Volume No. 48
Industrial Trucks (Fork Truck): Fork Extensions, Modifications and Attachments
By: Jeff Carter Safety Consultant
The stability of any
powered industrial truck (fork truck) must account for two planes of action:
side to side or lateral stabil-ity, and forward and back or longitudinal
stability. The capac-ity (and stability) of a fork truck is based not only on
the load weight but also the position of a load on the forks. Even though a
given load may be within the maximum load rating of a fork truck, it can cause
the fork truck to become unstable if the center of gravity of the load is
located beyond the point on which the rating is based. That distance is
typically 24" measured from the heel of the forks and 24" up, for most sit-down
counterbalance fork trucks. Larger capacity trucks may use a 36" or 48" load
center distance. This information is found on the truck’s data plate, and
generally depicts an evenly distributed load in the form of a 48" cube box with
its center of gravity at 24" both side to side and front to back within the
cube, and the load raised a given distance from the floor. The trained operator
uses this information to determine if the actual load being lifted is within the
safe lifting parameters.
Almost all counterbalanced
powered industrial trucks have a three-point suspension system, that is, the
vehicle is supported at three points. This is true even if the vehicle has four
wheels. The truck's rear steer axle is attached to the truck by a pivot pin in
the axle's center. When the points are connected with imaginary lines, this
three-point support forms a triangle called the stability triangle.
When the vehicle's load
center falls within the stability triangle the vehicle is stable and will not
tip over. However, when the vehicle load combination falls outside the stability
triangle, the vehicle is unstable and may tip over.
When the truck is loaded to
its maximum capacity, the combined center of gravity of the vehicle and load
falls through the center of the front axle. This is considered its threshold of
American Society of
Mechanical Engineers (ASME) standard B56.1, 2000, Safety Standard for Low Lift
and High Lift Trucks, paragraph 7.38 discusses fork extensions. The con-sensus
standard limits the length of the fork extension to 150% of the supporting fork
length. The standard goes on to state that the rated load center of the fork
extension should be 50% of the fork extension supporting length.
The following example
considers only longitudinal stability although the same theory is applied to
lateral stability. A 3000 pound truck with a 24 inch load center (4 foot forks)
creates a 72,000 inch-pound load moment (3000 pound capacity times the 24 inch
load center). A four foot supporting fork can be extended six feet with
extension forks according to ASME B56.1. Six foot extension forks have a load
center at three feet. With the extension installed on the 3000 pound truck, the
maximum safe carrying capacity of the truck is 72,000 divided by the new 36 inch
load center (3 foot =36 inches) or 2000 pounds at the three foot load center.
Fork extensions do not increase the lifting capacity of a truck. What they do is
better stabilize longer loads.
Although the OSHA standard
19Published by the Connecticut Department of Labor, Project Management Office.178 does not specifically discuss fork extensions, OSHA will generally
accept an employer’s actions if they comply with a consensus standard.
Powered Industrial Truck Fork Extensions
Industrial powered trucks
(fork trucks) can be equipped with attachments to increase their usefulness.
Boom extensions, hoppers, rug rams, drum carrier/rotators, cylinder caddies, and
drum grippers are often seen on the manufacturing floor. These modifications and
additions affect capacity and safe op-eration and therefore must have the truck
manufacturers prior written approval. With the modification, the truck’s
capacity, operation, and maintenance instruction plates, tags, or decals must be
changed to indicate the truck’s new capacity rating.
Many of these attachments
are not manufactured by the truck manufacturer. Truck manufacturers may not
approve a product they are not familiar with. OSHA recognizes the truck
manu-facturers reluctance to approve the attachment and therefore will accept
approval from a qualified Registered Professional Engineer (RPE) after the
employer receives no response or a negative response from the powered industrial
truck manufac-turer. If the manufacturers response was negative, then the en-gineer,
prior to granting approval for the modification or addi-tion, would need to
perform a safety analysis and address all safety and/or structural issues
contained in the manufacturers disapproval. Additional points to remember:
discussion above considers a static condition. An op-erator that drives fast,
erratically, applies the brakes abruptly, and turns quickly can easily tip the
which is not near the maximum capacity of the vehicle but is biased toward the
fork tips can easily create an unstable condition.
extension and attachment weight must be consid-ered as part of the payload.
