Thern 571 Series User manual

Read this Owner’s Manual
thoroughly before operating
the equipment. Keep it with
the equipment at all times.
Replacements are available
from Thern, Inc., PO Box 347,
Winona, MN 55987,
507-454-2996.
www.thern.com
Owner’s Manual
For
571 and 572 Series
Stationary Davit Cranes
IMPORTANT: Please record
product information on
page 2. This information is
required when calling the
factory for service.
A6255E-0811
Provided by: www.hoistsdirect.com

Owner's Manual for Thern 571 and 572 Series Stationary Davit Cranes
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Two-Year Limited Warranty
Thern, Inc. warrants its products against defects in material or workmanship for two years from the date of purchase
by the original using buyer, or if this date cannot be established, the date the product was sold by Thern, Inc. to the
dealer. To make a claim under this warranty, contact the factory for an RGA number. The product must be returned,
prepaid, directly to Thern, Inc., 5712 Industrial Park Road, Winona, Minnesota 55987. The following information
must accompany the product: the RGA number, the date of purchase, the description of the claimed defect, and a com-
plete explanation of the circumstances involved. If the product is found to be defective, it will be repaired or replaced
free of charge, and Thern, Inc. will reimburse the shipping cost within the contiguous USA.
This warranty does not cover any damage due to accident, misuse, abuse, or negligence. Any alteration, repair or
modification of the product outside the Thern, Inc. factory shall void this warranty. This warranty does not cover any
costs for removal of our product, downtime, or any other incidental or consequential costs or damages resulting from
the claimed defects. This warranty does not cover brake discs, wire rope or other wear components, as their life is
subject to use conditions which vary between applications.
FACTORYAUTHORIZED REPAIR OR REPLACEMENT AS PROVIDED UNDER THIS WARRANTY IS THE
EXCLUSIVE REMEDY TO THE CONSUMER. THERN, INC. SHALL NOT BE LIABLE FOR ANY INCIDENTAL
OR CONSEQUENTIAL DAMAGES FOR BREACH OF ANYEXPRESS OR IMPLIED WARRANTY ON THIS
PRODUCT. EXCEPT TO THE EXTENT PROHIBITED BYAPPLICABLE LAW, ANY IMPLIED WARRANTY
OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE ON THIS PRODUCT IS LIMITED IN
DURATION TO THE DURATION OF THIS WARRANTY.
Some states do not allow the exclusion or limitation of incidental or consequential damages, or allow limitations on
how long an implied warranty lasts, so the above limitation or exclusion may not apply to you. This warranty gives
you specific legal rights, and you may also have other rights which vary from state to state.
Note: Thern, Inc. reserves the right to change the design or discontinue the production of any product without
prior notice.
About This Manual
The Occupational Safety and Health Act of 1970 states that it is the employer’s
responsibility to provide a workplace free of hazard. To this end, all equipment
should be installed, operated, and maintained in compliance with applicable trade,
industrial, federal, state, and local regulations. It is the equipment owner's respon-
sibility to obtain copies of these regulations and to determine the suitability of the
equipment to its intended use.
This Owner’s Manual, and warning labels attached to the equipment, are to serve
as guidelines for hazard-free installation, operation, and maintenance. They
should not be understood to prepare you for every possible situation.
The information contained in this manual is applicable only to the Thern 571 and
572 Series Stationary Davit Cranes. Do not use this manual as a source of infor-
mation for any other equipment.
The following symbols are used for emphasis throughout this manual:
Failure to follow ‘WARNING!’ instructions may result in equipment damage,
property damage, and/or serious personal injury.
Failure to follow ‘CAUTION!’instructions may result in equipment damage,
property damage, and/or minor personal injury.
Important!
Failure to follow ‘important!’instructions may result in poor performance of
the equipment.
Please record the following:
Date Purchased:
Crane Model No.:
Crane Serial No.:
If sold with a winch:
Winch Model No.:
Winch Serial No.:
This information is required when
calling the factory for service.

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Suggestions for Safe Operation
DO the following:
Read and comply with the guidelines set forth in this Owner’s Manual. Keep
this manual, and all labels attached to the crane, readable and with the equip-
ment at all times. Contact Thern, Inc. for replacements.
Check lubrication before use.
Install the wire rope securely to the winch drum.
Keep at least 4 wraps of wire rope wound on the drum at all times, to serve as
anchor wraps. With less than 4 wraps on the drum the wire rope could come
loose, causing the load to escape.
Keep hands away from sheaves, gears, wire rope, and other moving parts of
the equipment.
Disconnect the power before servicing the equipment.
Keep all unnecessary personnel away from the crane while in operation. Keep
out of the path of the load, and out of the path of a broken wire rope that
might snap back and cause injury.
DO NOT do the following:
Do not lift people, or things over people. Do not walk or work under a load or
in the line of force of any load.
Do not exceed the load rating of the crane or any other component in
the system. To do so could result in failure of the equipment.
Do not use more than one crane to move a load that exceeds the load rating of
a single crane. A shift in load weight could overload the equipment.
Do not use damaged or malfunctioning equipment. To do so could result in
failure of the equipment.
Do not modify the equipment in any way. To do so could cause
equipment failure.
Do not wrap the wire rope around the load. This damages the wire rope and
could cause the load to escape. Use a sling or other approved lifting device.
Do not operate the crane with guards removed or improperly installed.
Do not divert your attention from the operation. Stay alert to the possibility of
accidents, and try to prevent them from happening.
Do not jerk or swing the load.Avoid shock loads by starting and stopping the
load smoothly. Shock loads overload the equipment and may cause damage.
Do not remove the winch or other components from the crane, and do not use
these components for any use other than for their original intended function.
Do not use the crane to drag or pull loads. This will create side pulls which
could damage the equipment or cause the load to tip.
Do not leave a suspended load unattended. Place the load on the ground if it
must be left unattended.
Do not adjust the winch brake with the load suspended.

