Danfoss PAHT Series User manual

danfoss.high-pressurepumps.com
Instruction
Disassembling and assembling
PAHT and PAHT G 256-308

Instruction Disassembling and assembling PAHT and PAHT G 256-308
2
180R9268 / 521B1236 / DKCFN.PI.011.B3.02 / 01.2015
This document covers the instructions for disassembling and assembling the axial piston pumps
PAHT and PAHT G 256-308.
Tools provided with toolset 180B4172:
• 10 mm combination wrench
• 13 mm combination wrench
• 6 mm allen key
• Adjustable pin wrench
• Stop for retainer plate
• Press bush for valve plate
• Shaft seal extractor Ø45
• M8 allen screw (20 mm and 140 mm)
• Press bush Ø45 (Plastic)
• M8 mm eye bolt
• M8 mm nut
• M8 x 70 mm screw
Important: It is essential that the pump is
serviced in conditions of absolute cleanliness.
Place the pump on a pallet or other stable
surface above the ground. Ensure that the pump
cannot roll. It must be possible to place the pump
vertically with the shaft pointing downwards. This
can be done between two pallets or between
two boards on a pallet provided that the distance
is minimum 50 mm.
For a better understanding of the pump, please
see the exploded view on page 19 and 21.
WARNING:
Do not reuse disassembled O-rings or shaft
seal as they might be damaged. Always use
new O-rings.
1. Introduction
Table of Contents Contents
1. Introduction 2
2. Disassembling the pump 3
3. Assembling the pump 6
4. Disassembling and assembling of the swash plate 10
5. Disassembling and assembling of cylinder barrel and valve plate 11
6. Changing pistons 12
6.2. Assembling 15
7. When should the pistons be replaced 17
8. Spare parts list for 18
PAHT 256-308 18
9. Spare parts list for 19
PAHT G 256-308 19

Instruction Disassembling and assembling PAHT and PAHT G 256-308
3
180R9268 / 521B1236 / DKCFN.PI.011.B3.02 / 01.2015
2. Disassembling the
pump
2. Using a 10 mm combination wrench,
unscrew the four bolts from shaft seal
ange.
If shaft seal ange is stuck, screw in two
bolts in holes in the ange to remove it.
1. Disconnect the pump from the rest of the
system.
4. Mount the M8 allen screw from the tool
set in the top of the shaft.
5. Wet the shaft and shaft seal with clean
ltered water.
3. Remove ceramic ring from ange by
gently pushing it from the back of the
sealing ring.
6. Carefully remove the shaft seal assembly
using the shaft seal extractor supplied in
the toolset. The extractor must t
underneath the shaft seal. Press the arms
of the extractor together when turning the
bolt.
7. Turn pump into vertical position with shaft
pointing downwards.

Instruction Disassembling and assembling PAHT and PAHT G 256-308
4
180R9268 / 521B1236 / DKCFN.PI.011.B3.02 / 01.2015
9. Unscrew the remaining three bolts. Turn
each bolt one round at the time to make
sure that the ange is removed as straight
forward as possible.
11. Swash plate must be placed so that its
surface is not scratched. For further
disassembling of swash plate, see page 10.
10. Screw the eye bolt in the M8 hole in the
middle of the ange. Pull it straight
upwards.
8. Using a 13 mm combination wrench,
remove all the bolts on the mounting
ange except the three shown in the next
picture.
WARNING:
Do not loosen the two screws keeping
swash plate in place.
12. Remove by hand the pistons one by one.
Be careful not to scratch the pistons. Tilt
the retainer plate to horizontal position for
easy removal of pistons, if required.
WARNING:
Do not use any tools.
13. Remove the retainer plate and the retainer
ball.
Note: As the retainer ball is not attached
to the retainer plate, it might fall out.

