Raise the impact block (1, Figure K-20) with a lifting device and sling so that the impact
block (1) hangs horizontally in the sling.
Ensure the impact block compression rings (3) are staggered.
The impact block compression ring (3) gaps must be positioned such that
no two gaps are directly in line. Each gap should be staggered 90
degrees from the adjacent gap.
Lubricate the impact block compression rings (3) and impact block (1) with MIL-L-2104
Push the impact block (1) into the lower cylinder (2). If necessary, use a ring
compressor to compress the impact block compression rings (3). Push the impact block
(1) fully into the lower cylinder (2).
Install the direct drive assembly onto the lower cylinder (Page K-44).
The impact block compression rings are normally removed to inspect, check the impact block
compression ring gap, rotating, and/or replacement.
Remove the direct drive assembly as an assembly from the lower cylinder and set aside
Remove the impact block from the lower cylinder (Page K-49).
Be careful not to deform (oversize or stretch) the compression ring during
removal, open just enough to slide compression ring over the diameter of
the impact block.
Using the piston ring pliers stored in the tool box, remove the impact block compression
Inspect the impact block compression rings (3, Figure K-20) for seizure in the grooves,
wear, and sharp edges or scoring marks.
Place the impact block compression rings (3) in the bore of the lower cylinder (2) and
measure the impact block compression ring gap with feeler gauges (i.e. the gap between
the ends). The impact block compression ring gap should be between 0.09 0.11
inches (2.29-2.79 mm).
Under normal wear conditions, only the first two impact block
compression rings closest to the end of the impact block require