Danfoss PAHT Series User manual

Service guide
PAHT / PAHT G pumps
PAHT 20-32 / PAHT G 20-32Product type -
Disassembling and assembling
hpp.danfoss.com

Service guide Disassembling and assembling PAHT / PAHT G 20-32
2
180R9175 / 521B1108 / DKCFN.PI.012.E3..02 / 01.2016
NOTE: If the pump is disassembled within the warranty period, the pump is no longer covered
by the warranty.
Introduction
Table of Contents
Contents
Introduction ............................................................................2
1. Disassembling the pump................................................................3
2. Inspection ..............................................................................9
2.1. Valve and thrust plate:...................................................................9
2.2. Swash plate: ............................................................................9
2.3. Pistons: ................................................................................10
3. Assembling ............................................................................11
4. Spare parts list for PAHT 20-32..........................................................20
6. Spare parts list for PAHT G 20-32........................................................21
8. Tool sets . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .22
This document covers the instructions for disassembling and assembling the axial piston pumps
PAHT / PAHT G 20-32.

Service guide Disassembling and assembling PAHT / PAHT G 20-32
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180R9175 / 521B1108 / DKCFN.PI.012.E3.02 / 01.2016
1. Disassembling the
pump
2. Loosen and remove 6 screws.1. Tools required for dismantling the pump.
3. Remove mounting flange.
4. Remove shaft sealing.
Caution: Avoid scratching the sealing
surface on the shaft.
5. Remove spring. 6. Remove 2 guide pins.

Service guide Disassembling and assembling PAHT / PAHT G 20-32
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180R9175 / 521B1108 / DKCFN.PI.012.E3..02 / 01.2016
7. Remove O-ring. 8. Turn pump upside down.
11. View to pistons and retainer plate.
9. Loosen and remove 10 screws. 10. Remove cover.
12. Remove pistons and retainer plate.

Service guide Disassembling and assembling PAHT / PAHT G 20-32
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180R9175 / 521B1108 / DKCFN.PI.012.E3.02 / 01.2016
13. Remove retainer ball. 14. Remove retainer.
15. Remove spring. 16. Remove cylinder barrel.
18. Remove 1 guide pin.17.Remove port plate.

Service guide Disassembling and assembling PAHT / PAHT G 20-32
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180R9175 / 521B1108 / DKCFN.PI.012.E3..02 / 01.2016
19. Turn pump upside down. Loosen and
remove 4 screws. 20. Remove port flange.
21. Remove 1 guide pin.
23. Loosen thrust plate from cylinder barrel.
22. Remove O-ring from port flange.
24. Remove thrust plate.

Service guide Disassembling and assembling PAHT / PAHT G 20-32
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180R9175 / 521B1108 / DKCFN.PI.012.E3.02 / 01.2016
25. Remove O-rings from thrust plate.
27. Remove 1 guide pin from end cover
plate.
26. Remove backup rings from thrust plate.
28. Loosen and remove screw from swash
plate.
30. Remove 2 guide pins from end cover
plate.29. Remove swash plate.

Service guide Disassembling and assembling PAHT / PAHT G 20-32
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180R9175 / 521B1108 / DKCFN.PI.012.E3..02 / 01.2016
31. Remove O-ring from end cover plate.
32. Remove shaft sealing from mounting
flange.
33.
34. Pump
disassembled.

Service guide Disassembling and assembling PAHT / PAHT G 20-32
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180R9175 / 521B1108 / DKCFN.PI.012.E3.02 / 01.2016
1. Neither valve plate nor thrust plate must
show any sign of wear. .
1. Check that surface of swash plate is
smooth and without any large scratches
(depth more than 0.1 mm)..
2. Hold a ruler against surface of plate and
check tightness against a light source..
2. Inspection
2.2. Swash plate:
2.1. Valve and thrust plate:
3. Check that both O-rings and back-up rings
are not broken and do not show severe
wear.

Service guide Disassembling and assembling PAHT / PAHT G 20-32
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180R9175 / 521B1108 / DKCFN.PI.012.E3..02 / 01.2016
5. Check main bearing for wear and
scratches.
4. Check bushes in cylinderbarrel for wear
and scratches.
1. Play in ball and socket joint must not
exceed 0.1 mm.
2. Thickness of piston shoes must be at least
4.1 mm.
3. Hold a ruler against surfaces of piston
shoes to check that the surfaces are even
and smooth and without any scratches. It
is acceptable that the (black) treated
surfaces of the pistons are partly worn..
2.3. Pistons:

Service guide Disassembling and assembling PAHT / PAHT G 20-32
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180R9175 / 521B1108 / DKCFN.PI.012.E3.02 / 01.2016
3. Assembling
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).
WARNING:
Do not use silicone when assembling the
pump. Do not reuse disassembled O-rings;
they might be damaged. Always use new
O-rings.
Important:
It is essential that the pump is serviced in
conditions of absolute cleanliness. All parts
must be absolute clean before mounting.
1. Tools required for assembly of the pump. 2. Parts needed for assembly of the pump.
3. Mount 1 guide pin in housing. 4. Mount O-ring in port plate.

