Thern 5334 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
Series 5334
Portable Davit Crane
IMPORTANT: Please record
product information on
page 2. This information is
required when calling the
factory for service.
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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
modication 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.
FACTORY AUTHORIZED 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 ANY EXPRESS OR IMPLIED WARRANTY ON THIS
PRODUCT. EXCEPT TO THE EXTENT PROHIBITED BY APPLICABLE 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 specic 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 Model
5334M1 Portable Davit Crane. Do not use this manual as a source of information
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 fall.
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 fall. 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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Important!
• A qualied 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.
1.1 Installing the Crane
Do not install the crane in an area dened as hazardous by the National Elec-
tric Code, unless installation in such an area has been thoroughly approved.
Do not install the crane near corrosive chemicals, ammable materials, ex-
plosives, 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 5/8 inch
coarse thread fasteners, grade 5 or better, torqued dry to 150 ft-lbs without
lubrication. Make sure 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 PRODUCTS 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, CONTACT A QUALIFIED PROFES-
SIONAL TO OBTAIN PROPER STRUCTURE OR FOUNDATION SPECI-
FICATIONS FOR THE MOUNTING OF THERN PRODUCTS.

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Important!
• Inspect the crane during assem-
bly according to the Instructions
for Periodic Inspection. This will
give you a record of the condition
of the crane with which to com-
pare 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 dam-
aged.
• Do not overtighten fasteners, this
may strip threads or cause dam-
age to other parts.
1.2 Assembling the Crane
1.2.1 STUDY PARTS DRAWINGS to understand how the crane is assembled. See
page 17.
1.2.2 LUBRICATE PINS and other components prior to assembly. Refer to the
Lubrication Instructions.
1.2.3 INSTALL THE BASE then assemble the crane in the following order.
a INSTALL THE MAST in the base.
b INSTALL THE GRAB HOOK between the upper mast ears using the spacer
and fasteners provided. Make sure the hook opening faces up. See gure 2.
c INSTALL THE BOOM SWIVEL, see figure 2.
• PLACE THE BUSHINGS in the boom swivel and position this assembly
between the lower mast ears. Make sure the swivel is positioned correctly.
• INSERT FASTENERS and tighten until cotter pins can be inserted. Make
sure cotter pins are locked in the slots of the hex nuts.
d INSTALL THE BOOM in the boom swivel using the pin provided. Make
sure the boom is positioned correctly, and install the boom extension.
e ATTACH ONE END OF THE LOAD CHAIN to the boom extension and the
other end to the grab hook. Avoid twisting the chain and make sure it is
seated in the saddle of the hook. See gure 2.
f INSTALL THE SHEAVE using the pins provided.
g INSTALL THE WINCH using the fasteners provided. Make sure the winch
is positioned correctly.
1.2.4 COMPLETE ASSEMBLY.
a MAKE SURE ALL FASTENERS are tightened, and cotter pins properly
bent to secure them in place, see gure 1.
b LUBRICATE THE ENTIRE CRANE.
c INSTALL THE WINCH HANDLE according to the instructions in the
Winch Owner’s Manual.
d INSTALL THE WIRE ROPE according to the instructions in the Winch
Owner’s Manual.
Figure 2 – Crane Assembly
spacer hook opening
faces up
chain link
turned sideways
and seated in
saddle of hook
ange on
underside
side holes
in boom
swivel
positioned
down
boom
pin
ange between
boom swivel and
mast ear
Figure 1 – Cotter Pins
bend arms back

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2.1 General Theory of Operation
2.1.1 THE PULL REQUIRED to move the load must not exceed the load rating 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.
a LOAD RATING represents the maximum pull that can be placed on new
equipment. Load ratings are assigned values for specic boom positions and
wire rope lengths. The load rating decreases as you increase boom length.
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, cor-
rosive, or explosive surroundings. Protect the equipment from harsh envi-
ronments 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 com-
ponents. Increase maintenance of the equipment if used in frequent op-
erations.
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
2.2.1 CONSIDER THE OPERATION. Do not begin until you are sure you can
perform the entire operation without hazard.
2.2.2 INSPECT ALL 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, by ad-
justing boom length and height. Avoid side pulls which could damage the
crane or cause the load to tip. See gure 3.
2.2.5 ADJUST BOOM LENGTH by unhooking the load chain, moving the boom
extension in or out, and reattaching the load chain. The load rating de-
creases as you lengthen the boom.
2.2.6 ADJUST BOOM HEIGHT by unhooking the load chain, raising or lowering
the boom, and reattaching the load chain. Do not position the boom below
horizontal or at an angle greater than 45°.
Important!
• When determining whether the
load will exceed the load rating,
consider the total force required
to move the load.
Figure 3 – Positioning the Boom
correctincorrect
center
center
Note: the load rating decreases as you lengthen the boom.

