MH
8
Owner’s Manual
• Installation
• Use
• Maintenance
General Pump is a
member of the
Interpump Group
GENERAL PUMP
INDEX
1. INTRODUCTION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Page 3
2. SYMBOL DESCRIPTIONS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Page 3
3. SAFETY . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Page 3
3.1 General warnings for safe operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Page 3
3.2 High pressure unit safety requirements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Page 3
3.3 Safety of operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Page 4
3.4 General procedures for high pressure lance/gun operation . . . . . . . . . . . . . . .Page 4
3.5 Safety of maintenance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Page 4
4. PUMP IDENTIFICATION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Page 5
5. TECHNICAL FEATURES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Page 5
6. DIMENSIONS AND WEIGHT . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Page 5
7. GENERAL INFORMATION ABOUT SPECIFIC PUMP USE . . . . . . . . . . . . . . . . .Page 6
7.1 Water temperature . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Page 6
7.2 Maximum flow and pressure ratings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Page 6
7.3 Lowest operating RPM . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Page 6
A member of the Interpump Group
MH SERIES
8. CONNECTION AND PLUGS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Page 6
9. PUMP INSTALLATION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Page 7
9.1 Positioning . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Page 7
9.2 Direction of rotation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Page 7
9.3 Water connections . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Page 7
9.4 Suction line . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Page 7
9.5 Filtration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Page 8
9.6 Delivery time . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Page 8
10. START UP AND RUNNING PROCEDURES . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Page 9
10.1 Before start up . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Page 9
10.2 Starting up . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Page 9
10.3 Water leakage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Page 9
11. MAINTENANCE INSTRUCTIONS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Page 10
11.1 Crank mechanism maintenance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Page 10
11.2 Fluid end maintenance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Page 10
11.3 Pumping unit maintenance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Page 12
12. SCREW CALIBRATION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Page 14
13. MAINTENANCE TOOLS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Page 14
14. PUMP STOPPED FOR LONG TIME . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Page 14
15. PRECAUTIONS AGAINST FREEZING . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Page 14
16. EXPLODED VIEWS AND PARTS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Page 15
17. TROUBLE SHOOTING . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Page 17
Page 2
GENERAL PUMP
A member of the Interpump Group
MH SERIES
1. INTRODUCTION
MH high pressure water plunger pumps have been
designed for long life industrial duties and provided they
are correctly installed and maintained will give long
trouble-free operation. Read and understand this
manual before using your pump; it contains the
necessary information for the correct installation, use and
maintenance as well as some practical suggestion for
trouble shooting.
Upon receipt of your pump, inspect for overall good
condition and that no items are missing. Any missing
item or damage should be reported before installing
and starting the pump.
2. SYMBOL DESCRIPTIONS
Warning
Potential Danger
Read carefully and understand
the manual before operating
the pump
Danger
High Voltage
Danger
Wear protective mask
Danger
Wear goggles
3. SAFETY
3.1 General warnings for safe operation
The misuse of a high pressure water unit and the nonobservance of the pump installation and maintenance
instructions may cause serious damages and/or injuries
to people or properties or both.
Any Manufacturer/Operator requested to assemble/use
a high pressure water unit should be competent to do so,
should have the necessary knowledge on every high
pressure component installed in the unit and on the
precautions to be taken in order to guarantee the largest
safety margins during operation. No precaution, so far
as is reasonably practical, should be left out in the
interest of safety, both from the Manufacturer and the
Operator.
3.2 High pressure unit safety requirements
1. A safety valve should be installed in any delivery line
and should be sized to discharge or by-pass the
entire pump flow rate
2. High pressure unit components, with particular regard
for those units working outside, should be adequately
protected against rain, frost and heat.
3. Electric components and wiring should be provided
with an adequate degree of protection, able to protect
them against spray coming from any direction. They
should also be suitable for working in a wet
environment.
4. High pressure hoses and any other accessory under
pressure should be sized in accordance with the
maximum unit working pressure and must always
work within the safety margins indicated by the nose/
accessory Manufacturer.
5. High pressure hose ends should be fastened to a
steady object in order to prevent them from
dangerous sweeping around, should they burst or
come off their end fittings.
