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MAINTENANCE (CONTINUED)
WEEKLY - AFTER EVERY 50 HOURS OF OPERATION (CONTINUED)
To change the knife (or knives), use the following:
A) Remove the five bolts that hold the knives and transition doors to the airlock knife shelves.
B) Remove the doors and knives.
C) Clean all dirt and debris from shelves.
D) Back out the two center jacking screws on each shelf.
E) Compare the replacement knife to the removed knife. If the new knife is wider, back the two
outside jacking screws out by at least that amount. Count the turns and back both screws
out evenly.
F) Lay the knife on the knife shelf. Ensure the knife is installed with the cutting angle edge
facing down. Loosely install the two outer, and the middle knife mounting bolts. Tighten the
mounting bolts enough to hold knife in position, while still allowing it to be moved.
G) Install a block of wood, approximately 2 in. x 4 in. x 6 in. (5cm x10cm x 15cm) between the
knife and the closest vane at the center of the rotor length. Pinch the wood between the
knife and the vane by turning the rotor shaft with a pipe wrench.
H) While keeping pressure on the knife, tighten the three mounting bolts.
I) Remove the wood block and check the clearance between the knife and the rotor vane,
using a feeler gauge at the three mounting bolts.
NOTE: If the knife touches the vane at any point, loosen the three
mounting bolts, back off the jacking screws evenly, and repeat
steps G, H, and I until clearance is obtained.
J) Loosen the three mounting bolts; use the jacking screws to close the gap. One full turn of
the screw moves the knife 0.070 in. (1.8 mm).
K) Tighten mounting bolts as explained in steps G and H.
L) Repeat steps, G, H, I, and J until a knife-to-vane clearance of no more than 0.006 in. (0.15
mm) is obtained at the closest point(s).
M) Once set, install the other two mounting bolts and tighten.
N) Run the two center jacking screws into contact with the knives. Lock all jacking screws in
place with the jam nuts.
O) Remove three mounting bolts for transition door, and install the door.
P) Repeat procedure for other knife (if equipped).
Q) Immediately have the removed knives sharpened. Do not attempt to grind the knives by
hand. The knives must be ground straight and true on a surface grinder by an experienced
knife sharpener. Have the knives ground to the profile shown in the illustration below.
When dimension “A” has been reduced to 2 - 3/8 in. (6 cm), the knife
must be discarded.
Knife Profile
40°
37°
A
1/4˝
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