5
BACKHEAD DISASSEMBLY
Straight
Forinspectionorreplacementoftheshut-offvalve,No.867890,
or valve seal, No. 869201, unscrew the air inlet bushing, No.
867882. On reversible tools, the reversing valve, No. 869253,
may be removed by unscrewing the valve retainer screw, No.
867878.
Theairinletscreen,No.833300, shouldbewashedinasolvent
and blown out in the reverse of normal air flow. Replace the
screen if clogged or torn.
Reversible Lever
Unscrew and remove the inlet bushing, No. 869753. This will
allowthethrottlevalve,No.867005,andrelatedcomponents to
beremovedfromthebackhead.Unscrewingthereversingvalve
retainer screw, No. 867878, will allow removal of the reversing
valve, No. 869253. The inlet screen, No. 867008, should be
washed in a solvent and blown out in the reverse of normal air
flow. Replace the screen if clogged or torn.
Pistol Grip
Onnon-reversibletools,removingthemotorblock,No.869236,
fromthe frontofthe backheadwillallow the removalofthe shut-
off valve and related components.
On reversible tools, removing the reversing knob screw, No.
613749, will allow the reversing valve and related components
to be removed from the front of the backhead.
The air inlet bushing, No. 867929, should be removed for
cleaningand inspection of theair inlet screen, No. 412775. The
screen should be washed in a solvent and blown out in the
reverseofnormalairflow.Replacethescreeniftornorclogged.
Pistol Grip With Trigger
Onnon-reversibletools,removingthemotorblock,No.869236,
fromthe frontofthe backheadwillallow the removalofthe shut-
off valve and related components.
On reversible tools, removing the reversing knob screw, No.
613749, will allow the reversing valve and related components
to be removed from the front of the backhead.
Remove the air inlet bushing, No. 867929, for inspection of the
throttlevalve,No.867055,andairinletscreen,No.412775.The
screen should be washed in a solvent and blown out in the
reverseofnormalairflow.Replacethescreenifcloggedortorn.
REASSEMBLY —GENERAL
All parts should be washed in a solvent and inspected for
damage or wear. Particular attention should be given to all
bearings, gears, gear pins, and rotor blades as failure of these
parts could cause damage to more expensive parts. Rotor
bladesshouldbereplaced every repair cycle or if they measure
less than 3/16" (4.7mm) on either end.
Inspect and replace any "O"-rings or seals that show signs of
wear or deterioration. All gears, gear pins, and open bearings
should receive a generous amount of No. 2 Moly grease during
reassembly. Reassembly of all of the various sub-assembies is
in the reverse order of disassembly however, the following
paragraphs list some of the more important reassembly proce-
dures.
IMPORTANT NOTE: During final assembly of 88C RSATP
models, the three "O"-rings No. 844315, No. 844313, and No.
863009, must be in place on the spindle bushing, No. 202756
as needed.
CLUTCH REASSEMBLY
During reassembly of the clutch all parts should receive a thin
coating of a mixture of 10W machine oil and No. 2 Moly grease.
MOTOR REASSEMBLY
Install the rear rotor bearing, No. 847609, into the rear bearing
plate. Press the bearing plate assembly (press on the bearing's
inner race) onto the rear rotor shaft until there is approximately
.0015" clearance between the rear bearing plate and rotor.
Install the cylinder with the slotted end toward the front bearing
plate.
PISTOL GRIP BACKHEAD WITH TRIGGER ASSEMBLY
When installing the throttle link pin, No. 867939, the notched
end should be installed into the backhead in a vertical position
to engage the throttle valve stem.
TRIP ROD SIZING —NON-TP MODELS
Assemble the tool completely, less the clutch housing, and
connect the tool to the air supply. Screw (left hand threads) the
clutch housing onto the gear case until air exhausts from the
backhead. Measure the gap between the clutch housing and
gear case. Grind this amount plus 1/16" off the trip rod.
TRIP ROD SIZING —TP MODELS
Assemble the tool completely, less the clutch housing, and
connect the tool to the air supply. Screw (left hand threads) the
clutch housing onto the gear case until air begins to exhaust
from the backhead. Screw the clutch housing down one and
three-quarters turn more. Measure the gap between the clutch
housing and gear case. Grind this amount off the trip rod.
OLD TRIP ROD SIZING
The tool should be reassembled complete less the trip rod,
clutch,andclutchhousing.Withtheairon,installthetriprodand
clutch into the tool and measure the distance between the rear
face of the ball retainer, No. 203272, and the front face of the
gearcase. Turn theairoff and depresstheclutchassembly and
measureclutchtravel.Clutchtravelmust beatleast3/32"Ifnot,
the trip rod should be replaced and sized.
SAFETY CHECK
After repair or replacement of parts, tools equipped with an
automatic shut- off device should be tested to verify that the
device is functioning properly.
Must be replaced if less than
3/16" (4.7mm) on either end.
.0015" (.038mm)
Clearance
