General Pump HF18 Operating instructions

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

Page 11
HF SERIES
GENERAL PUMP A member of the Interpump Group
Serial #10127003 and Later
The new roller bearing can be mounted at room temperature with a press or fly press; it is necessary to lay
them on the lateral side of the relevant ring nuts with opposite rings. The driving operation can be facilitated
by heating the relevant parts to a temperature ranging between 2500- 3000F, (1200- 1500C), making sure
that the ring nuts are correctly fitted in their seats.
Never invert the parts of the two bearings.
Determining the shim pack:
Perform the operation while the plunger/con-rod guide units are assembled, the con-rod caps are disconnect-
ed and the con-rods are pushed downwards. Insert the crankshaft without tab into the crankcase, making
sure the PTO shank comes out of the correct side.
Secure the PTO side flange to the crankcase, taking care with the lip seal as described previously and tighten
the fixing screws to the recommended torque.
Then feed the flange on the indicator side without shims in the carter and start to move it closer, manually
screwing the M6x40 service screws in equally, with small rotations such as to move the cover in slowly and
correctly.
At the same time, check that the shaft rotates freely by turning it manually.
Continuing the procedure in this way, a sudden increase in hardness during shaft rotation will soon be experi-
enced.
At this point, halt the forward movement of the cover and loosen the fixing screws completely.
With the aid of a feeler gauge, measure the clearance between the side cover and pump casing (see Fig. 14).
Fig. 14
Measurement Shim
Type
No. of
Pieces
From: 0.05 to 0.10 - -
From: 0.11 to 0.20 0.1 1
From: 0.21 to 0.30 0.1 2
From: 0.31 to 0.35 0.25 1
From: 0.36 to 0.45 0.35 1
From: 0.46 to 0.55 0.35
0.10
1
1
From: 0.56 to 0.60 0.25 2
From 0.61 to 0.70 0.35
0.25
1
1
Determine the shim pack as indicated in the table below:
Once the type and number of shims have been determined using the table, check the following: assemble the
shim pack on the indicator side cover centering (Fig. 15), secure the cover to the casing, following the proce-
dure in par. 2.1.2, and tighten the screws to their recommended torque.
Check that the shaft rotation stall torque is between 2.95 ft. lbs. (4 Nm) and 4.43 ft. lbs. (6 Nm).
If this torque is correct, connect the con-rods to the bend shaft and to the next stages. If it is not, redefine the
shim pack, repeating the operations.
Ref 300623 Rev. B
10-20

Page 12
HF SERIES
GENERAL PUMP A member of the Interpump Group
Serial #10127003 and Later
2.2 Fluid End Repair
2.2.1 Disassembly of the Head - Valve Units
Service operations are limited to valve inspection or replacement if needed, and in any case within the
intervals indicated in the table in Chapter 11 of the Owner’s Manual.
The valve units are assembled inside the head in a vertical position.
For their extraction proceed as follows:
Unfasten the 8 M14 x 40 valve cover screws (fig. 16); using a slide hammer p/n F26019400 extract:
A) the valve plugs (fig 17);
B) the outlet valve units (fig. 18);
C) the valve bushings (fig. 19), also using the tool #F27513600;
D) the inlet valve units (fig 20)
Fig. 16 Fig. 17
Fig. 18 Fig. 19 Fig. 20
Ref 300623 Rev. B
10-20

Page 13
HF SERIES
GENERAL PUMP A member of the Interpump Group
Serial #10127003 and Later
Fig. 21
• Disassemble the suction and outlet valve units, screwing a sufficiently long M8 screw in such a way
as to be able to reach the valve plate and extract the valve guide from the valve seat
(Fig. 21, pos. 1).
If the suction valve seats remain stuck on the head (for example because of
incrustations due to prolonged lack of use of the pump), proceed as follows:
- For HF18 versions use tools code 26019400, code 27513700, code 27513400,
(Fig. 22, Fig. 22/a).
- For HF20-22-HF25 versions use tools code 26019400, code 27513500, code 27513400,
(Fig. 22, Fig. 22/a).
Fig. 22 Fig. 22a
Note. Before extracting from the seats, always unscrew the handle code 27513400.
Ref 300623 Rev. B
10-20

