Text from the OSHA Logging PreambleSection
IV: Major Issues
A. Introduction
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6. Chain-saw protective devices. In the proposed standard,
OSHA did not include a provision requiring chain saws to be equipped with chain brakes or
other devices that prevent kickback. The proposed standard also did not require chain saws
to meet any performance criteria of any standards-setting organizations. Rather, OSHA
proposed only to require employers to inspect and maintain chain-saw safety devices when
chain saws were so equipped. The hearing notice requested further comment on the adequacy
of various chain-saw safety devices and what regulatory action OSHA should take in the
final standard regarding chain saws.
There was no dispute among commenters that chain-saw protective devices are necessary
to prevent operators from being injured. The record shows that the chain-saw bar can kick
back in less than 0.3 seconds (Ex. 4-172). The record also shows that average human
reaction time, however, is only 0.75 seconds (Ex. 4-172). That means in many cases the
operator cannot take action quickly enough to avoid being struck by the chain saw. The
record also shows that many injuries in the logging industry are the result of chain-saw
kickback. According to the WIR survey, 20 percent of all logging injuries reported
involved chain saws and almost two-thirds of those injuries were the result of chain-saw
kickback (Ex. 2-1). The Maine BLS survey also shows that chain-saw injuries account for a
significant number of logging injuries (26%) in that State (Ex. 4-175). Similar to the WIR
survey, the Maine BLS survey indicated that over half of all chain-saw accidents resulted
from kickback.
a. Devices to prevent chain-saw kickback. Information
submitted to the docket indicates that there are four devices that exist to reduce or
minimize the risk of injury due to chain-saw kickback. These devices are chain brakes, bar
tip guards, reduced-kickback guide bars, and low- or reduced-kickback saw chains.
Information about these devices was taken from a 1983 report prepared for the Consumer
Product Safety Commission (CPSC) (Ex. 5-13) as well as comments to the proposed rule. The
discussion that follows explains the different devices and their advantages and
disadvantages.
The "chain brake" is a device for stopping the saw chain when kickback occurs
before the chain can contact the operator. The most common type of chain brake is actuated
when the operator's hand or arm hits the brake lever that is located immediately ahead of
the front handle. When kickback occurs, the chain brake may either be actuated by the
operator's hand pivoting forward on the handle, or by the hand being dislodged from the
handle, striking the brake lever. According to the CPSC report, chain brakes, unlike new
technology chains and safety guide bars, do not have any adverse effect on the cutting
effectiveness of chain saws. The record also indicates that one of the advantages of chain
brakes is that, unlike other protective devices that can be removed, the chain brake is an
integral part of the saw and is difficult to remove (Ex. 4-174). As such, chain brakes
deter the disabling of the kickback prevention system by the operator (Ex. 5-19).
The "bar tip guard" (or nose tip guard) is a device that is bolted or screwed
onto the tip of the bar. Its primary function is to prevent contact with the tip of the
bar from which kickback is generated. Commenters identified three problems with bar tip
guards. First, one commenter said bar tip guards are not usable in felling and bucking of
some trees (Ex. 9-16). This commenter said forward leaning trees usually require the bar
tip to fell the tree safely.
Second, two commenters said the hazards associated with bar tip guards outweigh their
protective value (Ex. 5-42, 9-20). According to NIOSH bar tip guards reduce kickback
danger only under certain conditions, that is, when the log or limb is elevated and does
not have any off-angle to cause pinching of the bar (Ex. 5-42). NIOSH concluded that the
bar tip guard may pose greater hazards than saws without tips because they require the
bucker to maintain working stances that are less stable. The other commenter said that the
bar tip can get caught on limbs. Third, the major problem with bar tip guards is that they
are removable (Ex. 5-13, 5-13H). According to the CPSC report, the bar tip guard is
removed by operators because it reduces the utility of the saw by preventing boring and
the cutting of any logs that are wider than the guide bar. Evidence in the record
indicates that bar tip guards are being removed by a significant number of operators:
Only about half of the operators of saws so equipped always use such guards. About 36
percent never use them, and about 12 percent sometimes take them off the guide bar. Thus,
while nose tip guards are effective anti-kickback devices, many operators remove them from
their saws (Ex. 5-13).
The Portable Power Equipment Manufacturers Association (PPEMA) submitted testimony from
CPSC's own proceedings, which also acknowledged the extent to which bar tip guards are
removed from chain saws:
[T]he Commission received the benefit of a survey that was done on the part of the
NESDA, National Equipment Servicing Dealers Association. They on their own surveyed
hundreds of their dealers.
