General Pump HF18 Istruzioni operative
HF/N
Repair Manual
Ref 300623 Rev. B
10-20
Serial #10127003 and Later
NOTE: This Manual
covers HF pumps with
Serial Numbers starting at
10127003
HF25N
HF18 - HF20 - HF22 - HF25 WK355
General Pump
is a member of
the Interpump Group
Page 2
INDEX
1. INTRODUCTION ..................................................Page 3
2. REPAIR INSTRUCTIONS ...........................................Page 3
2.1 Crank Mechanism Repair. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Page 3
2.1.1 Crank Mechanism Disassembly .............................Page 4
2.1.2 Crank Mechanism Assembly ...............................Page 6
2.1.3 Disassembly / Assembly of Bearings and Shims ................Page 10
2.2 Fluid End Repair ...............................................Page 12
2.2.1 Disassembly of the Head - Valve Units .......................Page 12
2.2.2 Head Assembly - Valve Units ...............................Page 14
2.2.3 Disassembly of the Head - Seals ............................Page 16
2.2.4 Plunger Unit Disassembly..................................Page 17
2.2.5 Head Assembly - Seals - Plunger Unit ........................Page 18
3. SCREW CALIBRATION ............................................Page 19
4. REPAIR TOOLS ..................................................Page 20
5. MAINTENANCE LOG ..............................................Page 21
HF SERIES
GENERAL PUMP A member of the Interpump Group
Serial #10127003 and Later
Ref 300623 Rev. B
10-20
Page 3
1. INTRODUCTION
This manual describes the instructions for Repairing HF Series pumps, and must be carefully read and
understood before performing any repair intervention on the pump. Correct use and adequate maintenance is
fundamental for the pump’s regular operation and long wear. General Pump declines any responsibility for
damage caused by the misuse or the non-observance of the instructions described in this manual.
2. REPAIR INSTRUCTIONS
2.1 Crank Mechanism Repair
Crank mechanism repair operations must be carried out after draining the oil from the crankcase. To drain
the oil, remove the oil dipstick, 1, Fig. 1, and then the draining plug (2, fig. 1).
Exhausted oil must be collected in an appropriate receptacle and disposed of in
designated locations. In absolutely no case may it be disposed of in the environment.
HF SERIES
GENERAL PUMP A member of the Interpump Group
Serial #10127003 and Later
Warning
Potential Danger Danger
Wear goggles
Danger
Wear protective gloves
Read carefully and understand
the manual before operating
the pump
1.1 Description of Symbols
Fig. 1
Ref 300623 Rev. B
10-20
Page 4
2.1.1 Crank Mechanism Disassembly
Dismantling the mechanical part
The operations described must be performed after removing the hydraulic part, ceramic pistons and splash
guards from the pump (par. 2.2.3, 2.2.4).
Remove in the following order:
• pump shaft key
• rear cover
• connecting rod cap
• The con-rod cap as follows: unscrew the cap fixing screws, remove the con-rod caps with
their lower half-bearings (Fig. 2) paying attention to the numbered sequence during
disassembly.
• Push the plunger guides and connecting rods forward in order to facilitate the lateral
extraction of the pump shaft. Two marks are visible on the crankshaft, as shown in fig. 4 and in
fig. 4a; they must be turned towards the operator in order to facilitate extraction.
HF SERIES
GENERAL PUMP A member of the Interpump Group
Serial #10127003 and Later
Fig. 2 Fig. 2a
• The side covers using - for extraction 3 fully threaded M6x50 screws, inserting them in the
threaded holes as indicated in Fig. 3.
Fig. 3
Ref 300623 Rev. B
10-20
Page 5
HF SERIES
GENERAL PUMP A member of the Interpump Group
Serial #10127003 and Later
Fig. 4
Fig. 4a
• Remove the pump shaft
• rear cover
• Complete disassembly of the con-rod units by removing them from the pump crankcase and
removing the plunger guide pins.
• Remove the pump shaft seal rings using common tools.
• Remove the plunger guide seal rings as described below:
Use the extractor code 26019400 (Fig. 5, pos. 1) and the pliers code 27503900 (Fig. 5, pos. 2). Insert
the gripper as far as possible onto the seal ring with the aid of a hammer (Fig. 5/a), subsequently
screwing the extractor to the gripper, and use the extractor hammer (Fig. 5/b) until the ring to be
replaced is removed (Fig. 5/c).
Fig. 5 Fig. 5a
Fig. 5b Fig. 5c
Ref 300623 Rev. B
10-20
Page 6
HF SERIES
GENERAL PUMP A member of the Interpump Group
Serial #10127003 and Later
When disassembling the con-rod groups check the wear status of the piston guide rods (pos. 1,
Fig. 5/d), if necessary replace them removing the 2 fixing M6 screws (pos. 2, Fig. 5/d).
Fig. 5d
2.1.2 Crank Mechanism Assembly
After cleaning the crankcase, reassemble the crankcase mechanism as follows:
• Assemble the upper and lower half-bearings in their seats in the con-rods and caps.