Instruction Disassembling and assembling PAHT and PAHT G 256-308
5
180R9268 / 521B1236 / DKCFN.PI.011.B3.02 / 01.2015
14. Remove the retainer guide, the 4 springs
and the spring guide.
15. Mount a 8 mm eye bolt in the cylinder
barrel. Pull straight upwards. A continuous
lift will elevate the cylinder barrel out of
housing. This can only be done if shaft seal
is removed.
WARNING:
If the cylinder barrel is dropped or
lowered too fast into housing, the main
bearing/shaft bearing might be
damaged. It is not replaceable.
17. Remove the port plate by hand.
16. Place cylinder barrel upside down.
For further disassembling of cylinder
barrel and valve plate see page 11.
18. Remove, by hand, the two pins.
Note: The following operation is only
necessary if O-ring on port ange is to
be changed.
19. Place the pump horizontally.
Remove the remaining screws in port
ange by using a 13 mm combination
wrench. Carefully separate house and port
ange. Ensure that pin for the positioning
house is not lost.

Instruction Disassembling and assembling PAHT and PAHT G 256-308
6
180R9268 / 521B1236 / DKCFN.PI.011.B3.02 / 01.2015
3. Assembling the pump
4. Position housing alingning pin hole
over pin. Carefully press the port ange
downwards. Do not squeeze the O-ring. If
the O-ring is damaged, the pump will leak.
Screw in at least two screws.
3. Mount O-ring.
Insert pin for positioning housing
on port ange.
Ensure that two screw holes can be
reached from below.
Note:
Place the pump on a pallet or other stable
surface above the ground. Ensure that
the pump cannot roll. It must be possible
to place the pump vertically with the
shaft pointing downwards. This can be
done between two pallets or between
two boards on a pallet provided that the
distance is minimum 50 mm.
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. Place port ange with O-ring pointing
upwards.
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.

Instruction Disassembling and assembling PAHT and PAHT G 256-308
7
180R9268 / 521B1236 / DKCFN.PI.011.B3.02 / 01.2015
6. Place pump vertically. Place 10.5 mm pins
in port ange.
Position port plate by using the two pins.
Do not use force for this operation.
5. Place housing horizontally. Screw in the
rest of the screws on port ange. Tighten
screws to a torque of 30 ± 2 Nm.
8. Screw eye bolt in cylinder barrel.
10. Unscrew M8 eye bolt.
Place the four springs and spring guide in
cylinder barrel. Springs must be
positioned in the holes.
9. Make sure there is enough free space for
the shaft beneath the housing. Gently
lower cylinder barrel into housing.
WARNING!
If cylinder barrel is dropped or lowered
too fast into housing, main bearing and
shaft bearing might be damaged.
Replacement can only be done at
Danfoss, Nordborg.
7. Ensure port plate is tted tightly against
the bottom.
IMPORTANT:
Lubricate port plate with clean ltered
fresh water.
If valve plate is disassembled from
cylinder barrel please see page 11
before continuing.

Instruction Disassembling and assembling PAHT and PAHT G 256-308
8
180R9268 / 521B1236 / DKCFN.PI.011.B3.02 / 01.2015
13. Place retainer plate in cylinder barrel.
Note: If pistons are replaced, place new
pistons in clean ltered water for a
couple of minutes. Exercise piston shoes
to make them“run” smoother.
14. Place pistons in retainer plate and
cylinder barrel.
When pistons are placed, tilt retainer
plate for easier placement of swash plate.
If swash plate has been disassembled from
mounting ange, see page 10 for assembly
of swash plate.
15. Lubricate piston shoes and swash plate
with clean ltered water. Remember to
place the pins in housing.
11. Retainer guide, retainer ball and
retainer plate must be mounted as
indicated in below picture.
12. Ensure that retainer plate is oriented
correctly, i.e. with its slant surfaces
pointing downwards.
16. Place three bolts in mounting ange.
Turn each bolt one round at a time to
ensure mounting ange is mounted as
straight downwards as possible. Be careful
not to squeeze O-ring.
17. Screw in the rest of the bolts and cross
tighten all screws to a torque of
30 +/- 2 Nm.
Note: Screws for lifting eye are
shorter than the rest.

