GORMAN-RUPP HSK Series Application guide

OM-07305-01
December 10, 2019
Rev. B 5/4/20
GORMAN‐RUPP PUMPS
www.grpumps.com
2019 Gorman‐Rupp Pumps Printed in U.S.A.
INSTALLATION, OPERATION,
AND MAINTENANCE MANUAL
WITH PARTS LIST
HSK SERIES PUMP
Hydraulic Driven Sludge Pump
MODEL
HSK4A-KDI1903TCR FT4

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Gorman‐Rupp pump online at
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Please record your pump model and serial number in the
spaces provided below. Your Gorman‐Rupp distributor
needs this information when you require parts or service.
Pump Model:
Serial Number:
The engine exhaust from this
product contains chemicals
known to the State of California to
cause cancer, birth defects or
other reproductive harm.

TABLE OF CONTENTS
i
INTRODUCTION PAGE I - 1.................................................
SAFETY ‐ SECTION A PAGE A - 1............................................
INSTALLATION - SECTION B PAGE B - 1....................................
PREINSTALLATION INSPECTION PAGE B - 1............................................
Pump Dimensions PAGE B - 1.....................................................
Battery Specifications And Installation PAGE B - 2....................................
POSITIONING PUMP PAGE B - 2.......................................................
Lifting PAGE B - 2.................................................................
Mounting PAGE B - 2.............................................................
Remote Operation PAGE B - 2.....................................................
SUCTION AND DISCHARGE PIPING PAGE B - 3.........................................
Materials PAGE B - 3..............................................................
Line Configuration PAGE B - 3......................................................
Connections to Pump PAGE B - 3..................................................
Gauges PAGE B - 3...............................................................
SUCTION LINES PAGE B - 3...........................................................
Fittings PAGE B - 3...............................................................
Sealing PAGE B - 3...............................................................
Suction Lines In Sumps PAGE B - 4.................................................
Suction Line Positioning PAGE B - 4................................................
DISCHARGE LINES PAGE B - 5........................................................
Siphoning PAGE B - 5.............................................................
OPERATION - SECTION C PAGE C - 1......................................
OPERATION PAGE C - 1..............................................................
STARTING PAGE C - 1................................................................
PRIMING PAGE C - 2.................................................................
OPERATIONAL CHECKS PAGE C - 2...................................................
Hydraulic Oil Level/Temperature PAGE C - 2.........................................
Low Hydraulic Oil Shutdown PAGE C - 2.............................................
Hydraulic Oil Tank Temp Shutdown PAGE C - 2.......................................
Oil Cooler PAGE C - 2.............................................................
Pump Oil Pressure Shutdown PAGE C - 2...........................................
System Leaks PAGE C - 2.........................................................
STOPPING PAGE C - 2................................................................
CLEANING AND FLUSHING PAGE C - 3................................................
TROUBLESHOOTING - SECTION D PAGE D - 1..............................
PREVENTIVE MAINTENANCE PAGE D - 3...............................................
PUMP MAINTENANCE AND REPAIR - SECTION E PAGE E - 1................
Performance Curve PAGE E - 1.....................................................
PARTS LIST:
Pump Model PAGE E - 3..........................................................
Pump Sub Assembly PAGE E - 5...................................................
Pump Sub Assembly (Cont'd) PAGE E - 7...........................................

TABLE OF CONTENTS
(continued)
ii
Pump End Assembly PAGE E - 9......................................................
Pump End (Cont'd) PAGE E - 11....................................................
Pump End Sub Assembly PAGE E - 13...............................................
Hydraulic Reservoir Conversion Kit PAGE E - 15.......................................
MAINTENANCE INSTRUCTIONS PAGE E - 16............................................
Engine PAGE E - 17................................................................
Hydraulic Pump PAGE E -17........................................................
Hydraulic Oil PAGE E - 17..........................................................
Suction Strainer/Hydraulic Reservoir PAGE E - 17......................................
Relief Valve PAGE E - 17............................................................
Control Valve PAGE E - 17..........................................................
Fill Cap and Strainer PAGE E - 17....................................................
Return Line Filter PAGE E - 18.......................................................
Reservoir PAGE E - 18.............................................................
Oil Cooler PAGE E - 18.............................................................
PUMP AND SEAL DISASSEMBLY AND REASSEMBLY PAGE E - 18.........................
Clean Out Cover Removal PAGE E - 18...............................................
Discharge and Suction Assembly Removal PAGE E - 19................................
Pump End Assembly Removal PAGE E - 19...........................................
Pump End Disassembly PAGE E - 19................................................
Pump End Sub Assembly Disassembly PAGE E - 20...................................
Pump End Sub Assembly Reassembly PAGE E - 20...................................
Pump End Reassembly PAGE E - 21.................................................
Discharge and Suction Assembly Installation PAGE E - 21..............................
Clean Out Cover Installation PAGE E - 21.............................................

