PAGE 44 — MAYCO C-30HDNI PUMP — OPERATION AND PARTS MANUAL — REV. #0 (05/15/03)
C-30HDNI PUMP — MAINTENANCE (PUMP)
Roller Chain Application
A properly selected, installed and maintained
drive chain
(Figure 30) is an extremely versatile means of power
transmission. It is possible, however, to greatly reduce a chain’s
life and even induce failure if the chain is abused through
improper installation, operating or maintenance procedures. In
certain applications, failure can lead to personal injury or
property damage.
Recommendations and comments on how to get the most from
your roller chain drive are given in this section. The drive chain
used in the MAYCO C-30HDNI pump is manufactured by the
"DIAMOND CHAIN COMPANY
TM
"
Working Loads
UTS-Ultimate Tensile Strength-is the one time pull required to
break the chain. For single strand chain, the load (pull) applied
to the chain in service should never exceed 1/6th of the UTS for
the chain being used except as noted below.
It is possible to exceed the allowable working loads for a limited
number of cycles, but you should contact Diamond Chain
Company before this is considered. A roller chain should
never be loaded above 50% of UTS for even one cycle. To
do so will damage the chain structure and reduce its
capacity.
The UTS or one time breaking load of multiple strand chain is
the UTS of a single strand chain times the number of strands;
i.e., two strand chain is twice as strong as single.
When allowable working loads are considered, however, the
capacity of each strand in a multiple strand chain is only 65% of
the single strand rating; thus, three-strand chain would rate not
three times single but only 1.95 times. This is because the chain
load cannot be exactly distributed across all three strands of
the three-strand chain.
Installation and Drive Alignment
Chain and sprockets (Figure 31) must be installed correctly.
Sprockets must be properly aligned and sprocket shafts must
be parallel so the drive will run in a plane perpendicular to
them. Axial alignment should be checked with a straight edge
which will extend across the finished sides of the sprockets.
They should be true-running with minimum wobble and
eccentricity. The higher the drive speed, the more important
these details become.
Figure 31. Shaft and Drive Sprocket Alignment
The chain should be installed so the slack span is properly
tensioned. To check chain tension (Figure 32), turn one sprocket
to tighten the upper span of the chain while holding the other
sprocket fixed. The lack span should have 4-6% of span length
in the mid-span movement for horizontal drives and 2-3% for
vertical drives.
Figure 32. Drive Chain Tension
A roller chain’s capacity can be significantly reduced if it is
twisted or bent sideways in the direction of the pin axis. Exercise
particular care in alignment of hoist or other applications where
loads are suspended near personnel.
Lubrication
As a chain articulates in entering and leaving a sprocket,
there
is relative movement between pin and bushing surfaces. These
surfaces wear causing chain elongation. If a lubricant film can
be maintained between the pin and bushing, the wear rate is
very slow and the chain wear life very long. Maintaining the oil
film is relatively simple at low speeds but becomes increasingly
difficult as the speed increases.
It is recognized that good lubrication is not possible in many
applications, so shorter wear life must be accepted in these
situations.
In general, chain wear leads to rough or unsatisfactory service
prior to actual chain breakage. Good lubrication can help to
prevent chain failure by providing protection against rust or
corrosion. Rusting can allow pits to form in the surfaces of the
chain parts causing stress concentration points. This can lead
to chain failure at relatively low loads.
Figure 30. Drive Chain
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