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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 fall. 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 gure 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
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 the mast or other ob-
jects.
b PUSH AGAINST THE BOOM just in front of the winch to rotate the boom.
Do not push or pull the load, wire rope, or any other part of the crane
other than 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 cor-
rosion.
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 THE GRAB HOOK at least every 6 months. Use a grease gun
to apply an NLGI #2 grease to the grease tting until excess lubricant comes
out the sides.
3.2.2 LUBRICATE THE BOOM SWIVEL BUSHINGS at least every 6 months.
Apply 2 to 3 drops of 150 grade gear oil to the bushings. Rotate the boom to
allow oil to penetrate, and wipe off excess oil to avoid accumulation of dirt.
3.2.3 LUBRICATE ALL PINS before installation and at least every 3 months. Use
a grease brush to apply a light lm of NLGI #2 grease to all pins.
3.2.4 LUBRICATE THE WINCH. Refer to the Winch Owner’s Manual
for instructions.
3.2.5 LUBRICATE THE WIRE ROPE and other equipment by following the
manufacturer's recommendations.
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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Important!
• Start an inspection program as
soon as you put the crane into use.
• Appoint a qualied person to be
responsible for regularly in-
specting 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.
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 qualied
maintenance person who has completely corrected the problem.
Inspect the crane to detect signs of damage or poor operation before they
become hazardous.
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 to
the drum.
• Make sure the entire crane is properly lubricated.
• Make sure the load chain is not twisted and is securely fastened to the
boom and grab hook.
• Make sure all fasteners are tight and secure.
• Make sure mounting fasteners are tightened securely.
• 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 moving a test load equal to 10% of the
rated capacity.
• 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
devise. 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 it, and remains sta-
tionary 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 in need
of repair or adjustment.
Completely correct all problems before continuing. Use the Troubleshooting
Chart to help determine the cause of certain problems. See table 2.
Perform frequent inspections:
• Before each operation.
• Every 3 hours during operation.
• Whenever you notice signs of
damage or poor operation.

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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.
• Check the nish for wear, aking, 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, check for damage using magnetic or chemical
crack detecting procedures.
• Check all fasteners for stripped threads, wear, bending, and other damage.
• Make sure the entire crane is properly lubricated.
• Make sure all labels and plates are readable, rmly attached, free of dam-
age and clean. Replacements are available from the factory.
b REMOVE THE WIRE ROPE entirely from the crane.
• 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 gure 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 gure 9.
• 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 100 POUNDS of tension on the wire rope.
• Measure the diameter of the wire rope, especially in areas where wear is
noticeable. Replace the wire rope if the diameter measures below the min-
imum diameter at any point. See gure 6.
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 – 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
1/8 in 7/64 in (.1094 in)
3/16 in 11/64 in (.1719 in)
1/4 in 15/64 in (.2344 in)
5/16 in 19/64 in (.2969 in)

