SkyTrak 8042 Service Manual - Manual (Page 184)

3.123 Model 8042, 10042, 10054 Legacy Rev. 03/04
Boom
Edge Wear
Check the chain for wear on the link plate edges caused
by running back and forth over the sheave. The maximum
reduction of material must not exceed 5%. This can be
compared to a normal link plate height by measuring a
portion of chain that does not run over the sheave.
Intermediate Extend Chains and Retract Chains
The new chain link measures .713" (18 mm) (3). If the
measurement of the worn chain is less than .677"
(17 mm) (4), the chain must be replaced.
Inner Extend Chain
The new chain link measures .950" (24 mm) (3). If the
measurement of the worn chain is less than .903"
(23 mm) (4), the chain must be replaced.
All Chains
For replacement instructions refer to Section 3.7.6,
“Boom Extend and Retract Chains Removal and
Replacement.”
Distorted or Battered Link Plates
Distorted or battered link plates (5) on a leaf chain can
cause tight joints and prevent flexing.
Turning or Protruding Pins
Highly loaded chain, operating with inadequate
lubrication, can generate abnormal frictional forces
between pin and link plates. When chain is allowed to
operate in this condition, a pin or series of pins, can begin
to twist out of a chain, resulting in failure.
Examine the pin head rivets to determine if the “VEE” flats
are still in correct alignment (6). Chain with rotated/
displaced heads (7) or abnormal pin protrusion (8) must
be replaced immediately. (Refer to Section 3.7.6, “Boom
Extend and Retract Chains Removal and Replacement.”)
DO NOT attempt to repair the chain by welding or driving
the pin(s) back into the chain. Once the press fit integrity
between outside plates and pins has been altered, it
cannot be restored.
Any wear pattern on the pin heads or the sides of the link
plates indicates misalignment in the system. This
condition damages the chain as well as increases
frictional loading and must be corrected.
Cracked Plates
Inspect the chains very carefully, front and back as well
as side to side, for any evidence of cracked plates. If any
one crack is discovered, the chain must be replaced in its
entirety. (Refer to Section 3.7.6, “Boom Extend and
Retract Chains Removal and Replacement.”)
MM2051
3 4
MA9340
5
MM2060
6
7
8