Step 1- Remove lower pan to gain access to the collimator. If only the collimator is to be removed (for re-coating) then skip step 2

Step 2 (STRUT REPLACEMENT ONLY)- Using the hand paddle or the GUI drive the three collimator actuators to the forward software limit. The forward limit corresponds to positive encoder counts and will put the collimator farther away from the slit. This step is necessary to increase the access to the lock nut on the end of the strut that attaches to the actuators. REMOVAL OF A STUT WILL REQUIRE RE-ALIGNMENT OF THE COLLIMATOR.

Step 3- Attach the collimator handling fixture to the collimator. This is accomplished with a single screw and plug that grabs the collimator through the hole for the alignment telescope. The bottom edge of the fixture is hooked and padded to prevent the collimator from slipping out of the fixture. After attaching the fixture to the collimator support the fixture with a hand hoist hooked to the jibe crane. Take-up the slack with the hand hoist

Step 4- Remove the triangular shaped safety bracket of the backside of the collimator.

Step 5- Remove the three M6 cap screws on one of the three pucks. DO NOT LOOSEN THE BRASS LOCK -NUTS ON THE STRUT. DO NOT TURN THE STRUTS! THE OPPOSITE ENDS OF EACH STRUT ARE LEFT AND RIGHT HAND THREADED. TURNING THE STRUT WILL CHANGE ITS LENGTH AND ALTER THE COLLIMATOR ALIGNMENT.

Step 6- After removing the three cap screws from the face of the first puck, remove the two cap screws that loosely attaches the puck to the front safety hoop. Carefully move the puck radial away from the collimator until the safety cap screws can be reinstalled in the outer hole location. This will hold the puck clear of the collimator. NOTE: THE ALIGNMENT PIN IS PRESSED INTO THE REMOVABLE PUCK. IT MIGHT REQUIRE SOME EFFORT TO SLIP THE PIN OUT OF THE FIXED INVAR PUCK.

THIS OPERATION REQUIRES BENDING THE FLEXURES ON THE STRUTS. THIS SHOULD BE DONE WITH CARE TO PREVENT THE FLEXURES FROM GETTING DAMAGED. TWO PEOPLE SHOULD PREFORM ALL OPERATIONS THAT INVOLVE THE COLLIMATOR STUTS. ONE PERSON SHOULD CONTROL THE PUCK AT ALL TIMES WHILE THE OTHER PERSON REMOVES/REPLACES

SCREWS.

Step 7- Repeat step six for the other two pucks. During the removal of each puck pay careful attention to the position and tension on the hand hoist. Each flexure is designed for a couple of degrees of rotation. If the collimator is moving in a manner that is bending the flexure beyond a couple of degrees then the hoist is positioned wrong or the tension/ height is in-correct. Always keep the flexures as straight as possible.
 
 

Step 8- When all pucks are mounted in the outboard storage position the six struts and three pucks can support their own weight. Remove the collimator by swinging it back and lifting or lowering as needed.

Step 9- After re-coating the collimator can be installed by executing the above steps in reverse order

STUT REMOVAL: (This should be done only if a strut is damaged) This action requires three people to complete safely.

Before completing steps 1 through 8 including step #2, loosen the brass lock nuts on both ends of the strut to be removed. Then complete steps 1 through 8.

Step 10- Remove the puck with the damaged strut from the collimator safety. Person #1 will need to hold the safety at the point where the puck was attached to help support the other four struts.

Step 11- Person #2 holds the puck while person #3 turns the strut until it unscrews from the puck and the actuator.

Step 12- Lightly coat the threads of the replacement strut with anti-seize. Make sure the strut has lock nuts on each end. Check the mechanical spares area for new nuts.

Step13- Start the actuator end of the strut ½ turn. Note: the actuators are the left-hand threaded end of the strut.

Step 14- Engage the puck end of the strut by turning the strut which will thread it into both ends. Set the strut length to approximately the same length as the removed strut.

Step 15- Mount the puck to the safety frame

Step 16- Install the collimator by reversing steps 1 through 8

Step 17- Set the strut length using special Measuring tool. Use recorded values rather then attempting to measure the damaged strut before removing.

Step 18- Tighten lock nuts and recheck length

Step 19- Check alignment optically