Thern 462 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 Thern
Worm Gear Hand Winches
IMPORTANT: Please record
product information on
page 2. This information is
required when calling the
factory for service.
A6112F-0507

Owner's Manual for Thern Worm Gear Hand Winchespage 2
A6112F-0507
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 INCIDEN-
TAL OR CONSEQUENTIAL DAMAGES FOR BREACH OF ANY EXPRESS OR IMPLIED WARRANTY ON
THIS PRODUCT. EXCEPT TO THE EXTENT PROHIBITED BYAPPLICABLE LAW, ANY IMPLIED WAR-
RANTY 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 Worm
Gear Hand Winches. 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:
Model No.:
Code No.:
This information is required when
calling the factory for service.

Owner's Manual for Thern Worm Gear Hand Winches page 3
A6112F-0507
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 winch, readable and with the
equipment 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 the drum, wire rope, and other moving parts of the
equipment.
Keep all unnecessary personnel away from winch 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 winch or any other component in the
system. To do so could result in failure of equipment..
Do not use more than one winch to move a load unless each winch was de-
signed for use in a multiple winch system.
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 approved rigging connectors to secure the
wire rope to the load.
Do not lift loads or pull loads on an incline unless the winch is equipped with
a load brake.
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 leave a suspended load unattended unless specific precautions have
been taken to secure the load and keep people away from the winch and out
from under the load.

Owner's Manual for Thern Worm Gear Hand Winchespage 4
A6112F-0507
1.1 Installing the Winch
Do not install the winch in an area defined as hazardous by the National Elec-
tric Code, unless installation in such an area has been thoroughly approved.
Donotinstallthewinchnearcorrosivechemicals,flammablematerials,explosives,
orotherelementsthat maydamagethewinchorinjuretheoperator.Adequately
protect the winch and the operator from such elements.
Position the winch 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 winch to a rigid and level foundation that will support the winch
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 WINCH in an area clear of traffic and obstacles. Make sure
the winch is accessible for maintenance and operation.
1.1.3 POSITION THE WINCH HORIZONTALLY to insure proper lubrication.
Do not install the winch vertically or upside-down, unless it has been
modified for this type of installation. To convert the winch for vertical
installation, remove the four bolts holding the gearcase to the frame, turn the
frame 90°, and reinstall the bolts. See figure 1.
1.1.4 MAINTAIN A FLEET ANGLE between 1/2 and 1-1/2 degrees. The proper
fleet angle minimizes wire rope damage by helping the wire rope wind uni-
formly onto the drum. See figure 2.
1.1.5 POSITION THE WINCH to allow access for proper lubrication.
1.1.6 FASTEN THE WINCH securely to the foundation.
a FOR STANDARD PRODUCTS referred to in this manual, use 3/8 inch
coarse thread fasteners, grade 5 or better, torqued dry to 30 ft-lbs without
lubrication for Models 462 and 4622PB. Use 1/2 inch coarse thread fasten-
ers, grade 5 or better, torqued dry to 75 ft-lbs without lubrication for Models
472, 4722PB, 482 and 482B. Make sure the winch frame is secured to a solid
foundation able to support the winch 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, CONTACTA QUALIFIED PROFES-
SIONAL TO OBTAIN PROPER STRUCTURE OR FOUNDATION SPECIFICA-
TIONS FOR THE MOUNTING OF THERN PRODUCTS.
Important!
• Inspect the winch immediately
following installation according
to the Instructions for Periodic
Inspection. This will give you
a record of the condition of the
winch with which to compare
future inspections.
• A qualified professional should
inspect or design the founda-
tion to insure that it will provide
adequate support.
• Locate the winch so it will be vis-
ible during the entire operation.
• Do not weld the winch frame to
the foundation or support struc-
ture. Welding the frame may void
warranty, contact Thern, Inc. Use
fasteners as instructed.