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[T]heir survey corroborated my own personal observations, namely, that in real life
practice users of chain saws in the droves are simply not using that nose tip, and while
if it were used or if it were permanently established on the saw, it would be a complete
barrier to kickback, the fact of the matter is because it's temporary and because it is
removed, because in my view it affects in the case of the dealers, as you'll see from
their comments, it affects the efficacy of the saw, it is taken off, and as a result
provides no protection, zero.
Just to cite from the survey, 73.5 percent of the responding dealers to the NESDA
survey reported that only zero to five percent of the chain saws brought into their shops
for repair, of the ones that were originally equipped with the nose guards, that 73.5
percent of the dealers responded that only zero to five percent had nose guards in place.
Another 9.3 percent reported that six to ten percent of such saws had nose guards in
place, leaving only 17.1 percent of the dealers who put the figure of nose guards in place
at something more than ten percent.
The unmistakable conclusion is that the overwhelming majority of consumers are removing
the nose guards from their saws and not putting them on in the first place.
The survey also revealed that almost no consumers are interested in replacing nose
guards that are not in place. Eighty-eight percent of the dealers, 88 percent, stated that
zero percent of their customers wanted replacements, and an additional 8.9 percent put the
replacement request at a mere one to five percent (Ex. 5-13H).
There are two different types of "reduced-kickback guide bars". One is
designed and manufactured with a taper from the back of the bar and has a correspondingly
small radius of curvature at the tip of the bar. This type of bar is commonly referred to
as a narrow nose bar. The other type of reduced kickback guide bar has a reduced radius
nose but achieves its taper from the fact that the top and bottom edges of the bar a
asymmetrical (the top and bottom edges are curved and have a different radius of
curvature). This type bar is commonly called a banana bar because of its peculiar shape.
According to the CPSC report, both the narrow nose bar and the banana bar have significant
drawbacks, primarily in the useful life of the bar and chain and the efficiency of the
chain saw. The narrow nose bar, because of its reduced radius of curvature at the tip,
receives more stress at the tip, thereby requiring more frequent replacement. Because of
its asymmetrical design, the banana bar cannot be merely turned over when the bottom edge
of the bar becomes worn, but must be replaced. This type of bar also reduces the ability
of the operator to use the saw for boring. This disadvantage is compounded if the saw also
is equipped with a low- or reduced-kickback chain.
[T]he use of low-kickback guide bars results in a tradeoff of some reduction in utility
for an improvement in safety. Industry sources have suggested that this may be an
acceptable tradeoff for the less powerful saws which are probably purchased by consumers.
Since the tradeoff involves a marginal improvement in safety, however, manufacturers are
probably less willing to equip the more powerful, more performance oriented saws with the
low-kickback guide bars (Ex. 5-13).
Finally, the potential for kickback can be reduced by the "low- or
reduced-kickback chain". This chain is commonly referred to as new generation chain.
Low kickback chain can be identified by an idler or spacer link between each of the
cutting links. In other words, the chain has a left hand cutter link on the right side of
the chain, followed by a spacer link, followed by a right hand cutter link on the left
side of the chain followed by another spacer link before the sequence begins again.
Although the low-kickback chain can reduce kickback energy by 40 to 90 percent, there
are drawbacks to its use, according to the CPSC report. These drawbacks include: (1) New
technology chains generally exhibit some loss in cutting efficiency (speed and ease of
cutting), (2) these chains make cutting more tiring for the operator thereby causing more
operator fatigue, and (3) the loss of cutting efficiency may adversely affect the life of
the chain. The loss of cutting efficiency has been estimated to be anywhere from a 10 to
25 percent. OSHA has no estimates of the increase in operator fatigue and the degradation
in the service life of the chain.
Of the four protective devices, most commenters said OSHA should require chain saws to
be equipped with a chain brake because it is the most used and most effective for
professional logging operations (Ex. 4-175, 5-17, 5-19, 5-21, 5-27, 5-34, 5-42, 5-46, 9-3,
9-4, 9-13, 9-15, 9-18, 9-20; Tr. OR 536-37). Several of these commenters said that all
chain saws used at their establishments are equipped with chain brakes. These commenters
also said that almost all manufacturers now produce chain saws with some kind of chain
brake and that almost all chain saws manufactured for commercial logging operations now
have chain brakes (Ex. 5-19; Tr. OR 185-87, 536). In addition, one commenter said that
manufacturers have improved earlier mechanical problems with chain brakes so that they are
reliable in preventing kickback (Ex. 9-4). With regard to the effectiveness of chain
brakes, one commenter said:
The chain brake is, I'd say, one of the most important chain saw protective devices
developed in modern history. In Montana all of our current professional saws are equipped
with chain brakes. Most of our saws are in the four to six cubic inch range, primarily,
Stihl and Husqvarna with a few other minor brands and seldom on job visitations do I find
anyone who has disconnected the chain brake. It's so uncommon that it's startling when I
find that any more.