6. Proper safety guards should be provided to
adequately cover transmission joints, pulleys, belts or
auxiliary drives.
Danger
Wear protective gloves
Danger
Wear protective boots
Page 3
GENERAL PUMP
3.3 Safety of operation
The access into the area when a high pressure unit is
working should be strictly prohibited to unauthorized
personnel. The area should be suitably enclosed and its
perimeter, so far as is reasonably practical, cordoned
off and proper warning notices displayed in prominent
positions.
Personnel authorized to enter that area should have been
previously trained to do so and informed of the risks
arising from failures, misuse and any foreseeable
circumstance which may occur during operation. Before
starting the pump unit and bringing it up to pressure the
Operator is requested to carry out the following checks:
1. Make sure that a correct water supply to the pump
is provided.
2. Make sure that water inlet filters are properly clean.
3. Electrical components and wiring, with special
emphasis on connections, junction boxes, switches
and supply cables should be free from external
damage (i.e. exposed and broken wires) and
adequately protected against water.
4. High pressure hose should not show apparent
external wear and the fittings at both ends should be
free from signs of erosion or corrosion.
5. Make sure that all fluids (lubricating oil for pump and
engine, cooling water, hydraulic fluids) are at proper
levels and in good condition.
6. Make sure the safety guards are in good condition.
The work should stop immediately and the pressure must
be released in the event that leakage becomes apparent
or if any person becomes aware of an change in condition
or any hazard existing or being introduced. Any failure
must be promptly reported and then checked personnel.
3.4 General procedures for high pressure gun/lance
operation
1. The Operator should take reasonable care for the
safety of himself and of other persons who may be
affected by his acts or omission at work. His actions
should always be governed by his good sense and
responsibility.
2. The Operator should wear suitable waterproof
protective clothing, having regard to the type of work
being undertaken. The clothing set should include
adequate hand protection, suitable boots able to
ensure proper grip on wet floors, helmet provided with
full face shield, waterproof garment providing full
cover to the Operator, including his arms.
As most water jets produce noise levels in excess of
A member of the Interpump Group
MH SERIES
90 dB(A) suitable ear protection is advised.
NOTE: it must be emphasized that whereas protective
clothing provides adequate protection against spray and
flying particles, it does not constitute complete protection
protection against the direct impact of the water jet.
Additional protections in the form of suitable metal shields
or barriers may be necessary for certain jetting operation.
3. In most jetting operations it is an accepted practice
to employ a team of Operators consisting of two
members at least, in order to provide mutual
assistance in case of need and to rotate their duties
in case of long and heavy work. While the first
Operator holds the gun, the second Operator attends
the pump unit, keeping close watch on the first
Operator for signs of difficulty or fatigue, and
watching the surrounding area for intrusion by other
persons or unsafe situations. If required, he will shut
off the pressure unit until it is safe to continue.
4. The area in which the work is to proceed should be
clear of loose items and debris to prevent
tripping and slipping hazards.
5. The water jet should be directed only and always
against the workpiece even during preliminary
operating tests prior to starting work.
6. Where applicable, proper side shields should be
suitable placed to safeguard personnel and
equipment against contact with grit or particles
removed by the water jet.
7. On no account must the Operator be distracted
during operation until the jet has been stopped.
Personnel having reason to enter the water jetting
area should wait until the jet is stopped and his
presence known.
8. Each team member must always be aware of the
actions and intentions of other team members in order
to prevent any dangerous misunderstanding occurring
during jetting operation.
9. The pump unit should not be started and brought up
to pressure unless each team member is in his
designated position, the nozzle directed to the
workpiece and the lance or gun securely held.
3.5 Safety of maintenance
Apart from the working pressure regulation no attempt
should be made to adjust any nut, hose, fitting, etc., while
that part of the system is under pressure. The pump
should be stopped and any pressure in the line released
prior to making any adjustments.
1. The high pressure water unit should be maintained in
accordance with the Manufacturer’s instructions.
2. The unit should be maintained only by competent
personnel
3. Service and maintenance should be carried out with
proper tools in order to prevent any damage on high
pressure connections and fittings.
4. Use of other than original spar parts is strictly
forbidden.