Page 14
HF SERIES
GENERAL PUMP A member of the Interpump Group
Serial #10127003 and Later
Pay careful attention to the state of wear of the various components; replace them when
necessary, and in any case within the intervals indicated in the table in Chapter 11 of
the Owner’s Manual. At each valve inspection, replace all valve unit and valve plug O-rings
and anti-extrusion rings.
Before repositioning the valve units, clean and completely dry the relevant seats in the
head as indicated in fig. 23.
Proceed with reassembly by inverting the procedure indicated in paragraph 2.2.1, paying particular
attention to:
1. During the assembly of the inlet and outlet valve units (fig. 24 and 25) do not invert the
inlet springs with the previously disassembled outlet springs:
a) Inlet springs are white
b) Outlet springs are black
2.2.2 Head Assembly - Valve Units
Fig. 23
Fig. 24 Fig. 25
Ref 300623 Rev. B
10-20

Page 15
HF SERIES
GENERAL PUMP A member of the Interpump Group
Serial #10127003 and Later
Insert the inlet and outlet valve units with their bushes, checking that they are fully inserted
in the head seat. Take special care not to damage the anti-extrusion rings on the bushes
(Fig. 28, pos. 3). For correct positioning and adjustment of rings in their respective seats:
• Insert the bushes completely in the head, lubricating the external O-ring/anti-extrusion
rings diameter with OCILIS type silicone grease code 12001600.
• Remove the bushes, verifying the integrity of all the anti-extrusion and O-rings.
• Proceed with final reassembly.
2. Furthermore, for the HF18A version be careful not to invert the spherical inlet valve with the
“A” outlet valve (fig. 26 and fig. 27), exploded view position #46, as indicated in Chapter 16
of the Owner’s Manual.
Fig. 26 Fig. 27
Fig. 28
• Then apply the valve covers and calibrate the respective M14x40 screws. For the
values of the torques and tightening sequences follow the instructions in chapter 3.
Ref 300623 Rev. B
10-20

Page 16
HF SERIES
GENERAL PUMP A member of the Interpump Group
Serial #10127003 and Later
2.2.3 Disassembly of the Head - Seals
The replacement of the seals is necessary if water leaks are detected from the draining holes located at the
rear of the crankcase, and in any case within the intervals indicated in the table in Chapter 11 of the Owner’s
Manual.
A) Unfasten the M12x150 head screws as shown in fig. 29.
Fig. 29
B) Separate the head from the pump crankcase.
C) Extract the high pressure seals from the head and the low pressure ones from the support, using simple
tools as indicated in (Fig. 30, pos. 1), being careful not to damage the respective housings.
Fig. 30
Ref 300623 Rev. B
10-20

Check them for wear; replace if necessary.
At each disassembly, all the O-rings of the plunger unit must be replaced.
Page 17
HF SERIES
GENERAL PUMP A member of the Interpump Group
Serial #10127003 and Later
Pay careful attention to the order of sealing pack disassembly as shown in fig. 31 for
HF20A/22A/25A version pumps, and fig. 31a for HF18A version composed of:
1. Head ring
2. HP seal
3. Restop ring
4. Packings support
5. LP seal
6. Sealing ring
7, Circlip
8. O-ring
Fig. 31 Fig. 31a
2.2.4 Plunger Unit Disassembly
The plunger unit does not require periodic maintenance. Service interventions are limited to visual inspections
only. For plunger unit extraction operate as follows:
Unfasten the M7x1 plunger screws as shown in fig. 32.
Fig. 32
Ref 300623 Rev. B
10-20