HSK SERIES OM-07305
PAGE I - 1INTRODUCTION
INTRODUCTION
Thank You for purchasing a Gorman‐Rupp pump.
Read this manual carefully to learn how to safely
install and operate your pump. Failure to do so
could result in personal injury or damage to the
pump.
Because pump installations are seldom identical,
this manual cannot possibly provide detailed in
structions and precautions for every aspect of
each specific application. Therefore, it is the re
sponsibility of the owner/installer of the pump to
ensure that applications not addressed in this
manual are performed only after establishing that
neither operator safety nor pump integrity are com
promised by the installation. Pumps and related
equipment must be installed and operated ac
cording to all national, local and industry stan
dards.
If there are any questions regarding the pump or
its application which are not covered in this man
ual or in other literature accompanying this unit,
please contact your Gorman‐Rupp distributor, or
The Gorman‐Rupp Company:
The Gorman‐Rupp Company
P.O. Box 1217
Mansfield, Ohio 44901-1217
Phone: [phone]
or:
Gorman‐Rupp of Canada Limited
70 Burwell Road
St. Thomas, Ontario N5P 3R7
Phone: [phone]
For information or technical assistance on the
power source, contact the power source manufac
turer's local dealer or representative.
HAZARD AND INSTRUCTION
DEFINITIONS
The following are used to alert maintenance per
sonnel to procedures which require special atten
tion, to those which could damage equipment, and
to those which could be dangerous to personnel:
Immediate hazards which WILL result in
severe personal injury or death. These
instructions describe the procedure re
quired and the injury which will result
from failure to follow the procedure.
Hazards or unsafe practices which
COULD result in severe personal injury
or death. These instructions describe
the procedure required and the injury
which could result from failure to follow
the procedure.
Hazards or unsafe practices which COULD
result in minor personal injury or product
or property damage. These instructions
describe the requirements and the possi
ble damage which could result from failure
to follow the procedure.
NOTE
Instructions to aid in installation, operation, and
maintenance or which clarify a procedure.

HSK SERIES OM-07305
PAGE A - 1SAFETY
SAFETY ‐ SECTION A
This information applies to Hydraulic
Driven Sludge Pumps.
Before attempting to disconnect or ser
vice the hydraulic power source or
pump:
1. Familiarize yourself with this man
ual.
2. Shut down the engine and discon
nect the positive battery cable to
ensure that the hydraulic power
source and pump will remain inop
erative.
3. Allow the hydraulic oil and pump to
cool completely.
4. Use the hydraulic control (H.C.)
valve to ensure that all hydraulic
pressure is released from the sys
tem.
5. Check the temperature before
opening any covers, plates, or
plugs.
6. Vent the pump slowly and cau
tiously using ½” ball valves sup
plied.
7. Drain the pump.
This pump is designed to pump materi
als that may be volatile or flammable. Do
not attempt to pump any liquids for
which the pump is not designed, or
which may damage the pump or endan
ger personnel as a result of pump fail
ure. Consult the factory for specific ap
plication data.
This pump is designed to pump materi
als which could cause serious illness or
injury through direct exposure or emit
ted fumes. Wear protective clothing,
such as rubber gloves, face mask and
rubber apron, as necessary, before dis
connecting or servicing the pump or
piping.
Death or serious personal injury and
damage to the pump or components
can occur if proper lifting procedures
are not observed. Make certain that
hoists, chains, slings or cables are in
good working condition and of suffi
cient capacity and that they are posi
tioned so that loads will be balanced
and the pump or components will not be
damaged when lifting. Suction and dis
charge hoses and piping must be re
moved from the pump before lifting. Lift
the pump or component only as high as
necessary and keep personnel away
from suspended objects.
After the pump has been installed, make
certain that the pump and all piping or
hose connections are tight, properly
supported and secure before operation.