Owner's Manual for Thern Worm Gear Hand Winches page 5
A6112F-0507
Important!
• Use a sheave or roller guide to
direct the wire rope to the drum
whenever possible.
• Install sheaves, tracks and other
equipment so they will remain
fixed under all load conditions.
Follow the recommendations of
the equipment manufacturer.
• Use sheaves of proper diameter to
minimize wear on the wire rope.
Follow the recommendations of
the sheave manufacturer.
1.2 Installing the Breather Plug
Check if a breather plug is installed to vent heat and pressure from the gear-
box. Failure to do so could result in pressure buildup which can cause the
gearbox to leak or damage the equipment. Breather plugs are required for the
PB series. Refer to the parts list for your model.
This winch is shipped sealed with a plug and without lubricant in the gearbox.
1.2.1 INSTALL THE BREATHER PLUG in the proper location. Make sure the
breather plug is above the lubricant level. See figure 1.
1.2.2 CHECK LUBRICANT LEVEL in the gearbox before operating. Refer to
Section 3.2 Lubricating the Winch.
Figure 2 – Maintaining the Fleet Angle
When wire rope travels over a sheave or through a roller guide – maintain fleet
angle by locating the sheave or guide an appropriate distance from the drum,
shown as distance “A”. smooth
drum
1/2 to 1-1/2 degrees
distance “A”
center
line
fixed sheave or
roller guide
When wire rope travels directly to the load – maintain fleet angle by controlling side-
to-side movement of the load with tracks or guide rails. Allowing the load to move
too far to one side causes stress on the drum flange which may cause damage.
1/2 to 1-1/2 degrees center
line
smooth drum
tracks or guide rails
load
Figure 1 – Installing the Breather Plug
breather plug
breather plug
breather plug
floor mount wall mount ceiling mount

Owner's Manual for Thern Worm Gear Hand Winchespage 6
A6112F-0507
1.3 Installing the Handle
1.3.1 FOR MODELS 462, 472, 482 AND 482B, install the handle as follows, see
figure 3.
a INSERT THE HANDLE in the handle socket, adjust handle length to suit
the operation, and tighten the set screw to hold it in place.
b INSERT THE COTTER PIN in the end of the handle and bend the arms
back to secure in place.
1.3.2 FOR MODELS 4622PB AND 4722PB equipped with PB brakes, install the
handle as follows:
a LOOSEN THE THUMBSCREW and slide the handle toward the medallion
as shown. See figure 4A.
b LINE UP THE NOTCH in the handle with the point of the hex in the me-
dallion. See figure 4B.
c SLIDE THE HANDLEAND MEDALLION ASSEMBLY onto the hex
drive on the brake until the flat of the handle lines up with the groove in hex
drive. See figure 4C.
d SLIDE THE HANDLE outward away from the medallion to the desired
length and tighten the thumbscrew. See figure 4D.
Figure 4 – Installing the Handle
4A 4B
4C 4D
slide
thumbscrew
notch
loosen setscrew and slide
handle in direction shown
medallion notch
line up notch with point
of hex in medallion
groove
slide handle assembly
onto hex drive until handle
flat lines up with groove slide
thumbscrew
slide handle out to
desired length and
tighten thumbscrew
loosen
fastener
to adjust
handle
length
Figure 3 – Handle
Adjustment
larger turning radius:
heavier loads,
slower turns
smaller turning radius:
lighter loads,
faster turns
bend arms back
cotter pin

Owner's Manual for Thern Worm Gear Hand Winches page 7
A6112F-0507
1.4 Installing the Wire Rope
Install the wire rope securely to the winch drum.A poorly secured wire rope
could come loose from its anchor and allow the load to escape.
Install the wire rope so it is wound correctly as shown or the winch and brake
will not work properly, and could allow the load to escape, see figures 5 and 6.
1.4.1 PURCHASE THE PROPER WIRE ROPE for your application. Keep the
following in mind when selecting a wire rope. Contact a reputable wire rope
supplier for help.
a BREAKING STRENGTH of new wire rope should be at least 3 times
greater than the largest load placed on the winch. If loads are lifted or pulled
on an incline, the breaking strength must be at least 5 times greater than the
largest load. These are minimum values and will vary with the type of load
and how you are moving it.
b WIRE ROPE LAY must agree with the winding direction of the drum to help
insure proper winding.
c WE RECOMMEND 7 x 19 galvanized aircraft cable for diameters up to
5/16 inch, and 6 x 37 IWRC improved plow steel wire rope for diameters of
3/8 inch and up.
1.4.2 FOR MODELS 462 AND 4622PB anchor the wire rope using the cable
anchor. See figure 5.
a LOOSEN THEANCHOR BOLT and place the wire rope between the drum
flange and the bolt.
b WRAP THE WIRE ROPE around the drum one time, and insert it between
the anchor bolt and the drum, with at least 1/2 inch of rope extending beyond
the anchor bolt.
c TIGHTEN THE ANCHOR BOLT firmly until it flattens the wire rope
against the drum.
Important!
• Use wire rope and other rigging
equipment rated for the size of the
largest load you will be moving.
• Do not drag the wire rope
through dirt or debris that could
cause damage, or poor operation.
• Always wear protective clothing
when handling wire rope.
Figure 5 – Installing the Wire Rope – Models 462 and 4622PB
install wire rope OVERWOUND on
drum as shown or winch and brake
will not operate properly
tighten
anchor bolt
front view drum side view
rotate handle
CLOCKWISE to wind
wire rope onto the drum