Page 4
GENERAL PUMP
A member of the Interpump Group
4. PUMP IDENTIFICATION
Each pump is fitted with a rating plate (see Fig. 1)
containing the following information:
2. pump model and version
3. serial number
4. max RPM
5. max operating pressure (bar)
6. oil capacity (ltr) and oil specification
7. gear box ratio
8. max flow rate (l/min)
Pump model, pump version and serial number should
be specified when ordering spare parts. Should the pump
be modified (i.e by changing the original version) than
any change should be mentioned on the rating plate for
future reference.
5. TECHNICAL FEATURES
MH SERIES
1800 RPM (R = 1:3.29) 1500 RPM (R = 1:2.65)
Model
MH45 49.4 187 4350 300 147 108 51.2 194 4350 300 152 112
MH50 61.0 231 3600 250 151 111 63.4 240 3500 240 151 111
MH55 74.0 280 2950 205 149 110 76.6 290 2900 200 152 112
MH60 88.0 333 2550 175 152 112 91.1 345 2400 165 149 110
MH65 103 391 2100 145 148 109 107 405 2050 140 148 109
Flow Rate Pressure Power Flow rate Pressure Power
GPM l/min PSI bar Hp kW GPM l/min PSI bar Hp kW
6. DIMENSIONS AND WEIGHT
Page 5
GENERAL PUMP
A member of the Interpump Group
MH SERIES
7. GENERAL INFORMATION ABOUT PUMP
USE
The MH pump has been designed to pump fresh filtered
water at room temperature.
7.1 Water temperature
Water temperature is critical for the pump life, the higher it
is, the more likely it is to crate cavitation, resulting in
premature seal and valve failures.
Below is the temperature chart
and relevant limitations:
<104oF
from
104oF
to
140oF
Water is considered to be at room
temperature.
feed the plunger pump with a centrifugal
pump supplying at least twice the plunger
pump volume at 30 to 45 PSI
reduce pump rated RPM by 30% to 50%
Make sure the crankshaft turns as
indicated by the arrows located neat the
drive shaft projection
8. CONNECTIONS AND PLUGS
MH pumps are provided with (Fig. 3):
1 - 2 inlet ports IN Ø 3”-NPT
Suction line connection to any of the two inlet ports is
acceptable, the port not being used should be sealed
with the correct plug.
2 - 2 outlet ports OUT 1-1/4” NPT
3 - 1 hole DRAIN provided underneath the crankcase
and designed to drain out the water leakage of the
pressure packings. This hole must always be left
open (see paragraph 10.3 Fig. 7-page 9).
>140oF
7.2 Max flow and pressure ratings
The performance data indicated in the catalog and on the
rating plate refer to the maximum performance of the
pump. The use of the pump below the rated performances
does not allow the drop in power absorbed to be balanced
by altering the pressure or volume of the pump above its
maximum value.
7.3 Lowest operating RPM
The lowest operating speed of the crankshaft for all
MH’s (all versions is 350 RPM.
standard pump not suitable, contact our
Customer service Department
Page 6
GENERAL PUMP
A member of the Interpump Group
MH SERIES
9. PUMP INSTALLATION
9.1 Positioning
The pump should be installed flat on a rigid base by
means of the four feet Ø 16.5 mm.
The base should be rigid enough to avoid any
misalignment of flexing of flexing of the
pump/transmission coupling axis due to the torque involved
during operation.
On no account should the pump be installed in such a
way its fluid end rests on the base where the pump
is mounted. The fluid end should be left free and not
subjected to any force (Fig. 4).
9.2 Direction of rotation
Fig 5 shows the correct direction of rotation looking at the
pump from the fluid end side. Two arrows stamped on
the crankcase nearby the crankcase provide the
information as well.
9.3 Water connections
In order to isolate the high pressure equipment from the
pump vibrations it is suggested, where applicable, to use
flexible hoses for both suction and delivery lines at least
for the first length. The flexible suction hose must be
rigid enough to prevent it from collapsing during the
suction stroke, when a partial vacuum may occur.
9.4 Suction line
Plunger pumps are not self priming therefore a positive
suction head should always be provided. Information for
the correct suction line:
1. Internal diameter should be at least 3”, in any
point, possibly larger depending on the drop in
pressure due to the length and shape of the line.
