly Procedure
1.
Stack the backup washer (219*), U–cup seal (205*)
lips down, and female gland (220*), alternate the
polyethylene and leather v–packings (217*, 218*)
lips
up, and stack the male gland (213*) one at a time onto
the piston valve (224).
See Fig 15.
2.
Tighten the packing retaining nut (214) onto the piston
valve (224) and torque to 3–4 in–lb (0.34 – 0.35 N.m).
See Fig 13.
NOTE: NOTE THE ALIGNMENT of the piston (224) to
the nut (214). Maintain this alignment through-
out Steps 2, 3 and 4.
NOTE AND MAINTAIN
THIS ALIGNMENT
THROUGHOUT STEPS
3,4, AND 5
Fig 13
TORQUE NUT TO
3–4 IN-LB
(0.34–0.35 N.M)
APPLY ONE DROP
OF SEALANT TO
THESE THREADS
203*
224
214
3.
Apply
1 drop only of sealant, supplied with the repair
kit, to the piston valve threads. Place the small ball
(203*) on the valve. See Fig 13. Hand tighten the
valve into the rod (223) just until the nut contacts the
rod. Place the flats of the displacement rod in a vise.
Fig 14
214
TORQUE NUT AGAINST ROD
TO 19 FT-LB (25 N.M)
223
DO NOT ALLOW THIS NUT TO
MOVE RELATIVE TO THE
PISTON (224) WHEN
INSTALLING PISTON ONTO ROD
4.
Torque the nut (214) against the rod (223) to 19 ft–lb
(25 N.m). Use two wrenches to maintain the align-
ment as mentioned in the NOTE.
See Fig 14.
5.
Stack the male gland (211*), alternate the polyethyl-
ene and leather v–packings (218*, 209*)
lips down
and stack the female gland (212*) one at a time into
the top of the cylinder.
See Fig 15.
6.
Loosely install the packing nut (221) and plug (201).
7.
Insert the oiled piston rod (223) into the bottom of the
cylinder.
8.
Assemble the intake valve. Use a new gasket (206*).
Screw the valve into the cylinder and tighten to 80 ft–
lb (107 N.m).
See Fig 15.
9.
Screw down the cylinder locknut (112) until it is finger
tight at the bottom of the external cylinder threads.
See Fig 15.
10. Install the displacement pump on the sprayer. See
page 16.
Lips must face up
*208
216
APPLY 1 DROP
OF ADHESIVE
(in repair kit)
TO THESE
THREADS
Fig 15
201
223
*204
215
222
*206
*207
Lips must
face up
217*
Lips must
face down
218*
Lips must
face down
*209
224
Lips of seal
must face down
*205
203*
213*
220*
211*
*212
219*
TORQUE TO
80 ft–lb
(107 N.m)
221
112
214