SkyTrak 6036 Service Manual - Manual (Page 85)

3.45 Model 6036 Legacy
Boom
2. Fully extend the boom until the extend chain is taut.
Shut the engine OFF.
The extend chains will be visible for inspection with
the vehicle in this state. The retract chain can be
visually inspected, at the rear of the boom, as the
boom is slowly retracted.
While doing the chain inspection, check all chain
clevis ends for distortion or cracking and sheaves for
bearing wear or grooving from the chain.
3. Inspect the chains for the following conditions:
Elongation
When the original length (Fig. 3 -96, 1) of 12.00"
(305 mm) per foot of new chain has elongated from
wear to a length (2) of 12.36" (313 mm), the chain
should be discarded and replaced. (Refer to Section
3.3.7, e. “Chain 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.
The ends of the chains, near the clevis terminals, will
not have flexed as frequently, if at all, as nearer to the
middle of the chains.
Measure across a span of 17 pins (16 links) at the
center of the extend chain. Measure from pin center
to pin center. Because the retract chain is inside the
boom, you will not be able to measure the chain.
The maximum measurement allowed is 12.36"
(313 mm). If the measurement is more than 12.36"
(313 mm), the chain should be replaced. (Refer to
Section 3.3.7, e. “Chain Replacement”.)
Figure 3-96 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 should 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. 3-97,
3). If the measurement of the worn chain is less than
.677" (17 mm) (4), the chain should be replaced.
(Refer to Section 3.3.7, e. “Chain Replacement”.)
Figure 3-97 Inspect Link Plates for Edge Wear
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 (Fig. 3-98, 1). Chain
with rotated/displaced heads (2) or abnormal pin
protrusion (3) should be replaced immediately.
(Refer to Section 3.3.7, e. “Chain 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 should be corrected.
Figure 3-98 Inspect the Pin Head Rivets
MM2120
1
2
MM2050
3 4
MM2060
3 1
2