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PAGE 46 — MAYCO C-30HDNI (PRECISION) PUMP — OPERATION AND PARTS MANUAL — REV. #7 (04/03/12)
The clearance between pin and bushings is very small
(Figure 31), on the order of .003 to .005 inches. A lubricant must
be thin enough to flow into the chain. SAE 30 weight oil is about
right for room temperature. Lighter oil should be used for lower
ambients and heavier for higher operating temperatures. Grease
should not be used as it cannot penetrate chain clearances.
C-30HDNI (PRECISION) PUMP — MAINTENANCE (PUMP)
Figure 31. Chain-Link Cross Section
Drive Chain 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.