Topic ID: id_16157524
Version: 4.0
Date: Jan 20, 2020 8:34:31 PM

Gantry Front Cover Removal and Re-Install

Prerequisites

Table 2. Safety

notice

Potential for front and rear cover damage. Front and rear cover removal and installation can be safely accomplished by (1) person using the dollies provided with the system. Failure to use these dollies will significantly increase the likelihood of damage to the covers. Do not lean covers against walls.

note:

Before beginning this procedure, please read the safety information in Equipment Service - Gantry.

Overview

This procedure explains how to remove and re-install the CT Gantry front cover.

1 Redesigned Front Cover Dolly Setup

Procedure

danger

EQUIPMENT TIP HAZARD
Do not use dollies on uneven surfaces such as steps or elevator thresholds. The dollies are designed to be used on flat level floors within the scanning suite only. Misuse can result in personal injury or damage to covers or other facility items.
ONLY USE DOLLIES ON FLAT SURFACES.

notice

Rotating arms on the stand are supposed to be stiff. If they fall freely, tighten the tensioning nuts. Loose rotating arms will reduce the stability of the dollies when supporting the front cover. Do not lubricate.

notice

Top fans must be fixed at forward tilt.

Bring Dolly out of storage into open space (see Figure 1).

Figure 1. Front Cover Dolly in Storage Mode
Pull feet out to form cross (see Figure 2).

Figure 2. Front Cover Dolly Base Assembly
Place the pin to secure the feet into position (see Figure 3).

Figure 3. Place Pin to Secure Feet
Remove the pin from the cover bracket tube (see Figure 4).

Figure 4. Remove Pin from Tube

warning

EQUIPMENT TIP HAZARD
COVER DOLLIES MAY TIP OVER IF NOT CONFIGURED PROPERLY.
ENSURE that all SCREWS ARE TIGHTENED SECURELY AND THE LEGS ARE secured TIGHTLY BETWEEN THE BASE TOP AND BOTTOM PLATES. FAILURE TO DO SO WILL RESULT IN INSTABILITY DURING FRONT COVER HANDLING.

Raise the bracket to the proper height and secure it by inserting the pin into the upper hole on the support tube (see Figure 5).

Figure 5. Secure Bracket with Pin
Position dolly so the pivot bolt for the feet is on the table side (front side) of the gantry (see Figure 6).

Figure 6. Dolly Feet Configuration

note:
The short part of the feet faces outwards toward the wall. The L and R stickers (If existing) (see Figure 7) refer to the sides as you face the gantry from the front.

Figure 7. Direction Stickers
Once the studs are secured on the cover, tighten the ratcheting handle (see Figure 8).The handle can be pulled out and turned to clear the support tube.

Figure 8. Ratcheting Handle Button
Turn the handle to HAND TIGHT.

2 Removal

Procedure

Position the table at its lowest position.
Stop the rotor of X-ray tube in case of Liquid Bearing Tube before HVDC off. Refer to Liquid Bearing Tube Rotor stop procedure for details.

notice

Always turn OFF the HVDC before the 120 VAC. Turning OFF 120 VAC power before HVDC power can result in equipment damage.

Remove gantry side and top covers, if you have not already done so.
Assemble the front cover dolly.
1. Tighten the two (2) shoulder bolts to the gantry securely. This will make cover installation easier. See Figure 9.
  
  Figure 9. Front Side Dolly
2. Attach side dolly to the shoulder bolts and secure assembly with two (2) wing nuts.
3. Repeat Step 4.a and Step 4.b to assemble the other side dolly.
Detach front cover J1 and J3 and LAN cables.

Figure 10. Front Cover Cables
Remove the Mylar (scan) window.
Remove front cover.
1. Disengage upper cantrell bracket on right side of the cover.
  Figure 11. Releasing Cover Brackets
  1. Disengage the locking mechanism on the upper cantrell brackets by using your thumb to slide the trigger (red lever) back. This will release the locking mechanism and allow the cantrell to be rotated upwards with steady and firm pressure.
  2. Disengage the rubber retaining straps on right side. See Figure 12. You may find it helpful to lift “up” on the cover to align the stud while attaching the rubber retaining straps.
    Figure 12. Rubber Retaining Straps and Cover Locking Mechanism
2. Disengage the left side of the front cover
  1. Remove the small cover from the front cover.
  2. Loosen M12 screw.
    