Owner's Manual for Thern Worm Gear Hand Winchespage 8
A6112F-0507
1.4.3 FOR MODELS 472, 4722PB, 482 AND 482B anchor the wire rope using
the recessed anchor. See figure 4B.
a PASS THE END OF THE WIRE ROPE through the anchor hole, until at
least 1/2 inch of rope extends out the other side.
b TIGHTEN THE SET SCREW until it flattens the wire rope against the an-
chor hole. Use enough force to drive the point of the set screw securely into
the wire rope.
1.4.4 TURN THE HANDLE CLOCKWISE to wind wire rope onto the drum. If
wire rope unwinds from the drum when the handle is rotated clockwise, the
wire rope is installed incorrectly. Install the wire rope correctly before
continuing. See figure 5 and figure 6.
1.4.5 WIND FOUR FULL WRAPS of wire rope onto the drum by operating the
winch while holding the wire rope taught. These wraps serve as anchor
wraps and must remain on the drum at all times.
UP
Figure 6 – Installing the Wire Rope – Models 472, 4722PB, 482 and 482B
install wire rope OVERWOUND
on drum as shown or winch and
brake will not operate properly
tighten
set screw
front view drum side view
rotate handle
CLOCKWISE to
wind wire rope
onto the drum

Owner's Manual for Thern Worm Gear Hand Winches page 9
A6112F-0507
2.1 General Theory of Operation
2.1.1 THE PULL REQUIRED to move the load must not exceed the load rating of
the winch. 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 USE A DISC BRAKE on all hand winches used to lift loads or pull loads on
an incline. Although a new winch may appear to hold the load in place, this
characteristic will diminish with use. Do not depend on worm gearing to
hold the load in place.
2.1.4 PERFORMANCE RATINGS of the equipment are affected by the amount of
wire rope wound on the drum, the way in which it is wound, and the way the
winch is used.
a DRUM CAPACITY depends on how tightly and evenly the wire rope is
wound on the drum. Actual drum capacities are usually 25-30% less than
values shown in performance tables, due to loose winding and overlapping.
b FORCE REQUIRED TO LIFT the load increases with each additional layer
of wire rope wound onto the drum.
c LOAD RATING represents the maximum pull that can be placed on new
equipment. Load ratings are assigned values for specific amounts of load
travel or wire rope accumulation. The load rating decreases as layers of wire
rope accumulate on the drum.
2.1.5 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, 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
and by maintaining the proper
fleet angle.
• It is your responsibility to detect
and account for different fac-
tors affecting the condition and
performance of the equipment.

Owner's Manual for Thern Worm Gear Hand Winchespage 10
A6112F-0507
2.2 Breaking-In the Winch
2.2.1 BREAK-IN OCCURS during the first few hours of normal operation. Dur-
ing break-in, mating surfaces become polished, and clearances increase. This
is desired for efficient operation of bearings and gears.
2.2.2 INSPECT THE WINCH following break-in according to the Instructions for
Periodic Inspection. See section 3.3 Inspecting the Equipment.
2.3 Preparing for Operation
2.3.1 CONSIDER THE OPERATION. Do not begin until you are sure you can
perform the entire operation without hazard.
2.3.2 INSPECTALL COMPONENTS of the system.
a INSPECT THE WINCH and other equipment according to the Instructions
for Frequent Inspection. Do not operate winch until all defects have been
corrected.
b 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).
c 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.
2.3.3 KNOW YOUR LOAD and make sure you do not exceed the load rating of
the winch or any other equipment in the system.
Important!
• When determining whether the
load will exceed the load rating,
consider the total force required
to move the load.