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Figure 8 – Grab Hook
Inspection
d REMOVE THE WINCH and inspect it by following the instructions in the
Winch Owner’s Manual.
e DISASSEMBLE THE CRANE, and inspect each part for damage.
f PLACE 50 POUNDS OF TENSION on the load chain. Measure the length
of several 10 link sections of chain, and measure the diameter at several
points on each link. Replace the load chain if it shows signs of wear, stretch-
ing, or other damage. See gure 7.
g REMOVE THE GRAB HOOK, and measure the throat opening, thickness,
and twist of the hook. Replace the hook if it shows signs of damage. See
gure 8.
h 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.
i FASTEN THE CRANE BASE securely to the foundation.
j REASSEMBLE THE CRANE.
k TEST CRANE PERFORMANCE by operating the crane with a test load
equal to 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
devise. 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 it, and remains sta-
tionary 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 in need
of repair or adjustment.
Completely correct all problems before continuing. Use the Troubleshooting
Chart to help determine the cause of certain problems. See table 2.
length - 10 link section
diameter
throat
opening
twist
thickness
The hook must be replaced if the
throat opening is 15% wider than
nominal, if the thickness is 10%
less than nominal, or if the hook is
twisted 10° or more.
Figure 7 – 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.
Figure 7 – Load Chain
Inspection
The load chain must be replaced if
the length of any 10 link section ex-
ceeds maximum allowable length,
or if the diameter of any link mea-
sures 20% less than nominal.

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Table 1 – Inspection Checklist
damages problems
general nish weathered, aking, 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
grab hook twisted, bent, worn, otherwise damaged, see gure 8 grease tting is clogged or dirty
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 =
boom assembly holes worn, distorted, or otherwise damaged does not rotate freely
load chain corroded, worn, or otherwise damaged, see gure 7 twisted or improperly installed
replace if any 10 link length is more than nominal 10 link length =
replace if any link diameter is reduced 20% link diameter =
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
wire rope bent, crushed, otherwise damaged wire rope loosely or unevenly wound
broken wires, see gure 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 gure 6
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 gure 9 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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Important!
• It is your responsibility to de-
termine 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.
• Appoint a qualied person to be
responsible for all repairs to the
equipment.
3.4 Repairing the Crane
3.4.1 GET FACTORY AUTHORIZATION 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
Table 2 – Troubleshooting Chart
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
• ange bearing broken or locked. . .. . .. . .. . . inspect and replace as necessary
• grab hook spacer broken or seized. . .. . .. . . 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.

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4.1 Transporting the Crane
4.1.1 PARTIALLY DISASSEMBLE THE CRANE into parts that can be easily
transported.
4.1.2 PACK THE CRANE for transport, using the original packaging materials, if
appropriate.
4.1.3 REASSEMBLE THE CRANE at its new location following the instructions
under Assembling the Crane.
4.1.4 INSPECT THE CRANE according to the Instructions for Frequent Inspec-
tion before installing it for operation.
4.2 Storing the Crane
4.2.1 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 REASSEMBLE THE CRANE at its new location following the instructions
under Assembling the Crane.
4.2.3 INSPECT THE CRANE according to the Instructions for Periodic Inspec-
tion before installing it for operation.
Important!
• Keep a record of what you ship,
and when you send it.

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Portable Davit Crane Model 5334M1
item description part number qty.
1 Capscrew HxHd .625-11NC x 2.750 SST A3347 1
2 Flat Washer SAE .625 SST A3348 1
3 Spacer A1382 1
4 Hex Jam Nut NyLk .625-11NC SST A4331 1
5 Hook Weldment B1778 1
6 Chain A2723 1
7 Clevis Pin .750 x 1.765 SST A4438 1
8 Sheave B2462 1
9 Boom Swivel Pin A3263 2
10 Bushing A2808 2
11 Slotted Hex Nut .500-13NC SST A3265 2
12 Headless Pin .750 DIA x 3.032 A2462 1
13 Flat Washer .516 SST A3266 2
14 Boom Swivel B1776 1
15 Capscrew HxHd .375-16NC x 1.000 SST A3355 4
16 Hex Nut .375-16NC SST A3356 4
17 Lock Washer HlSpr .375 SST A3357 4
18 Quick Release Pin .500 x 2.125 STL ZNPL A2463 1
19 Boom Extension C2599 1
20 Double Clevis Link .312-.375 A4581 1
21 Cotter Pin .125 x 1.250 SST A4305 5
22 Boom C3108 1
23 Mast C1416 1
24 Hand Winch (not shown) M4312PB-K 1

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MAST-HOOK WELDMENT ASSEMBLY
BOOM TIP ASSEMBLY
BOOM SWIVEL ASSEMBLY
23
15, 16, 17
1918
22
20
11, 21
11, 21
13
14
21
13
10
9
12
9
10
7
8
21
1 2 56
3
4

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