.Replacing and Preventing broken couplings
When the power stand is being operated there is twelve inches of travel. When this travel is at its limit the motor has enough torque to twist the flexiable coupling. The coupling has the ability to withstand this twisting for a long period. However when this twisting is excessive the rubber material fatigues and tears. For this reason care should be taken not to continue pushing the control button after the stand is obviously out of travel.
We also recommend the use of an electronic switching Power Supply. This Power Supply acts like a limit switch and cuts the power when the stand runs out of travel. All Remote Mast systems are now shipped with this type Power Supply
Step by Step Procedure to Replace Coupling
You may remove the motor assembly steps 1-5
and ship it back to Chapman Machine and we will replace the coupling for you. Or you may choose to follow these instructions and replace the coupling yourself. The coupling and electronic power supply are available on our parts page.
Remove the (3) set screws and electrical jack nut
Step 1 Lower the Stand Mast to its lowest position.
Step 2 Place the Stand across a table using soft towels underneath for protection..
Step 3 Remove the three set screws located in the column just above the base.
Step 4 Remove the nut from the electrical jack.
Step 5 Gently remove the motor.
Step 6 Using a 1/16 Allen Wrench loosen the set screws from the broken coupling.
Note: The drive screw may be out of reach up in the column. Use a rod or screw driver to turn it counter clockwise out but only 5-6 inches.
Step 7 Remove the four screws from the motor flange. Gently remove the shaft with the flange. If a gear comes out with the shaft do
not be alarmed, Set it aside for now.
At this point make sure your hands are clean and take care to keep parts clean.
Step 8 Place new coupling on motor shaft. Place a .005 shim (Something approximately that thickness like a peice of paper) between the thrust bearing and the new coupling. Tighten set screw and remove the shim.
Note: If all gears remained in place when flange was removed, reinstall the flange assembly now. If even one gear was dislodged then all the gears need to be removed using needle nose pliers and placed on the shaft gear plate.
Before installing motor manualy run the main Mast tube through its full travel. If it drags or binds the bushings may need reboring. Call 864-226-4028
Step 9 Reinstall the motor coupling to the Drive Screw and then push the motor into the housing. The 1/4 pockets in the urethane motor mount need to be alligned with the three holes in the column.
Step 10 Reinstall the three 1/4-20 set screws turning them in until FLUSH ONLY. The motor needs to float Reinstall the electrical jack nut.
( If set screw socket is stripped out you may need to place the coupling in a vise and drive the shaft out.)
Then slide the assembled unit into the ring gear housing. If the assembly will not seat then you may have to remove the first and second stage gears and install the cluster on the shaft plate and reinstall.
Gently push the unit into the ring gear housing while turning slightly..