Service guide Disassembling and assembling PAHT / PAHT G 20-32
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180R9175 / 521B1108 / DKCFN.PI.012.E3..02 / 01.2016
5. Mount port flange on housing. Use pin as
guide. 6. Mount 4 screws (M8x50).
7. Tighten screws to 30Nm.
9. Mount 1 guide pin inside the housing on
the back side of the port plate.
8. Turn pump upside down.
10. Mount port plate. Be aware of
orientation/ guide pin.

Service guide Disassembling and assembling PAHT / PAHT G 20-32
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180R9175 / 521B1108 / DKCFN.PI.012.E3.02 / 01.2016
11. Mount backup rings on the thrust plate.
13. Spray with water on cylinder barrel and
thrust plate.
12. Mount O-rings on the thrust plate.
14. Mount thrust plate on cylinder barrel.
16. Mount cylinder barrel in housing.15. Press thrust plate into cylinder barrel.

Service guide Disassembling and assembling PAHT / PAHT G 20-32
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180R9175 / 521B1108 / DKCFN.PI.012.E3..02 / 01.2016
17. Mount spring. 18. Mount retainer on top of the spring.
19. Spray with water and mount retainer ball.
21. Spray with water and mount pistons.
20. Place retainer plate on top of retainer
ball.
22. Spray with water and mount O-ring on
end cover.

Service guide Disassembling and assembling PAHT / PAHT G 20-32
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180R9175 / 521B1108 / DKCFN.PI.012.E3.02 / 01.2016
23. Mount 2 guide pins on endcover.
25. Mount screw (M8x16).
24. Mount swash plate.
26. Tighten screw to 30Nm.
28. Spray piston shoes with water.27. Mount 1 guide pin on housing.

Service guide Disassembling and assembling PAHT / PAHT G 20-32
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180R9175 / 521B1108 / DKCFN.PI.012.E3..02 / 01.2016
29. Mount endcover on the housing. 30. Mount 10 screws (M8x16).
31. Tighten 10 screws to 30Nm.
33. Spray with water and mount O-ring.
32. Turn pump upside down and mount 2
guide pins.
34. Spray shaft sealing with water before
mounting.

Service guide Disassembling and assembling PAHT / PAHT G 20-32
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180R9175 / 521B1108 / DKCFN.PI.012.E3.02 / 01.2016
35. Use tool and press shaft sealing into
place.
37. Mount spring.
36. Mount metal ring.
38. Mount special tool on shaft.
40. Mount sealing (smallest diameter
pointing down).39. Spray with water.

Service guide Disassembling and assembling PAHT / PAHT G 20-32
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180R9175 / 521B1108 / DKCFN.PI.012.E3..02 / 01.2016
41. Mount mounting flange. 42. Mount 6 screws.
43. Tighten screws to 30Nm.

Service guide Disassembling and assembling PAHT / PAHT G 20-32
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180R9175 / 521B1108 / DKCFN.PI.012.E3.02 / 01.2016
Finished.

Service guide Disassembling and assembling PAHT / PAHT G 20-32
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180R9175 / 521B1108 / DKCFN.PI.012.E3..02 / 01.2016
180B4055 - Seal set (PAHT 20-32) 180B4054 - Cylinder barrel set (PAHT 20-32) 180B4052 - Valve plate set (PAHT 20-32) 180B4053 - Piston set (PAHT 20-32) 180B4251 - Swash plate set (PAHT 20) 180B4254 - Swash plate set (PAHT 25) 180B4257 - Swash plate set (PAHT 32)
Pos. Qnt. Designation Material
1 1 Housing AISI 316
2 2 Pin Ø4 x 14 AISI 304 x
510 Screw M8 x 16 AISI 304 x
9 1 O-ring Ø102 x 3 NBR x
11 1End cover CW AISI 316
31 1 Swash plate AISI 431 x x x
32 1 Screw Ø8 x 16 AISI 304 x x x
34 2 Pin Ø4 x 14 AISI 304 x x x
61 1Cylinder barrel AISI 431 x
62 1Spring AISI 304 x
63 1Retainer PEEK x
64 1Retainer ball AISI 304 x
65 1Retainer plate 1.4301 x
66 9Piston AISI 431 / PEEK x
67 1 Key 8 x 7 x 32 AISI 316Ti x
91 1 Port plate AISI 304 / PEEK x
92 1 Valve plate AISI 431 x
93 9 Back up ring PTFE x
94 9 O-ring Ø13 x 2 NBR x
121 1Port flange AISI 316
122 1 O-ring Ø102 x 3 NBR x
123 1 O-ring Ø59,5 x 3 NBR x
124 1Shaft sealing AISI 304 / NBR x
125 1End cover AISI 316
126 1 Pin Ø5 x 10 AISI 304 x
127 6 Screw M8 x 60 AISI 304 x
128 4 Screw M8 x 50 AISI 304 x
1Service instruction xxxxxxx
4. Spare parts list for
PAHT 20-32