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Service guide 

|

 Disassembling and Assembling, APP 

 

21 - 46 and APP W HC 15 -30

© Danfoss | 2023.03

2 | 180R9406 |  AX274339308034en-000302

This document covers the instructions for disassembling and assembling the axial piston pumps 

APP 21-46 and APP W HC 15-30

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 

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 andassembling of cylinder barrel and valve plate ......................................................11

6. 

Disassembling and assembling of the flush valve ....................................................................................11

7. 

Changing pistons ..................................................................................................................................................12

8. 

When should the pistons be replaced ...........................................................................................................17

9. 

 Exploded view APP 21-26 , APP 30/1500 and APP W HC 15-24  ..........................................................18

10. 

 Exploded view APP 30/1200, APP 38/1500, APP 46/1780 and APP W HC 30 ..................................19

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 18 and 19.

WARNING:

Do not reuse disassembled O-rings or shaft 

seal as they might be damaged. Always use 

new O-rings.

Summary of Contents for APP 21

Page 1: ...Service guide APP pumps APP 21 46 and APP W HC 15 30 Disassembling and assembling hpp danfoss com...

Page 2: ...e 10 5 Disassembling andassembling of cylinder barrel and valve plate 11 6 Disassembling and assembling of the flush valve 11 7 Changing pistons 12 8 When should the pistons be replaced 17 9 Exploded...

Page 3: ...he system Remove non return valve and connector from the pump 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 filtered water 3 Remove cer...

Page 4: ...0 10 Screw the eye bolt in the M8 hole in the middle of the flange Pull it straight upwards 8 Using a 13 mm combination wrench remove all the bolts on the mounting flange except the three shown in the...

Page 5: ...d 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 cylinde...

Page 6: ...h 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 thre...

Page 7: ...rrel 13 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 bea...

Page 8: ...ing flange see page 10 for assembly of swash plate 20 Lubricate piston shoes and swash plate with clean filtered water Remember to place the pins in housing 21 Place the pins in the housing 16 Retaine...

Page 9: ...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 flange 27 Use plastic assembly tool...

Page 10: ...he O ring and pin are in good condition provided with seal 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 p...

Page 11: ...up rings and the liners in the cylinder barrel with clean filtered 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...

Page 12: ...embling 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 above Note The...

Page 13: ...e remaining three screws have been loosened The guide bolt must remain mounted 7 Carefully turn the flange and push it backwards to make it rest on the housing surface Ensure not to scratch the swash...

Page 14: ...anfoss 2023 03 14 180R9406 AX274339308034en 000302 11 Warning Ensure that the piston shoes and the pistonsurfacesarenotdamagedduring removal Itisrecommendedtoplacethe pistons upside down on an even an...

Page 15: ...filtered water Insert the pistons arbitrarily 2 Remove the stop for retainer plate 4 Place the retainer plate in an angle corresponding to the orientation of the swash plate 5 Tilt the flange and rep...

Page 16: ...46 and APP W HC 15 30 Danfoss 2023 03 16 180R9406 AX274339308034en 000302 8 Remove the guide bolt Mount the remaining screws and cross tighten them to a torque according to exploded view 9 Connect the...

Page 17: ...ston shoes New inspection is required in 2 000 hours 3 Cavitation of the piston shoes All pistons must be replaced within the next 1 000 hours This section provides guidance on how to deter mine wheth...

Page 18: ...Service guide Disassembling and Assembling APP 21 46 and APP W HC 15 30 Danfoss 2023 03 18 180R9406 AX274339308034en 000302 9 Exploded view APP 21 26 APP 30 1500 and APP W HC 15 24...

Page 19: ...Service guide Disassembling and Assembling APP 21 46 and APP W HC 15 30 Danfoss 2023 03 180R9406 AX274339308034en 000302 19 10 Exploded view APP 30 1200 APP 38 1500 APP 46 1780 and APP W HC 30...

Page 20: ...Danfoss DCS SGDPT SI 2023 03 180R9406 AX274339308034en 000302 20...

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