Adj 4.7 Knife Down Switches Adjustment - Challenge CMT-130TC Service Manual

ADJ 4.7 Knife Down Switches Adjust-
ment
There are two knife down switches, each com-
prised of a steel collar and an isolated stop block
(Figure 4-18). When the cutting mechanism
reaches the bottom of its stroke, each stop block
comes in contact with its corresponding collar,
thereby acting as a closed switch. This provides
a signal to the computer to raise the cutting
mechanism.
The vertical position of the two collars must re-
main in sync with each other so that both
switches close at the same time. If the collars
become slightly out of sync, the knife will cut
deeper on one side than on the other. If the col-
lars become too far out of sync, one of the
switches will not be able to close and the knife
mechanism will not return up.
To adjust the knife down switches and re-sync
them, use the following procedure.
Procedure
1. Switch the main power OFF. Move the
waste bin aside and open the rear door.
2. Remove the knife from the machine (see
REP 4.2 Knife Replacement).
3. Remove the cover near the bottom of the
machine that covers the knife adjustment
belt and pulleys.
4. Turn the knife adjustment knob clockwise
and keep turning it until it stops. This should
move the timing belt and pulleys as far down
as possible.
5. Locate the two timing pulleys attached to the
large leadscrews (Figure 4-18). Are both
timing pulleys up tight against the threads of
the leadscrews?
4. Repair/Adjustment Procedures
Y N
Loosen the pulley's set screws and slide the
pulley up until it is tight against the threads
of the leadscrew. Then re-tighten the set
screws.
6. Measure the distance between the bottom
flange of each of the three timing pulleys
and the top surface of the bracket beneath
them. Are all three distances approximately
the same, and therefore all three pulleys
level with each other?
Y N
Loosen the timing belt tensioning bracket
and disengage the timing belt from the three
pulleys. Manually turn one or both of the
large lead screws until their timing pulleys
match the height of the adjustment screw
timing pulley.
Re-engage the timing belt with the pulleys
and tighten the belt as much as possible us-
ing the tensioning bracket.
7. Measure the distances between the bottom
of each collar and the top of its correspond-
ing timing pulley. Is the distance approxi-
mately 1" (25.4mm) for both collars?
Y N
Adjust one or both collars until they are both
approximately 1" (25.4 mm) above the top of
the timing pulleys beneath them. To do this,
loosen the clamping screw on the collar then
turn the collar clockwise or counterclockwise
to lower or raise the collar as needed.
When finished, tighten the clamping screw.
8. Adjust the trimmer's clamp pressure down
as low as possible, to 0 psi.
9. Close the rear door and switch the main
power ON. Press the green start button to
initialize the trimmer, then press the "Setup"
button to enter the setup screen.
MAY 2019
4-10
10. Press the "Enable Cut Cycle" button near
the bottom right of the screen. Then press
the green start button to initiate a cut cycle.
The knife should travel down, then stall in
the down position since the knife down
switches are set lower than the knife mecha-
nism will travel.
11. Turn the knife adjustment knob counter-
clockwise until it stops. This should bring
one or both of the collars up to the stop
blocks.
12. Remove the electric panel door, and look at
the DI/HS PWB (Figure 4-19). Are there any
"Hard Stop" LEDs lit up?
Y N
Go to RAP 2.46 Knife Down Switches.
13. Are there two "Hard Stop" LEDs lit up?
Y N
Determine which collar is not making contact
with its stop block by shorting each collar to
the stop block above it using a metal object
such as a screwdriver. Whichever collar
lights up the 2nd LED on the DI/HS PWB us-
ing this method needs to be adjusted up un-
til it makes contact. To do this, loosen the
clamping screw on the collar then turn the
collar counterclockwise to raise it. When fin-
ished, tighten the clamping screw.
14. Install a knife (REP 4.2 Knife Replacement),
and set the knife depth (ADJ 4.3 Knife Depth
Adjustment). Replace all covers and close
all doors. Restore the clamp pressure to its
proper setting. Run several books through
the trimmer.
15. Does the knife cut to an even depth (left to
right) when trimming each side of each
book?
CMT-130TC Book Trimmer