Make sure that the reference marks on the upper half-bearings (Fig. 6, pos. 1) and lower
half-bearings (Fig. 6/a, pos. 2) are positioned in their respective seats in the con-rod and
cap.
Fig. 6 Fig. 6a
If the piston guide rods have been disassembled, before reassembling them check the correct positioning
of the sealing O-rings (pos. 1, Fig. 6/b) replace them if necessary. Tighten the piston guide rods through the
respective two M6 screws to the tightening torque indicated in the table of page 24.
Ref 300623 Rev. B
10-20
Page 7
HF SERIES
GENERAL PUMP A member of the Interpump Group
Serial #10127003 and Later
Fig. 6b
• Insert the plunger/con-rod guide units into the pump crankcase, directing the numbering on the
con-rod shank towards the top of the crankcase.
To facilitate pump shaft insertion (without the tab), it is essential to repeat the operation performed during dis-
assembly, pushing the piston/con-rod guide units as far down as possible (par. 2.1.1).
• Before assembling the side cover on the PTO side, check the conditions of the radial ring lip
seal and relative contact area on the shaft.
If replacement is necessary, position the new ring using a tool (code 27904800) as shown in Fig. 7.
If the pump shaft shows diametrical wear in the area of contact with the lip seal, in order
to prevent the grinding operation, it is possible to reposition the ring in abutment with the
cover as shown in Fig. 7.
Before assembling the side covers, make sure there are O-rings on both of them and shim rings on the indi-
cator side cover only.
To facilitate filling of the first section and relative press fitting of the covers on the casing, we recommend
using 3 partially-threaded M6 x 40 screws (Fig. 8, pos. 1), then completing the operation with the screws sup-
plied (M6x18).
Fig. 7 Fig. 8
Ref 300623 Rev. B
10-20
Page 8
HF SERIES
GENERAL PUMP A member of the Interpump Group
Serial #10127003 and Later
• Couple the con-rod caps to their shanks, referring to the numbering (Fig. 9, pos. 1).
Note the correct assembly direction of the caps.
Fig. 9
• Fasten the caps to their respective con-rod shanks by means of M8x1x48 screws (Fig. 10)
lubricating both the underhead and the threaded shank, proceeding in two different stages:
1. Manually turn the screws until they begin to tighten
2. Tightening torque Alternatively, ensure: 30Nm
1. Pre-tightening torque: 10-15 NM
2. Tightening torque: 30 Nm
Fig. 10
• After having completed tightening operations, check that the con-rod head has a side
clearance in both directions.
Ref 300623 Rev. B
10-20
Page 9
HF SERIES
GENERAL PUMP A member of the Interpump Group
Serial #10127003 and Later
• Insert the new plunger guide seal rings as far as possible into the relative seat on the pump
casing (Fig. 11), following the procedure described: use the tool code 27904900 composed
of a tapered bush and a buffer. Screw the tapered bush into the hole in the piston guide
(Fig. 11/a), insert the new seal ring on the buffer as far as it will go
(determined by the height of the buffer) into its seat on the pump casing (Fig. 11/b), remove
the tapered bush (Fig. 11/c).
Fig. 11 Fig. 11a
Fig. 11b Fig. 11c
• Mount the rear cover complete with the O-ring, positioning the dipstick hole upward.
• Insert oil in the crankcase as indicated in the Owner’s Manual.
Ref 300623 Rev. B
10-20
Page 10
HF SERIES
GENERAL PUMP A member of the Interpump Group
Serial #10127003 and Later
2.1.3 Disassembly / Assembly of Bearings and Shims
The type of bearings used (tapered roller bearings), ensures the absence of axial play on the crankshaft; the
shims are to be determined to reach this purpose. To assemble / disassemble, or to replace them if needed,
carefully follow the indications below:
A) Assembly / Disassembly of the crankshaft without replacing the bearings
After removing the side covers, as indicated in paragraph 2.1.1, check the rollers and their races for wear; if
all parts are in good condition, fully clean the components with a suitable degreaser and grease them again
evenly using the same oil in the crankcase. The same shims can be used again, being careful to fit them
under the cover on the site glass side. After installing the complete unit (sight glass side flange, shaft and
engine side flange), check that the shaft’s rolling torque - with the connecting rods free - is at least 3 Ft. Lbs.
(4 Nm), Max 5 Ft. Lbs. (7 Nm). To position the two side covers on the crankcase, initially use 3 M6 x 40
screws as shown in fig. 8, and then the fastening screws. The shafts rolling torque (with connecting rods cou-
pled must not exceed 6 Ft. Lbs. (8 Nm).
B) Disassembly / Assembly of the Crankshaft With Bearings Replacement
After disassembling the side covers as indicated in paragraph 2.1.1, remove the outer ring nut of the bearings
from their covers and the inner ring nut, with the remaining part of the bearing, from the two shaft extremities
using a standard pin extractor or similar tool as indicated in fig. 12, fig. 12a and fig. 13.
Fig. 12 Fig. 12a
Fig. 13
Ref 300623 Rev. B
10-20
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