
Instruction Sheet
MRS-1, 2, AND 5
MRS-1001, 2001, 3001, AND 5001
SPRING LOADED CLAMPING CYLINDERS
EIS 57.110-1 Rev. A 04/99
1.0 IMPORTANT RECEIVING INSTRUCTIONS
Visually inspect all components for shipping damage.
Shipping damage is not covered by warranty. If shipping
damage is found, notify carrier at once. The carrier is
responsible for all repair and replacement costs resulting
from damage in shipment.
SAFETY FIRST
2.0 SAFETY ISSUES
Read all instructions, warnings, and cautions
carefully. Follow all safety precautions to
avoid personal injury or property damage
during system operation. Enerpac cannot be
responsible for damage or injury resulting from unsafe
product use, lack of maintenance or incorrect product
and/or system operation. Contact Enerpac when in doubt
as to the safety precautions and operations. If you have
never been trained on high-pressure hydraulic safety,
consult your distribution or service center for a free
Enerpac Hydraulic safety course.
Failure to comply with the f ollowing cautions and w arnings
could cause equipment damage and personal injury.
A CAUTION is used to indicate correct operating or
maintenance procedures and practices to prevent
damage to, or destruction of equipment or other property.
A WARNING indicates a potential danger that requires
correct procedures or practices to avoid personal injury.
A DANGER is only used when your action or lack of
action may cause serious injury or even death.
WARNING: Wear proper personal protective gear
when operating hydraulic equipment.
WARNING: Stay clear of loads supported by
hydraulics. A cylinder, when used as a load lifting
device, should never be used as a load holding
device. After the load has been raised or lowered, it must
always be blocked mechanically.
WARNING: USE ONLY RIGID PIECES TO HOLD
LOADS. Carefully select steel or wood blocks that
are capable of supporting the load. Never use a
hydraulic cylinder as a shim or spacer in any lifting or
pressing application.
DANGER: To avoid personal injury keep hands
and feet away from cylinder and workpiece
during operation.
WARNING: Do not exceed equipment ratings.
Never attempt to lift a load weighing more than the
capacity of the cylinder. Overloading causes
equipment failure and possible personal injury. The
cylinders are designed for a max. pressure of 700 bar. Do
not connect a jack or cylinder to a pump with a higher
pressure rating.
Never set the relief valve to a higher pressure than
the maximum rated pressure of the pump. Higher
settings may result in equipment damage and/or
personal injury.
WARNING: The system operating pressure must
not exceed the pressure rating of the lowest rated
component in the system. Install pressure gauges in
the system to monitor operating pressure. It is your window
to what is happening in the system.
CAUTION: Avoid damaging hydraulic hose.
Avoid sharp bends and kinks when routing hydraulic
hoses. Using a bent or kinked hose will cause severe
back-pressure. Sharp bends and kinks will internally
damage the hose leading to premature hose failure.
Do not drop heavy objects on hose. A sharp
impact may cause internal damage to hose wire
strands. Applying pressure to a damaged hose
may cause it to rupture.
IMPORTANT: Do not lift hydraulic equipment by
the hoses or swivel couplers. Use the carrying
handle or other means of safe transport.
CAUTION: Keep hydraulic equipment away
from flames and heat. Excessive heat will
soften packings and seals, resulting in fluid leaks.
Heat also weakens hose materials and packings. For
optimum performance do not expose equipment to
temperatures of 65°C [150°F] or higher. Protect hoses and
cylinders from weld spatter.
DANGER: Do not handle pressurized hoses.
Escaping oil under pressure can penetrate the skin,
causing serious injury. If oil is injected under the
skin, see a doctor immediately.
WARNING: Only use hydraulic cylinders in a
coupled system. Never use a cylinder with
unconnected couplers. If the cylinder becomes
extremely overloaded, components can fail catastrophically
causing severe personal injury.