Owner's Manual for Thern Worm Gear Hand Winches page 11
A6112F-0507
2.4 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.
2.4.1 CLEAR OBJECTS from the path of the load so you can move it freely and
observe it at all times during the operation.
2.4.2 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 7.
b CENTER THE LOAD on the hook so it will remain balanced and not tip or
rotate to one side.
2.5 Moving the Load
2.5.1 MOVE THE LOAD slowly and smoothly, only a small distance at first.
Make sure the load is balanced and securely attached before continuing.
2.5.2 TURN THE HANDLE CLOCKWISE to wind wire rope onto the drum. If
wire rope unwinds from the drum when the handle is rotated clockwise, the
wire rope is installed incorrectly. Install the wire rope correctly before
continuing. See figures 5 and 6.
2.5.3 GRIP THE HANDLE TIGHTLY at all times during operation. If you release
the handle the load may backdrive causing the handle to spin. Do not try to
stop a spinning handle, step clear until the spinning stops.
2.5.4 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.
2.5.5 OBSERVE THE GEARBOX during operation for signs of overheating. Fre-
quent overheating may be a sign of damage, or may indicate the need
for a larger winch.
a WATCH FOR SMOKE, the smell of burnt lubricant, and other signs of over-
heating. Use a thermocouple or other device to monitor gearbox temperature.
b STOPTHE OPERATION if the gearbox overheats, and allow the winch to
cool. Continued operation may cause damage.
Figure 7 – Attaching Load
latch closed
tight against
hook
sling seated in
saddle of hook
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 winch 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.
• Remove the winch handle when
the winch is not in use, to help
avoid unauthorized use.

Owner's Manual for Thern Worm Gear Hand Winchespage 12
A6112F-0507
UP
3.1 Cleaning the Winch
Clean the winch to remove dirt and help prevent rust and corrosion.
3.1.1 CLEAN THE WINCH 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 them against rust
and corrosion.
c WIPE OFF excessive amounts of oil to avoid the accumulation of dirt.
3.1.2 REMOVE ALL UNNECESSARY OBJECTS from the area surrounding the
winch.
Important!
Increase the frequency of mainte-
nance procedures if the winch is:
• Operated for long periods.
• Used to pull heavy loads.
• Operated in wet, dirty, hot, or
cold surroundings.
Figure 8 – Lubricating the Outboard Bearing and Brake
lubricate the disc brake
with 1 to 2 drops of SAE
30 non-detergent oil
front view side view
lubricate the outboard bearing
with 2 to 3 drops of SAE 30
non-detergent oil

Owner's Manual for Thern Worm Gear Hand Winches page 13
A6112F-0507
3.2 Lubricating the Winch
Do not over lubricate the brake bushings. Over lubricating may cause oil to
leak onto the friction discs, which may damage the friction discs or result in
poor operation of the disc brake.
Make sure the breather plug is clean and open to vent heat and pressure.
Poor ventilation may cause overheating and result in equipment damage.
Breather plugs are required for the PB series. Refer to the parts list for your
model.
Fill the gearbox to the proper level without overfilling. Too much or too little
lubricant will cause overheating and result in equipment damage.
The winch is shipped without lubricant in the gearbox. Lubricate the winch
properly to help protect it from wear and rust. Read the following instruc-
tions carefully.
3.2.1 CHANGE GEARBOX OIL after the first 40 hours of operation.
3.2.2 CHECK OIL LEVEL and fill, if needed, before every operation, and every
10 hours during operation. Fill the gearbox through the breather plug hole
until oil reaches the level check plug. Use 90 weight gear oil. See figure 9.
3.2.3 CHANGE GEARBOX OIL every 6 to 12 months, or when it is dirty or otherwise
contaminated. Remove the drain plug to drain oil from the gearbox. See figure 9.
3.2.4 LUBRICATE THE OUTBOARD BEARING at least every 10 hours of
operation. Place 2 to 3 drops of SAE 30 non-detergent oil into the hole in the
bearing housing marked “oil”. Rotate the drum 1/2 turn, and add 2 to 3 more
drops of oil. See figure 8.
3.2.5 LUBRICATE THE DISC BRAKE at least every 6 months. Place 1 or 2 drops
of SAE 30 non-detergent oil into the hole in the brake housing marked “oil”,
and turn the brake several times to allow the oil to penetrate. See figure 8
3.2.6 LUBRICATE THE WIRE ROPE and other equipment by following the
manufacturer’s recommendations.
Important!
• Do not leave plug holes in the
gearbox open. Open plug holes
will allow dirt and moisture to
contaminate the lubrication.
• Make sure lubricant has a tem-
perature rating appropriate for
the ambient temperatures of the
operation.
Figure 9 – Lubricating the Winch
breather plug
breather plug
breather plug
level
check
plug
drain plug drain plug
level
check
plug
drain plug
level
check
plug
floor mount wall mount ceiling mount

