Section III. TECHNICAL PRINCIPLES OF OPERATION
The engine is a two-stroke cycle engine that uses a mixture ratio 16:l of gasoline and OE/HDO 40 Oil, MIL-L-2104,
(item 7, Appendix E) offering a high power output with less weight. It is reversed with the crankcase above and the
engine cylinder below. The engine is directly connected to the drill/breaker.
The engine performs four functions with two strokes of the piston. On the first stroke (piston ascending), the
scavenging port is replaced with a new charge from the crankcase. The exhaust port opens and exhaust flow starts.
This in turn opens the scavenging port and the burned charge is removed from the power cylinder and replaced with a
On the second stroke (piston descending), a new charge (air and fuel) is taken through the carburetor and into the
crankcase. With the scavenging port and the exhaust port closed, the charge in the power cylinder is compressed. It is
then ignited by the spark plug and explodes at the end of the stroke.
AIR COMPRESSOR OPERATION.
The air compressor piston works in a opposing motion to the engine piston. When the engine piston is descending,
the compressor piston takes in air from the air cleaner. At the descending of the engine piston, the compressor piston
compresses and sends the air to a cushion chamber below the flange of the hammer piston. This step occurs when the
hammer piston arrives at its original position. The air pressure keeps the hammer piston from descending before
ignition. After ignition has taken place, the hammer piston impacts the drill rod. The air pressure in the cushion
chamber is forced out and escapes around the drill rod clearing away stone fines.
HAMMER DRILL OPERATION.
The drill rod is rotated or driven by the hammer piston depending on the direction the selector switch is turned. In the
drilling mode, the clutch wheel is locked on the ratchet wheel. This permits the clutch wheel to turn with the hammer
piston which rotates the drill rod. In the hammering mode, the ratchet wheel remains attached to the lead spline of the
hammer piston. The clutch wheel is unattached from the ratchet wheel, which causes the hammer piston to impact the