.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

Step 1Lower the mast to its lowest position.

Step 2Place the stand across a table using                        soft towels underneath for protection.

Step 3Remove the three set screws located in                    the column just above the base.

Step 4Remove the nut that secures the                             1/4 electrical jack.

Step 5Gently remove the motor

Step 6If the drive screw remains out of reach                       up inside the column, with a long screw                   driver or rod turn the drive screw                                counter clockwise until it extends out                        three or four inches.

Step 7Using 1/16 Allen wrench remove the set                    screws from the broken coupling on                          the motor and the drive screw. ( If set                        screw is stripped you may need to                            place the metal part of the coupling in

                a vise and drive the shaft through.

At this point it is extremely important that            your hands and the motor be very clean.

Step 8Remove the four screws that secure the                    motor end flange. Gently remove the                         shaft and the flange. ( Hopefully the                          gears will remain in the motor but if                           they come out with the shaft plate just                      set them aside for now.)

Step 9Place New Coupling on shaft. Place                         .005 shim (washer) between coupling                         and thrust bearing. Tighten set screw.

                Remove the shim. 

Step 10      If gears remained in place when flange                      was removed, replace flange assembly                      and replace the four flange screws.

                If even one gear is out of place then

                using needle-nose pliers remove all                           three gears and place them on the

                shaft gear plate. Then slide the three                         gears into the ring gear housing.

              If the flange will not seat you may have                      to remove the first and second stage                         gears placing the entire cluster on the                       shaft plate. Then gently push into the                        ring gear housing while slightly turning.

   At this point it is recommended that you               manualy run the main mast tube through its full         travel. If it drags and is not free, the bushings             may need to be re-boared. Call 864-226-4028

Step 11     Reinstall motor with new coupling on

                drive screw and push into housing                             making sure the pockets in the motor                       mount line up with the set screw holes.

               

Step 12      Reinstall the three set screws turning

                them in until flush only.

                Reinstall the nut that secures the 1/4

                electrical jack. 

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.

<Shim here

    .005

First stage

  Gears

Second Stage

     Gears

Drive Screw

Motor Flange

Remove the (3) set screws and electrical jack nut

1/16 Allen wrench.