Owner's Manual for Thern Worm Gear Hand Winchespage 14
A6112F-0507
3.3 Inspecting the Equipment
Do not use damaged or malfunctioning equipment. Place an “OUT OF ORDER”
sign on the winch. Do not use the winch until the sign is removed by a qualified
maintenance person who has completely corrected the problem.
Inspect the winch to detect signs of damage or poor operation before they
become hazardous. See Table 1 - Inspection Checklist.
3.3.1 CONSULT APPLICABLE CODES AND REGULATIONS for specific rules
on inspecting the winch and other equipment.
3.3.2 CONSULT MANUFACTURER’S RECOMMENDATIONS for
information on inspecting the wire rope and other equipment.
3.3.3 Instructions for Frequent Inspection
a VISUALLY INSPECT the entire winch 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 winch and brake are properly lubricated.
• Check the gearbox for signs of leakage and make sure it is filled with the
proper lubricant.
• Make sure the breather plug is clean, open, and installed properly. See
figure 1.
• Make sure the fastener holding the handle in place is tight. See figure 3 or 4.
• Make sure mounting fasteners are tightened securely.
• Make sure the foundation is in good condition, and capable of supporting
the winch and its load under all load conditions.
b TEST WINCH PERFORMANCE by moving a load equal to the load rating.
• Listen for unusual noises, and look for signs of damage as you operate the
winch.
• 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 handle rotates freely in both directions.
• Make sure the load moves smoothly, without hesitation or strain.
• On models equipped with a brake, make sure the disc brake ratchet pawl
clicks firmly as the brake handle is turned clockwise.
• On models equipped with a brake, 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 conditions, the friction discs may be
worn and in need of replacement. Contact the factory.
Completely correct all problems before continuing. Use the Troubleshooting
Chart to help determine the cause of certain problems. See table 2.
Important!
• Start an inspection program as
soon as you put the winch into
use.
• Appoint a qualified 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.
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 c and figure 10.
• Check the wire rope for reduction
of rope diameter from loss of core
support, or wear of outside wires.
See figure 12.
• 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.

Owner's Manual for Thern Worm Gear Hand Winches page 15
A6112F-0507
3.3.4 Instructions for Periodic Inspection, see table 1.
a VISUALLY INSPECT the winch and all other equipment.
• Disassembly may be required in order to properly inspect individual com-
ponents. Contact factory for assembly/disassembly instructions. Disas-
sembly of the gearbox before contacting Thern, Inc voids all warranties.
• Check the finish for wear, flaking, or other damage.
• Check all equipment, including wire rope, for cracks, dents, bending, rust,
wear, corrosion and other damage. If the equipment was overloaded, or
if you notice cracks or 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 EQUIP-
MENT OR WIRE ROPE.
• Check all fasteners for stripped threads, wear, bending, and other damage.
• Check the foundation for cracks, corrosion, and other damage.
• Check the gearbox for signs of leakage.
• Make sure the breather plug is clean, open and installed correctly.
• Make sure all labels and plates are readable, firmly attached, free of dam-
age and clean. Replacements are available from the factory.
b DRAINA SMALLAMOUNT OF OIL from the gearbox into a clean container.
• Check the oil for dirt, metal particles, water, and other signs of
contamination. Completely drain the gearbox if oil is contaminated.
• Make sure the gearbox is properly lubricated. See 3.2 Lubricating the Winch.
c INSPECT THE WIRE ROPE according to the wire rope manufacturer's rec-
ommendations, 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 10.
• 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, broken,
or otherwise damaged.
• Measure the throat opening, thickness, and twist of the hook. Replace the
hook if it shows signs of damage. See figure 11.
• Make sure hook latch opens without binding and closes when released.
• Check the anchor holes for signs of wear or distortion.
Perform periodic inspections:
• Every 6 months.
• Whenever you return the winch
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 winch.
Figure 10 – 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 11 – 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.