Instruction Disassembling and assembling PAHT and PAHT G 256-308
9
180R9268 / 521B1236 / DKCFN.PI.011.B3.02 / 01.2015
19. Place stop for shaft seal on shaft.
WARNING:
Ensure that carbon ring is pointing
outwards.
18. Place pump horizontally to get access to
shaft.
21. Press new ceramic ring into retainer ring
by using plastic tool provided.
WARNING:
Ensure that the face with rubber seal is
positioned against shoulder in shaft
seal ange.
20. Use plastic assembly tool provided with
large diameter pointing downwards, to
press seal home against shoulder of stop
for shaft seal.
23. Place shaft seal ange on shaft. Tighten
the bolts with a torque of 10Nm +/-2 Nm.
22. Remove old O-ring and t new one on
shaft seal ange.
Shaft seal

Instruction Disassembling and assembling PAHT and PAHT G 256-308
10
180R9268 / 521B1236 / DKCFN.PI.011.B3.02 / 01.2015
1. Place the swash plate upside down.
Remove the 2 bolts holding the swash
plate. Remove the mounting ange from
the swash plate.
3. Change the O-ring on the mounting
ange.
2. Check that the O-ring and pin are in good
condition (Provided with sealing set).
4. Mount the swash plate on the 2 pins.
Carefully by hand tilt the unit to
horizontal position and mount the 2 bolts
which hold the swash plate. Tighten the
bolts with a torque of 30 Nm +/-2 Nm.
Finally check the surface on the swash
plate for any marks or foreign particles.
Mount the assembled part on the pump.
4. Disassembling and
assembling of the
swash plate
WARNING:
Make sure that the surface on the swash
plate does not get any marks.

Instruction Disassembling and assembling PAHT and PAHT G 256-308
11
180R9268 / 521B1236 / DKCFN.PI.011.B3.02 / 01.2015
2. Remove the O-rings and backup rings. If
they have been removed they can not be
reused.
Mount the new back-up rings on the valve
plate rst and then mount the O-rings.
1. Push a screwdriver into the hole between
cylinder barrel and valve plate. Carefully
push downward the screwdriver so that it
makes a gap between cylinder barrel and
valve plate. Use this gap to put in another
screwdriver and loosen the valve plate
from the cylinder barrel.
4. Remove the press bush again by screwing
the nut counter-clockwise.
Turn the nut slowly clockwise. The valve
plate must slide gently into the cylinder
barrel. Stop when the gap between
cylinder barrel and valve plate is 1-2 mm.
3. Lubricate the new O-rings/back-up rings
and the liners in the cylinder barrel with
clean ltered water. Lower the valve plate
upside down on the cylinder barrel. Place
the press bush for valve plate (provided in
tool set) like on the picture. Screw the bolt
into the shaft of the cylinder barrel. Turn
the nut slowly clockwise. The valve plate
must slide carefully into the cylinder
barrel. Stop when the gap between
cylinder barrel and valve plate is 1-2 mm.
5. Disassembling and
assembling of cylinder
barrel and valve plate
Mount then
O-rings
Mount
backup
rings rst

Instruction Disassembling and assembling PAHT and PAHT G 256-308
12
180R9268 / 521B1236 / DKCFN.PI.011.B3.02 / 01.2015
6. Changing pistons Note : It is essential that the pump is serviced
in conditions of absolute cleanliness.
Tools needed:
• 13 mm combination wrench
• 6 mm allen key
• Tool set 180B4347
1. Disconnect the pump from the rest of the
system.
WARNING:
Never unscrew the 4 screws marked
with coloured sealer.
2. Loosen all screws on the pump except the
three screws as shown in the picture
above.
Note: There is still water inside the
pump.
4. Unscrew the remaining three screws by
using a combination wrench to turn each
screw a couple of rounds at a time so
the ange is removed as straight outward
as possible.3. Mount the guide bolt in the top hole.
6.1 Disassembling
Stop for
retainer ball

Instruction Disassembling and assembling PAHT and PAHT G 256-308
13
180R9268 / 521B1236 / DKCFN.PI.011.B3.02 / 01.2015
6. Remove the ange when the remaining
three screws have been loosened. The
guide bolt must remain mounted.
5. If the ange does not move forward -
loosen the drain plug to empty the pump
from water by releasing vacuum.
8. Adjust the retainer plate to be parallel to
the end ange.
7. Carefully turn the ange and push it
backwards to make it rest on the housing
surface. Ensure not to scratch the swash
plate surface.
9. Screw the stop for the retainer ring into
the centre to keep the retainer ball in
place.
Drain
plug
Swash plate
surface
10. Carefully remove the pistons one by one.