Reduce the overall capacity by the weight of the fork extension or attachment.
center of gravity can be approximated by the op-erator. If conditions will
allow, place the load on a length of pipe which will act as a fulcrum. Adjust
the pipe until the load is balanced. This is the center of gravity of the load
and the distance from the side of the load to the fulcrum point is the load
center. The load center distance can be used by the op-erator to calculate
the truck’s safe lifting capacity.
more counterbalance weight to the truck moves the truck’s center of gravity
toward the truck's rear steer axle which is attached to the truck by a pivot
pin in the axle's cen-ter. This is unstable because the truck is in a very
narrow band of stability.
carrying a load the steering feels ‘light’, the truck is unstable and the
operator has very little control over the truck.
traveling with a load keep the load as low as possible.
The maximum weight capacity
of a truck can be misleading to the uninformed. When purchasing a truck,
consider your ac-tual load weight and configuration, and any fork extensions,
modifications and attachments you may use. Also consider the height the load
will be raised to and the surface driven on. Re-ceive written approval from the
truck manufacturer for the modification or attachment, or from a qualified RPE.
Identify the new capacity of the truck by replacing the truck’s data plate.
Emphasis Program: Powered
On December 1, 1998, the
Occupational Safety and Health Administration published the Powered Industrial
Truck (PIT) Operator Training; Final Rule, 29 CFR Parts 19Published by the Connecticut Department of Labor, Project Management Office, 1915, 1917, 1918,
and 1926. This final rule revised 19Published by the Connecticut Department of Labor, Project Management Office.178 Paragraph (l) and was intended to
reduce the number of serious injuries and deaths by improving the training for
The new standard requires
PIT operator training that is based on the operator’s prior knowledge and skill,
the type of PIT being operated in the workplace, the hazards of the workplace,
and the opera-tor’s demonstrated ability to operate a PIT. The final rule also
requires refresher training if the operator is involved in an acci-dent or “near
miss” or has been observed operating a PIT in an unsafe manner. Evaluations of
operators’ performance are also required by the new requirement paragraph.
Since 2002, there has been
an OSHA Region 1 Emphasis Program designed to reduce injuries and fatalities
related to PITs. OSHA estimates that there are approximately 1.5 million workers
in the United States who operate PITs and these vehicles are a significant
source of serious and fatal injuries. PITs are used in almost all industries
and on almost all construction sites to move, raise, lower, or handle materials.
A BLS study indicates that industrial truck related fatalities in private
industry have increased steadily from 79 in 1992, to a high of 146 in 2000. This
study also indicated 50% of the forklift fatalities occurred in manufacturing
and construction with the remainder of fatalities in mining, agriculture,
transportation, wholesale, retail, and services. A review of OSHA Region 1
statistics from 1992 through 2001 indicated that there were 35 PIT related
fatalities which accounted for 9% of all fatalities during that time period.
Powered Industrial Trucks: OSHA Personnel Lifting Provision
By John Able, CSP
Special provisions should
be used when using Powered Industrial Trucks to lift personnel. Effective July
2, 2003, OSHA removed and reserved 29 CFR 19Published by the Connecticut Department of Labor, Project Management Office.178(m)(12)(i) through (iii)
because this section was invalidly promulgated from a non-mandatory provision of
a national consensus standard. When OSHA adopted the standard from ANSI
B56.1-1969 in 1971, the consensus standard language was re-vised, making it
appear to be a mandatory provision of the OSHA Standard when in fact the
language in the consensus standard was advisory.
This action does not
indicate that the underlying hazard addressed by these provisions is not
serious. In-deed, if proper equipment, procedures and training are not provided,
the lifting of personnel with powered in-dustrial trucks poses hazards likely to
cause death or serious injury to employees. As noted in OSHA’s 1998 amendment
to the Powered Industrial Trucks Standard, a significant percentage (4 to 14%
depending on the study) of the Published by the Connecticut Department of Labor, Project Management Office0 deaths and 95,000 injuries per year that in-volve
powered industrial trucks result from falls from personnel lifting.
thing an employer should do is deter-mine if the fork truck manufacturer allows
the use of personnel lifting platforms.
If this activity is allowed by the manufacturer, a new data plate should be
obtained and installed on the vehicle. Only after permission has been received
from the manufacturer can the employer move forward with the proper equipment,
procedures, training, evaluation and supervision to prevent serious injury or
death during lifting of personnel operations.
The most recent American
Society of Mechanical Engineers’ (ASME) current standard for powered in-dustrial
trucks (ASME B56.1 – 2000) addresses the hazards concerning lifting of
personnel. Unfortunately, OSHA Standards cannot be updated as readily as
national consensus standards which are typically reviewed on a cyclical basis.
