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ACCESSORIES
1. Plastic Washer
2. Locknut
3. Pressure Relief Valve
4. Filler Plug
5. Cover and Seal
6. O-Ring Seal
7. Sleeve
8. Washer
9. Ram
10. Piston
11. Packing Cup
12. Piston Follower
13. Locknut
14. Motor
15. Shaft Seal
16. Pump Housing
17. Poppet
18. Spring
19. Guide
20. Retainer
21. Setscrew
22. Aluminum Washer
23. Jamnut
24. Acorn N ut
25. Stud
26. Brass Washer
27. 2-Way Solenoid
28. 2-Way Coil
29. 2-Way Valve
30. Base and Strainer
31. Valve Block
32. Socket Head Cap Screw
33. Filter
34. Plug
35. Strainer
36. Check Valve Retainer
37. Ball
38. Insert Valve
39. Cylinder Tank
40. Cylinder
41. 4-Way Solenoid
42. 4-Way Valve
43. 4-Way Coil
44. 3-Way Solenoid
45. 3-Way Valve
46. 3-Way Coil
47. Cap Plug
48. Check Spring
49. Cylinder Tank
50. Valve Block
51. Cage
52. O-Ring Seal/Glide Ring
53. Crossover Valve
54. Pilot Check Valve
55. Spacer
56. Disc
57. Adjustment Screw
59. Drain Plug
J9001-6
LEGEND FOR FIG. 9
POWER UNIT
DISASSEMBLY/INSPECTION
(1) Remove t h e d r a i n p l u g (Fig. 9). D r a i n t h e u n i t .
(2) Extend t h e r a m a n d piston r o d completely t o
d r a i n t h e r e m a i n i n g o i l from t h e cylinder.
(3) Remove t h e cover locknuts ( F i g . 9) and remove
t h e cover.
(4) Inspect t h e casting for damage a n d cracks, a n d
t h e seal for cuts ( F i g . 9).
(5) Remove t h e r a m and t h e piston. Inspect t h e n y -
l o n sleeve, t h e piston, and t h e piston follower for ex-
cessive wear (Fig. 10).
COVER
ASSEMBLY
TANK
RESERVOIR
CYLINDER
(E
RAM
O-RING
WASHER
PISTON
FOLLOWER
RB531
Fig. 10 Lift Cylinder Components
(6) Inspect t h e cylinder for p i t t i n g a n d scoring i n
t h e bore (Fig. 10).
(7) Inspect t h e r a m for nicks, scratches, a n d rust/
corrosion (Fig. 10).
(8) Inspect t h e piston packing cup for wear a n d
sealing l i p cut (Fig. 10).
(9) Clean a n d inspect t h e base strainer.
(10) Replace a l l t h e O-ring seals d u r i n g assembly.
(11) Loosen t h e motor a t t a c h i n g bolts. Do n o t re-
move the bolts from t h e motor. Retain or secure t h e
motor end plate in-place d u r i n g removal, t h e n t e m -
p o r a r i l y i n s t a l l two 1/4-20 nuts on t h e motor attach-
i n g bolts to r e t a i n t h e motor intact.
B o t h P r e s t o l i t e
a n d A m e r i c a n B o s c h
m o t o r s
a r e u s e d i n s n o w p l o w p o w e r unit. A P r e s t o l i t e
motor c a n be identified b y a d o m e d t o p c o v e r
a n d t h e trade n a m e s t a m p e d o n the b o d y . A m e r -
i c a n B o s c h motors h a v e a flat top c o v e r a n d n o
identifying n a m e o r m a r k s .
(12) Remove the pump drive shaft seal ( i f damaged)
w i t h a pointed tool.
(13) Verify t h a t t h e seal k i t replacement
compo-
nents are correct for t h e u n i t .
(14) D i p t h e replacement seal i n o i l a n d i n s t a l l i t
over t h e pump shaft w i t h t h e seal l i p facing down.
(15) Position t h e seal i n t h e p u m p h o u s i n g s l i g h t l y
below t h e boss face.
(16) Remove solenoid valve " A " coil f r o m t h e base
and test i t for electrical c o n t i n u i t y . The n o r m a l coil
DC resistance is 9.0 ohms ±10%.
(17) Remove solenoid valve " A " cartridge (two-way
valve) w i t h a 1 1/8-inch diameter deep socket wrench
and inspect for external damage.
(18) Remove t h e filters and clean t h e screens w i t h
cleaning solvent a n d compressed air. Discard t h e O-
r i n g seals and t h e n y l o n r e t a i n i n g rings.
(19) Remove t h e pump housing (Fig. 9), a n d t h e n
remove t h e insert valve, t h e b a l l , t h e s p r i n g , and t h e
retainer from t h e pump housing (Fig. 11). Inspect a l l
the components for damage a n d contamination. Dis-
card t h e O-ring seals.
(20) Remove t h e socket-head
screws a n d remove
the valve block from t h e p u m p housing ( F i g . 9). Dis-
card the O-ring seals.
(21) Remove solenoid valve " B " (three-way
valve)
w i t h special tool J-25399 (Fig. 9).
(22) Remove the b a l l and t h e spring f r o m t h e valve
block (Fig. 9). Clean t h e solenoid valve a n d inspect i t
for external damage.
(23) Disassemble t h e three-way valve ( F i g . 9). Dis-
card t h e O-ring seal.
(24) Remove and clean solenoid valve " C " (four-way
valve) w i t h special tool J-25399 (Fig. 9). Inspect t h e
solenoid valve for external damage.
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