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Table 1 – Crane Reactions
Crane Mast Suggested Axial Force1
Model Moment Bolt Size Per Bolt
571 117,700 in-lbs 1/2 inch 5,200 lbs
572 204,100 in-lbs 3/4 inch 7,300 lbs
1Force in tension
Important!
• A qualified professional should
inspect or design the founda-
tion to insure that it will provide
adequate support.
• Locate the crane so it will be vis-
ible during the entire operation.
• Do not weld the crane base to the
foundation or support structure.
Welding the crane base may void
warranty contact Thern, Inc. Use
fasteners as instructed.
1.1 Installing the Crane
Do not install the crane in an area defined as hazardous by the National Electric
Code, unless installation in such an area has been thoroughly approved.
Do not install the crane near corrosive chemicals, flammable materials,
explosives, or other elements that may damage the crane or injure the
operator. Adequately protect the crane and the operator from such elements.
Position the crane so the operator can stand clear of the load, and out of the
path of a broken wire rope that could snap back and cause injury.
Attach the crane to a rigid and level foundation that will support the crane
and its load under all load conditions, including shock loading.
1.1.1 CONSULT APPLICABLE CODES AND REGULATIONS for specific
rules on installing the equipment.
1.1.2 LOCATE THE CRANE in an area clear of traffic and obstacles that could
interfere with operation. Make sure the crane is accessible for maintenance
and operation.
1.1.3 INSTALL THE CRANE on a level surface. An unlevel surface may cause
the boom to rotate in the direction the mast is leaning.
1.1.4 FASTEN THE BASE securely to the foundation.
a FOR STANDARD PRODUCTS referred to in this manual, use 1/2-inch
coarse thread fasteners, grade 5 or better torqued dry to 75 ft-lbs without
lubrication for 571 series. Use 3/4-inch coarse thread fasteners, grade 5 or
better torqued dry to 260 ft-lbs without lubrication for 572 series. Make
sure the mounting holes are secured to a solid foundation able to support the
crane and the load under all conditions with design factors based on accepted
engineering practices.
b NON-STANDARD PROUCTS that vary from the original design may have
different fastening requirements. Contact a structural engineer or Thern, Inc
for this information.
TO COMPLY WITH LOCAL CODES, CONTACTAQUALIFIED PROFES-
SIONAL TO OBTAIN PROPER STRUCTURE OR FOUNDATION SPECIFI-
CATIONS FOR THE MOUNTING OF THERN PRODUCTS.

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Important!
• Inspect the crane during assembly
according to the Instructions for
Periodic Inspection. This will
give you a record of the condition
of the crane with which to
compare future inspections.
• Save all boxes and crates that the
crane was shipped in, use them
again if you need to repackage
the crane.
• Contact the factory immediately if
any parts are missing or damaged.
• Do not overtighten fasteners, this
may strip threads or cause
damage to other parts.
1.2 Assembling the Crane
When installing the boom brace or ratchet jack, support the end of the boom
so the boom does not escape causing damage or injury
1.2.1 STUDY PARTS DRAWINGS to understand how the crane is assembled.
1.2.2 INSTALL THE BASE then assemble the crane in the following order.
1.2.3 LUBRICATE THE ENTIRE CRANE as you assemble it. Refer to the
Lubrication Instructions.
1.2.4 FASTEN THE BOOM to the mast. Make sure the boom is positioned cor-
rectly with the boom brace ears pointing down.
a TIGHTEN THE CRANE LOCK to secure the mast and prevent it from
rotating during assembly.
b FASTEN THE WINCH MOUNTING END OF THE BOOM to the mast
using the boom pin and cotter pins provided.
c ON HAND OPERATED MODELS, install the sheave, cable keeper, and
spacers on the boom pin as you fasten the boom to the mast.
1.2.5 INSTALL THE BOOM BRACE or ratchet jack.
a FASTEN ONE END OF THE BOOM BRACE or ratchet jack to the brace
ears on the boom using the pin and cotter pins provided.
b RAISE THE BOOM and fasten the other end of the boom brace or ratchet
jack to the brace ears on the mast using the pin and cotter pins provided.
1.2.6 FASTEN THE WINCH to the appropriate mounting plate, using the
fasteners provided. On some models you will need to use the winch adapter
plate and fasteners provided to fasten the winch to the crane. Make sure the
winch is positioned correctly. See page 16 and 17.
1.2.7 INSTALL THE WINCH HANDLE on hand winches, or connect electric
current on power winches. Refer to instructions in the Winch Owner’s Manual.
1.2.8 INSTALL THE WIRE ROPE.
a REMOVE THE QUICK RELEASE PINS from both cable keepers.
b PASS THE WIRE ROPE through the cable keeper and over the sheave at the
end of the boom.
c ON HAND OPERATED MODELS, pass the wire rope through the cable
keeper and over the second sheave at the winch mounting end of the boom.
Make sure the wire rope passes through the slot in the boom and does
not rub against the boom at any point.
d RE-INSTALL BOTH QUICK RELEASE PINS.
e ANCHOR THE WIRE ROPE to the winch drum and wind 4 wraps of wire
rope onto the drum to act as anchor wraps. Refer to the instructions in the
Winch Owner’s Manual.
1.2.9 MAKE SURE ALL FASTENERS are tightened, and cotter pins properly
bent to secure them in place. See Figure 1.
Figure 1 – Cotter Pins
bend arms back