The other protective device that I see that's had substantial improvement is the
throttle lock mechanism where it has to be held down with your palm in order for the
trigger to operate. For years it was common that the first thing a logger did was he got a
roll of black tape and he would tape that down so you didn't have to operate that. Through
our progressive Montana Sawyer Safety Program and other efforts I brag to people that we
now have developed a genetically superior timber faller in Montana that can now squeeze
with his palm and pull with his trigger finger at the same time.
These two chain saw protective devices combined with leg protection have had a
significant impact on the reduction of accidents in Montana relative to timber falling. In
fact, it's been so significant that I don't even consider the other options of even any
application to logging when we talk about the low kickback bar, the low kick-back chains
and even the bar tipped guards. They may have individual special application but I'm
thoroughly convinced with the chain brake, the throttle lock and the leg protection we've
so significantly reduced chain saw injuries that any further attention is maybe some
wasted effort and just further develops additional conflict (Tr. OR 536).
Mr. David Kludt, Logging Safety Program Supervisor for the State of Idaho, testified
that 10 percent of all logging accidents each month are the result of chain-saw kickback
and that these accidents could be drastically reduced by the use of chain brakes (Ex.
9-4).
In addition, Maine BLS says that chain brakes have played a significant role in
lessening the effects of chain-saw injuries in that State (Ex. 5-174). They reported that
only 13 percent of chain-saw accidents where chain brakes were present resulted in
hospitalization, while nearly half of all other accidents required hospitalization.
Some commenters, however, disputed the effectiveness of chain brakes for preventing
kickback (Ex. 5-39, 5-59, 5-66). One of these commenters said chain brakes were not
reliable and required frequent maintenance, however, no evidence or data were presented to
support the contention (ex. 5-59). Another commenter said that a study showed that while
chain brakes reduced kickback by 80 percent, non-kickback accidents showed a 400 percent
increase (Ex. 5-66). However, the commenter also admitted that the study was from 1972 and
that chain brakes had undergone significant improvement since that time. Another commenter
said chain brakes, depending on their design, could become entangled in the brush the saw
is clearing and create a safety hazard (Ex. 5-39). The WIR survey, however, does not
support the commenter's argument. None of the chain-saw operators reporting injuries said
their chain brake had become caught (Ex. 2-1).
b. OSHA regulatory action. Many commenters said that the
final rule should include requirements for chain-saw protective devices (Ex. 5-17, 5-19,
5-21, 5-27, 5-34, 5-42, 5-46, 9-3, 9-4, 9-13, 9-15, 9-18, 9-20; Tr. OR 536-37). However,
some commenters, including chain-saw and chain-saw accessory manufacturers, said OSHA
should include performance requirements for chain saws in the final standard rather than
specification requirements (Ex. 5-4, 5-8, 5-13, 5-15, 5-26, 5-37, 5-59). Many of these
commenters supported incorporating by reference the American National Standards Institute
(ANSI) B175.1-1985 standard on "Safety Requirements for Gasoline Powered Chain
Saws" (Ex. 5-4, 5-8, 5-13, 5-15, 5-26, 5-37, 5-59). The ANSI standard specifies a
performance criteria for manufacture and testing of chain saw safety features, such as
protection from chain-saw kickback. One commenter summed up their rationale:
[T]he Status Report on Chain Saw Related Hazards since the 1985 Revision to The
Voluntary Standard ANSI B175.1, which was prepared for the Consumer Product Safety
Commission in March of this year, is a testimonial to the fact that the reduction in chain
saw injuries is the result of adherence by manufacturers to the voluntary standard. There
truly is little to be said in defense of OSHA when it chooses to knowingly ignore the
demonstrated success of the chain saw voluntary standard, which equates compliance with
the use of a combination of devices, in favor of an arbitrary and inexpert agency decision
to the effect that one specific device, in and of itself, is superior to any other device
or combination of devices permitted by the standard (Ex. 5-4).
These commenters stated that OSHA would create "confusion in the marketplace"
if OSHA adopted requirements that were significantly different from the ANSI chain-saw
standard that all manufacturers have been voluntarily following (Ex. 5-4).
