SkyTrak 8042 Service Manual - Manual (Page 108)

3.47 Model 8042, 10042, 10054 Legacy Rev. 03/04
Boom
a. Inspection Guidelines
Expose the extend and retract chains (refer to Section
3.4.1, b. “Expose Extend Chain for Inspection,” or Section
3.4.1, c. “Expose Retract Chain for Inspection.”) and
inspect the chains for the following conditions:
Elongation
When the original length (1) of 12" (305 mm) per foot of
new chain has elongated from wear to a length (2) of
12.36" (313 mm), the chain must be discarded and
replaced. (Refer to Section 3.4.5, “Boom Extend and
Retract Chains Removal and Replacement.”)
It is important to measure the chain in the section that
moves over the sheaves because it receives the most
frequent articulation. Measuring the chain near its clevis
terminals could give an inaccurate reading.
Measure across a span of 17 pins at the center of the
extend chain. Measure from pin center to pin center.
The maximum measurement allowed is 12.36" (313 mm).
If the measurement is more than 12.36" (313 mm), the
chain must be replaced. (Refer to Section 3.4.5, “Boom
Extend and Retract Chains Removal and Replacement.”)
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.
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. (Refer to
Section 3.4.5, “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.
MM2120
1
2
MM2051
3 4
MA9340
5