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2.1 General Theory of Operation
2.1.1 THE FORCE REQUIRED to move the load must not exceed the load rat-
ing of the crane. Consider the total force required to move the load, not the
weight of the load.
2.1.2 THIS EQUIPMENT CAN develop forces that will exceed the load rating.
It is the responsibility of the equipment user to limit the size of the load.
Inspect the equipment regularly for damage according to the instructions
contained in this manual.
2.1.3 PERFORMANCE RATINGS of the equipment are affected by the position
of the boom, and the amount of wire rope you use. See the Performance
Characteristics Tables on page 19.
a LOAD RATING represents the maximum pull that can be placed on new
equipment. Load ratings are assigned values for specific boom positions and
wire rope lengths. On Models equipped with a ratchet jack, the load rat-
ing decreases as you lower the boom.
b LIFT varies with the position of the boom and the length of the wire rope.
c REACH varies with the position of the boom.
2.1.4 DUTY RATINGS refer to the type of use the equipment is subject to. Con-
sider the following when determining duty rating.
a ENVIRONMENT: harsh environments include hot, cold, dirty, wet,
corrosive, or explosive surroundings. Protect the equipment from harsh
environments when possible.
b MAINTENANCE: poor maintenance, meaning poor cleaning, lubrication,
or inspection, leads to poor operation and possible damage of the equipment.
Minimize poor maintenance by carefully following the instructions con-
tained in this manual.
c LOADING: severe loading includes shock loading and moving loads that
exceed the load rating of the equipment. Avoid shock loads, and do not
exceed the load rating of the equipment.
d FREQUENCY OF OPERATION: frequent or lengthy operations increase
wear and shorten the life span of gears, bearings, sheaves, and other
components. Increase maintenance of the equipment if used in
frequent operations.
CONTACT THE FACTORY FOR MORE INFORMATION.
Important!
• Limit nonuniform winding by
keeping tension on the wire rope.
• It is your responsibility to detect
and account for different fac-
tors affecting the condition and
performance of the equipment.

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2.2 Preparing for Operation
When positioning the boom, avoid side pulls which could damage the crane or
cause the load to tip.
When operating the ratchet jack, do not position the boom below horizontal.
The load rating decreases as you lower the boom.
When operating the ratchet jack, do not raise the boom at an angle greater
than 45-degree and do not force the ratchet handle pass the travel limits. To
do so could cause the boom to fall resulting in damage or injury. See Figure 2.
2.2.1 CONSIDER THE OPERATION. Do not begin until you are sure you can
perform the entire operation without hazard.
2.2.2 INSPECTALL COMPONENTS of the system.
a INSPECT THE CRANE and other equipment according to the Instructions
for Frequent Inspection.
b INSPECT THE WINCH according to the instructions in the Winch Owner’s
Manual.
c OPERATORS must be in good health, alert, thoroughly trained in operat-
ing the equipment, and properly clothed (hard hat, safety shoes and safety
glasses, no loose clothing).
d THE LOAD must be clear of other objects and free to move. Make sure the
load will not tip, spin, roll away, or in any way move uncontrollably.
2.2.3 KNOW YOUR LOAD and make sure you do not exceed the load rating of
the crane or any other equipment in the system.
2.2.4 POSITION THE BOOM so the load hook is centered over the load. See
Figure 3.
2.2.5 ON MODELS EQUIPPED WITHARATCHET JACK, adjust boom height
and reach by operating the ratchet jack.
Important!
• When determining whether the
load will exceed the load rating,
consider the total force required
to move the load.
45o max
0o min
Figure 3 – Positioning the BoomFigure 2 – Boom Travel
Limits
incorrect
correct
center line center line

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2.3 Attaching the Load
Do not wrap the wire rope around the load. This damages the wire rope and
could cause the load to escape. Use a sling or other approved lifting device.
2.3.1 CLEAR OBJECTS from the path of the load so you can move it freely and
observe it at all times during the operation.
2.3.2 MAKE SURE THE WIRE ROPE is not twisted. A twisted wire rope could
cause the load to spin when it is raised off the ground.
2.3.3 ATTACH THE LOAD using a nylon sling, or other approved lifting device.
Follow the recommendations of the sling manufacturer.
a SEAT THE SLING in the saddle of the hook with the hook latch completely
closed. See Figure 4.
b CENTER THE LOAD on the hook so it will remain balanced and not tip or
rotate to one side.
2.4 Moving the Load
When operating the ratchet jack, do not raise the boom at an angle greater
than 45-degree and do not force the ratchet handle pass the travel limits. To
do so could cause the boom to fall resulting in damage or injury. See Figure 2.
2.4.1 MOVE THE LOAD slowly and smoothly, only a small distance at first.
Make sure the load is balanced and securely attached before continuing.
2.4.2 OPERATE THE WINCH to raise or lower the load. Refer to the
instructions in the Winch Owner’s Manual.
2.4.3 OBSERVE THE WIRE ROPE as it winds onto the drum. If it becomes
loose, uneven, or overlapped, stop the operation and rewind the wire rope
before continuing. Continued operation with overlapped or uneven wire
rope can damage the wire rope and shorten its life.
2.4.4 ROTATE THE BOOM to move the load side-to-side.
a ROTATE THE BOOM slowly and smoothly to avoid swinging the load or
causing shock loads. Do not jam the boom against other objects.
b USE THE HANDLE to rotate the boom. Do not push or pull the load or
the wire rope to rotate the boom.
Important!
• Obey a stop signal from anyone.
• Maintain tension on the wire
rope to keep it tightly and evenly
wound on the drum.
• If the crane and load are not vis-
ible during the entire operation,
get help from another person.
• Appoint a supervisor if more
than one person is involved in
the operation. This will reduce
confusion and increase safety.
• When lifting a load, use a tag line
to keep the load from swinging or
twisting, while keeping yourself
away from the load.
Figure 4 – Attaching Load
latch closed
tight against
hook
sling seated in
saddle of hook

