Are your forks safe?
A 10% reduction in fork blade thickness results in a 20% reduction of capacity. This must be measured between the heel of the fork and where the fork begins to tapper down to the tip. For example, a 5,000-lb capacity forklift with properly specified forks capacity has been reduced to only handling 4,000-lbs. At this 10% reduction in blade thickness ANSI/ITSDF B56.1 and B56.6 Safety Standards require the forks to be replaced immediately. If you find this to be true, you should tag out your forklift and keep it out of service until the forks have been replaced. You may ask yourself what causes these heavy-duty steel forks to wear. Generally, driving while the forks are in touch with the concrete floor due to mast angle or mast chain elongation creates a grinding effect much like sharpening a knife with a grinding stone.
Many other factors contribute to blade wear and must be inspected. OSHA requires fork inspections to be performed by a qualified agent. If you do not have the training and competence to examine the fork blades, you may choose to have a forklift dealer perform preventive maintenance regularly on your truck. Part of their inspection will include an examination of the forks as well as many other safety concerns. Outsourcing this maintenance will, also, satisfy OSHA’s requirement to document fork inspections. Generally, preventive maintenance is performed several times each year. The frequency is determined by the model of forklift and hours of usage. The fork inspections must be completed at least once a year.
Other factors contributing to blade wear include: 1) Surface cracks caused by metal fatigue in the steel, 2) A 3% deviation in fork angle exceeds allowable safety standards. You may notice this in both forks and this may have been caused by lifting loads heavier than the combined fork capacity or by lifting heavy loads out at the tips of the forks. Traveling in this condition accelerates the effect. You may notice only one bent fork and this often is caused by using a lifting chain around one fork to lift heavy objects or by putting one fork under a heavy load and trying to lift the forks. One bent fork, also, increases the difficulty of entering pallets, 3) Shaft mounted forks must be examined for unacceptable wear to the collar or hook of the fork, 4) If your forks are designed to be equipped with locking pins and these pins are missing or defective in some way, your forks may not need to be scrapped, but the truck should be kept out of service until properly functioning locking pins are installed. These pins lock the fork to the carriage and prevent the forks from sliding off the carriage, 5) You must remove fork from service if blade or shank straightness is in excess of 0.5% of corresponding blade length or shank height, and 6) Check the angle between the upper face of blade (A) and the front face of shank (B). Remove the fork from service if angle (C) exceeds 93 degrees.
You, also, need to inspect forks for capacity stamped on the side of the forks. This must always be visible.
Here are some factors that will result in forks becoming worn or damaged:
- Forks can be overloaded either by picking up a load too far out on the forks, or simply by picking up loads heavier than truck rating.
- Maintenance shops may unadvisedly bend forks back into shape, weld on them, or drill a hole through them. Lift truck users can add attachments to the truck that stress the forks. Drum clamps and portable booms can be supported on the forks – but what is contained in the drum or on the boom hook makes the safety difference.
- Any attempt to straighten forks must be done by a qualified metallurgist in accordance with the ANSI/ITSDF standard. This requires forks to be heat treated and load tested. This is rarely done as it is often more financially responsible to simply replace bent forks.
- Note: unrepairable forks must be cut in half at the heel area.
- Forks are often used to open rail car doors and break loads out or away from other loads. They are, also, used to pick up capacity loads not seated against the fork shank and to pick up off-balanced loads far to the side of the truck. The fork tips are sometimes inserted under other fork trucks to lift them during maintenance operations.
- Anytime excessive heat is applied to any part of a fork – during repair, for instance – hidden damage may occur. This damage is often not visible to the naked eye. Magnafluxing can be used to determine if the metal of the fork has been compromised. This testing is best applied to trying to determine application effects on forks rather than an attempt to return one pair of forks into service due to the cost of testing.
In summary, have your forks inspected at least once a year by a qualified service technician. As there are many other safety inspections required on your forklift outsourcing these inspections to your servicing forklift dealer as part of regular periodic maintenance is a good way to document these inspections and keep your plant safe by minimizing the dangers of using damaged forks in your operations.
If you need to replace forks that have been damaged or worn, contact your nearby forklift dealer. Here are some part numbers for some popular fork sizes to get you started.
|Hyster Part #||Carriage Class||Size in inches||Taper|