Danfoss PAH 50 User manual

Service guide
PAH pumps
PAH 50-100
Disassembling and assembling
hpp.danfoss.com

Service guide | Disassembling and assembling PAH 50-100
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180R9098 | 521B1072 | DKCFN.PI.011.NC5.02 | 06.2017
NOTE: If the pump is disassembled within the warranty period, the pump is no longer covered
by the warranty.
Introduction
Table of Contents 1. Disassembling the pump ................................................................................................................... 3
2. Inspection.............................................................................................................................................. 7
2.1. Port plate and thrust plate................................................................................................................. 7
2.2. Pistons.................................................................................................................................................... 7
2.3. Cylinder barrel ..................................................................................................................................... 8
2.4. Housing.................................................................................................................................................. 8
2.5. Swash plate .......................................................................................................................................... 8
3. Assembling ........................................................................................................................................... 9
4. Service kit list for PAH 50-100.......................................................................................................... 14
5. Exploded view PAH 50-100 .............................................................................................................. 15
This document covers the instructions for
disassembling and assembling the axial piston
pumps PAH 50-100

Service guide | Disassembling and assembling PAH 50-100
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180R9098 | 521B1072 | DKCFN.PI.011.NC5.02 | 06.2017
1. Disassembling the
pump
2. Remove the parallel key and unscrew the
front cover.1. Tools required for dismantling.
3. Unscrew the screws in the front flange. 4. Remove the front flange.
4. Remove the shaft seal using two
screwdrivers.
Caution: Avoid scratching the sealing
surface on the shaft.
6. Remove the guide pin from the housing
and the two guide pins from the
swash plate.

Service guide | Disassembling and assembling PAH 50-100
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180R9098 | 521B1072 | DKCFN.PI.011.NC5.02 | 06.2017
7. Remove the swash plate using the front
screw.
8. Remove the cylinder barrel from the
housing.
10. Separate the housing and the end cover.9. Unscrew the six screws in the end cover.
12. Remove the guide pins and the guide.11. Remove the valve plate from the end cover.

Service guide | Disassembling and assembling PAH 50-100
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180R9098 | 521B1072 | DKCFN.PI.011.NC5.02 | 06.2017
14. Remove the retaining plate.13 Remove the pistons.
15.Remove the retaining ball.
16. Remove the the thrust plate using two
screwdrivers.
18. The ceramic ring removed from the front
flange.17. Remove shaft sealing from front flange.

Service guide | Disassembling and assembling PAH 50-100
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180R9098 | 521B1072 | DKCFN.PI.011.NC5.02 | 06.2017
19. Wash all parts and replace all seals
(inclusive shaft seal).
21. If the pump has failed, the reason for the
failure must be found and fixed before the
repaired pump is re-installed.
20. Inspect all parts carefully (see ”Inspection”)
and replace any worn parts.
Front Flange
Housing with
bearing
Port flange
Screws for flanges
Washer and
screw (for fixing
swash plate)
Key
Five guide pins
Swash plate
Cylinder barrel
Retainer ball
Retaining guide
Thrust plate
with sealings
Port plate
Pistons
Ceramic ring
Shaft seal
Retainer plate

Service guide | Disassembling and assembling PAH 50-100
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180R9098 | 521B1072 | DKCFN.PI.011.NC5.02 | 06.2017
2. Hold a ruler against the surface of the
plates and check the tightness against a
light source.
1. Neither port plate nor thrust plate must
show any sign of wear.
3. Check that both O-rings and back-up rings
are not broken and do not show severe
wear.
2. Inspection 2.1. Port plate and thrust plate
3. Hold a ruler against the surfaces of the
piston shoes to check that the surfaces
are even and smooth and without any
scratches.
4. It is acceptable that the (black) treated
surfaces of the pistons are partly worn.
1. The play in the ball and socket joint must
not exceed 0.1 mm.
2. The thickness of the piston shoes must be
at least 4.3 mm.
2.2. Pistons

Service guide | Disassembling and assembling PAH 50-100
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180R9098 | 521B1072 | DKCFN.PI.011.NC5.02 | 06.2017
2. Check the bearing (the black part) for
large wear grooves (not critical).
2. Check that the bushings are free from
seizure and large scratches.
3. Ensure that the pistons can move freely in
the bushings.
1. Check the outer bearing surface for large
wear grooves (not critical).
2.3. Cylinder barrel
2.4. Housing
1. Check that the surface of the swash plate
is smooth and without any large scratches
(depth more than 0.1 mm).
2.5. Swash plate

Service guide | Disassembling and assembling PAH 50-100
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180R9098 | 521B1072 | DKCFN.PI.011.NC5.02 | 06.2017
1. Lubrication:
• To prevent seizing-up, lubricate all
threads with PTFE lubrication type.
• O-rings inside pump may be lubricated
only with clean filtered water.
• O-rings for port flange, mounting flange
and flushing valve must be lubricated.
• It is important to lubricate ALL parts to
be assembled with clean filtered water
(Especially all PEEK parts).
2. Parts and tools required for assembly.
Check that all parts are OK. Replace all
seals.
WARNING:
Do not use silicone when assembling the
pump. Do not reuse disassembled O-rings;
they might be damaged. Always use new
O-rings.
3. Assembling
Important:
It is essential that the pump is serviced in
conditions of absolute cleanliness. All parts
must be absolute clean before mounting.
4. Mount the valve plate in its right position
using the pin as guide.
3. Mount the O-ring, the guide and the guide
pins on the port flange.
Guide pin

Service guide | Disassembling and assembling PAH 50-100
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180R9098 | 521B1072 | DKCFN.PI.011.NC5.02 | 06.2017
5. Mount the housing using the pin as guide.
6. Place housing and port flange near table
edge and mount screws from below.
8. Press the thrust plate into the cylinder
barrel using a table or the like as support.
10. Slide the retaining ball (smallest diameter
pointing upwards) down the shaft.
7. Mount the thrust plate with sealings on
the cylinder barrel.
9. Mount the cylinder barrel in the housing.