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3.1 Cleaning the Crane
Clean the crane to remove dirt and help prevent rust and corrosion.
3.1.1 CLEAN THE CRANE every six months or whenever it is dirty.
a WIPE ALL EQUIPMENT to remove dirt and grease.
b LEAVE A LIGHT FILM of oil on all surfaces to protect against rust
and corrosion.
c WIPE OFF excessive amounts of oil to avoid the accumulation of dirt.
3.1.2 REMOVE UNNECESSARY OBJECTS from the area surrounding
the crane.
3.2 Lubricating the Crane
Lubricate the crane properly to help protect it from wear and rust. Read the
following instructions carefully.
3.2.1 LUBRICATE ALL PINS at least every 3 months. Use a grease brush to ap-
ply a light film of NLGI #2 grease to all pins.
3.2.2 LUBRICATE THE ROLLERS at least every 3 months. Use a grease gun to
apply an NLGI #2 grease to the grease fitting on each side of the mast until
excess grease can be seen.
3.2.3 LUBRICATE THE MAST ROLLER BEARING at least every 3 months or
whenever it squeaks or sounds dry when rotated. Use a grease gun to insert 5
to 10 pumps of an NLGI #2 grease to the grease fitting at the top of the mast.
3.2.4 LUBRICATE THE RATCHET JACK, if applicable, at least every 3 months.
Use a grease gun to apply an NLGI #2 grease to the grease fittings on the
ratchet jack until excess grease can be seen.
3.2.5 LUBRICATE THE WINCH at least every 3 months. Refer to the Winch
Owner’s Manual for instructions.
3.2.6 LUBRICATE THE WIRE ROPE and other equipment by following the
manufacturers recommendation.
Important!
Increase the frequency of mainte-
nance procedures if the crane is:
• Operated for long periods.
• Used to lift heavy loads.
• Operated in wet, dirty, hot, or
cold surroundings.
Important!
• Make sure lubricant has a tem-
perature rating appropriate for
the ambient temperatures of the
operation.

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3.3 Inspecting the Equipment
Do not use damaged or malfunctioning equipment. Place an “OUT OF ORDER”
sign on the crane. Do not use the crane until the sign is removed by a qual-
ified maintenance person who has completely corrected the problem.
Inspect the crane to detect signs of damage or poor operation before they
become hazardous. See Table 2 - Inspection Checklist.
3.3.1 CONSULT APPLICABLE CODES AND REGULATIONS for specific rules
on inspecting the crane and other equipment.
3.3.2 REFER TO THE WINCH OWNER’S MANUAL for information regarding
winch inspection.
3.3.3 Instructions for Frequent Inspection
a VISUALLY INSPECT the entire crane and all other equipment involved in
the operation.
• Check all equipment for cracks, dents, bending, rust, wear, corrosion and
other damage.
• Make sure the wire rope is installed correctly and anchored securely.
• Make sure the entire crane is properly lubricated.
• Make sure all fasteners are tight and secure.
• Make sure mounting fasteners are tightened securely.
• Check the ratchet jack, if applicable, for signs of leakage or damage, and
make sure it operates smoothly to raise and lower the boom.
• Make sure the foundation is in good condition, and capable of supporting
the crane and its load under all load conditions.
b TEST CRANE PERFORMANCE by operating the crane with a load not
exceeding the load rating.
• Listen for unusual noises, and look for signs of damage as you operate the
crane.
• Make sure the wire rope winds evenly and tightly onto the drum. If it is
loose or uneven, rewind it before continuing.
• Make sure the load moves smoothly, without hesitation or strain.
• On hand operated models, make sure the winch handle rotates freely in
both directions.
• On power operated models, make sure the winch responds to the control
device. It must rotate as shown on the control labels, and it must turn off
when you release the control.
• Make sure the boom rotates freely when you push the handle, and re-
mains stationary when you release it.
• Check the brake. Raise the load, then lower it and stop it a few feet off the
ground. If the load continues to coast or creep, the brake may be worn and
in need of repair or replacement. Contact the factory.
Completely correct all problems before continuing. Use the Troubleshooting
Chart to help determine the cause of certain problems. See Table 4.
Important!
• Start an inspection program as
soon as you put the crane into use.
• Appoint a qualified person to be
responsible for regularly inspecting
the equipment.
• Keep written records of inspec-
tion. This allows comparison with
comments from previous inspec-
tions so you can see changes in
condition or performance.
Perform frequent inspections:
• Before each operation.
• Every 3 hours during operation.
• Whenever you notice signs of
damage or poor operation.
Frequent Wire Rope Inspection:
 Use ASME B30.7 as a guideline
for rope inspection, replacement
and maintenance.
 Check the wire rope, end connec-
tions and end fittings for corrosion,
kinking, bending, crushing, bird-
caging or other signs of damage.

