Proper Torque Wrench
Use and Maintenance
A torque wrench is a precision instrument
designed to apply a specific amount of force to
a fastener. Whether tightening head bolts
on an automobile engine, lugs for tire and rim
installation or inspecting fastener tolerances
on high-performance equipment, it is extremely
important that proper care is used.
Guidelines are typically provided noting
acceptable torque ranges, the order in which
specific fasteners are tightened and the number
of times a fastener must be tightened and
loosened to ensure uniform torque application.
Failure to properly torque fasteners can lead to
equipment damage, personal injury or worse.
It is important to follow acceptable
maintenance and use practices, such as:
- Safety glasses or goggles should be worn at
all times when using any hand tool.
- Always follow the manufacturer’s directions
regarding torque direction, proper force, torque
pattern/sequence, use or non-use of lubrication
on fasteners and torque “tighten/release”
- Do not exceed the recommended working range of
the torque wrench. Reliable measurements
are based on a percentage of the working range.
In general, most mechanical wrenches have a
useable range from 20% to 100% of full scale.
Most electronic wrenches have a useable range
from 10% to 100% of full scale.
- Do not use accessories or handle extensions
unless specifically allowed by the torque wrench
- Take time to inspect the tool and check for worn
or cracked sockets. Properly lubricate and
replace worn parts.
- Avoid dropping or sliding a torque wrench.
Dropping a torque wrench on a hard surface can
cause the instrument to lose reliable
calibration. If you suspect that a wrench
has been dropped, have the tool inspected by the
manufacturer or reputable calibration service.
- Always store a torque wrench in a
protective case and/or location when not in
- Avoid exposure to temperature extremes,
high humidity, fluid immersion and corrosive
- If using a click-type torque wrench, always
store it at the lowest level on the scale.
- Avoid marking, etching or placing labels on
- Use a torque wrench to apply a specific torque
value during the final assembly process.
Do not use a torque wrench as the primary means
of tightening or loosening fasteners.
- As most torque wrenches are length
specific, always grasp the torque wrench in
the center of the handle. If two hands need
to be used, place one hand on top of the
- Apply torque in a slow, methodical manner and
avoid sudden, “jerking” movements.
- When the wrench signals (by clicking,
beeping or lights) that a specific torque
has been reached, stop pulling immediately.
- After 5000 cycles or up to one year of use,
whichever comes first, have your torque wrench
inspected and recalibrated by the manufacturer
or reputable calibration service.
With proper care, a high-quality torque
wrench should provide accurate measurements for
About Snap-on Tools
Snap-on Tools Company, LLC is a leading global
innovator, manufacturer and marketer of tools,
diagnostics and equipment solutions for
professional users. Product lines include hand
and power tools, tool storage, diagnostics
software, information and management systems,
shop equipment and other solutions which are
used by technicians and professionals at vehicle
dealerships and repair centers and in the
marine, powersports and aviation industries.
Snap-on is one of the largest non-food franchise
companies in the world, selling its products
through more than 4,000 franchisees worldwide
and through company-direct sales and over the
Internet. Snap-on Tools is a subsidiary of
Snap-on Incorporated, which was founded in 1920
and is a $2.8 billion, S&P 500 company
headquartered in Kenosha, Wis. For additional
information on Snap-on, visit