Dynabrade 52050, Operating Instructions

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Disassembly/Assembly Instructions – .4Hp/Straight-Line/Planetary/Rear Exhaust
Important: The Manufacturer’s warranty is void if the tool is disassembled before the warranty expires.
Notice: Dynabrade recommends the use of the 52296 Repair Collar (sold separately) during the disassembly and assembly of this sander. All of the special repair tools
referred to in these instructions can be ordered from Dynabrade. Please refer to this parts page for the proper part identification.
Motor Disassembly:
1. Shut the air supply and disconnect the sander from the air supply hose.
2. Remove the mandrel and abrasive.
3. Use the 52296 Repair Collar to hold the housing in a vise.
4. Remove the 53152 Gear Case from the housing by turning it counterclockwise.
5. Pull the air motor from the housing.
6. Fasten the 96346 , 2" Bearing Separator around the portion of the 01476 Cylinder that is closest to the 02676 Rear Bearing Plate. Place the separator on the table of the
96232 , #2 Arbor Press so that the pinion is pointing down.
7. Use a 3/16" dia. flat end drive punch as a press tool and push the rotor out of the 02696 Bearing.
8. Remove the 02696 Bearing from the 02676 Rear Bearing Plate with the 96210 Bearing Removal Tool and the arbor press.
9. Position the 01478 Front Bearing Plate against the flat side of the bearing separator with the pinion pointing up. Place these on the arbor press and push the rotor
from the 02649 Bearing.
10. Push the 02649 Bearing out of the 01478 Front Bearing Plate and remove the shims.
11. Slip the 01479 Spacer off the rotor.
Motor Disassembly Complete.
Gear Case Disassembly:
1. Shut the air supply and disconnect the sander from the air supply hose.
2. Remove the mandrel and abrasive.
3. Use the 52296 Repair Collar to hold the 53456 Housing in a vise.
4. Remove the 53152 Gear Case from the housing by turning it counterclockwise.
5. Remove the 01547 Insulator Collar and hold the wrench flats of the gear case in a vise with aluminum or bronze jaws so that the collet or arbor assembly is pointing up.
6. Use a 2.5mm adjustable pin spanner wrench or the 50971 Lock Ring Wrench to remove the 50781 Rear Exhaust Cover by turning it counterclockwise.
7. Use the 96401 , 2mm Hex Key to remove the 50784 Lock Screw from the 53152 Gear Case.
8. Pull the planetary gear assembly from the 53152 Gear Case.
9. Fasten the 96346 , 2" Bearing Separator between the rear 54520 Bearing and the 54468 Ring Gear so that the flat side of the separator is against the ring gear. To remove
the bearing from the planetary carrier, place the separator on the table of the 96232 #2 Arbor Press so that the pinion gear is pointing down. Use a 3/8" dia. flat end drive
punch as a press tool to push the planetary carrier from the 54520 Bearing.
10. Remove the shafts and gears from the planetary carrier.
11. Carefully hold the 56786 Planetary Carrier in a vise with aluminum or bronze jaws. Apply localized heat to the 50782 Adapter to soften the thread adhesive. Use an
adjustable wrench to remove the adapter by turning it counterclockwise.
12. Use the bearing separator and the arbor press to remove the front 54520 Bearing.
Gear Case Disassembly Complete.
Valve Disassembly:
1. Use the 52296 Repair Collar to hold the housing in a vise. Position the air inlet so that it is pointing up.
2. Hold the 94523 Inlet Adapter stationary with an adjustable wrench and remove the air fitting with another wrench by turning it counterclockwise.
Important: The 94523 Inlet Adapter must be held stationary with a wrench when the air fitting is installed or removed to avoid damage to the housing.
3. Remove the 94523 Inlet Adapter by turning it counterclockwise. Note: Carefully remove the 01564 Air Control Ring saving it to avoid loss. Refer to the exploded view to
identify muffler components and the order of disassembly/assembly.
4. Use a needle nose pliers to remove the 01468 Spring and the 01472 Tip Valve. The 01464 Seal can be picked out of the housing with a small flat bladed screwdriver.
5. Use a 2.5mm flat end drive punch to remove the 12132 Pin and throttle lever.
6. Use the retaining ring pliers to remove 95558 Retaining Ring and push the 01469 Speed Regulator Assembly along with the 01449 Valve Stem out of the housing.
Valve disassembly complete.
Valve Assembly:
1. Install the 01469 Speed Regulator Assembly (o-rings included) along with the 01449 Valve Stem into the housing and hold it in place with the 95558 Retaining Ring.
2. Install the 01464 Seal into the inlet opening of the housing.
3. Align the hole in the 01449 Valve Stem with the inlet opening of the housing.
4. Use needle nose pliers to install the 01472 Tip Valve so that the metal pin fits into the hole of the 01449 Valve Stem.
5. Install the 01468 Spring so that the small end of the spring fits against the tip valve.
6. Assemble the 94519 Muffler Assembly and install the 01564 Air Control Ring onto the inlet opening of the housing.
7. Apply a small amount of the Loctite ® #567 (or equivalent) to the male threads of the 94523 Inlet Adapter.
8. Install the muffler assembly onto the housing. (Torque to 23 N•m/200 in. lbs.)
Valve Assembly Complete.
Important: Clean and inspect parts before assembling.
Motor Assembly:
1. Install the 01479 Spacer onto the rotor.
2. Place .003" (.08mm) thickness shims from the 54529 Shim Pack into the 01478 Front Bearing Plate as an initial spacing. Install the 02649 Bearing into the 01478 Front
Bearing Plate. Use the 96240 Bearing Press Tool against the inner race of the bearing and press the assembly onto the rotor.
3. Check the clearance between the rotor and the bearing plate by using a .001" (.03mm) to .0015" (.04mm) thick feeler gauge. The clearance should be .001" (.03mm) to
.0015" (.04mm). If necessary, adjust the clearance by repeating steps 1-3 changing shims as required. Once the proper rotor/bearing plate clearance is achieved, install
blades that have been lubricated with the
95842 Dynabrade Air Lube (10W/NR or equivalent).
4. Install the 01476 Cylinder so that it rests against the 01478 Front Bearing Plate. Make sure that the air inlet holes of the cylinder line up with the air inlet holes in the
02676 Rear Bearing Plate.
5. Use the 96216 Bearing Press Tool against the outer race of the bearing to press the 02696 Bearing into the 02676 Rear Bearing Plate. Use the 96216 Bearing Press Tool
against the inner race of the bearing to press this assembly onto the rotor. Important: The fit must be snug between the bearing plates and the cylinder. If it is too tight the
rotor will not turn freely. The rotor must turn freely while still maintaining a snug fit. A loose fit will not achieve proper preload of the motor bearings. Place a small amount of
grease on the seal of the
02696 Bearing and stick the 02679 Shield against the bearing.
6. Use the 52296 Repair Collar to secure the housing in a vise. Position the opening of the housing so that the motor cavity is pointing up.
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