SkyTrak 6042 Service Manual - Manual (Page 93)

3.47 Model 6042 Legacy Origin 7/02
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 Inspec-
tion”) and inspect the chains for the following conditions:
Elongation
When the original length (Fig. 3 -100, 1) of 12"
(305 mm) per foot of new chain has elongated from
wear to a length (2) of 12-3/8" (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 12-3/8"
(313 mm). If the measurement is more than 12-3/8"
(313 mm), the chain must be replaced. (Refer to Sec-
tion 3.4.5, “Boom Extend and Retract Chains Remov-
al and Replacement.”)
Figure 3-100 Check for Chain Elongation
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)
(Fig. 3-101, 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.”)
Figure 3- 101 Inspect Link Plates for Edge Wear
Distorted or Battered Link Plates
Distorted or battered link plates (Fig. 3-102, 5) on a
leaf chain can cause tight joints and prevent flexing.
Figure 3-102 Inspect Link Plates for Distortion
MM2120
1
2
MM2051
3 4
5
MA9340