Doosan D50S-5 Operation & Maintenance Manual page 134

A fork failure during use can cause damage to the A fork failure during use can cause damage to the
equipment and the load. A fork failure can also equipment and the load. A fork failure can also
cause serious injury. cause serious injury.
A good fork inspection and maintenance program A good fork inspection and maintenance program
along with the proper application can be very along with the proper application can be very
effective in preventing sudden failures on the job. effective in preventing sudden failures on the job.
Repairs and modifications should be done only by Repairs and modifications should be done only by
the fork manufacturer or a qualified technician who the fork manufacturer or a qualified technician who
knows the material used and the required welding knows the material used and the required welding
and heat treatment process. and heat treatment process.
Users should evaluate the economics of returning Users should evaluate the economics of returning
the forks to the manufacturer for repairs or the forks to the manufacturer for repairs or
purchasing new forks. This will vary depending on purchasing new forks. This will vary depending on
many factors including the size and type of fork. many factors including the size and type of fork.
Forks should be properly sized to the weight and Forks should be properly sized to the weight and
length of the loads, and to the size of the machine length of the loads, and to the size of the machine
on which they are used. The general practice is to on which they are used. The general practice is to
use a fork size such that the combined rated use a fork size such that the combined rated
capacity of the number of forks used is equal to or capacity of the number of forks used is equal to or
greater greater than the than the "Standard(or
the lift truck. the lift truck.
The individual load rating, in most cases, will be The individual load rating, in most cases, will be
stamped on the fork in a readily visible area. This is stamped on the fork in a readily visible area. This is
generally on the top or side of the fork shank. generally on the top or side of the
A fork rated at 1500 pounds at 24 inch load A fork rated at 1500 pounds at 24 inch load
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center will be stamped 1500X24. center will be stamped 1500X24.
A fork rated at 2000 kg a A fork rated at 2000 kg at 600 mm load center
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will be stamped 2000X600. will be stamped 2000X600.
The manufacturer identification and year and date of The manufacturer identification and year and date of
manufacture is also usually shown. manufacture is also usually shown.
Some countries have standards or regulations which Some countries have standards or regulations which
apply specifically to the inspection and repair of apply specifically to the inspection and repair of
forks. forks.
Maintenance Section Maintenance Section
Causes of Fork Failure Causes of Fork Failure
Improper Modification or Repair Improper Modification or Repair
Fork failure can occur as a result of a field Fork failure can occur as a result of a field
modification involving welding, flame cutting or other modification involving welding, flame cutting or other
similar processes which affect the heat treatment similar processes which affect the heat treatment
and reduces the strength of the fork. and reduces the strength of the
In most cases, specific processes and techniques In most cases, specific processes and techniques
are also required to achieve proper welding of the are also required to achieve proper welding of the
particular alloy steels involved. Critical areas most particular alloy steels involved. Critical areas most
likely to be affected by improper processing are the likely to be affected by improper processing are the
heel section, the mounting components and the fork heel section, the mounting components and the fork
"Standard(or rated) rated) Capacity" Capacity" of of
fork shank.
t 600 mm load center
fork.
Register 1910.178 Powered Industrial Truck, and Register 1910.178 Powered Industrial Truck, and
ANSI/ASME Safety Standard(s) B56.1, B56.5 or ANSI/ASME Safety Standard(s) B56.1, B56.5 or
B56.6 as applicable to the type of machine(s) in use. B56.6 as applicable to the type of machine(s) in use.
Environment Protection Environment Protection
When servicing this lift truck, use an authorized When servicing this lift truck, use an authorized
servicing area and an approved container to collect servicing area and an approved container to collect
coolant, oil, fuel, grease, electrolyte and any other coolant, oil, fuel, grease, electrolyte and any other
potential environmental pollutant before any lines, potential environmental pollutant before any lines,
fittings or related items are disconnected or removed. fittings or related items are disconnected or removed.
After servicing, dispose of those materials in an After servicing, dispose of those materials in an
authorized place and container. When cleaning the authorized place and container. When cleaning the
lift truck, be sure to use an authorized area. a. lift truck, be sure to use an authorized are
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Wear Wear
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Forks are constantly subjected to abrasion as Forks are constantly subjected to abrasion as
they slide on floors and loads. The thickness of they slide on floors and loads. The thickness of
the fork blade is gradually reduced to the point the fork blade is gradually reduced to the point
where it may not be capable of handling the where it may not be capable of handling the
load for which it was designed. load for which it was designed.
Stress Risers Stress Risers
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Scratches, nicks and corrosion are points of Scratches, nicks and corrosion are points of
high stress concentration where cracks can high stress concentration where cracks can
develop. These cracks can progress under develop. These cracks can progress under
repetitive loading in a typical mode of fatigue repetitive loading in a typical mode of fatigue
failure. failure.