2. Should be as straight as possible minimizing changes
in size and direction and positioned in such a way
to allow air pockets and bubbles to escape.
3. Should be perfectly airtight.
4. Should be completely free from 90oelbows, diameter
reductions, counter slopes, “T” connections and
should not be connected to other pipelines.
5. Should positioned in such a way to prevent the pipe
emptying after the pump stops.
6. Do not use high pressure flexible hoses for the
suction line.
7. Do not use high pressure hydraulic fittings like 90
elbows, high pressure adapters, high pressure 3 or
4 way nipples and so on.
8. Do not install any kind of detergent injector along the
suction line.
9. Do not install standing valves, check valves or other
kind of one-way valves.
10. Make sure that the feed tank capacity and the water
minimum level do not give rise to turbulence at the
tank outlet port, which, in turn, might create
cavitation at the pump.
11. Do not connect the by-pass line from the valve directly
to the pump suction line.
12. The water flow from the valve should be directed back
in the tank. Make sure that the by-pass and tank
feeding flows to not give rise to turbulence at the
tank outlet port, which, in turn, might create
cavitation at the pump. Proper baffle plates should
be provided inside the tank.
13. Before connecting the suction line to the pump inlet
port make sure the pipe is perfectly clean inside.
o
Page 7
GENERAL PUMP
A member of the Interpump Group
MH SERIES
9.5 Filtration
All pumps require a suitable filter. The filter should be
installed as close as possible to the pump, should allow
easy inspection and have the following characteristics:
1. The filter capacity should be at least three times the
rated pump volume.
2. Filter port diameters should not be smaller than the
pump inlet ports.
3. Filtration degree in between 50 and 80 mesh (360
to 200 microns.
IMPORTANT NOTE: In order to properly safeguard the
pump it is very important to plan cleaning of the filter
with a frequency depending on the water quality,
filtration degree and number of hours of each
application.
9.6 Delivery line
For a correct delivery line comply with the following
instructions:
1. The first length of delivery hose should be flexible
in order to isolate the pump vibrations from the
rest of the system.
2. Use only high pressure hoses and fittings able to
guarantee the largest possible safety margins in
any working conditions.
3. A suitable relief valve should be installed in the
delivery line.
4. Use glycerine filled pressure gauges, as the most
suitable for pulsating loads.
5. When designing the delivery line, take into proper
account the unavoidable drop in pressure, due to
its length and size.
6. If necessary, the effects of the pump pulsations
can be reduced by installing a proper pulsation
dampener in the pressure line.
Page 8
GENERAL PUMP
A member of the Interpump Group
MH SERIES
10. START UP AND RUNNING PROCEDURES
10.1 Before start up
Before start up make sure that the following conditions
have been complied with:
1. Suction line should be connected: the pump must
never run dry.
2. Suction line must be perfectly air-tight.
3. Any ON-OFF valve in between the pump and water
source should be open and make sure the water
gets into the pump freely.
4. Set the pressure line in dump mode in order to let
the air in the pump get out easily thus facilitating
the pump priming.
5. Make sure all suction/delivery line connections are
fully tightened.
6. Joint alignment, belt tightening and PTO shaft
inclination tolerances should remain within the
values indicated by the transmission Manufacturer.
7. Make sure the oil level is correct.
Note: in case the pump has not run for a long period of
time check the suction and delivery valves for scaling
(see paragraph 11.2).
10.3 Water leakage
During operation a small amount of water (a few drops a
minute) is released from the pump fluid end; this leakage
is designed to provide lubrication for the pressure
packings. The leakage is drained out of the pump
through a hole in the lower cover (Fig. 7).
This hole must always be kept open.
10.2 Starting up
1. Pump and motor/engine should start offload, set the
regulating valve to zero or set the pressure line in
dump mode by means of proper dumping devices.
2. When starting the pump up for the first time or after
every wiring re-connection check for the proper
direction of rotation.
3. Check that the rotating speed does not exceed the
rated value.
4. Before putting the pump under pressure let it run for
some time until the oil flows freely.
5. Before stopping the pump release the pressure from
the system by operating the dump device or by
releasing the regulating valve and reduce RPM to a
minimum (diesel applications).
