General Information; Description Of Operation; Air Compressor Pump; Throttle Control - Craftsman 919.157251 Owner's Manual

You have purchased an air compressor unit consisting of
a 2 cylinder, single-stage air compressor pump and air
tank. Included with portable compressors are wheels,
gauges, and handle.
Your air compressor can be used for operating paint spray
guns, air tools, caulking guns, grease guns, air brushes,
sandblaster, or inflating tires and plastic toys, spraying
weed killers, insecticides, etc.
An air pressure regulator is usually required for most of
these applications. Regulators can be purchased from
most Sears stores or through the Sears Power Tool
Catalog.
Separate air transformers which combine the functions or
air regulation and/or moisture and dirt removal should be
used where applicable.
ON/OFF
SWITCH-_-_
UNLOADER VALVE
VALVE
SHUTOFF VALVE
CHECK
VALVE
Figure 1
Air Compressor Pump: To compress air, the pistons
move up and down in the cylinders. On the downstroke,
air is drawn in through the air intake filter and then through
the air intake valves. The exhaust valve remains closed.
On the upstroke of the piston, air is compressed. The
intake valves close and compressed air is forced out
through the exhaust valve, th rough the outlet tube, through
the check valve and into the air tank. Working air is not
available until the compressor has raised airtank pressure
above that required at the air outlet.
Throttle Control: Athrottle control has been incorporated
as an extra feature. When maximum tank pressure is
reached and the unloader valve unloads air, it also
activates a throttle control on the engine. This gas saving
featu re holds the engine at a factory-set idling speed until
air pressure in the air tank drops to reset pressure; it then
reactivates the throttle control and accelerates the engine
to full throttle.
Unloader Valve: All models are continuously running
outfits controlled by tank pressure. When the maximum
tank pressure is obtained, the unloader valve will exhaust
the compressed air to the atmosphere (blow-off). When
the pressure drops to a predetermined point, the unloader
valve closes and causes the tank pressure to increase.
Safety Valve: If the pressure switch does not shut off the
air compressor at or near its cut-out pressure setting, the
safety valve will protect against high pressure by "pop-
ping out" at its factory set pressure (slightly higherthan the
pressure switch cut-out setting).
Check Valve: When the air compressor is operating, the
check valve is "open," allowing compressed air to enter
the air tank. When the air compressor reaches "cut-out"
pressure, the check valve "closes," allowing air pressure
to remain inside the air tank. If the air is not unloaded, the
motor will try to start, but will be unable to. The check valve
allows the motor to restart freely.
Shut Off Valve: Turn the knob counterclockwise to open
the valve and clockwise to close.
7 - ENG
D20396 Rev 0 2/16/00