Danfoss PAH Series User manual

Servie guide
PAH, PAHT, PAHT G pumps
PAH 10-12.5, PAHT 10-12.5 and
PAHT G 10-12.5
Disassembling and assembling
hpp.danfoss.com

Service guide | Disassembling and assembling PAH 10-12.5, PAHT 10-12.5 and PAHT G 10-12.5
2180R9095 | 521B0986 0 | DKCFN.PI.010.NA4.02| 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 valve plate .................................................................................................................7
2.2. Pistons....................................................................................................................................................7
2.3. Cylinder barrel .....................................................................................................................................8
2.4. Housing..................................................................................................................................................8
2.5. Swash plate ..........................................................................................................................................8
3. Assembling ...........................................................................................................................................9
4. Spare parts list for PAH 10-12.5 / PAHT 10-12.5 ...........................................................................15
4.1. Exploded view PAH 10-12.5 / PAHT 10-12.5..................................................................................16
5. Spare parts list for PAHT G 10-12.5.................................................................................................17
5.1. Exploded view PAHT G 10-12.5 .......................................................................................................18
This document covers the instructions for
disassembling and assembling the axial piston
pumps PAH / PAHT / PAHT G 10-12.5.
Tools provided with tool set 180Z0235:
• Shaft bush, torpedo
• Press bush ø18 (Plastic)

Service guide | Disassembling and assembling PAH 10-12.5, PAHT 10-12.5 and PAHT G 10-12.5
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1. Disassembling the
pump
2. Remove the parallel key and unscrew the
front cover.1. Tools required for dismantling.
3. Dismantle the front cover using a vice.
4. Remove the shaft seal using two
screwdrivers.
Caution: Avoid scratching the sealing
surface on the shaft.
5. Remove the two small O-rings from the
ange. Remove the seal from the front
cover using a screwdriver. 6. Unscrew the four screws for the housing.

Service guide | Disassembling and assembling PAH 10-12.5, PAHT 10-12.5 and PAHT G 10-12.5
4180R9095 | 521B0986 0 | DKCFN.PI.010.NA4.02| 06.2017
7. Remove the housing. 8. Remove the cylinder barrel.
10. Remove the retainer guide.
9. Remove the pistons and the retainer plate
from the cylinder barrel.
12. Remove the spring.11. Remove the spring guide.

Service guide | Disassembling and assembling PAH 10-12.5, PAHT 10-12.5 and PAHT G 10-12.5
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180R9095 | 521B0986 0 | DKCFN.PI.010.NA4.02| 06.2017
14. Remove the valve plate.
13. Loosen the valve plate using two
screwdrivers. Place one of the
screwdrivers in the slot of the valve plate.
15. Remove the ve O-rings and the ve
back-up O-rings. 16. Remove the port plate from the ange.
17. Wash all parts and replace all seals
(inclusive shaft seal).
19. If the pump has failed, the reason for the
failure must be found and xed before the
repaired pump is re-installed.
18. Inspect all parts carefully (see “Inspection” )
and replace any worn parts.

Service guide | Disassembling and assembling PAH 10-12.5, PAHT 10-12.5 and PAHT G 10-12.5
6180R9095 | 521B0986 0 | DKCFN.PI.010.NA4.02| 06.2017
Front cover
Flange
Plugs
Front
cover crews
Valve plate with
sealing
Cylinder barrel
Housing with
swash plate
and bearing
Retainer guide
Retainer plate
Spring guide
Spring
Pistons
Shaft seal
Port plate

Service guide | Disassembling and assembling PAH 10-12.5, PAHT 10-12.5 and PAHT G 10-12.5
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180R9095 | 521B0986 0 | DKCFN.PI.010.NA4.02| 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 valve 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 valve 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.
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 4.1 mm.
2.2. Pistons