Check the number, distribution and
type of visible broken wires. See
paragraph 3.3.4 b and Figure 5.
 Check the wire rope for reduc-
tion of rope diameter from loss of
core support, or wear of outside
wires. See Figure 7.
 Take extra care when inspecting
sections of rapid deterioration
such as sections in contact with
saddles, sheaves, repetitive pickup
points, crossover points and end
connections.

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Table 2 – Inspection Checklist
damages problems
general finish weathered, flaking, otherwise damaged equipment not properly lubricated
parts cracked, bent, rusted, worn, otherwise damaged unusual noises, other signs of malfunction
foundation loose, unstable, otherwise damaged not level - boom swerves
fasteners stripped threads, bent, worn, otherwise damaged loose, not tightened to the proper torque
boom assembly holes worn, distorted, or otherwise damaged does not rotate freely
winch assembly gears, bearings, and other parts worn, otherwise damaged winch jerks or hesitates under load
brake corroded, cracked, worn, otherwise damaged brake does not operate properly
sheave holes worn, distorted, or otherwise damaged does not rotate freely
bearings corroded, worn, seized, or otherwise damaged not properly lubricated
wire rope bent, crushed, otherwise damaged wire rope loosely or unevenly wound
broken wires, see Figure 5
replace if more than 6 wires in one lay, number per strand =
or 3 wires in one strand in one lay, are broken number per lay =
diameter reduced, see Figure 7
replace if diameter is excessively worn diameter =
end connections corroded, rusted, worn, otherwise damaged not securely attached
load hook twisted, bent, worn, otherwise damaged, see Figure 6 hook latch fails to close when released
replace if twist is 10 degrees or more twist =
replace if throat width is 15% larger than nominal throat width =
replace if thickness is 10% less than nominal thickness =
labels and plates dirty, illegible, otherwise damaged loosely attached or missing
comments:
authorized signature: date
checked boxes indicate damage or problem in need of repair

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Figure 5 – Broken Wires
wire
strand
one
lay
Wire rope assembly must be re-
placed if more than 6 wires are
broken in one lay, or if more than
3 wires are broken in one strand
in one lay.
Figure 6 – Load Hook
Inspection
throat
opening
twist
thickness
The wire rope assembly must be
replaced if the throat opening is
15% wider than nominal, if the
thickness is 10% less than nomi-
nal, or if the hook is twisted 10°
or more.
Perform periodic inspections:
• Every 6 months.
• Whenever you return the crane to
service from storage.
• Whenever you notice damage
or poor operation in a frequent
inspection.
• Whenever you have, or think you
may have, overloaded or shock
loaded the crane.
3.3.4 Instructions for Periodic Inspection.
a VISUALLY INSPECT the crane and all other equipment.
• Disassembly may be required in order to properly inspect individual compo-
nents. Contact factory for assembly/disassembly instructions. Disassembly
of the winch or crane before contacting Thern, Inc. voids all warranties.
• Check the finish for wear, flaking, or other damage.
• Check all equipment for cracks, dents, bending, rust, wear, corrosion and
other damage. If the crane was overloaded, or if you notice cracks and
other signs of overloading and damage, promptly remove equipment from
use and have it repaired or replaced. DO NOT CONTINUE TO USE
DAMAGED OR OVERLOADED EQUIPMENT OR WIRE ROPE.
• Check all fasteners for stripped threads, wear, bending, and other damage.
• Make sure the entire crane is properly lubricated.
• Check the ratchet jack, if applicable, for signs of leakage or damage, and
make sure it operates smoothly to raise and lower the boom.
• Make sure all labels and plates are readable, firmly attached, free of dam-
age and clean. Replacements are available from the factory.
b INSPECT THE WIRE ROPE according the wire rope manufacturer's recom-
mendations, or follow accepted industry standards for wire rope inspection.
• Always wear protective clothing when handling wire rope.
• Check the entire length of wire rope for bent wires, crushed areas, broken
or cut wires, corrosion, and other damage. Carefully inspect areas that
pass over sheaves or through roller guides.
• Note the location and concentration of broken wires. Replace wire rope if
more than 6 wires are broken in one lay, or more than 3 wires are broken
in one strand in one lay. See Figure 5.
• Make sure the load hook or other device is securely attached to the wire
rope, and the wire rope where it is attached is not frayed, corroded, bro-
ken, or otherwise damaged.
• Measure the throat opening, thickness, and twist of the hook. Replace the
hook if it shows signs of damage. See Figure 6.
• Make sure hook latch opens without binding and closes when released.
• Check the anchor holes in the drum and the surrounding area for signs of
wear or distortion.
c PLACE enough weight to keep the wire rope straight and tightly drawn.
• Measure the diameter of the wire rope, especially in areas where wear
is noticeable. Replace the wire rope if the diameter measures below the
minimum diameter at any point. See Figure 7.
d REMOVE THE WINCH and inspect it by following the instructions in the
Winch Owner’s Manual.
e DISASSEMBLE THE CRANE by removing the boom brace or ratchet jack,
the boom, and the sheaves. Inspect each component for damage.
f REMOVE THE CRANE BASE from the foundation.
• Check fasteners for stripped threads, wear, bending, and other damage.
• Check the foundation for cracks, corrosion, and other damage.