Owner's Manual for Thern Worm Gear Hand Winchespage 16
A6112F-0507
d MOVE THE DRUM with your hands.
• Check for excessive movement indicating worn or loose gears, bearings,
or shafts. Slight end play in the drive shaft is normal. Excessive movement
is caused by overloading or overheating, and is a sign that your application
may require a larger winch.
• Contact factory for assembly/disassembly instructions. Disassembly of
the gearbox before contacting Thern, Inc voids all warranties.
e 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 min-
imum diameter at any point. See figure 12.
f INSPECT THE FOUNDATION AND RIGGING
• Check mounting fasteners for stripped threads, wear, and other damage.
• Check the foundation for cracks, corrosion, and other damage.
g TEST WINCH PERFORMANCE by operating the winch with a load equal
to the load rating.
• Listen for unusual noises, and look for signs of damage as you operate the
winch.
• Make sure the wire rope winds evenly and tightly onto the drum. If it is
loose or uneven, rewind it before continuing.
• Observe the rotating drum, look for signs of loose or misaligned bearings.
• Make sure the handle rotates freely in both directions.
• Make sure the load moves smoothly, without hesitation or strain.
• On models equipped with a brake, make sure the disc brake ratchet pawl
clicks firmly as the brake handle is turned clockwise.
• On models equipped with a brake, 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 friction discs may be worn and in need of replacement.
Completely correct all problems before continuing. Use the troubleshooting
chart to help determine the cause of certain problems. See Table 2.
Figure 12 – Rope Diameter
diameter
incorrect
correct
The wire rope assembly must be
replaced if the diameter measures
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)
3/8 in 11/32 in (.3438 in)
1/2 in 15/32 in (.4688 in)

Owner's Manual for Thern Worm Gear Hand Winches page 17
A6112F-0507
Table 1 – Inspection Checklist
damages problems
general finish weathered, flaking, otherwise damaged winch jerks or hesitates during operation
parts cracked, bent, rusted, worn, otherwise damaged unusual noises, other signs of malfunction
fasteners stripped threads, bent, worn, otherwise damaged loose, not tightened to proper torque
worm gearbox gears, bearings, or shafts loose, worn, otherwise damaged not filled with proper lubricant
oil leakage lubricant contaminated
brake assembly brake corroded, cracked, worn, otherwise damaged brake does not operate properly
drum anchor hole or bolt worn, distorted, otherwise damaged excessive movement or backlash
wire rope bent, crushed, otherwise damaged wire rope loosely or unevenly wound
broken wires, see figure 10
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 12
replace if diameter is excessively worn diameter =
end connections corroded, rusted, worn, otherwise damaged not securely attached
hook or other device twisted, bent, worn, otherwise damaged, see figure 11 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