®
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WARNING: BE SURE SETUP IS STABLE
BEFORE LIFTING LOAD.
Cylinders should be placed on a flat surface that
can support the load. Where applicable, use a cylinder base
for added stability. Do not weld or otherwise modify the
cylinder to attach a base or other support.
Avoid situations where loads are not directly
centered on the cylinder plunger. Off-center loads
produce considerable strain on cylinders and
plungers. In addition, the load may slip or fall, causing
potentially dangerous results.
Distribute the load evenly across the entire saddle
surface. Always use a saddle to protect the plunger.
IMPORTANT: Hydraulic equipment must only be
serviced by a qualified hydraulic technician. For
repair service, contact the Authorized ENERPAC
Service Center in your area. To protect your warranty, use
only ENERPAC oil.
WARNING: Immediately replace worn or damaged
parts by genuine ENERPAC parts. Standard grade
parts will break causing personal injury and
property damage. ENERPAC parts are designed to fit
properly and withstand high loads.
3.0 DESCRIPTION
Spring loaded clamping cylinders use high force internal
springs to clamp and hydraulic pressure to release
clamping. Each clamping cylinder has an oil port for
hydraulic input. The maximum operating pressure of all
MRS-cylinder types is 350 bar.(See Table A.)
The plunger has internal threads for attaching clamp
arms or suitable clamping devices. The cylinder body is
threaded for installing and adjusting in mounting flanges
or fixtures. (See Figure 1.)
4.0 APPLICATION
These cylinders are designed for prolonged clamping
applications in moveable machine parts, tools, fixtures,
pallets and workpieces.To ensure maximum lifetime, it is
advisable to use these cylinders only within their effective
working area. (See Figures 2 and 3.)
The clamping action is instantaneous with the release of
hydraulic pressure. Due to the unique design, these
cylinders provide uninterrupted mechanical clamping
force.
5.0 INSTALLATION
Install the cylinders as close to the work piece as possible
to provide maximum clamping force and minimum stroke
which prolong the lifetime of the cylinder. Use mounting
flanges or suitable fixtures to provide a stable, secure
mounting. Cylinder hydraulic ports can be use to connect
hydraulic hose or pipe. Always use high pressure tubes
and fittings in all applications. Use hydraulic gauges in
each hydraulic system to indicate safe operating
pressures and loads.
CAUTION: To avoid cylinder damage, do not
subject the plunger to severe side loading.
6.0 OPERATION
Available mechanical clamping forces varies from a
maximum level at fully retracted to minimum at fully
extended. (See Figures 2 and 3.)
IMPORTANT: The effective clamping force is influenced by
the tolerances on the work piece to be clamped.
All spring loaded clamping cylinders are reverse singleacting cylinders using the spring to apply working forces
and hydraulic pressure to release them. Due to the
design, these cylinders provide uninterrupted mechanical
clamping force.
7.0 SERVICE AND MAINTENANCE
Maintenance is required when wear and/or leakage is
noticed. Occasionally inspect components to detect any
problem requiring service and maintenance. ENERPAC
offers ready-to-use spare parts kits for repairs and/or
replacements. Repair parts sheets are available. Contact
your ENERPAC representative.
2
Figure 1, Example of Installation
®

3
Model Operating Maximum Maximum Effective Oil Maximum Weight
No. Pressure Clamping Stroke Working Capacity Oil flow
Force Stroke
(bar) (kN) (mm) (mm) (cm3) (I/min) (kg)
MRS-1 50 - 350 8,6 2,2 2,2 0,7 2 0,5
MRS-2 50 - 350 22,5 2,2 2,2 1,6 2 0,9
MRS-5 50 - 350 45,9 2,2 2,2 3,2 2 1,8
MRS-1001 135 - 350 9,8 4,8 2,4 3,4 2 1,2
MRS-2001 185 - 350 17,4 5,3 2,6 5,1 2 2,1
MRS-3001 180 - 350 26,7 5,6 2,8 8,9 3 3,0
MRS-5001 235 - 350 39,6 5,6 2,8 8,9 3 3,5
45,9 kN
22,5 kN
8,6 kN
MRS/WRS-1 and 2
Effective Working Area
Effective Working Area
MRS/WRS-5
350 bar
MRS/WRS-1
350 bar
MRS/WRS-2
350 bar
MRS/WRS-5
0
1,0
2,0
2,2
Figure 2, MRS-1, 2 and 3
Problem Probable Cause
Cylinder will not advance 1. Spring broke. Replace spr ing(s).