Note: in case of feeding by a centrifugal pump, make sure
that the plunger pump start only when the correct
inlet pressure is provided.
Page 9
GENERAL PUMP
A member of the Interpump Group
MH SERIES
11. MAINTENANCE INSTRUCTIONS
11.1 Crank mechanism maintenance.
Check oil level on a weekly basis by means of the two
oil dipsticks (1, Fig. 8) provided with notches for min.
and max. levels.
If necessary, top up from the oil plug 3, Fig. 8
Check the oil when cold and change the oil when still
hot (pump still at working temperature.).
In order to drain the oil from the pump remove the
magnetic plug 2, Fig. 8.
At every oil change clean the magnetic plug 2, Fig. 8 and
check the lower cover of Fig. 7 for grease
sediments or deposits.
11.2 Fluid end maintenance
The fluid end does not require periodical maintenance.
Service operations are limited to valve inspection
and/or replacement, when necessary.
In order to remove the valves:
Loosen and remove the valve cover screws. 1, Fig. 9
OIL CHANGES Hours Qty.
First Change 50
Subsequent
Changes
Oil should be changed at least once a year.
Recommended oils:
BRAND TYPE
AGIP ACER 220
ARAL MOTANOL HP 220
AVIA AVILUB RSL 220
BP ENERGOL HL 220
CASTROL ALPHA ZN 220
ESSO NUTO 220
FINA SOLNA 220
IP HYDRUS 220
MOBIL DTE OIL BB
SHELL TELLUS C 220
TEXACO REGOL OIL 220
TOTAL CORTIS 220
500
14.8
quarts
Oil
Type
ISO
220
Tighten the two grub screws, 1, Fig. 10 of each valve
cover until the complete valve unit moves upward
enough to allow easy extraction.
Valve components of each
valve unit are screwed
together in one single block
and therefore they can be
easily serviced, replaced
and installed back
in place. Separating the
various components of the
valve unit is carried out by
means of simple tools as
shown in Fig. 11, 12 and
13 on the next page.
Page 10
GENERAL PUMP
A member of the Interpump Group
MH SERIES
Should excessive scaling inside the fluid end hinder the
valve extraction open one of the two lateral inlet ports,
remove the three plugs 1, Fig. 15, insert our special tool
p/n F200030090 (2, Fig. 15), or a corresponding one,
and push the valve unit out as shown in Fig. 15.
Check the valve components for wear and replace where
necessary.
Every time valves are inspected all o-rings of the valve
units and valve covers should be replaced.
Reassemble the valve units and fit them
back in the fluid end. Valve cover screws
should be tightened with a torque wrench
set for 86.7 ft. lbs.
Page 11
GENERAL PUMP
11.3 Pumping unit maintenance
The only maintenance operation required for the pumping
unit is the pressure packings greasing through the proper
greasers (1, Fig. 16).
Greasing should be carried out at even intervals
at least every 100 hours by means of a hand pump.
Stop greasing when the pump trigger becomes harder
to operate: that means the grease chamber is full. Use
top quality silicone grease (i.e. DANKELL OCILIS 250,
penetration coefficient 290 or a corresponding one).
A member of the Interpump Group
MH SERIES
Loosen and remove the plunger screws (1, Fig. 18).
Periodically check the amount of water drained out by
the pump through the hole provided in the lower cover
(Fig. 7, page 9). It clearly shows the pressure packing
state of wear; replace them if water dripping becomes
continuous and not intermittent.
For inspecting the pumping unit remove the head by
loosening the eight head screws (1, Fig 17).
Remove the upper cover by loosening the four screws
(1, Fig. 19).
Push the plungers forward by rotating the crankshaft,
then introduce our tool pn/ F200030060 (or equivalent)
in between the piston guide and the packing support
(1, Fig. 20).
Page 12
GENERAL PUMP
With the tool in place, rotate the crankshaft until the
packing support is pushed out together with plungers
and cylinders (Fig. 21). Repeat the operation for each
pumping unit.
A member of the Interpump Group
MH SERIES
Remove the wipers from the piston guides (1, Fig. 22
and Fig. 23).
