Lull 944E-42 Service Manual - Manual (Page 77)

3.29 Model 644E-42/944E-42 Rev. 6/04
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:
Check for Chain Elongation
When the original length (1) of 12" (305 mm) per foot of
new chain has elongated from wear to a length (2) of
12-3/8" (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.
For the Extend Chain; measure across a span of 13
pins (3) at the center of the extend chain. Measure from
pin center to pin center.
For the Retract Chain; measure across a span of 17
pins (4) at the center of the retract 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 Section
3.4.5, “Boom Extend and Retract Chains Removal and
Replacement.”)
Inspect Plates for 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 0.713" (18 mm) (5). If the
measurement of the worn chain is less than 0.677"
(17 mm) (6), the chain must be replaced. (Refer to
Section 3.4.5, “Boom Extend and Retract Chains
Removal and Replacement.”)
Inspect Plates for Distorted or Battered Link Plates
Distorted or battered link plates (7) on a leaf chain can
cause tight joints and prevent flexing.
MU4840
1
2
3
4
MM2051
5 6
MA9340
7