Instruction Disassembling and assembling PAHT and PAHT G 256-308
14
180R9268 / 521B1236 / DKCFN.PI.011.B3.02 / 01.2015
11.WARNING:
Ensure that the piston shoes and the
piston surfaces are not damaged during
removal. It is recommended to place the
pistons upside down on an even and
clean base/surface.
12. Remove the retainer ring by sliding it
across the stop for the retainer ball. If
necessary, tilt the ange.
13. Inspect the piston liners. Replace any worn
parts.

Instruction Disassembling and assembling PAHT and PAHT G 256-308
15
180R9268 / 521B1236 / DKCFN.PI.011.B3.02 / 01.2015
2. Insert the pistons randomly.1. Carefully push the retainer ring in place.
4. Place the retainer ring in an odd angle
corresponding to the orientation of the
swash plate.3. Remove the stop for retainer ball.
6. Turn the ange and gently push it into the
housing.
5. Tilt the ange and replace the ange
O-ring.
6.2. Assembling

Instruction Disassembling and assembling PAHT and PAHT G 256-308
16
180R9268 / 521B1236 / DKCFN.PI.011.B3.02 / 01.2015
8. Remove the guide bolt. Mount the three
screws. Tighten them to a torque of
30 Nm ± 3 Nm.
Connect the pump to the rest of the
system.
7. Mount the three screws as shown above.
Tighten them to a torque of 30 Nm ± 3 Nm.
9. Bleed the pump.

Instruction Disassembling and assembling PAHT and PAHT G 256-308
17
180R9268 / 521B1236 / DKCFN.PI.011.B3.02 / 01.2015
1. No wear or cavitation of the piston
shoe. New inspection is required in
4,000 hours.
3. Cavitation of the piston shoes.
All pistons must be replaced within the
next 1,000 hours.
2. Cavitation of the piston shoes.
New inspection is required in 2,000 hours.
7. When should the
pistons be replaced
This section provides guidance on, how to
determine whether the parts of the pump are
worn and should be replaced.
In case of doubt - the pistons must be replaced.
The pictures below are meant as a guideline for
evaluating the wear of the sliding surface.
Note: If the pistons break down, the pump
will suer a disastrous breakdown.