HSK SERIESOM-07305
PAGE A - 2 SAFETY
Make sure hydraulic hose connections
are fully tightened. Hydraulic hoses are
equipped with check valves in each end to
prevent oil from escaping when discon
nected. Hose connections must be tight to
fully open these check valves. Failure to
tighten connections can cause excessive
hydraulic system pressure, resulting in
damage to the hydraulic motor and/or oth
er components.
Do not operate the pump against a
closed discharge valve for long periods
of time. If operated against a closed dis
charge valve, pump components will
deteriorate, and the liquid could come
to a boil, build pressure, and cause the
pump casing to rupture or explode.
Do not remove plates, covers, gauges,
pipe plugs, or fittings from an over
heated pump. Vapor pressure within the
pump can cause parts being disen
gaged to be ejected with great force. Al
low the pump to completely cool before
servicing.
Do not operate an internal combustion
engine in an explosive atmosphere.
When operating internal combustion
engines in an enclosed area, make cer
tain that exhaust fumes are piped to the
outside. These fumes contain carbon
monoxide, a deadly gas that is color
less, tasteless, and odorless.
Fuel used by internal combustion en
gines presents an extreme explosion
and fire hazard. Make certain that all fu
el lines are securely connected and free
of leaks. Never refuel a hot or running
engine. Avoid overfilling the fuel tank,
and clean up any fuel spills immediate
ly. Always use the correct type of fuel.
Never tamper with the governor to gain
more power. The governor establishes
safe operating limits that should not be
exceeded. See the performance curve
on page E-1 for the maximum continu
ous operating speed for this pump.

OM-07305HSK SERIES
PAGE B - 1INSTALLATION
INSTALLATION - SECTION B
Review all SAFETY information in Section A.
Since pump installations are seldom identical, this
section offers only general recommendations and
practices required to inspect, position, and ar
range the pump and piping.
For further assistance, contact your Gorman‐Rupp
distributor or the Gorman‐Rupp Company.
PREINSTALLATION INSPECTION
The pump assembly was inspected and tested be
fore shipment from the factory. Before installation,
inspect the pump for damage which may have oc
curred during shipment. Check as follows:
a. Inspect the pump assembly for cracks, dents,
damaged threads on the hydraulic connect
ing hoses, and other obvious damage.
b. Check for and tighten loose attaching hard
ware. Since gaskets tend to shrink after dry
ing, check for loose hardware at mating sur
faces.
c. If the pump was shipped with hydraulic
hoses, inspect the hoses for cuts or damage
to the threaded ends.
d. Check the pump hydraulic motor for any oil
leaks, and tighten any hardware as required.
e. Carefully read all tags, decals, and markings
on the pump assembly, and perform all duties
as indicated.
f. Check levels and lubricate as necessary.
g. If the pump and engine have been stored for
more than 12 months, some of the compo
nents or lubricants may have exceeded their
maximum shelf life. These must be inspected
or replaced to ensure maximum pump serv
ice.
If the maximum shelf life has been exceeded, or if
anything appears to be abnormal, contact your
Gorman‐Rupp distributor or the factory to deter
mine the repair or updating policy. Do not put the
pump into service until appropriate action has
been taken.
Pump Dimensions
See Figure B-1 for the approximate physical di
mensions of your pump.
OUTLINE DRAWING
3.00" DIA
LUNETTE
TOWING
EYE
50 GAL CAPACITY
HYDRAULIC OIL
RESERVOIR
DISCHARGE:
4.00 NOMINAL WITH 8 HOLES
.75/[19,0] DIA EQUALLY SPACED
ON A 7.50/[190,5] DIA BC
SUCTION:
4.00 NOMINAL WITH 8 HOLES
.75/[19,0] DIA EQUALLY SPACED
ON A 7.50/[190,5] DIA BC
POWERED BY: KOHLER KDI1903TCR FT4 DIESEL ENGINE
76.00
[ 1930,4 ]
84.92
[ 2157,1 ] APPROX 146.41 [ 3718,7 ] APPROX
138.40
[ 3515,5 ]
38.96
[ 989,6 ]
19.79
[ 502,6 ]
APPROX
38.07
[ 966,9 ]
56.41
[ 1432,7 ]
77.24
[ 1961,8 ]
APPROX
33.35
[ 847,1 ]
37.90
[ 962,5 ]
38.00
[ 965,3 ]
Figure B-1 HSK4A-KDI1903TCR FT4.

