Repairing GAST Air Motors
Many printers use GAST air motors. They have all at some point have tried to install a spare part kit or vanes without the proper tools. We hope the following instructions will make your job a little easier. To make it successful you will need the Tool Kit that is mentioned throughout the procedure. These can be ordered from Powerwise.
To install a spares kit part# 1002 (K203A) perform the following:
Disassembly:
1: Using a black magic marker, make a line on the front of the dead end plate & motor body to ensure proper alignment during reassembly.
2: Remove end cap with large crescent wrench.
3: Remove 6 screws on dead end plate. To remove the dead end plate, use the dead end plate puller.
4: After removing the dead end plate, tap the 2 split pins down so that they are below the machined surface of the dead end plate with a punch or nail.
5: With a board on a concrete floor and the motor in your hand, use a drop and bang motion on the drive end of the rotor assembly until it pops out of motor body.
6: Remove all vanes.
7: Remove bearing from dead end plate by using the dead end disassembly bearing pusher (smaller) and a mallet.
8: Remove bearing and seal from drive end of motor with 2nd bearing disassembly pusher (larger) and a mallet.
Examine all parts for damage, defects, or flaws. Spray all parts with Simple Green degreaser/cleaner and clean up all parts with rag, scotch brite and fine file where needed. Use Q-tips to clean out all holes and ports on rotor assembly and motor body. After all parts have been cleaned and prepared, use 1002 spares kit to reassemble.
Reassembly:
1: Starting with the drive end first, put a few drops of SAE 10W motor oil in the motor body and spread around to coat inner surface area.
2: Place the rotor assembly in side the motor body. Turn by hand to allow bottom of rotor assembly to slide on the oiled surface. While holding the rotor assembly in place, turn unit over and install the large bearing on the drive side of the motor with drive end bearing pusher (Larger) and mallet.
3: Tap down on bearing until seated. (Turn rotor assembly by hand to make sure it is not too tight. If you cannot turn by hand, tap the end of the rotor shaft with brass key stock to loosen the fit.)
4: Turn motor over again and insert the vanes with angled corners facing in towards rotor assembly.
5: Place 1 red shim gasket on top of motor body. Make sure the air intake hole is not blocked. Split pins will make their own holes when tapped down at the end of the assembly.
6: Replace dead end plate with black marker lines matched up for proper alignment. Replace 6 screws, but do not tighten all the way. Snug up and then back off 1/8".
7: Install small bearing in dead end plate with dead end assembly bearing pusher (smaller). Tap in with mallet. Spot check to see that rotor assembly can still be turned by hand. Then tighten down the 6 screws completely.
8: Place motor in vice by drive end plate and air ports facing up with the dead end side facing you. Apply air pressure after installing needle valve and muffler. While motor is running apply pressure to each end of rotor assembly separately with brass key stock. If one side slows down, stop motor and tap w/ brass key stock and mallet on the side that slows down a time or two. Then run again until both sides rpm are about equal.
9: When that is accomplished, take the motor out of the vice and grease drive end of arbor assembly with all purpose grease and install the bearing seal with seal pusher tool. Do not tap down all the way. Leave approx./ 1/16" above shoulder of housing. Apply air pressure to test. If it tests ok tap down the roll pins.
10: Install new cork gasket on end cap and tighten down. Apply air pressure for final check and paint motor if necessary.
This has been an instructional white paper from Powerwise Ink Pumps. www.powerwise.com
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