An attachment for conventional tool grinders is
shown in figure 12-27. In a shop where a high degree
of hole accuracy is required and a large amount of
sharpening is to be done, a machine or attachment is a
A compressor is a machine for compressing air
from an initial intake pressure to a higher exhaust
pressure through reduction in volume. A compressor
consists of a driving unit, a compressor unit, and
accessory equipment. The driving unit provides power
to operate the compressor and may be a gasoline or
diesel engine. Compressors are governed by a pressure
control system adjusted to compress air to a maximum
pressure of 100 psi.
Compressed Air System
A compressed air system consists of one or more
compressors, each with the necessary power source,
control of regulation, intake air filter, aftercooler, air
receiver, and connecting piping, together with a
distribution system to carry the air to points of use.
The object of installing a compressed air system
is to provide sufficient air at the work area at pressures
adequate for efficient operation of pneumatic tools
Many construction projects require more cubic
feet of air per minute than any one compressor will
produce. Terrain conditions often create problems of
distance from the compressor to the operating tool.
Since the air line hose issued with the compressor
causes considerable line loss at distances farther than
200 feet, a system has been devised for efficient
Figure 12-27.A drill bit sharpening attachment mounted on
a conventional bench grinder.
transmission of compressed air over longer distances.
This system is called air manifolding (fig. 12-28). An
air manifold is a pipe having a large diameter used to
transport compressed air from one or more
compressors over a distance without detrimental
friction line loss. In construction work, air manifolds
are usually constructed of 6-inch diameter pipe. A
pipe of this size can carry 1,200 cubic feet per minute
(cfm) of air (output from two 600 cfm air compressors)
at 100 psi with less than .035 pound pressure loss per
100 linear feet. One or more compressors pump air
into the manifold and eventually pressurize it at 100
psi; then air may be used at any point along the
manifold by installing outlet valves and connecting air
lines and pneumatic tools.
Compressor Operation and Maintenance
The following paragraphs will give generaI
instructions on operating and maintaining air
A compressor must be located on a reasonably
level area. Most compressors permit a 15-degree
lengthwise and a 15-degree sidewise limit on
out-of-level operation. The limits are placed on the
engine, not the actual compressor. When the unit is to
be operated out-of-level, it is important to do the
following: (1) keep the engine crankcase oil level near
the high-level mark (with the unit level) and (2) have
the compressor oil gauge show nearly full (with the
unit on the level).
An instruction plate, similar to the one shown in
figure 12-29, is attached to all compressors. Notice
that this plate refers you to the manufacturers engine
and compressor manuals for detailed instructions.
STARTING THE UNIT. Take the following
steps when starting the engine during mild weather:
Figure 12-28.Methods of manifolding compressors.