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INTRODUCTION:
The cabs on heavy equipment have been designed to protect the
operators in a variety of ways. Enclosed cabs often have windows
made of polycarbonate material. This material requires special
care and may lose its ability to protect the operator as the
machine ages. It is important to know how to maintain this material,
and to know when it has lost its protective properties.
GENERAL
FEATURES: The material of which windows and skylights on
equipment are made is often called plexiglass. Often the equipment
has no additional window bars or other steel structure to protect
the operator. This plexiglass is often a General Electric product
called Lexan, which is a safety glazing material. However, this
material deteriorates with age and loses some of its strength,
due to the effects of sunlight. Working conditions, cleaning
methods, and impacts from rocks, branches, or debris can also
affect its integrity over time.
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Fig.
1: Plexiglass windows discolor and lose strength with age,
or as a result of inappropriate maintenance.
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OPERATION:
Lexan window and skylight material must be replaced when it:
1) is four years old, regardless of appearance;
2) becomes yellow or hazed;
3) is scratched on either side with scratches that can be felt with
the fingernail (.003 of an inch or more);
4) has cracks coming from edges or mounting holes, or fine cracks
in the surface area;
5) has contacted any fluids that have caused cloudiness.
Any
of these conditions can cause Lexan to lose enough strength to prevent
its protecting the operator as designed.
MAINTENANCE OF LEXAN: Weakened conditions can result from cleaning
with inappropriate cleaning solvents. Normal window cleaning fluids,
especially those containing ammonia, fuel or brake cleaner, or ether
may damage Lexan. Follow these guidelines:
- Pre-rinse
glazing with water to remove gritty substances.
- Wash glazing
with a mild solution of household liquid detergent and warm water.
(Lemon Pledge is recommended for Lexan or Marguard. It provides
a waxy protective cover.)
- Apply cleaner
with sponge or soft cloth. Rinse well with water, and dry with a
clean chamois cloth or soft rubber squeegee.
- Do not use
abrasive or highly alkaline cleaners.
- Impacts from
branches and stems, as well as overtightening of the frame hardware
can cause cracks. ¥ Do not operate windshield wipers on a dry surface.
- Do not clean
with metal blades or scrapers.
The
original equipment manufacturer, your local dealer, or a local glass
retailer can provide the proper maintenance information regarding
your window glazing.
Dan Phillips
The Oliver Stores
21 Freedom Park
Bangor, Maine 04401
207/848-7840
Reviewed By:
Patrick Hackley
Northeastern Technical Division Forester |
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