OM-07305 HSK SERIES
PAGE B - 2 INSTALLATION
Battery Specifications And Installation
Unless otherwise specified on the pump order, the
engine battery was not included with the unit.
When selecting a battery, refer to the specifications
on the paper tag attached to the battery box in or
der to ensure the proper size and electrical charac
teristics of the battery.
Refer to the information accompanying the battery
and/or electrolyte solution for activation and charg
ing instructions.
Before installing the battery, clean the positive and
negative cable connectors, and the battery termi
nals. Secure the battery by tightening the
holddown brackets. The terminals and clamps
may be coated with petroleum jelly to retard corro
sion. Connect and tighten the positive cable first,
then the negative cable.
Positioning Pump
Lifting
Death or serious personal injury and
damage to the pump or components
can occur if proper lifting procedures
are not observed. Make certain that
hoists, chains, slings or cables are in
good working condition and of suffi
cient capacity and that they are posi
tioned so that loads will be balanced
and the pump or components will not be
damaged when lifting. Suction and dis
charge hoses and piping must be re
moved from the pump before lifting. Lift
the pump or component only as high as
necessary and keep personnel away
from suspended objects.
Pump unit weights will vary depending on the
mounting and drive provided. Check the shipping
tag on the unit packaging for the actual weight, and
use lifting equipment with appropriate capacity.
Drain the pump and remove all customer‐installed
equipment such as suction and discharge hoses
or piping before attempting to lift existing, installed
units.
The pump assembly can be seriously
damaged if the cables or chains used to lift
and move the unit are improperly wrapped
around the pump.
Mounting
Locate the pump in an accessible place as close as
practical to the liquid being pumped. Level mount
ing is essential for proper operation. To ensure suf
ficient lubrication and fuel supply to the engine, do
not position the pump and engine more than 15
off horizontal for continuous operation.
The pump may have to be supported or shimmed
to provide for level operation or to eliminate vibra
tion.
If the pump has been mounted on a moveable
base, make certain the base is stationary by setting
the brake and blocking the wheels before attempt
ing to operate the pump.
Remote Operation
It is possible to operate the hydraulic driven sludge
pump dismounted from the hydraulic power unit.
The sludge pump can be used up to 150 feet from
the power unit when properly connected with com
patible hoses. The hoses must be connected in the
correct order. Remotely operating the sludge
pump may affect performance. Locate the pump in
an accessible place as close as practical to the liq
uid being pumped. Ensure the pump will remain
level and will not be able to shift or move during op
eration. For remote operation it is necessary to re
move the pressure switch (Item 45 figure 4 in
PUMP MAINTENANCE AND REPAIR - SEC
TION E) and replace with a pipe plug. Consult fac
tory for additional instruction as necessary.
Death or serious personal injury and

OM-07305HSK SERIES
PAGE B - 3INSTALLATION
damage to the pump or components
can occur if lifting bail is not properly
secured to the base of the unit. Use only
the hardware provided from the factory
to relocate or remount the lifting bail.
NOTICE
Ensure the hydraulic hoses are correctly
attached to the hydraulic power unit for re
mote operation. Connecting these hoses
in reverse order will not allow the pump to
cycle or produce discharged fluid.
To operate the hydraulic driven sludge pump dis
mounted from the hydraulic power unit, it may be
come necessary to adjust the location of the power
unit lifting bail for level lifting. This should be done
using caution to ensure all factory provided
mounting hardware is utilized. Use only the hard
ware provided with the unit as it is appropriately se
lected to secure the load.
SUCTION AND DISCHARGE PIPING
Pump performance is adversely effected by in
creased suction lift, discharge elevation, and fric
tion losses. Friction losses will increase with
greater viscosity of material being pumped. See
the performance curve and notes on Page E‐1 to
be sure your overall application allows pump to op
erate within the safe operation range.
Always keep the pump as close as possible to the
product to be pumped. Keep the suction line
length, number of fittings and direction changes to
a minimum. Do not use a suction line smaller than
the pump suction connection. This pump is self‐
priming on water from a dry start to 21 foot depths.
Materials
Either pipe or hose maybe used for suction and
discharge lines; however, the materials must be
compatible with the liquid being pumped. If hose is
used in suction lines, it must be the rigid‐wall, rein
forced type to prevent collapse under suction. Us
ing piping couplings in suction lines is not recom
mended.
Line Configuration
Keep suction and discharge lines as straight as
possible to minimize friction losses. Make mini
mum use of elbows and fittings, which substantial
ly increase friction loss. If elbows are necessary,
use the long‐radius type to minimize friction loss.
Connections to Pump
Before tightening a connecting flange, align it ex
actly with the pump port. Never pull a pipe line into
place by tightening the flange bolts and/or cou
plings.
Lines near the pump must be independently sup
ported to avoid strain on the pump which could
cause excessive vibration and strain on support
brackets. If hose‐type lines are used, they should
have adequate support to secure them when filled
with liquid and under pressure.
Gauges
Most pumps are drilled and tapped for installing
discharge pressure and vacuum suction gauges.
Use only liquid filled gauges for reciprocating
pump.
SUCTION LINES
To avoid air pockets which could affect pump prim
ing, the suction line must be as short and direct as
possible. When operation involves a suction lift, the
line must always slope upward to the pump from
the source of the liquid being pumped; if the line
slopes down to the pump at any point along the
suction run, air pockets will be created.
Fittings
Suction lines should be the same size as, or larger
than, the pump inlet. If reducers are used in suction
lines, they should be the eccentric type, and
should be installed with the flat part of the reducers
uppermost to avoid creating air pockets. Valves
are not normally used in suction lines, but if a valve
is used, install it with the stem horizontal to avoid air
pockets.
Sealing
Since even a slight leak will affect priming, head,
and capacity, especially when operating with a

