Danfoss PAH Series User manual

Service guide
PAH, PAHT, PAHT C, PAHT G pumps
PAH 2-6.3/PAHT 2-6.3/PAHT C 2-6.3
and PAHT G 2-6.3
Disassembling and assembling
HPP.danfoss.com

Instruction Disassembling and assembling PAH 2-6.3, PAHT 2-6.3, PAHT C 2-6.3 and PAHT G 2-6.3
2
180R9094 / 521B0985 / DKCFN.PI.011.N5.02 / 09.2015
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 .............................................................................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 / PAHT / PAHT C 2 ...............................................16
5. Spare parts list for PAHT G 2............................................................17
6. Spare parts list for PAH / PAHT / PAHT C 3.2-6.3 .........................................18
7. Spare parts list for PAHT G 3.2-6.3 ......................................................19
This document covers the instructions for
disassembling and assembling the axial piston
pumps PAH / PAHT / PAHT C / PAHT G 2-6.3.
Tools provided with tool set 180Z0235:
• Shaft bush, torpedo
• Press bush Ø18 (Plastic)

Instruction Disassembling and assembling PAH 2-6.3, PAHT 2-6.3, PAHT C 2-6.3 and PAHT G 2-6.3
3
180R9094 / 521B0985 / DKCFN.PI.011.N5.02 / 09.2015
1. Disassembling the
pump
2. Remove the parallel key and unscrew the
front cover.
1. Tools required for dismantling.
Caution: Avoid scratching the sealing
surface on the shaft
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.

Instruction Disassembling and assembling PAH 2-6.3, PAHT 2-6.3, PAHT C 2-6.3 and PAHT G 2-6.3
4
180R9094 / 521B0985 / DKCFN.PI.011.N5.02 / 09.2015
7. Remove the housing. 8. Remove the cylinder barrel.
10.1.b. Remove the stop.10.1.a. Remove the spring
9. Remove the pistons and the retainer plate
from the cylinder barrel.
NB: Items 10.1.a. and 10.1.b. concern PAH 2, PAHT 2, PAHT C 2 and PAHT G 2 only

Instruction Disassembling and assembling PAH 2-6.3, PAHT 2-6.3, PAHT C 2-6.3 and PAHT G 2-6.3
5
180R9094 / 521B0985 / DKCFN.PI.011.N5.02 / 09.2015
10.2.a. Remove the retainer guide. 10.2.b. Remove the spring guide.
10.2.c. Remove the spring.
NB: The following items concern PAH 2-6.3, PAHT 2-6.3, Paht C 2-6.3 and
PAHT G 2-6.3 only
NB: Items 10.2.a. through 10.2.c. concern PAH 4-6.3, PAHT 3.2-6.3, PAHT C 3.2-6.3 and
PAHT G 3.2-6.3 only
12. Remove the valve plate.
11. Loosen the valve plate using two
screwdrivers. Place one of the
screwdrivers in the slot of the valve plate.

Instruction Disassembling and assembling PAH 2-6.3, PAHT 2-6.3, PAHT C 2-6.3 and PAHT G 2-6.3
6
180R9094 / 521B0985 / DKCFN.PI.011.N5.02 / 09.2015
13. Remove the ve O-rings and the ve
back-up O-rings. 14. Remove the port plate from the ange.
15. Wash all parts and replace all seals
(inclusive shaft seal).
17. If the pump has failed, the reason for the
failure must be found and xed before
the repaired pump is re-installed.
16. Inspect all parts carefully
(see “Inspection”) and replace any worn
parts.
Stop
Spring
Pistons
Retainer plate
Cylinder barrel
Housing with
swash plate
and bearing
Port plate
Valve plate
with sealing
Front cover
Flange

Instruction Disassembling and assembling PAH 2-6.3, PAHT 2-6.3, PAHT C 2-6.3 and PAHT G 2-6.3
7
180R9094 / 521B0985 / DKCFN.PI.011.N5.02 / 09.2015
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.
PAHT only:
It is acceptable that the (black) treated
surfaces of the pistons are partly worn o.
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 2.85 mm.
2.2. Pistons

Instruction Disassembling and assembling PAH 2-6.3, PAHT 2-6.3, PAHT C 2-6.3 and PAHT G 2-6.3
8
180R9094 / 521B0985 / DKCFN.PI.011.N5.02 / 09.2015
2. Check that the bushings are free from
seizure and large scratches, and 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
1. Check that the swash plate surface is
smooth and without any big scratches
(depth more than 0.1 mm).
2. Check the bearing (the black part) for
large wear grooves (not critical).
2.4. Housing
1. Unscrew center bolt from the swash plate.Mounted swash plate:
2.5. Swash plate

Instruction Disassembling and assembling PAH 2-6.3, PAHT 2-6.3, PAHT C 2-6.3 and PAHT G 2-6.3
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180R9094 / 521B0985 / DKCFN.PI.011.N5.02 / 09.2015
Guide pin2. 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.

Instruction Disassembling and assembling PAH 2-6.3, PAHT 2-6.3, PAHT C 2-6.3 and PAHT G 2-6.3
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180R9094 / 521B0985 / DKCFN.PI.011.N5.02 / 09.2015
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.