Separate the pumping unit components and check them
for wear. Pressure packing replacement is carried out
by hand without need of special tools (Fig. 24)
A little bit of grease helps when sliding the packings into
the packing support. Pressure packings and o-rings
should always be replaced at every disassembling of
the pumping unit.
In order to fit the new scraper in place shape it manually
as shown in Fig. 25.
VERY IMPORTANT! The scraper is provided with an
internal lip which performs the correct scraping effect only
if oriented toward the fluid end. See window inside Fig. 25.
Put the pumping unit components together and fit them
back in the pump crankcase. Tighten the plunger screws
(1, Fig. 18) with a torque wrench set for 72.3 ft. lbs.
Grease the pressure packings through the greasers (2,
Fig. 23) by means of a hand pump. Stop greasing when
the pump trigger becomes hard to operate: that means the
grease chamber is full. Head back in place, head screws
tightened at 260.3 ft. lbs.
Page 13
GENERAL PUMP
A member of the Interpump Group
MH SERIES
12. SCREW CALIBRATION
Screw calibration is to be carried out by
means of a torque wrench only:
DESCRIPTION Ft. Lbs. N-m Kgm.
Valve cover
screws
Head Bolts 260.3 353 36
Plunger bolts 72.3 98 10
Connecting Rod
Screws
86.7 117.6 12
54.2 73.5 7.5
13. MAINTENANCE TOOLS
The following tools are designed to
facilitate mounting and dismounting
operations of some pump components:
for disassembling:
-packing support extractor F200030060
-main gear (gear box) F200030010
15. PRECAUTIONS AGAINST FREEZING
In the risk of freezing the following
precautions should be taken:
- After use drain the entire suction and delivery lines
(filter included) by means of discharging devices,
provided and positioned specifically for this purpose
along the lowest point of the lines.
- Run the pump only for a few seconds in order to
drain the water collected inside the fluid end.
Or when applicable
- Add a recommended amount of anti-freeze into the
water tank and run the pump until the anti-freeze
works all through the system.
- valve extractor F200030090
14. PUMP STOPPED FOR LONG TIME
Before starting the pump for the very first
time after a long period from the date of
shipment check for the correct oil level,
check the valves as indicated in chapter
11 and then comply with the starting
procedures indicated in chapter 10. When
a long inactivity is scheduled drain the
entire suction and delivery line and then
run the pump dry only for a few seconds
in order to drain out the water collected
inside the fluid end.
If a pump is frozen or appears frozen ON NO ACCOUNT
SHOULD THE PUMP BE OPERATED until the entire
system has been thawed out.
Page 14
GENERAL PUMP
16. EXPLODED VIEW AND PARTS LIST
A member of the Interpump Group
MH SERIES
Page 15
GENERAL PUMP
A member of the Interpump Group
Item Part # Description QTY.
1 F080100200 Gearbox body 1
2 F872047006 Lockwasher Ø12 8
3 F871131100 Screw M12 x 40 6
4 F052000060 Driven gear 1500 RPM (Z53) 1
F052000080 Driven gear 1800 RPM (Z56) 1
5 F030000080 Retaining flange 1
6 F042000000 Flange screw retainer 1
7 F871024107 Screw M10 x 25 2
8 F872126004 Retaining pin Ø 12 x 40 3
9 F871125109 Screw M10 x 45 8
10 F871121151 Screw M8 x 16 13
063100070Pinion cover
11F
080600090Gasket, pinion cover
12F
881080028Seal, Ø 60x80x10
13F
811110012Bearing
14F
063100050Cover, gearbox
15F