Owner's Manual for Thern 571 and 572 Series Stationary Davit Cranes page 13
A6255E-0811
g FASTEN THE CRANE BASE securely to the foundation.
h REASSEMBLE THE CRANE.
i TEST CRANE PERFORMANCE by operating the crane with a load equal
to the load rating.
• Listen for unusual noises, and look for signs of damage as you operate.
• Make sure the wire rope winds evenly and tightly onto the drum. If it is
loose or uneven, rewind it before continuing.
• Make sure the load moves smoothly, without hesitation or strain.
• On hand operated models, make sure the winch handle rotates freely in
both directions.
• On power operated models, make sure the winch responds to the control
device. It must rotate as shown on the control labels, and it must turn off
when you release the control.
• Make sure the boom rotates freely when you push the handle, and
remains stationary when you release it.
• Check the brake. Raise the load, then lower it and stop it a few feet off
the ground. If the load continues to coast or creep under normal operating
condition, the brake may need repair or replacement. Contact the factory.
Completely correct all problems before continuing. Use the Troubleshooting
Chart to help determine the cause of certain problems. See Table 4.
3.4 Repairing the Crane
3.4.1 GET FACTORYAUTHORIZATION for all repairs. Unauthorized repairs
will void the warranty, and may lead to damage or failure of the crane.
3.4.2 REPLACE DAMAGED OR POORLY OPERATING PARTS with Thern
repair parts.
3.4.3 REFINISH AREAS where the paint is worn or flaking. A good finish helps
to protect against corrosion and weather damage.
a REMOVE THE FINISH from damaged areas, down to the bare metal.
b CLEAN THE AREA thoroughly.
c REPAINT with a high quality primer and finishing coat.
3.4.4 TO ORDER REPAIR PARTS, contact your local dealer. Include the fol-
lowing information when ordering:
• model number
•serial number (or code number)
• part number
• date purchased, and from whom
• description of what happened, or what is wrong
• your name and return address
Figure 7 – Rope Diameter
diameter
incorrect
correct
The wire rope assembly must
be replaced if the diameter mea-
sures less than the minimum
diameter at any point.
wire rope
diameter minimum diameter
3/16 in 11/64 in (.1719 in)
1/4 in 15/64 in (.2344 in)
5/16 in 19/64 in (.2969 in)
3/8 in 11/32 in (.3438 in)
Important!
• It is your responsibility to
determine when to replace parts.
When considering whether to
continue using a part or to replace
it, remember that replacing it
is the best way to avoid further
equipment damage.
• If repair or replacement of the
mast, base, or bearings within
should become necessary,
please call the factory.
• Appoint a qualified person to
be responsible for all repairs to
the equipment.

Owner's Manual for Thern 571 and 572 Series Stationary Davit Cranes
page 14
A6255E-0811
4.1 Transporting the Crane
4.1.1 PARTIALLY DISASSEMBLE THE CRANE into components that can be
transported.
4.1.2 PACK THE CRANE for transport, using the original packaging materials, if
appropriate.
4.1.3 PACK THE WINCH in an upright position for transport, using the original
packaging materials, if possible.
4.1.4 REASSEMBLE THE CRANE at its new location following the instructions
under Section 1.2 Assembling the Crane.
4.1.5 INSPECT THE CRANE according to Section 3.3.3 Instructions for Fre-
quent Inspection before installing it for operation.
4.2 Storing the Crane
4.2.1 PARTIALLY DISASSEMBLE THE CRANE and store all parts in a cool
clean place away from corrosive chemicals and moisture.
4.2.2 SEAL THE CRANE in plastic with a desiccant to help protect it from rust,
corrosion, and other damage.
4.2.3 SEAL THE WINCH in plastic with a desiccant to help protect it from rust,
corrosion, and other damage.
4.2.4 REASSEMBLE THE CRANE at its new location following the instructions
under Assembling the Crane.
4.2.5 INSPECT THE CRANE according to the Instructions for Section 3.3.4 Peri-
odic Inspection before installing it for operation.
4.2.6 LUBRICATE THE CRANE PROPERLY prior to operation. See Section 3.2
Lubricating the Crane.
Important!
• Keep a record of what you ship,
and when you send it.
Model Weight
LB KG
M4312PB-K 26 11.79
M452B-K 78 35.38
4WM2V-K 37 16.78
4WP2-K 77 34.93
4777-K 80 36.29
4771-K 80 36.29
4WS3M6-K 272 123.40
Table 3 – Winch Weight Chart

