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HAND-ARM
VIBRATION SYNDROME |
Ergonomic
Requirements of an
Antivibration Glove
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| Five ergonomic factors must be considered in the design of an
antivibration glove. Paying proper attention to these factors increases the effectiveness
of the glove in reducing vibration while making the glove comfortable to wear. |
| • The vibration-damping material
placed in a glove to reduce vibration must be relatively thin. |
| Placing vibration-damping material in the palm and the finger and
thumb stalls of a glove increases the effective diameter of a tool handle when clasped
while wearing the glove. Placing a material with too great a thickness in a glove can make
the glove feel bulky and uncomfortable when clasping a hand tool or work piece. This can
also make it difficult to maintain proper control of a tool. A larger diameter handle
requires a greater grip force to clasp the handle with the same grip effort, as compared
to a smaller diameter handle. This increases muscle fatigue and the intracompartment
pressure in the carpal tunnel in the wrist. Increased muscle fatigue and intracompartment
pressure in the carpal tunnel raises the risk of developing carpal tunnel syndrome. Both
HAVS and carpal tunnel syndrome must be considered when designing an antivibration glove.
Increasing the thickness of the vibration-damping material in a glove usually increases
the effectiveness of the glove in reducing vibration. However, thicker material can cause
a glove to feel bulky and be uncomfortable. It can also increase the risk of developing
carpal tunnel syndrome when using the glove over an extended time period. Material placed
in the finger and thumb stalls of a glove should have a thickness less than 4.6 mm (0.18
in.) and in the palm area less than 6.4 mm (0.25 in.). |
| • Vibration-damping materials placed in a glove should be flexible and
pliable, and they should not interfere with tactile feedback. |
| Vibration-damping materials should easily conform to the natural
flex-lines in the palm and fingers. This allows the worker to more easily maintain control
of his tool or work piece. Vibration-damping materials should minimize the reduction in
tactile feedback associated with their use. To properly perform work operations, an
operator must often be able to feel his tool and/or work piece. |
| • The
vibration-damping material must cover the full palm area and all of the digits of the
fingers and thumb. |
| Vibration from a tool or work piece enters the hand at
the palm, fingers and thumb. The primary damage associated with HAVS occurs in the fingers
and thumb. Thus, to protect the fingers and thumb, all of the digits of the fingers and
thumb must be isolated from the tool or work piece. Figure 1 shows a schematic drawing of
an air bladder between a handle and the hand. |
Figure 1 - Schematic of AntiVib Air Bladder
between Hand and Handle |
| • An antivibration glove must have an opposed thumb. |
| Figure 2 shows a glove with a wing thumb. A wing thumb is often
used in a glove because it simplifies the manufacturing of the glove. When a glove that
contains vibration-damping material and that has a wing thumb is used to clasp a tool
handle, the material in the thumb stall rotates to the outside surface of the thumb. This
places the thumb in direct contact with the tool handle, exposing it to vibration. As is
shown in Figure 3, using an opposed thumb can prevent this. When a glove with an opposed
thumb is used to clasp a tool handle, the vibration-damping material always stays properly
positioned between the thumb and handle. |
Figure 2 - Glove with Wing Thumb |
Figure 3 - Glove with Opposed Thumb |
| • An
antivibration glove should be loose fitting. |
| Vibration-damping material that is placed in an
antivibration glove can make the glove feel tight and stiff, particularly in the finger
and thumb stalls. This usually reduces manipulative dexterity. Oversizing a glove to
accommodate vibration-damping material will increase manipulative dexterity. It is
particularly important to oversize the finger and thumb stalls. |
ErgoAir®, Inc. Hand-arm Vibration Technical Information
Copyright © 1998, ErgoAir®, Inc
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