Owner's Manual for Thern Worm Gear Hand Winchespage 18
A6112F-0507
Table 2 – Troubleshooting Chart
Contact the factory for detailed instructions on re-sealing the gearbox if you are required to disassemble the
gearbox for any reason. Disassembly of the gearbox before contacting Thern, Inc. voids all warranties.
problem cause correction
handle turns, drum doesn’t turn • loose or broken spring pins inspect winch and brake, repair as necessary
• loose, stripped or broken gears or keys inspect gears and repair as necessary
handle turns hard or not at all • winch overheated allow to cool
• load too heavy lighten load
• gearbox contaminated with dirt or debris inspect and relubricate as necessary
• spring pins loose or broken on winch or brake inspect winch and brake, repair as necessary
• disc brake damaged or locked inspect brake, repair as necessary
• gears or keys broken or locked inspect and repair as necessary
• outboard bearing broken or seized inspect and replace as necessary
brake does not operate properly • friction discs worn or damaged inspect and replace as necessary
• friction discs damaged from over lubrication inspect and replace as necessary
• disc brake ratchet pawl damaged inspect and repair as necessary
oil leakage • damaged gasket cement inspect and replace as necessary
• cracked or damaged gearbox inspect and repair as necessary
excessive end play on drive shaft • thrust washer or bearing worn out inspect and replace as necessary
• excessively worn gears inspect and repair as necessary
excessively worn gears or bearings • load too heavy lighten load
(excessive backlash) • poor lubrication of gearbox inspect and relubricate as necessary
overheating • operated too long without rest allow to cool
• load too heavy lighten load
• poor lubrication inspect and lubricate as necessary
• vent plug clogged or damaged clean or replace vent plug as needed
• outboard bearing seized up inspect and replace as necessary
unusual noises
high pitched squeak • poor lubrication inspect and relubricate as necessary
grinding noise • contaminated lubrication clean and relubricate winch
• dirt in brake or winch gears inspect and clean as necessary
• broken gears or outboard bearing inspect and replace as necessary
rattling noise • loose bolts, set screws or other fasteners tighten all bolts and other fasteners
uneven clicking noise in brake • broken gear tooth in brake inspect and repair as necessary
weak clicking noise in brake • spring or ratchet pawl dirty or damaged inspect and clean or repair as necessary
• worn brake ratchet pawl, gear, or spring inspect and replace as necessary
no clicking noise in brake • ratchet incorrectly installed disassemble and install correctly
• ratchet pawl damaged or worn excessively inspect and replace as necessary
heavy thump during operation • contaminants in oil flush gearbox and relubricate the winch
• loose set screws or keys in gears inspect and repair as necessary
• thrust washer or bearing defective inspect and replace as necessary
• outboard bearing defective inspect and replace as necessary

Owner's Manual for Thern Worm Gear Hand Winches page 19
A6112F-0507
3.4 Repairing the Winch
3.4.1 GET FACTORYAUTHORIZATION for all repairs. Unauthorized repairs
will void the warranty, and may lead to damage or failure of the winch.
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
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.
• Replace all spring pins and re-
taining rings when you
disassemble the winch or brake
for repair or inspection.
• During reassembly, use Loctite
598 Ultra Black to create a seal
between the two halves of the
gearbox. Contact the factory for
detailed instructions. Disassembly
of the gearbox before contacting
Thern, Inc voids all warranties.
• Appoint a qualified person to
be responsible for all repairs
to the equipment.

Owner's Manual for Thern Worm Gear Hand Winchespage 20
A6112F-0507
Important!
• Keep a record of what you ship,
and when you send it.
4.1 Transporting the Winch
4.1.1 DRAIN OIL from the gearbox.
4.1.2 REMOVE THE BREATHER PLUG and install a sealed oil plug to prevent
the loss of lubrication during shipment.
4.1.3 PACK THE WINCH in an upright position for transport, using the original
packaging materials, if possible.
aFASTEN THE WINCH to a wooden base using lag bolts, to keep it from
moving during transport.
bSEAL THE WINCH in plastic with a desiccant to help protect it from rust,
corrosion, and other damage.
cCONSTRUCT WOODEN SIDES and top to enclose the winch in a solid
protective crate.
dPACK LOOSE PARTS in small boxes or ship separately.
4.1.4 INSPECT THE WINCH according to Section 3.3 Inspecting the Equipment
before installing it in a new location.
4.2 Storing the Winch
4.2.1 LUBRICATE THE WINCH as necessary, and make sure the breather plug is
clean and properly installed. Add a rust preventative for long term storage.
4.2.2 SEAL THE WINCH in plastic with a desiccant to help protect it from rust,
corrosion, and other damage.
4.2.3 STORE THE WINCH upright, in a cool clean place away from corrosive
chemicals and moisture.
4.2.4 ROTATE THE DRUM periodically to keep bearing and gears surfaces from
becoming lacquered.
4.2.5 INSPECT THE WINCH according to Section 3.3 Inspecting the Equipment
before installing it in a new location.
4.2.6 LUBRICATE THE WINCH PROPERLY prior to operation. See section 3.2
Lubricating the Winch.