080600080Gasket, gearbox
16F
17 F872098009 Key, pinion gear 1
F872097013 Key, pinion gear Ø48 1
18 F052000070 Pinion 1500 RPM (Z20) MH 1
052000090Pinion 1800 RPM (Z17) MH
F
F052000190 Pinion 1500 RPM (Z20) Ø48 1
052000200Pinion 1800 RPM (Z17) Ø48
F
19 F811110006 Bearing 1
20 F871131107 Screw, M12 x 50 2
21 F812000000 Bearing, connecting rod 3
22 F872046006 Lock washer Ø12 6
23 F035000070 Connecting rod bolt 6
24 F040000030 Lower cover 1
25 F871115152 Screw, M6 x 14 16
26 F080600070 Gasket, lower cover 1
27 F060100180 Crankcase 1
28 F811110021 Bearing 1
29 F080600050 Gasket, side 2
30 F801057002 Magnetic plug, G 1/2” 1
31 F872043002 Aluminum washer Ø1/2” 4
32 F063400500 Rear cover 1
33 F080600040 Gasket, rear cover 1
34 F001000000 Oil level dipstick 2
35 F872041501 Washer Ø3/8” 2
36 F872026003 Eye bolt M 16 2
37 F030000030 Washer, eyebolt 2 - 4
38 F801054027 Vented plug G 1” 1
39 F881010116 O-ring, Ø29.82 x 2.62 4
40 F801056002 Plug G 1/2” 1
41 F040000010 Top cover 1
42 F080600060 Gasket, top cover 1
43 F872101009 Key 1
44 F050000000 Crankshaft 1
45 F811111014 Bearing 1
46 F811920014 Bearing retainer bushing 1
47 F872069016 Washer MB16 1
48 F872020016 Nut KM16 1
49 F871131103 Screw M12 x 30 8
50 F063400460 Side cover 1
51 F801077003 Grease fitting M10 x 1 3
52 F250000040 Complete connecting rod 3
53 F250001080 Complete piston guide 3
54 F872142015 Retainer pin Ø 5 x 36 3
55 F071000050 Wrist pin Ø 35 3
56 F881081001 Oil seal Ø 35 x 47 x 8.5 Spec. 3
57 F881010128 O-ring Ø 72.69 x 2.62 3
58 F063400480 Oil seal cover 3
59 F205000010 Flinger washer 3
60 F024202600 Plunger MH45 3
F024200270 Plunger MH50 3
REPAIR KITS
2, 6, 12, 13, 16, 22, 26, 29, 31, 33, 35,
39, 42, 47, 51, 54, 56, 57, 61, 67, 68,
73, 74, 79, 84, 85, 89, 90, 92, 93, 94
Item MH45 MH50 MH55 MH60 MH65
61, 64, 85, 89, 90, 92, 93 F1190 F1191 F1192 F1193 F1194
31, 67, 68, 73, 94, 94 F1195
F1196 F1197 F1198 F1199 F1200
MH SERIES
Item Part # Description QTY.
60 F024200280 Plunger MH55 3
F024200290 Plunger MH60 3
F024200330 Plunger MH65 3
61 F872040004 Washer Ø 14 Spec. 3
871135518Screw M14 x 140 inox MH45
62F
871135510Screw M14 x 80 inox MH50, 55, 60, 65
F
208005230Valve assembly
63 F
871245356Set screw M10 x 20
64 F
871135102Screw M14 x 40
65F
063002400Valve cover
66 F
881112003Anti-extrusion ring
1
1
1
1
1
1
1
1
67 F
881011252O-ring Ø 70 x 4 Spec.
68F
021200280Discharge valve guide
69 F
090200050Discharge valve spring
70 F
082200060Discharge valve poppet
71 F
205000110Discharge valve seat
72 F
73 F881011168 O-ring Ø 72 x 3 Spec. 3
74 F881011161 O-ring Ø 56 x 3 Spec. 6
75 F021200260 Inlet valve guide 3
090200040Inlet valve spring
76F
082200050Inlet valve poppet
77 F
78 F081200060 Inlet valve seat 3
79 F872041300 Gasket washer Ø 1/4” 8
80 680115 Plug NPT 1/4” 8
81 F871151172 Screw M20 x 200 8
82 F164000400 Manifold 1
83 F084000010 Plug 1/2” NPT 3
84 F881011054 O-ring Ø 96 x 2 9
85 F881011253 O-ring Ø 72 x 4 Spec. 3
86 F062200170 Cylinder MH45 3
F062200180 Cylinder MH50 3
F062200190 Cylinder MH55 3
F062200200 Cylinder MH60 3
F062200210 Cylinder MH65 3
87 F031300120 Spacer MH45 3
F031300050 Spacer MH50 3
F031300060 Spacer MH55 3
F031300070 Spacer MH60 3
F031300080 Spacer MH65 3
88 F031200110 Head ring MH45 3
F031200210 Head ring MH50 3
F031200220 Head ring MH55 3
F031200230 Head ring MH60 3
F031200250 Head ring MH65 3
89 F881020012 Packing MH45 6
F881020014 Packing MH50 6