Service guide | Disassembling and assembling PAH 10-12.5, PAHT 10-12.5 and PAHT G 10-12.5
8180R9095 | 521B0986 0 | DKCFN.PI.010.NA4.02| 06.2017
2. Check the bearing (the black part) for
large wear grooves (not critical).
1. Check that the swash plate surface is
smooth and without any big scratches
(depth more than 0.1 mm).
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
2
2. Unscrew center bolt from the swash plate.1. Mounted swash plate:
2.5. Swash plate

Service guide | Disassembling and assembling PAH 10-12.5, PAHT 10-12.5 and PAHT G 10-12.5
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Guide pin1. Remove swash plate and guide pin.
1. Lubrication:
• To prevent seizing-up, lubricate all
threads with PTFE lubrication type.
• O-rings inside pump may be lubricated
only with clean ltered water.
• O-rings for port ange, mounting ange
and ushing valve must be lubricated.
• It is important to lubricate ALL parts to
be assembled with clean ltered 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.

Service guide | Disassembling and assembling PAH 10-12.5, PAHT 10-12.5 and PAHT G 10-12.5
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4. Mount the port plate in its right position
using the pin as guide.3. Mount the O-ring on the ange.
Guide pin
6. Press the valve plate into the cylinder
barrel using a piece of plastic.
5. Mount the valve plate with seals on the
cylinder barrel.
8. Mount the cylinder barrel in the ange.
7. Check that the gap between the cylinder
barrel and the valve plate is 1.5-2.5 mm.

Service guide | Disassembling and assembling PAH 10-12.5, PAHT 10-12.5 and PAHT G 10-12.5
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10. Mount the spring guide.9. Mount the spring in the centre hole.
12. Mount the retainer plate on the retainer
guide. Ensure that the bended surface
points downwards.
11. Mount the retainer guide on the spring
guide.
14. All pistons inserted.13. Insert the pistons.

Service guide | Disassembling and assembling PAH 10-12.5, PAHT 10-12.5 and PAHT G 10-12.5
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15. Place pin and place swash plate ttet on
guide pin and center hole.
17. Tighten to a torque of 10 ±1 Nm.16. Place the screw in the center hole.
19. Press the housing down by hand and
insert the screws.
18. Mount the pump housing using the pin as
guide.
Alignment
hole
Guide pin

Service guide | Disassembling and assembling PAH 10-12.5, PAHT 10-12.5 and PAHT G 10-12.5
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21. Mount the two O-rings in the ange and
the O -ring on the front cover.20. Tighten the screws to a torque of 22 Nm.
23. Mount the washer with the edge pointing
upwards.
22. Wet the shaft seal with water and mount it
in the front cover. Ensure that it is pressed
to the bottom.
25. Fit the hollow bush onto the shaft.24. Mount the spring.

Service guide | Disassembling and assembling PAH 10-12.5, PAHT 10-12.5 and PAHT G 10-12.5
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26. Wet the shaft seal and slide it over the
bush.
27. Use the shaft seal tool when pressing the
shaft seal downwards.
28. Press the shaft seal in position. 29. Remove the bush.
30. Mount the front cover and align it to the
screw holes. 31. Tighten the screws to a torque of 7 Nm.

