DISASSEMBLY/ASSEMBLY INSTRUCTIONS
Never apply excessive pressure by a holding device which
may cause distortion of a part.
Apply pressure evenly to parts which have a press fit.
Apply even pressure to the bearing race that will be press
fitted to the mating part.
Use correct tools and fixtures when servicing this tool.
Don’t damage “O” rings when servicing this tool.
Use only genuine ARO replacement parts for this tool. When
ordering, specify part number, description, tool model number
and serial number.
DISASSEMBLY
Clamp the tool in a smooth face vise, with the drive end of the
anvil in an upright position.
Remove cap screws (47) releasing hammer case (48) and
gasket (45).
Grasp the hammer frame (38) and lift the impact mechanism
fromthe housing and set it on the workbench, drive end of an-
vil upward.
Grasp the anvil and lift it from the hammer frame.
Remove two hammer pins (40), releasing hammer (39).
Grasp the splined end of rotor (32) and pull motor assembly
from housing.
Remove washer (37).
Grasp cylinder in one hand and tap drive end of rotor with a
soft face hammer; motor will come apart.
Remove retaining ring (28) releasing end plate (30)and bear-
ing (29).
Remove gasket (27) from housing.
Removescrew (II), releasing knob (10). NOTE: Screw (11)is
assembled with thread adhesive.
Remove reverse valve (8) from housing. -‘.
Using a pin punch, tap retaining pin (20) out the right side of
housing, releasing throttle valve assembly.
Remove trigger (13) from throttle valve (14).
Remove “O” rings (18 and 19) from valve bushing (17).
Remove “O” ring (19) from housing.
Tap out retaining pin (15), releasing throttle valve (14) from
bushing (17).
Unscrew and remove inlet bushing (2) retaining rings (3)and
exhaust deflector (4).
Iftool is equipped with a built-in muffler, remove inlet bushing
(22) releasing exhaust deflector (24) and deflector gasket
(25). Remove exhaust silencer (28).
PART NUMBER FOR ORDERING
PARTS NOT SHOWN
Side Label . . . . . . . . . . . . . . . . . . . . . . . . . .
ACCESSORIES (available at extra cost)
Socket Adapter . . . . . . . . . . . . . . . . . . . . . .
Vertical Hanger . . . . . . . . . . . . . . . . . . . . . .
Horizontal Hanger . . . . . . . . . . . . . . . . . . . .
Lube injector . . . . . . . . . . . . . . . . . . . . . . . .
Quick Change Chuck
for 1/4” hex . . . . . . . . . . . . . . . . . . . . . . . . .
for 7/18” hex , . . . . . . , . . . . . . . . . . . . . . . .
48957-l
48951-114
48951-37
48951-38
636012
48951-120
48951-149
ASSEMBLY
Grease and assemble “O” rings (7) to grooves in reverse
valve bushing in housing.
Coat reverse valve (8) with ARO 29885 spindle oil.
Assemble spring (9) and ball (8) into reverse valve and as-
semble reverse valve into left side of housing.
Assemble knob (10)to reverse valve.
Apply thread adhesive, such as Loctite 242, to the first 2 or 3
threads of screw (11)and assemble to tool, securing reverse
valve. NOTE: Tighten to 8 - 15 in. Ibs.
Assemble “O” ring (18) to groove in throttle valve (14).
Grease and assemble “O” rings (18 and 19) to grooves in
valve bushing (17).
Grease and assemble “O” ring (19) into housing.
Assemble throttle valve (14) into valve bushing (17) aligning
cross hole in throttle valve with hole in bushing.
Assemble retaining pin (15) into hole, securing bushing and
throttle valve.
Press trigger (13) onto throttle valve.
Assemble throttle valve assembly into housing, aligning cross
hole in bushing (17)with hole in housing. Secure with retain-
ing pin (20) inserting pin from right side of housing.
Insert exhaust silencer (28) into housing.
Install retaining ring (3) exhaust deflector (4)and other retain-
ing ring (3) securing with inlet bushing (2).
For tools with built-in muffler, assemble gasket (25) and ex-
haust deflector (24) securing with inlet bushing (22). NOTE:
Tighten inlet bushings to 20 - 25ft Ibs.
Assemble gasket (27) into housing, aligning holes in gasket
with holes in housing.
Lubricate bearing (29)with ARO 33153 grease and assemble
to rear end plate (30) pressing on outer race of bearing.
Assemble rear end plate (30)to rotor,pressing on inner raceof
bearing.
Assemble retaining ring (28) to rotor.
Coat rotor blades (31) with ARO 29885 spindle oil and as-
semble to rotor slots.
Coat i.d. of cylinder (33) with ARO 29685 spindle oil and as-
semble over rotor.
Lubricate bearing (35)with ARO 33153 grease and assemble
to end plate (34) pressing on outer race of bearing.
Assemble end plate (34) to rotor, pressing on inner race of
bearing.
Insert a guide rod (1/8” diameter x 8” long) thru aligned dowel
holes in end plates and cylinder.
Using the rod as a guide, install rod into dowel hole in housing
and slide motor assembly into housing.
Remove guide rod and replace with cylinder dowel (38).
Assemble washer (37) to rotor.
Coat the spline and pin holes of hammer frame (38)with ARO
33153 grease and assemble to rotor.
Coat hammer (39)with ARO 33153 grease and assemble into
hammer frame.
Coat hammer pins (40)with ARO 33153 grease and insert into
holes in hammer frame, engaging notches in hammer.
Cast the anvil with ARO 33153 grease and slide into hammer
frame until it seats.
Coat bushing (44) with ARO 33153 grease and press into
hammer case (48).
Assemble gasket (45) to motor housing.
Assemble hammer (48)to housing, securing with cap screws
(47). NOTE: Tighten screws to 45 in. Ibs.
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