F881020015 Packing MH55 6
F881020016 Packing MH60 6
F881020017 Packing MH65 6
90 F881011163 O-ring Ø 59.5 x 3 MH45 3
F881011165 O-ring Ø 65 x 3 MH50 3
F881011167 O-ring Ø 69.5 x 3 MH55 3
F881011169 O-ring Ø 76 x 3 MH60 3
F881011170 O-ring Ø 80 x 3 MH65 3
91 F022300290 Packing support MH45 3
F022300300 Packing support MH50 3
F022300310 Packing support MH55 3
F022300320 Packing support MH60 3
F022300330 Packing support MH65 3
92 F881011053 O-ring Ø 80 x 2 3
93 F881061017 Scraper MH45 3
F881061018 Scraper MH50 3
F881061019 Scraper MH55 3
F881061021 Scraper MH60 3
F881061023 Scraper MH65 3
94 F010500290 Anti-extrusion ring 6
Also Included:
F1201 Inlet flange, closed
F1299 Inlet flange, open, 3” NPT
680096 Drain valve kit
Page 16
3
3
3
6
2
1
3
3
3
3
3
3
3
3
3
GENERAL PUMP
17. TROUBLE SHOOTING
A member of the Interpump Group
MH SERIES
THE PUMP DOES NOT PRODUCE ANY
NOISE: the pump is not primed
and is running dry!
- No water in the inlet line
- The valves are blocked
- The pressure line is closed and does
not allow the air to get out the fluid
end.
THE PUMP KNOCKS:
- Air suction.
- Insufficient feeding:
- bends, elbows and fittings along the
suction line throttle the amount of
water which passed through.
- too small inlet filter.
- dirty inlet filter.
- the feeding pump, where provided is
not of the suitable type or provides
insufficient pressure or volume.
- The pump is not primed due to
insufficient feeding or the delivery line
is closed during start up.
- The pump is not primed because some
valves are stuck (i.e pump inactivity
for long time).
- Jammed or worn out valves.
- Worn out pressure packings.
- The pressure regulating valve does not
work properly.
- Clearance in the drive system.
- RPM are higher than rated.
THE PUMP DOES NOT DELIVER THE
RATED VOLUME:
- Insufficient feeding (due to the cause
listed above).
- RPM are less than rated.
- Excessive amount of water by-passed
by the pressure regulating valve.
- Worn out valves
- Excessive leakage from pressure
packings
INSUFFICIENT PUMP PRESSURE:
- The nozzle is (or has become) too large.
- RPM are less than rated
- Excessive leakage from pressure
packings
- Excessive amount of water by-passed
by the pressure regulating valve or
faulty valve operation.
- Worn out valves.
EXCESSIVE WATER LEAKAGE FROM
THE PUMP:
- Pressure packing are excessively worn
out (due to normal wear or excessive
cavitation).
- Worn out plungers
OVERHEATED PUMP:
- The direction of rotation is not correct.
- Pump is overloaded (pressure or RPM
over the rated values).
- The oil level is too low or the oil is not of
a suitable type or fully used
- Water in the oil
- Excessive belt tension or incorrect
alignment of the joint (where provided).
- Excessive inclination of the pump
during operation.
PIPE VIBRATIONS OR KNOCKING:
- Air suction.
- The pressure regulating valve does not
work properly.
- The by-pass line is undersized.
- Jammed up valves.
- Drive transmission motion is irregular.
Page 17
GENERAL PUMP
MAINTENANCE LOG
OIL CHANGE
GREASE
PACKING
REPLACEMENT
A member of the Interpump Group
MH SERIES
HOURS & DATE
PLUNGER
REPLACEMENT
VALVE
REPLACEMENT
GP Companies, Inc.
1174 Northland Drive
Mendota Heights, MN 55120
Phone:651.686.2199 Fax: 800.535.1745
www.generalpump.com email: sales@gpcompanies.com
Ref 300019 Rev.C
08/07
Page 18
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