Owner's Manual for Thern 571 and 572 Series Stationary Davit Cranes page 15
A6255E-0811
Table 4 – Troubleshooting Chart
Contact the factory for detailed instructions if you are required to disassemble the crane or winch for any reason.
Disassembly of the crane or winch before contacting Thern, Inc. voids all warranties.
problem cause correction
overheating • operated too long without rest. .. . .. . .. . .. . .. . allow to cool
• load too heavy .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . lighten load
• poor lubrication.. . .. . .. . .. . .. . .. . .. . .. . .. . .. . inspect and lubricate as necessary
• bearing seized up .. . .. . .. . .. . .. . .. . .. . .. . .. . inspect and replace as necessary
boom bounces up and down • load too heavy .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . lighten load
• mounting bolts loose .. . .. . .. . .. . .. . .. . .. . .. . tighten mounting bolts to proper torque
• sheave worn or damaged. . .. . .. . .. . .. . .. . .. . inspect and replace as necessary
• foundation loose or unlevel .. . .. . .. . .. . .. . .. . inspect and repair as necessary
• winch gears worn or damaged .. . .. . .. . .. . .. . inspect and repair as necessary
boom does not rotate • rotation points contaminated or worn .. . .. . .. . inspect and repair as necessary
• flange bearing broken or locked. . .. . .. . .. . .. . inspect and replace as necessary
boom rotates on its own • foundation loose or unlevel .. . .. . .. . .. . .. . .. . inspect and repair as necessary
• mast bent, distorted, or leaning.. . .. . .. . .. . .. . inspect and repair as necessary
unusual noises
high pitched squeak • poor lubrication.. . .. . .. . .. . .. . .. . .. . .. . .. . .. . lubricate entire crane properly
grinding noise • contaminated lubricant at rotation points .. . .. . clean and lubricate rotation points
rattling noise • loose bolts, set screws or other fasteners. . .. . tighten all bolts and other fasteners
Refer to the Winch Owner’s Manual for possible problems with the winch and brake.
Model 571 Part Numbers Component Weight Assembly/Disassembly Weight (with pins)
Component Standard LB KG LB KG
Mast C3212 260 118.10 262 118.74
Boom B3256 96 43.28 98 44.55
Boom Brace B1533 14 6.28 14 6.28
Jack C3213 35 15.88 35 15.88
Handle B3292 4 1.59 4 1.59
TOTAL 409 185.12 413 187.04
Model 572 Part Numbers Component Weight Assembly/Disassembly Weight (with pins)
Component Standard LB KG LB KG
Mast C3193 388 176.05 394 178.59
Boom C3196 190 86.23 194 88.15
Boom Brace B1498 32 14.28 32 14.28
Jack C3235 101 45.55 101 45.55
Handle B3292 4 1.59 4 1.59
TOTAL 715 323.70 725 328.17
Table 5 – Crane Weight Chart

Owner's Manual for Thern 571 and 572 Series Stationary Davit Cranes
page 16
A6255E-0811
Stationary Davit Crane 571M1 572M1 571M2 571E2
item description part number qty. part number qty part number qty. part number qty.
1 MAST SUBASSEMBLY C3212 1 C3193 1 C3212 1 C3212 1
21BOOM BRACE B1533 1 B1498 1 B1533 1 B1533 1
3 BOOM SUBASSEMBLY B3257 1 C3196 1 B3257 1 B3257 1
4 HAND WINCH M4312PB-K 1 M452B-K 1 4WM2V-K 1 4WP2-K 1
5 CAPSCREW HEXHD A2975 4 A3164 4 A3355 4 A3355 4
6 FLAT WASHER — A2932 8 — —
7 HEX NUT NYLK A3231 4 A2897 4 A3356 4 A3356 4
8 SHEAVE ASSEMBLY B3050 1 A6884 1 B3050 1 B3050 1
9 SPACER A6831 2 A6831 2 A6831 2 A6831 2
10 QUICK RELEASE PIN A4905 1 A4511 1 A4905 1 A4905 1
11 CABLE GUIDE A6856 1 A6832 1 A6856 1 A6856 1
12 LOAD RATING LABEL A7604 1 A7605 1 A7604 1 A7604 1
1For adjustable boom option, replace boom brace with ratchet jack. Part number C3213 for 571 Series, C3235 for 572 Series.
572M1
Adjustable Ratchet-Jack
Part Number C3213 for 571 Series, C3235 for 572 Series
571M1
571E2 571M2
11
10
4
7
3
8
5
4
5
4
5
4
6
5
9
2
12
1

Owner's Manual for Thern 571 and 572 Series Stationary Davit Cranes page 17
A6255E-0811
572E3
572E5
Adjustable Ratchet Jack
Part Number C3213 for 571 Series, C3235 for 572 Series
C3114 Mounting Plate Assembly
571E4
12a 12b
6
57
4
1
3
12c
12d 12e 12f
12
4
12
4
13
Stationary Davit Crane 571E4 572E3 572E5
item description part number qty. part number qty. part number qty.
1 MAST SUBASSEMBLY C3212 1 C3193 1 C3193 1
21BOOM BRACE B1533 1 B1498 1 B1498 1
3 BOOM SUBASSEMBLY B3257 1 C3196 1 C3196 1
4 ELECTRIC POWER WINCH 4777-K 1 4771-K 1 4WS3M6-K 1
5 CAPSCREW HEXHD — — A3164 4
6 FLAT WASHER — — A2932 8
7 HEX NUT NYLK — — A2897 4
12 MOUNTING PLATE ASSEMBLY C3114 1 C3114 1 —
12a MOUNTING PLATE C3111 1 C3111 1 —
12b CAPSCREW HEXHD A2975 4 A2975 4 —
12c WASHER HELSPRLK A2926 4 A2926 4 —
12d CAPSCREW HEXHD A5042 6 A5042 6 —
12e HEX NUT NYLK A2927 6 A2927 6 —
12f FLAT WASHER SAE A2924 6 A2924 6 —
13 LOAD RATING LABEL A7604 1 A7606 1 A7607 1
1For adjustable boom option, replace boom brace with ratchet jack. Part number C3213 for 571 Series, C3235 for 572 Series.