Other commenters, however, opposed incorporating the ANSI standard in the final rule
(Ex. 5-27, 5-48; Tr. OR 118). These commenters said the ANSI standard was developed to
protect consumer chain-saw users, not professional loggers:
The ANSI B175.1 Standard was developed from an injury data base that was consumer based
and therefore its direct application to pro-logging may not be justified (Ex. 5-27).
Two commenters said that ANSI standards were not known to most loggers, were not
readily available, and were not written in language that the average logger would
comprehend (Ex. 5-27; Tr. OR 118). One of these commenters said OSHA, therefore, should
put its requirements in the standard rather than requiring logging employers to obtain and
read another document (Tr. OR 118). He added that placing the requirements in the
regulatory text would increase compliance.
As discussed above, many commenters supported a requirement that all chain saws be
equipped with chain brakes rather than just referencing the ANSI standard. In general,
these commenters said chain brakes were the most effective device to protect operators
from kickback and to provide extra protection when the saws are carried between cutting
jobs. In addition, one commenter supported a chain brake requirement for the following
reason:
The U.S. should follow the lead of other countries (European) and require that all saws
have an operating chain brake if purchased after the adoption of these regulations. The
cost would be minimal since the majority of saws now come equipped with these devices.
This would also help deter the disabling of the brake system by operating personnel (Ex.
5-19).
OSHA agrees with commenters that the final standard should include requirements on
chain-saw protective devices. The final rule does incorporate by reference the ANSI B175.1
consensus standard, but the Agency believes that the ANSI standard alone does not provide
the necessary degree of safety for logging employees. Accordingly, for several reasons,
the final rule also requires that chain saws placed into initial service after the
effective date of the standard be equipped with chain brakes. First, there is considerable
evidence in the record that chain brakes are effective and the most used device to prevent
kickback. Second, they have strong acceptance by logging professionals, and as a result,
already are standard equipment on almost all chain saws currently manufactured. Third,
chain brakes do not have the disadvantages of the other protective devices. For example,
unlike bar tip guards, chain brakes are not removed by operators. Unlike reduced-kickback
guide bars and low- or reduced-kickback chains, chain brakes do not affect production
efficiency. Fourth, other countries also have adopted provisions requiring chain saws to
be equipped with chain brakes (Ex. 5-19).
Fifth, OSHA agrees with commenters who are concerned that, in order to maximize
compliance, the standard be comprehensible to the average loggers. This is especially
important for chain-saw safety, since many employees provide their own chain saws. These
employees and their employers need plain and simple direction about what protection must
be provided for each chain-saw operator. OSHA does not believe that the ANSI standard
contains the type of information needed by those operating the chain saw. It requires the
use of sophisticated equipment and exacting procedures that are beyond the expertise of
the average logging employer. Much of the ANSI standard deals with a computer program for
simulating chain-saw kickbacks and tests to determine the accuracy of the computer
program. As such, the ANSI standard is primarily directed to manufacturers of chain saws,
rather than employers and employees in the logging industry. For example, the standard
states:
The purpose of this standard is to establish minimum safety requirements with respect
to the manufacture of portable, hand-held, gasoline-powered chain saws (Ex. 4-66).
The requirements of the ANSI standard are primarily within the unique purview of
manufacturers, such as requirements for the throttle control system, handles, pull-type
starters, fuel tanks and oil tanks, exhaust systems, sound levels, and vibration. Only the
following requirements are directed at the employer:
It shall be the responsibility of the owner to maintain the chain saw in accordance
with the instructions in the owner's manual.
Chain saws shall be used in accordance with the operating instructions and safety
precautions listed in the owner's manual. It shall be the responsibility of the owner to
see that such instructions and precautions are given to every operator who uses the saw
(Ex. 4-66).
In addition, the ANSI standard does not require the employer to ensure that each chain
saw used in their workplace is equipped with kickback protection. That is, the ANSI
standard does not require the employer to ensure that kickback prevention devices are not
removed or disabled by operators. By specifying that chain saws used by logging employees
be equipped with chain brakes, OSHA emphasizes that responsibility for compliance with
OSHA standards rests with the employer, not the manufacturer or the employee.
In order to retain flexibility in the final rule, OSHA is requiring chain saws placed
in service after the effective date of this standard to be equipped with chain brakes or
other protective device that prevents or minimizes kickback. OSHA notes that whatever
kickback device is present, the final rule requires that it not be removed or otherwise
disabled.
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