APT M155 Rock Drill

The APT Model 155 Rock Drill is a tough, 60 lb class Rock Drill. This tool can be used in general construction as well as in utility work and plant maintenance. It is designed for drilling through granite, hard faced rock, quarry drilling, and drilling secondary holes for blasting. This tool can also be used with dowel hole drilling machines. Adaptable to wet drilling applications by attaching the APT valve, wet tube and swivel assembly.


Part # Units 5229 5230 5231 5232 5233 5234
Type in Dry Wet Dry Wet Dry Wet
Hex Chuck Size in 7/8" x 3 - 1/4" 7/8" x 4 - 1/4" 1" x 4 - 1/4"
Bore Diameter in 2 - 5/8"
Stroke  in 3"
Blows per Minute bpm 2100
CFM @ 90 psi in 110 - 120
Weight lbs 61
Length in 22 - 3/8"
Air Inlet NPT   3/4 MALE NPT


  • 3 Drilling Speeds
  • Built-in automatic oiler
  • Replaceable piston stem bearing
  • Available in wet or dry models
  • Counter clockwise rotation
  • Rubber handle grips

Air Pressure

The recommended air requirement for the operation of APT tools is 90 psi (6.2 bar). Lower air pressure will decrease power, too high a pressure will increase unwanted stresses in the tool. For proper CFM ratings, please refer to the specification charts shown for each tool in this catalog.

Hose Size

APT recommends the use of at least 1⁄2” inside diameter or larger hoses to assure sufficient air flow to the tool. For portable compressor hose and longer lengths, 3⁄4 “ hose is recommended. Keep the overall length of the hose to a minimum to prevent pressure loss at the tool.

Connecting Hoses

Hoses should be rated for a minimum of 250 psi (17.2 bar). Before connecting the air hose to the tool, check the tool inlet connector to be sure it is clean and free of dirt or debris. Keeping dirt and debris from entering the tool will assure long and satisfactory operation.