Inspection
Measure and assess fork wear
The 90 % cross-section rule at the fork heel
The forks carry the whole load, and they wear most at the fork heel. A fork must not be worn thinner than 90 % of its original cross-section at the heel — because load capacity falls with the square of the thickness, so a loss of just 10 % corresponds to approx. 20 % less capacity. Here is how you measure and document the wear.
Find the original wall thickness
Read or measure the fork's original blade thickness. It can typically be measured on the vertical part of the fork (the shank), which does not wear in operation, or it is shown on the fork's data sheet/marking. This is the reference figure you compare the wear against.
Measure the material thickness at the fork heel
Measure the material thickness with a calliper exactly at the bend between the vertical shank and the horizontal blade — the fork heel. This is where the moment, and therefore the wear, is greatest. Measure on both forks; they may be worn differently.
Calculate the remaining cross-section percentage
Remaining percentage = current thickness at the heel divided by the original thickness, multiplied by 100. Example: a fork with an original thickness of 50 mm that is worn to 46 mm has 46/50 = 92 % left — just above the limit. At 45 mm it is down to 90 % and must be scrapped.
Rejection limitbelow 90 % cross-sectionExample50 mm → limit at 45 mmUnderstand why the limit is so strict
The section modulus of the fork heel is rectangular (Z = b·t²/6), so the load capacity is proportional to the square of the thickness. A thickness loss of 10 % therefore gives approx. 20 % loss in load capacity (0.9² ≈ 0.81). That is why the 90 % limit is a hard rejection limit, not a guideline figure.
The cross-section only measures the remaining material — the real load-bearing capacity has dropped even more.
Also check for cracks, deformation and locking
In addition to thickness: look for cracks (especially at the heel and at the hooks), permanent deformation/bending and differences in the height of the fork tips. Check that the forks' locking pins are engaged so the forks cannot slide sideways on the carriage.
Check fork extensions separately
If fork extensions are fitted, they may be no more than 50 % longer than the original forks and must be securely locked. They must also be CE-marked and included in the truck's load chart for the combination — an extension that is too long moves the load centre far forward and eats heavily into the residual capacity.
Max. length+50 % of the originalDocument the result and act on findings
Record the measurement in the inspection log. If wear below 90 % cross-section, cracks or other damage is found, the truck is taken out of service immediately — it must not be used until the forks have been replaced or approved by a competent person. Fork wear is also part of the statutory main inspection every 12 months.
Source
Based on BFA Industri »Trucks« (Oct. 2023), p. 23, and ISO 5057:2022 »Industrial trucks — Inspection and repair of fork arms«.