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
2
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
3
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.