Service guide | Disassembling and assembling PAH 50-100
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180R9098 | 521B1072 | DKCFN.PI.011.NC5.02 | 06.2017
12. Mount the pistons.
11. Mount the retaining plate (smallest centre
diameter pointing upwards).
14. Mount the ceramic ring by pressing the
tool as far down in the front flange as
possible.
16. Mount the shaft seal (carbon surface
pointing downwards), the spring, and the
washer (edge pointing downwards) by
sliding them over the tool.
13. Mount the ceramic ring on the tool.
15. Push the tool through the front flange.
Shaft seal
Washer
Spring

Service guide | Disassembling and assembling PAH 50-100
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180R9098 | 521B1072 | DKCFN.PI.011.NC5.02 | 06.2017
18. Press the swash plate against the flange
and screw the tools together.
20. Mount the washer and the screw in the
front flange to fix the swash plate.
22. Mount the tool over the shaft.
19. Mount the O-ring on the front flange.
21. Tighten the screw to a torque of 8 Nm and
remove the tool.
17. Mount the swash plate on the front flange
using the pins as guide.

Service guide | Disassembling and assembling PAH 50-100
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180R9098 | 521B1072 | DKCFN.PI.011.NC5.02 | 06.2017
23. Mount the front flange on the housing
using the pin as guide.
24. Remove the tool.
Guide pin
26. Tighten the screws to a torque of 30 Nm
and mount the parallel key on the shaft.
25. Mount the screws in the front flange.

Service guide | Disassembling and assembling PAH 50-100
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180R9098 | 521B1072 | DKCFN.PI.011.NC5.02 | 06.2017
4. Service kit list for PAH 50-100
180B4121 - Screw & seal kit 180B4122 - Valve plate kit 180B4125 - Piston kit PAH 50-80 (Standard pump) 180B4493 - Piston kit PAH 100 (Standard pump) 180B4123 - Piston kit (Tech. Water pump) 180B4126 - Cylinder Barrel (Standard pump) 180B4124 - Cylinder Barrel (Tech. water pump) 180B4127 - Cylinder Barrel CCW (Standard pump) 180B4009 - Swash plate kit PAH 50 180B4010 - Swash plate kit PAH 63 180B4011 - Swash plate kit PAH 70 180B4012 - Swash plate kit PAH 80 180B4492 - Swash plate kit PAH 100 180Z0237 - Tool set
Pos. Qty. Unit Designation Material
- 1 Pcs. Shaft bush, torpedo - X
- 1 Pcs. Press tool for 35 mm shaft - X
- 1 Pcs. Mounting screw - X
1 1 Pcs. Housing AISI 304
2 2 Pcs. Pin AISI 304 X
3 2 Pcs. Plug AISI 304
4 2 Pcs. O-ring NBR X
31 1 PC Swash plate Stainless steel (1.4057) X X X X X
34 2 PC Pin AISI 304 X
61 1 PC Cylinder barrel Stainless steel (1.4057) X X X
64 1 PC Retainer ball Stainless steel (1.4057) X X X
65 1 PC Retaining plate Stainless steel (1.4057) X X X
66 9 PC Piston Stainless steel (1.4057) X X X
67 1 PC Key AISI 304 X
91 1 PC Port plate AISI 304 / PEEK X
92 1 PC Valve plate Stainless steel (1.4057) X
93 9 PC Back-up ring PTFE X X
94 9 PC O-ring NBR X X
181 1 PC Port flange AISI 304
182 1 PC O-ring NBR X
183 1 PC Guide pin AISI 304
184 1 PC Pin AISI 304 X
186 8 PC Screw AISI 304 X
187 1 PC Threaded plug AISI 304
188 1 PC Threaded plug AISI 304
211 1 PC Mounting flange AISI 304
212 1 PC O-ring NBR X
215 1 PC Shaft seal AISI 304 / NBR X
218 8 PC Screw AISI 304 X
219 1 PC Screw AISI 304 X
220 1 PC Usit-ring AISI 304 / NBR X
- 1 Pcs. Service instruction (180R9098) X X X X X X X X X X X X X

Service guide | Disassembling and assembling PAH 50-100
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180R9098 | 521B1072 | DKCFN.PI.011.NC5.02 | 06.2017
5. Exploded view
PAH 50-100

© Danfoss | DCS (im) | 2017.06
180R9098 | 521B1072 | DKCFN.PI.011.NC5.02 | 16
Danfoss A/S
High Pressure Pumps
Nordborgvej 81
DK-6430 Nordborg
Denmark