Service guide | Disassembling and assembling PAH 10-12.5, PAHT 10-12.5 and PAHT G 10-12.5
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4. Spare parts list for
PAH 10-12.5 / PAHT 10-12.5
180B4105 - Seal set (PAHT 10 -12.5) 180B4107 - Cylinder barrel set (PAHT 10 -12.5) 180B4113 - Cylinder barrel set (PAH 10-12.5) 180B4108 - Valve plate set (PAHT 10 -12.5) 180B4106 - Piston set (PAHT 10 -12.5) 180B4114 - Piston set (PAH 10-12.5) 180B4305 - Swash plate set (PAHT 10) 180B4306 - Swash plate set (PAHT 12.5) 180Z0235 - Tool set
Pos. Qty. Designation Material
- 1 Shaft bush, torpedo - X
- 1 Press bush - X
1 1 Housing AISI 304 / PEEK
2 1 Pin AISI 316 X
5 4 Screw AISI 304 X
31 1Swash plate AISI 431 X X
32 1Screw AISI 304 X X
33 1Washer AISI 304 X X
34 1Pin AISI 316 X X
61 1Cylinder barrel AISI 431 / PEEK X X
62 1Spring AISI 316Ti X X
63 1Spring guide PEEK X X
64 1Retainer ball PEEK X X
65 1Retainer plate AISI 304 X X
66 5Piston AISI 431/ PEEK X X
67 1Key AISI 316Ti X
91 1Port plate AISI 304 / PEEK X
92 1Valve plate AISI 431 X
93 5 Back up ring PTFE X X
94 5O-ring NBR X X
121 1Port ange AISI 304 / PEEK
122 1O-ring NBR X
123 1O-ring NBR X
124 1Shaft seal AISI 304 / NBR X
125 1End cover AISI 304
126 1Pin AISI 316
127 2Screw AISI 304 X
130 2O-ring NBR X
135 1Pin AISI 316 X
136 2O-ring NBR X
- 1 Service instruction (180R9095) - X X X X X X X X

Service guide | Disassembling and assembling PAH 10-12.5, PAHT 10-12.5 and PAHT G 10-12.5
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4.1. Exploded view
PAH 10-12.5 / PAHT 10-12.5

Service guide | Disassembling and assembling PAH 10-12.5, PAHT 10-12.5 and PAHT G 10-12.5
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5. Spare parts list for
PAHT G 10-12.5
180B4312 - Seal set (PAHT G 10-12.5) 180B4315 - Cylinder barrel set (PAHT G 10-12.5) 180B4313 - Valve plate set (PAHT G 10-12.5) 180B4314 - Piston set (PAHT G 10-12.5) 180B4321 - Swash plate set (PAHT G 10) 180B4322 - Swash plate set (PAHT G 12.5) 180Z0235 - Tool set
Pos. Qty. Designation Material
- 1 Shaft bush, torpedo - X
- 1 Press bush - X
1 1 Housing AISI 304 / PEEK
2 1 Pin AISI 316 X
5 4 Screw AISI 304 X
31 1Swash plate AISI 431 X X
32 1Screw AISI 304 X X
33 1Washer AISI 304 X X
34 1Pin AISI 316 X X
61 1Cylinder barrel AISI 431 / PEEK X
62 1Spring AISI 316Ti X
63 1Spring guide PEEK X
64 1Retainer ball PEEK X
65 1Retainer plate AISI 304 X
66 5Piston AISI 431/ PEEK X
67 1Key AISI 316Ti X
91 1Port plate AISI 304 / PEEK X
92 1Valve plate AISI 431 X
93 5 Back up ring PTFE X X
94 5O-ring NBR X X
121 1Port ange AISI 304 / PEEK
122 1O-ring NBR X
123 1O-ring NBR X
124 1Shaft seal AISI 304 / NBR X
125 1End cover AISI 304
126 1Pin AISI 316
127 2Screw AISI 304 X
130 2O-ring NBR X
135 1Pin AISI 316 X
136 2O-ring NBR X
- 1 Service instruction (180R9095) - X X X X X X

Service guide | Disassembling and assembling PAH 10-12.5, PAHT 10-12.5 and PAHT G 10-12.5
18 180R9095 | 521B0986 0 | DKCFN.PI.010.NA4.02| 06.2017
5.1. Exploded view
PAHT G 10-12.5

Service guide | Disassembling and assembling PAH 10-12.5, PAHT 10-12.5 and PAHT G 10-12.5
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180R9095 | 521B0986 0 | DKCFN.PI.010.NA4.02| 06.2017

© Danfoss | DCS (im) | 2017.06 180R9095 | 521B0986 | DKCFN.PI.010.NA4.02 | 20
Danfoss A/S
High Pressure Pumps
Nordborgvej 81
DK-6430 Nordborg
Denmark