OM-07305 HSK SERIES
PAGE B - 4 INSTALLATION
high suction lift, all connections in the suction line
should be sealed with pipe dope to ensure an air
tight seal. Follow the sealant manufacturer's rec
ommendations when selecting and applying the
pipe dope. The pipe dope should be compatible
with the liquid being pumped.
Suction Lines In Sumps
If a single suction line is installed in a sump, it
should be positioned away from the wall of the
sump at a distance equal to 1 1/2 times the diame
ter of the suction line.
If there is a liquid flow from an open pipe into the
sump, the flow should be kept away from the suc
tion inlet because the inflow will carry air down into
the sump, and air entering the suction line will re
duce pump efficiency.
If it is necessary to position inflow close to the
suction inlet, install a baffle between the inflow
and the suction inlet at a distance 1‐1/2 times the
diameter of the suction pipe. The baffle will allow
entrained air to escape from the liquid before it is
drawn into the suction inlet.
If two suction lines are installed in a single sump,
the flow paths may interact, reducing the efficiency
of one or both pumps. To avoid this, position the
suction inlets so that they are separated by a dis
tance equal to at least 3 times the diameter of the
suction pipe.
Suction Line Positioning
The depth of submergence of the suction line is
critical to efficient pump operation. Figure 2 shows
recommended minimum submergence vs. veloci
ty.
NOTE
The pipe submergence required may be reduced
by installing a standard pipe increaser fitting at the
end of the suction line. The larger opening size will
reduce the inlet velocity. Calculate the required
submergence using the following formula based
on the increased opening size (area or diameter).

OM-07305HSK SERIES
PAGE B - 5INSTALLATION
DISCHARGE LINES
Siphoning
Do not terminate the discharge line at a level lower
than that of the liquid being pumped unless a
siphon breaker is used in the line. Otherwise, a si
phoning action causing damage to the pump
could result.

OM-07305
HSK SERIES
OPERATION PAGE C - 1
OPERATION - SECTION C
Review all SAFETY information in Section A.
Refer to the INSTALLATION section of this man
ual before startup.
Follow the instructions on all tags, labels and
decals attached to the power source.
Do not operate an internal combustion
engine in an explosive atmosphere.
When operating internal combustion
engines in an enclosed area, make cer
tain that exhaust fumes are piped to the
outside. These fumes contain carbon
monoxide, a deadly gas that is color
less, tasteless, and odorless.
Never tamper with the governor to gain
more power. The governor establishes
safe operating limits that should not be
exceeded. Consult the factory or the
power unit specification data sheet for
the maximum continuous operating
speed.
This pump is designed to pump materi
als that may be volatile or flammable. Do
not attempt to pump any liquids for
which the pump is not designed, or
which may damage the pump or endan
ger personnel as a result of pump fail
ure. Consult the factory for specific ap
plication data.
STARTING
1. Ensure that the hydraulic pressure control valve
located on the reservoir tank is fully open prior
to starting. This takes approximately a quarter
turn.
2. Refer to the engine operation manual or decal,
start the engine, and allow it to warm up for one
or two minutes. Adjust engine speed to be
tween 1200 and 2000 RPM after warm up.
3. Turn the hydraulic pressure control valve clock
wise until it stops. This energizes the hydraulic
system.
Do not use the hydraulic pressure control
valve to regulate hydraulic pressure; this
valve is on/off only.
4. Check the hydraulic driven sludge pump to en
sure it is operating.
5. Check all connections and the pump hydraulic
motor for any oil leaks, and correct as required.
Make sure hydraulic hose connections
are fully tightened. Hydraulic hoses are
equipped with check valves in each end to
prevent oil from escaping when
disconnected. Hose connections must be
tight to fully open these check valves.
Failure to tighten connections can cause
excessive hydraulic system pressure,
resulting in damage to the hydraulic motor
and/or other components.
6. De‐energize the hydraulic system. Connect the
discharge hose and install the pump as de
scribed in INSTALLATION, Section B. Energize
the hydraulic system again and adjust the en
gine speed to achieve the desired pump out
put.
7. If full volume is not required, the engine speed
may be slowed down as necessary to conserve
fuel. Do not increase engine speed once the
factory‐set system operating pressure is
achieved.