    Figure 13. Disengage the Left Side of the Front Cover
3. Lift and rotate cover locking arm to unlocked position.
Rotate front cover away from gantry.
1. Move front cover away from gantry, leaving space (about 5 feet) between cover and gantry.
2. Pull the locking pin and rotate front cover away from gantry. Place locking pin in one of the side dolly perforations. See Figure 14.
  
  Figure 14. Releasing Front Cover Dolly Hinge
3. Continue cover removal per Figure 15.
  
  Figure 15. Front Cover Removal Sequence
Rotate the cover horizontally and move it back and over the table to a safe location. Once in a safe location, you may over-rotate the cover full vertically but upside down.
Remove the gantry display from the front cover and place it into its service position if scan is required during maintenance.
1. The gantry display is held in place with (6) thumb screws. Use a flat-blade screwdriver to remove the Display. See Figure 16.
  
  Figure 16. Gantry Display Removal
2. Loosen two lock screws of the rear cover.
  
  Figure 17. Lock Screws of the Rear Cover
3. Side the rear cover backward.
  
  Figure 18. Rear Cover Slide
4. Loosen the lock screw of the right top fan of the gantry, and rotate the right top fan.
  
  Figure 19. Top Fan Rotation
5. Connect the LAN cable to the Gantry Display.
Remove right gantry control assemblies, and place it into its service position.
1. Loose five (5) screws that fasten the control panel to the cover. See Figure 20. Keep one hand on the control panel at all times to prevent it from dropping to the floor.
2. Set dip switch s19-4 to ON position.
  
  Figure 20. Dip Switch S19 - 4 Setting
3. Connect FCVR BKHD J1 cable to terminator located on the cantrell arm. See Figure 21.
  
  Figure 21. Gantry Service Mode Cable Terminator
4. Connect the FRT CVR J3 cable to the extension cable 5369987 and connect the other end of the connectors to display and control panel.
  
  Figure 22. FRT CVR J3 Cable

3 Installation

Procedure

Remove the gantry display and control assembly from their service positions and reattach them to the gantry cover.
1. Disconnect cables from Display and Gantry Control Panels.
2. Install Gantry Display in front cover. Secure the 6 thumbscrews. With a flat-blade screwdriver, gently tighten past finger-tight.
3. Set the dip switch on the control panel to original position.
4. Install the gantry control panel, Secure the 5 screws.
5. Reattach cables.

notice

Potential for front cover damage. When you rotate the gantry back to its vertical position, make sure not to scratch the front cover with the edge of the table cradle.

Rotate gantry front cover back to its vertical position.
Attach the front cover.
1. Align the studs on both sides of the front cover with each associated receiver. Receiver is located on the gantry frame.
  
  Figure 23. Cover Stud and Mounting Bracket Receiver
2. For Right Side:
  
  Insert the stud on one side into its associated receiver and attach the rubber retaining straps.Then insert the stud on the other side into its associated receiver and attach its rubber retaining straps.
  
  You may find it helpful to lift "up" on the cover to align the stud while attaching the rubber retaining straps.
3. Reattach upper cantrell brackets on right side.
4. For Left Side:
  
  Insert the stud onto it's associated receiver and fasten the M12 screw and install the small cover (see Figure 13).
Remove dolly, disassemble and store safely away for later use.
Reattach cables to cover.
Re-install the Mylar (scan) window.

4 Finalization

Procedure

Continue with other cover installation procedures as necessary. When AC power is restored to the system, prior to enabling axial drive or HVDC, remember to rotate the gantry by hand to ensure there is no interference between covers and rotating components.
Verify all covers, especially side covers are properly secured.
Ensure there is no interference during all tilt range.