Owner's Manual for Thern 571 and 572 Series Stationary Davit Cranes
page 18
A6255E-0811
RATING
LOAD LOAD
RATING
16
20
17
15
14
13 3
2
1
911
19
10
12
18
89
67
5
4
Stationary Mast Subassembly C3212 C3193
item description part number qty. part number qty.
1 MAST WELDMENT D1077 1 D1115 1
2 OUTSIDE MAST WELDMENT C1256 1 C3192 1
3 CRANE LOCK A1903 1 A1903 1
4 ZERK A3196 2 A3196 2
5 LARGE ROLLER A2073 48 A2088 50
6 CAPSCREW HEXHD A2922 1 A3112 1
7 HEX JAM NUT A3231 1 A3195 1
8 BRACE PIN A2072 1 A2093 1
9 COTTER PIN A3155 4 A3155 4
10 ZERK DRIVE A3197 1 A3197 1
11 BOOM PIN A2071 1 A2089 1
12 TAPERED ROLLER BEARING CONE A2759 1 A2761 1
13 HANDLE B3292 1 B3292 1
14 CAPSCREW HEXHD A3472 1 A3472 1
15 HEX NUT A3235 1 A3235 1
16 THERN LOGO A2178 1 A2179 1
17 WARNING LABEL A1961 1 A1961 1
18 NAME PLATE SST A1976 1 A1976 1
19 LOAD RATING LABEL - RIGHT A6912 1 A6918 1
20 LOAD RATING LABEL - LEFT A6914 1 A6919 1
Stationary Boom Subassembly B3257 C3196
item description part number qty. part number qty.
1 BOOM WELDMENT B3256 1 C3195 1
2 SHEAVE ASSEMBLY B3050 1 A6884 1
3 CABLE GUIDE A6856 1 A6832 1
4 QUICK RELEASE PIN A4905 1 A4511 1
5 SPACER A6831 2 A6831 2
6 SHEAVE PIN A2070 1 A2092 1
7 COTTER PIN A3155 4 A3155 4
8 BRACE PIN A2072 1 A2093 1
9 LOAD RATING LABEL LEFT A6915 1 A6920 1
10 LOAD RATING LABEL RIGHT A6913 1 A6921 1
109 78 67
1345
2
Mast Subassembly
C3212 for 571
C3193 for 572
Boom Subassembly
B3257 for 571
C3196 for 572

Owner's Manual for Thern 571 and 572 Series Stationary Davit Cranes page 19
A6255E-0811
571 Series Performance Characteristics
3
wire load rating for 571M1, 571M2 and 572E2 load rating for 571E41lift below
rope wire rope position A position B position C position D position A position B position C position D floor level
dia.
length (min – max)2
1/4 in 28 ft 1200 lb 1350 lb 1500 lb 1500 lb 1200 lb 1350 lb 1500 lb 1500 lb 4 – 9 ft
1/4 in 36 ft 1200 lb 1350 lb 1500 lb 1500 lb 1200 lb 1350 lb 1500 lb 1500 lb 12 – 17 ft
1/4 in 45 ft 1200 lb 1350 lb 1400 lb 1400 lb 1200 lb 1350 lb 1500 lb 1500 lb 21 – 26 ft
1/4 in 60 ft 1200 lb 1300 lb 1300 lb 1300 lb 1200 lb 1350 lb 1400 lb 1400 lb 36 – 41 ft
1/4 in 75 ft - - - - 1200 lb 1300 lb 1300 lb 1300 lb 51 – 56 ft
1Add 2 ft to lift below floor level for Model 571E4.
2 Lift below floor level varies depending on boom position and winch configuration. For longer lifts contact factory.
3Performance Characteristics are for standard products referred to in this manual. Non-standard products may vary from the original
design. Contact Thern, Inc. for this information.
572 Series Performance Characteristics
3
wire load rating for 572M1 and 572E51load rating for 572E31lift below
rope wire rope position A position B position C position D position A position B position C position D floor level
dia.
length (min – max)2
5/16 in 28 ft 1700 lb 2000 lb 2200 lb 2200 lb 1700 lb 1700 lb 1700 lb 1700 lb -1 – 5 ft
5/16 in 36 ft 1700 lb 2000 lb 2200 lb 2200 lb 1700 lb 1700 lb 1700 lb 1700 lb 7 – 13 ft
5/16 in 45 ft 1700 lb 2000 lb 2200 lb 2200 lb 1500 lb 1500 lb 1500 lb 1500 lb 16 – 22 ft
5/16 in 60 ft 1700 lb 2000 lb 2200 lb 2200 lb 1300 lb 1300 lb 1300 lb 1300 lb 31 – 37 ft
5/16 in 75 ft 1700 lb 2000 lb 2200 lb 2200 lb 1300 lb 1300 lb 1300 lb 1300 lb 46 – 52 ft
1 Add 3 ft to lift below floor level for Model 572E3 and 572E5.
2Lift below floor level varies depending on boom position and winch configuration. For longer lifts contact factory.
3Performance Characteristics are for standard products referred to in this manual. Non-standard products may vary from the original
design. Contact Thern, Inc. for this information.
lift below
floor level
B
C
D
A
Positions A, B and D require
separate order of ratchet jack.

Thern, Incorporated
5712 Industrial Park Road
Winona, MN 55987
PHN 507-454-2996
FAX [phone]
EMAIL: [email protected]
www.thern.com