Instruction Disassembling and assembling PAHT and PAHT G 256-308
18
180R9268 / 521B1236 / DKCFN.PI.011.B3.02 / 01.2015
180B4082 - Screw & seal set (PAHT 256-308) 180B4079 - Cylinder barrel set (PAHT G 256-308) 180B4078 - Valve plate set (PAHT 256-308) 180B4084 - Retainer set (PAHT 256-308) 180B4083 - Piston set (PAHT 256-308) 180B4080 - Swash plate set (PAHT 256) 180B4081 - Swash plate set (PAHT 308)
Pos. Qty. Designation Material
Pos Qnt Designation Material
1 1 Housing Duplex / PEEK
2 2 Pin ø6 x 10 AISI 316 x
3 4 Bleeding plug G 1/4" Super duplex x
4 4 O-ring ø11 x 2 NBR x
517 Screw M8 x 30 AISI 316 x
9 1 O-ring ø228 x 4 NBR x x x x
10 2 O-ring ø9,19 x 2,62 NBR x x x
11 1End cover CW Duplex
13 2 Screw M8 x 16 AISI 316 x
31 1Swash plate Super Duplex x x
34 2 Pin ø10,5 x 20 Duplex x x x
61 1Cylinder barrel Super duplex / PEEK x
62 4Spring Duplex x
63 1Spring guide Polypropylen x
64 1Retainer Ball Super duplex x
65 1Retainer plate Super duplex x
66 9Piston Super duplex / PEEK x
67 1 Key 12 x 8 x 70 AISI 316 x
71 1Retainer Guide Super duplex / PEEK x
91 1Port plate Super duplex / PEEK x
92 1Valve plate Super duplex x
93 9 Back up ring PTFE x
94 9 O-ring ø30,2 x 3 NBR x
121 1Port ange Duplex
122 1 O-ring ø68 x 2 NBR x
123 1 O-ring Ø228 x 4 NBR x
124 1Shaft sealing Hasteloy C276 x
125 1Cover Super duplex
126 2 Pin ø10,5 x 20 Super duplex x x
127 4 Screw M6 x 16 AISI 316 x
128 15 Screw M8 x 90 AISI 316 x
132 2 Bleeding plug G 1/4" Super duplex x
133 2 O-ring ø11 x 2 NBR x
142 1Washer for shaft seal Polypropylen x
147 1 Screw M8 x 16 AISI 316 x
1Service instruction xxxxxxx
8. Spare parts list for
PAHT 256-308

Instruction Disassembling and assembling PAHT and PAHT G 256-308
19
180R9268 / 521B1236 / DKCFN.PI.011.B3.02 / 01.2015
180B4370 - Screw & seal set (PAHT G 256-308) 180B4369 - Cylinder barrel set (PAHT G 256-308) 180B4367 - Valve plate set (PAHT G 256-308) 180B4366 - Retainer set (PAHT G 256-308) 180B4368 - Piston set (PAHT G 256-308) 180B4331 - Swash plate set (PAHT G 256) 180B4332 - Swash plate set (PAHT G 308)
Pos. Qty. Designation Material
Pos Qnt Designation Material
1 1 Housing Duplex / PEEK
2 2 Pin ø6 x 10 AISI 316 x
3 4 Bleeding plug G 1/4" Super duplex x
4 4 O-ring ø11 x 2 NBR x
517 Screw M8 x 30 AISI 316 x
9 1 O-ring ø228 x 4 NBR x x x x
10 2 O-ring ø9,19 x 2,62 NBR x x x
11 1End cover CW Duplex
13 2 Screw M8 x 16 AISI 316 x
31 1Swash plate Super Duplex x x
34 2 Pin ø10,5 x 20 Duplex x x x
61 1Cylinder barrel Super duplex / PEEK x
62 4Spring Duplex x
63 1Spring guide Polypropylen x
64 1Retainer Ball Super duplex x
65 1Retainer plate Super duplex x
66 9Piston Super duplex / PEEK x
67 1 Key 12 x 8 x 70 AISI 316 x
71 1Retainer Guide Super duplex / PEEK x
91 1Port plate Super duplex / PEEK x
92 1Valve plate Super duplex x
93 9 Back up ring PTFE x
94 9 O-ring ø30,2 x 3 NBR x
121 1Port ange Duplex
122 1 O-ring ø68 x 2 NBR x
123 1 O-ring Ø228 x 4 NBR x
124 1Shaft sealing Hasteloy C276 x
125 1Cover Super duplex
126 2 Pin ø10,5 x 20 Super duplex x x
127 4 Screw M6 x 16 AISI 316 x
128 15 Screw M8 x 90 AISI 316 x
132 2 Bleeding plug G 1/4" Super duplex x
133 2 O-ring ø11 x 2 NBR x
142 1Washer for shaft seal Polypropylen x
147 1 Screw M8 x 16 AISI 316 x
1Service instruction xxxxxxx
9. Spare parts list for
PAHT G 256-308

Instruction Disassembling and assembling PAHT and PAHT G 256-308
20
180R9268 / 521B1236 / DKCFN.PI.011.B3.02 / 01.2015
Danfoss A/S
High Pressure Pumps
DK-6430 Nordborg
Denmark