2. Plunger binding. Check cylinder internal parts.
3. No oil or too low oil level in pump. Refill reservoir.
4. Pump release valve open.Close pump’s valve.
Cylinder leaks oil 1. Worn or damaged plunger. Replace plunger and seals.
2. Seals damaged. Replace seals.
3. Leaking or loose oil connections.
Cylinder will not retract. 1. Pump release valve closed.Open this valve.
2. Couplers not completely connected. Check hydraulic line.
3. Internally damaged plunger. Check par ts.
8.0 TROUBLESHOOTING GUIDE
TABLE A

0123456
Plunger In,
Hydraulically Activated
Plunger Out
Stroke (mm)
MRS-5001
MRS-3001
MRS-2001
MRS-2001
Effective
Working Area
235
200
100
0
180
100
185
100 135
100
40
30
20
10
0
PRESSURE (bar)
FORCE (kN)
Figure 3, MRS-1001, 2001, 3001, and 4001
Enerpac Worldwide Locations ✦
Australia
ENERPAC, Applied Power Australia Ltd.
Block V Unit 3
Regents Park Estate
391 Park Road
Regents Park NSW 2143
(P.O. Box 261) Australia
Tel: +61 297 438 988
Fax: +61 297 438 648
Canada
Applied Power Canada Ltd.
6615 Ordan Drive, Unit 14-15
Mississauga, Ontario L5T 1X2
Tel: +1 905 564 5749
Fax: +1 905 564 0305
Toll Free:
Tel: +1 800 268 4987
Fax: +1 800 461 2456
China
Applied Power China Ltd.
1F, 269 Fute N. Road
Waigaoqiao Free Trade Zone
Pudong New District
Shanghai, 200 131
China
Tel: +86 21 5866 9099
Fax: +86 21 5866 7156
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ENERPAC
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P.O. Box 300113
D-40401 Düsseldorf
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Tel: +49 211 471 490
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ENERPAC
Room 907 Workingberg
Commercial Building
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India
ENERPAC
Hydraulics (India) Pvt Ltd
Plot No. A-571
MIDC, TTC Industrial Area
Mahape-400 701
Navi Mumbai, India
Tel: +91 22 769 47 78
Fax: +91 22 769 84 73
Italy
ENERPAC
Applied Power Italiana S.p.A.
Via Canova 4
20094 Corsico (Milano)
Tel: +39 2 486 111 00
Fax: +39 2 486 012 88
All Enerpac products are guaranteed against defects in workmanship and materials for as long as you own them.
For your nearest authorized Enerpac Service Center, visit us at www.enerpac.com
e-mail: info@enerpac.com
Japan
Applied Power Japan Ltd.
1-1-11, Shimomae
Toda-shi
Saitama Pref.
Japan 335-0016
Tel: +81-48-430-2311
Fax: +81-48-430-1117
Mexico
ENERPAC Applied Power
Mexico S.A. de C.V.
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#01-00
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Thomson Road
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Singapore 915704
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Fax: +65 484 5669
✦
internet: www.enerpac.com
South Korea
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Applied Power Korea Ltd.
163-12 Dodang-Dong
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Kyunggi-Do
Republic of Korea
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Fax: +82 32 675 30 02/73
Spain, Portugal
ENERPAC
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28709 Madrid
Spain
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01.05.01