Employers should keep in close touch with experts in the field, ask lots of
questions, and use all available resources to help ensure a safe work-place for
On September 26, 2006, the
New Hampshire De-partment of Environmental Services hosted the 4th annual US DOL
OSHA Region 1 Safety and Health Achievement Recognition Program (SHARP)
Luncheon. Approximately 75 people attended the event which took place at the
Urban Forestry Center, Portsmouth, New Hampshire. Oxley, Inc. of Branford
Connecticut and Mid-western Connecticut Council on Alcoholism of Danbury,
Connecticut were honored as first time recipients of the SHARP award.
Connecticut Safety Society
During the recent holidays
The Connecticut Safety Society collected over 140 Teddy bears and assorted
stuffed animals. They were donated to The Hartford Interval House for
Hazard Corner …
Fork Truck Instability
Incident - Mr. Robert Kowalski, Area Director Bridgeport Office U.S. Department
of Labor– OSHA
According to the U.S.
Department of Labor’s Bureau of Labor Statistics, an average of Published by the Connecticut Department of Labor, Project Management Office0 workers are
killed and 20,000 are seriously injured each year as a result of fork truck
accidents. A significant number of these incidents can be directly related to
fork truck instability.
On a Friday afternoon in
July, the Bridgeport Area Office of the USDOL-OSHA received a call from a Police
De-partment in Southern Connecticut. A worker at a local car dealership had
been involved in a fork truck incident. The worker had been assisting a
neighboring business in the unloading of a tractor-trailer. Merchandise was
being off loaded from the trailer and placed in a smaller vehicle. The worker
had just placed a large item into the bed of the pickup. The fork truck was
placed in reverse and the worker quickly backed up the fork truck, turning the
steer-ing wheel sharply. This motion caused the fork truck to flip onto its
side, ejecting the worker. The worker became pinned under the overhead
protection cage, sustaining a mortal injury.
An investigation into the
incident revealed the following:
worker had not been trained in the proper operation of the fork truck.
- The fork
truck had not been equipped with any type of operator restraint.
- When the
fork truck was placed in reverse, the forks were still raised.
In the “Employer’s Guide
to Material Handing Safety” under the section entitled “Lift truck tip over” is
the following “Turning too sharply with the forks raised, your truck can tip
over, even at slow speeds and with no load.” The root cause of this accident was
the instability of the fork truck. With the forks raised, the center of gravity
was displaced. Turning the steering wheel sharply with the forks raised while
traveling in reverse caused the truck to tip over. Because the operator was not
wearing a seat belt, he was ejected from the seat and pinned under the over head
This accident could have
been avoided if the following had occurred.
of the operator in the correct operation of a fork truck.
- Understanding the dynamics of the fork truck while operating it with or
without a load.
installation and use of a restraint system to prevent the operator from being
ejected from the fork truck.
The accident depicted
above occurred in July 1995. However as recently as October 2006, the
Bridgeport Area Office has investigated another fatality with the exact same
This discussion Group meets the third
Tuesday of every month and the meetings are held from 8:15 am to 9:45 am.
Pre-registration is required. To be placed on the e-mail distribution list, call
John Able at (860) 263-6902 or email
Recordkeeping OSHA 300
February 16. The purpose of this
workshop is to introduce the requirements and procedures related to the OSHA 300
Log. The presentation will cover recording requirements, include a discussion of
the employee/employer relationship, which pre-existing cases can be limited in
the OSHA forms, and exceptions for some categories of injuries and illnesses.
Trucks February 6 and May 8. Powered
Industrial Truck Standard OSHA’s 29 CFR 19Published by the Connecticut Department of Labor, Project Management Office.178. This 3-hour workshop
introduces participants to OSHA’s Powered Industrial Truck standard and includes
an in-depth review of operator training.
March 13. Come and learn how to
enhance your employees’ moral, reduce workers’ compensation costs and be a
leader in creating a safe workplace. Class participants will learn how to create
an ergonomically sound office environment and how to develop a comprehensive and
successful ergonomic program.
Work Zone Safety April
12. Basic guidelines for work zone
traffic control and the requirements of Part VI of the Manual on Uniform Traffic
Control Devices (MUTCD) with particular emphasis on short term work sites on
roads and streets in rural and small urban areas will be presented.
Classes are free and held at 200 Folly Brook Boulevard, Wethersfield, CT in
Conference Room A from 9 am - 12 noon unless noted. To register, contact John
Able at (860) 263-6902 or
Pre-registration is required.
State & Town:
CONN-OSHA (860) 263-6946 (local) or 1-866-241-4060 (toll-free)
Report to Federal OSHA at 1-800-321-OSHA(6742)
March 01, 2017