OM-07305 HSK SERIES
OPERATIONPAGE C - 2
Pump speed and operating conditions
must be within the performance range
shown on page E‐1.
PRIMING
Install the pump and piping as described in IN
STALLATION. Make sure that the piping connec
tions are tight, and that the pump is securely
mounted. The pump is self‐priming on water from a
dry start to 21 foot depths. It is designed to handle
a wide variety of sludge applications. A general rule
of thumb is the shovel test. If a shovel is stuck into
the sludge and falls over, the material will most like
ly be pumped. The thickness / viscosity of the
pumped material may affect the priming or lift ca
pabilities of the pump. The performance may also
deviate from that shown on the curve on page
E-1, which was tested using water, based on the
characteristics of the pumped material.
OPERATIONAL CHECKS
Hydraulic Oil Level/Temperature
1. Maintain the hydraulic oil at the level shown on
the side of the hydraulic reservoir.
2. After initial startup, check the hydraulic oil level
in the reservoir. Filling the hydraulic hoses ini
tially will cause the level to drop.
3. During operation, check to be sure the hydrau
lic oil operating temperature never exceeds
170F (77C). If the temperature becomes ex
cessive, shut down the system and allow the oil
to cool. Check for insufficient oil in the reservoir,
kinked hydraulic hoses, inadequate ventilation
of the reservoir or oil cooler, a clogged return
line filter, or the hydraulic driven sludge pump
may be running dry for extended periods of
time.
Low Hydraulic Oil Shutdown
1. The low oil shutdown switch is mounted on the
engine side of the hydraulic oil reservoir. It will
shut down the engine in the event of loss of hy
draulic oil to protect against damage to the sys
tem.
Hydraulic Oil Tank Temp Shutdown
1. The hydraulic oil temperature shutdown switch
is mounted on the engine side of the hydraulic
oil reservoir. It will shut down the engine in the
event the hydraulic oil becomes too hot, pro
tecting against damage to the system.
Oil Cooler
1. Your hydraulic power unit is equipped with an
engine‐mounted air/oil cooler to cool the hy
draulic oil. Be sure the cooling fins are kept
clean so air can circulate freely through it.
Pump Oil Pressure Shutdown
1. During operation, there may be a small amount
of hydraulic oil in the clear braided hose located
between the product cylinders towards the
front of the sludge pump. This is used to lubri
cate the piston seals. If the hose contains any
amount of the material being pumped, it could
be a sign of leaking seals between the pistons
and cylinders. If this scenario creates 10 PSI or
more, the engine will be shut down by the pump
oil pressure shut down switch. This switch is
mounted on the top of the sludge pump, be
tween the pump cylinders.
System Leaks
1. Check all system components regularly for
leaks. Replace or repair tubing, fittings, oil cool
er or any other components at the first sign of
leakage.
STOPPING
1. To stop the pump, de‐energize the system (turn
the hydraulic control valve counter‐clockwise).
2. Reduce the engine speed slowly before stop
ping to prevent possible system damage.

