PHQ250JHMAVL Jackleg MK 1 Parts and Repair Manual PDF

Page 32
Rotate the control handle forward so the piston in the built in cylinder pushes the drill forward
Run the drill under full leg pressure at partial throttle for no more than 15 minutes.
Running the drill under controlled conditions in the shop accomplishes several things:
The rifle bar polishes the bronze of the rifle nut.
The piston splines polish the bronze of the chuck driver nut.
The drill doctor listens for irregular sounds and to be sure the drill runs smoothly.
The drill doctor places his hand on the cylinder of the drill near where the front head
joins the cylinder to check for heat that may be generated
If the drill sounds smooth during the running and the body remains fairly cool to the touch during
and after the run in period the Rock Drill Doctor can be satisfied that the repairs were done
properly and that the drill is running properly. This ensures smoother running later on when the
drill is run at full throttle in actual drilling operations.
The drill is now ready for torque testing and already in the proper position on the test bench.
Testing the Jackleg
Remove spring loaded shank steel assembly from the bench and replace with the torque test head
Before engaging the drill to the head make sure the torque head is “loosened off” at least five
rotations. This will allow the drill revolution to build up momentum going into the torque test.
Move the drill forward with the pneumatic pusher cylinder built into the torque test bench.
Insert the rod shank adapter on the torque tester into the chuck bushing and close the steel retainer
Release the feed pressure on the drill by shutting off the air to the pusher leg.
With the drill in position and no pusher leg pressure suddenly throw the throttle handle forward
opening the valve fully to operate the drill for a short burst at full throttle ending in a stall.
Observe the reading on the air consumption gauge, which should read 5000 LPM (170 CFM).
When the drill stalled the reading on the torque gauge should be minimum 2000 Nm (140 ft lbs)
When testing a sinker drill, the same test procedure is used.
Version 200711