Page 18
HF SERIES
GENERAL PUMP A member of the Interpump Group
Serial #10127003 and Later
2.2.5 Head Assembly - Seals - Plunger unit
Reassemble the various components by inverting the operations previously listed in paragraph 2.2.3, paying
careful attention to the following:
A) Sealing packing: follow the same order used during disassembly.
B) Lubricate components 2,3 and 5 with silicone grease type OCILIS, p/n F12001600; this operation is also
considered necessary in order to facilitate the settling of the seal lip on the plunger.
C) For correctly assembling the HP seals in their related seats on the head without damaging the lips, use
the appropriate tools depending on the pumping assembly diameters as indicated in Chapter 4.
D) Reassemble the plungers by fastening the screws with a torque wrench, following the fastening torque
value indicated in Chapter 3.
E) Reassemble the head proceeding as follows:
1. Position the seal supports in their respective seats on the crankcase;
2. Using two screws - auxiliary pin (p/n F27508200) fastened to the crankcase as indicated in fig. 33,
position the complete head, being sure that it is centered on the central plunger only.
3. Complete the operations by following the fastening procedures; for fastening torque values and
sequences, follow what is indicated in Chapter 3.
Fig. 33
Ref 300623 Rev. B
10-20

3. SCREW CALIBRATION
Screw calibration by means of a torque wrench only.
Description Exploded View Position
(From Owner’s Manual)
Fastening Torque
(Ft. Lbs.)
Fastening Torque
(Nm)
Cover fastening screws 9 7.4 10
Plunger fastening 29 14.8 20
Plunger guide rod fixing screw 100 7.4 10
Con-rod caps fastening screws 16 28 38*
Head fastening screws 39 59 80**
Valve cover screws 41 132.8 180***
Lifting bracket fastening screws 63 29.5 40
Oil discharge plug 11 29.5 40
* The con-rod caps fastening screws must be tightened respecting the phases indicated in “Point D”
of page 6
** The head fastening screws, exploded view position 39 from the Owner’s Manual, must be tightened
using a torque wrench, lubricating the threaded stem and respecting the order of the scheme in
fig. 34.
*** the valve cover screws, exploded position 41 from the Owner’s Manual, must be fastened using a
torque wrench, lubricating the threaded stem and respecting the order of the scheme in fig. 34.
Page 19
HF SERIES
GENERAL PUMP A member of the Interpump Group
Serial #10127003 and Later
Fig. 34
Ref 300623 Rev. B
10-20

Page 20
HF SERIES
GENERAL PUMP A member of the Interpump Group
Serial #10127003 and Later
4. REPAIR TOOLS
Pump maintenance may be carried out using simple tools for assembling and disassembling components.
The following tools are available:
For Assembly:
Gasket Bushing Ø 32; HP alternative seal ring Ø 18x32x7/4.5 p/n 27472700
p/n 27385200
Gasket Bushing Ø 35; HP alternative seal ring Ø 20x35x7.5/4.5 p/n 27472800
p/n 26134600
Gasket Bushing Ø 35; HP alternative seal ring Ø 22x35x7/4.5 p/n 27472800
p/n 26134600
Gasket Bushing Ø 38; HP alternative seal ring Ø 25x38x7/4.6 p/n 27472900
p/n 27385400
Gasket Bushing Ø 26; LP alternative seal ring Ø 18x26x5.5 p/n 27470600
p/n 26242500
Gasket Bushing Ø 28; LP alternative seal ring Ø 20x28x5.5 p/n 27531500
p/n 27365300
Gasket Bushing Ø 30; LP alternative seal ring Ø 22x30x5.5 p/n 27470700
p/n 26134600
Gasket Bushing Ø 33; LP alternative seal ring Ø 25x33x5.5 p/n 27470800
p/n 27385200
Pump shaft oil seal p/n 27904800
Plunger guide oil sea p/n 27904900
Head Assembly p/n 27508200
For Disassembly:
Valve bushes p/n 26019400
p/n 27513600
Pump inlet valves version HF18A
p/n 26019400
p/n 27513700
p/n 27513400
Pump inlet valves version HF20A/22A/25A
p/n 26019400
p/n 27513500
p/n 27513400
Outlet valves p/n 26019400
Valve plugs p/n 26019400
Plunger guide oil seal p/n 26019400
p/n 27503900
COPYRIGHT
The copyright of these operating instructions is property of General Pump/ the Interpump
Group. The instructions contain technical descriptions and illustrations that may not be
electronically copied or reproduced, entirely or in part, nor distributed to third parties in
any form without authorized written permission.
Offenders will be prosecuted according to the laws in force.
Ref 300623 Rev. B
10-20