OM-07305
HSK SERIES
OPERATION PAGE C - 3
CLEANING AND FLUSHING
NOTICE
After each pumping cycle, it is necessary
to thoroughly flush the cylinders and pip
ing of all debris. As a final cleaning step, at
least 5 minutes of water should be pumped
through to clear out settled material. Fail
ure to do so can lead to damage to the
pump and will void the warranty.
To ensure continued performance of the hydraulic
driven sludge pump, thoroughly flush all debris
from the cylinders and piping after each use. Use a
solvent compatible with both the materials of pump
construction and liquid being pumped. Additional
ly, if the pump is to be periodically inactive and the
liquid being pumped is prone to settling out or
hardening if not in motion, flush the pump more fre
quently as necessary.
Do not remove plates, covers, gauges,
pipe plugs, or fittings from an over
heated pump. Vapor pressure within the
pump can cause parts being disen
gaged to be ejected with great force. Al
low the pump to completely cool before
servicing.
The pump is equipped with clean out covers on the
discharge header (both sides) to aid in removing
materials that settle, harden of get stuck in the unit.
See Clean Out Cover Removal in MAINTE
NANCE and Review all SAFETY information in
Section A before attempting service.

OM-07305
HSK SERIES
TROUBLESHOOTING PAGE D - 1
TROUBLESHOOTING - SECTION D
Review all SAFETY information in Section A.
Before attempting to disconnect or ser
vice the hydraulic power source or
pump:
1. Familiarize yourself with this man
ual.
2. Shut down the engine and discon
nect the positive battery cable to
ensure that the hydraulic power
source and pump will remain inop
erative.
3. Allow the hydraulic oil and pump to
cool completely.
4. Use the hydraulic control (H.C.)
valve to ensure that all hydraulic
pressure is released from the sys
tem.
5. Check the temperature before
opening any covers, plates, or
plugs.
6. Vent the pump slowly and cau
tiously using ½” ball valves sup
plied.
7. Drain the pump.
Table 1. Trouble Shooting Chart
TROUBLE POSSIBLE CAUSE PROBABLE REMEDY
PUMP FAILS TO PRIME Air leak in suction line.
Lining of suction hose collapsed.
Leaking or worn seal or pump gas
ket.
Suction lift or discharge head too
high.
Pumped fluid too thick.
Correct leak.
Replace suction hose.
Check pump vacuum. Replace leak
ing or worn seal or gasket.
Check piping installation and install
bypass line if needed. See INSTAL
LATION.
Dilute fluid being pumped if possible.
PUMP STOPS OR FAILS
TO DELIVER RATED
FLOW OR PRESSURE
NOTE: PERFORMANCE
MAY DEVIATE FROM
THAT SHOWN ON THE
CURVE BASED ON THE
CHARACTERISTICS OF
THE PUMPED MATERIAL.
Pumped fluid too thick.
Air leak in suction line.
Lining of suction hose collapsed.
Leaking or worn piston seal or
pump gasket.
Suction intake not submerged at
proper level or sump too small.
Pump clogged.
Discharge head too high.
Suction lift too high.
Pump speed too slow.
Dilute fluid being pumped if possi
ble.
Correct leak.
Replace suction hose with full vacu
um rated hose.
Check pump vacuum. Replace
leaking or worn seal or gasket.
Check installation and correct sub
mergence as needed.
Free pump of debris.
Consult pump performance curve.
Measure lift w/vacuum gauge. Re
duce lift and/or friction losses in
suction line.
Check engine output; consult en
gine operation manual.

OM-07305 HSK SERIES
TROUBLESHOOTINGPAGE D - 2
Table 1. Trouble Shooting Chart (cont.)
TROUBLE POSSIBLE CAUSE PROBABLE REMEDY
PUMP STOPS OR FAILS
TO DELIVER RATED
FLOW OR PRESSURE
(cont.)
NOTE: PERFORMANCE
MAY DEVIATE FROM
THAT SHOWN ON THE
CURVE BASED ON THE
CHARACTERISTICS OF
THE PUMPED MATERIAL.
Discharge hose kinked, plugged or
collapsed.
Hydraulic oil level low.
Lack of liquid in pump (pump inlet
obstructed)
Hydraulic pump or bearing seized.
Check and clear or replace dis
charge hose with rigid hose or pipe.
Check level, add oil as required.
Check and clear debris from inlet.
Adjust submergence as necessary.
Check and replace as required.
PUMP REQUIRES TOO
MUCH POWER
Pump speed too high for pumped
fluid.
Pumped fluid too thick.
Pump piston frozen.
Check engine output reduce as
necessary.
Dilute fluid being pumped if possi
ble.
Disassemble pump and check pis
tons, seals and cylinders for dam
age. Replace components as nec
essary.
PUMP CLOGS
FREQUENTLY
Solids in fluid pumped fluid too
large.
Pumped fluid too thick.
Consult pump performance curve
for solids handling. Install strainer
as necessary.
Dilute fluid being pumped if possi
ble.
EXCESSIVE NOISE Cavitation in pump.
Pump or drive not securely mounted.
Pump clogged or damaged.
Reduce suction lift and/or friction
losses in suction line. Record vacu
um and pressure gauge readings
and consult local representative or
factory.
Secure mounting hardware.
Clean out debris; replace damaged
parts.
CONTROL PANEL TROU
BLE CODES - ENGINE
SHUTDOWN
REFERENCE OPERA
TIONAL CHECKS IN THIS
MANUAL
“Oil Tank Temp” - Temperature too
high in the hydraulic oil tank.
“Oil Tank Level” - Hydraulic oil level
too low in tank.
“Pump Oil Pressure” - The pressure
on the back side of the pistons is too
high.
Temperature too high in the hydraulic
oil tank. Allow to cool before attempt
ing to restart engine.
Check for leaks and refill tank as re
quired with recommended hydraulic
oil.
Check white braided line between
pump cylinders for evidence of the
pumped fluid. Replace piston seals
as necessary. May require being sent
to Gorman-Rupp for repairs.

OM-07305
HSK SERIES
TROUBLESHOOTING PAGE D - 3
PREVENTIVE MAINTENANCE
Since pump applications are seldom identical, and
pump wear is directly affected by such things as
the abrasive qualities, pressure and temperature
of the liquid being pumped, this section is intended
only to provide general recommendations and
practices for preventive maintenance. Regardless
of the application however, following a routine pre
ventive maintenance schedule will help assure
trouble‐free performance and long life from your
Gorman‐Rupp pump. For specific questions con
cerning your application, contact your Gorman‐
Rupp distributor or the Gorman‐Rupp Company.
Record keeping is an essential component of a
good preventive maintenance program. Changes
in suction and discharge gauge readings (if so
equipped) between regularly scheduled inspec
tions can indicate problems that can be corrected
before system damage or catastrophic failure oc
curs. The appearance of wearing parts should also
be documented at each inspection for comparison
as well. Also, if records indicate that a certain part
(such as the seal) fails at approximately the same
duty cycle, the part can be checked and replaced
before failure occurs, reducing unscheduled down
time.
For new applications, a first inspection of wearing
parts at 250 hours will give insight into the wear rate
for your particular application. Subsequent inspec
tions should be performed at the intervals shown
on the chart below. Critical applications should be
inspected more frequently.
General Condition (Temperature, Unusual
Noises or Vibrations, Cracks, Leaks,
Loose Hardware, Etc.) I
Pump Performance (Gauges, Speed, Flow) I
Discharge Clean Out Ports C
Hydraulic Reservoir Oil Level I R
Piston Seal Lubrication I R
Piping or Hoses I
Schedule Subject to Change Based on Results of Field Testing and Applications
Driver Lubrication and Maintenance - See Mfgr's Literature
Hydraulic Pump Maintenance - See Mfgr's Literature
Legend:
I = Inspect, Clean, Adjust, Repair or Replace as Necessary
C = Clean
R = Replace
* Service interval based on an intermittent duty cycle equal to approximately 4000 hours annually.
Adjust schedule as required for lower or higher duty cycles or extreme operating conditions.
Preventive Maintenance Schedule (Tentative Based on Field Tests and Pumped Fluid)
Item Daily Weekly Monthly Semi‐
Annually
Annually
Service Interval*

HSK SERIES OM-07305
MAINTENANCE PAGE E - 1
PUMP MAINTENANCE AND REPAIR - SECTION E
MAINTENANCE AND REPAIR OF THE WEARING PARTS OF THE PUMP WILL MAINTAIN PEAK
OPERATING PERFORMANCE.
STANDARD PERFORMANCE FOR PUMP MODEL HSK4A-KDI1903TCR FT4
Based on 70F (21C) clear water at sea level
with minimum suction lift. Since pump installations
are seldom identical, your performance may be dif
ferent due to such factors as viscosity, specific
gravity, elevation and temperature.
If your pump serial number is followed by an “N”,
your pump is NOT a standard production model.
Contact the Gorman‐Rupp Company to verify per
formance or part numbers.
Pump speed and operating condition
points must be within the continuous per
formance range shown on the curve.

OM-07305 HSK SERIES
MAINTENANCEPAGE E - 2
PARTS PAGE
ILLUSTRATION
45
6
2
8
8
9
10
7
2
1
3
4 5 6
Figure 1. Pump Model HSK4A-KDI1903TCR FT4