Maintenance Technology November 2015 - (Page 39)
Maintenance is key to
greater returns from
Deal with Elongation
Don't overlook chains and
components during your
THE CHAIN SYSTEMS in
your operations keep your
production processes and
profitability moving in the right
direction. Although they may
often be out of sight, don't let
the components in these critical
systems slip your mind when
it comes to equipment maintenance. The power-transmission
experts at U.S. Tsubaki® offer
these reminders for production
facilities that want to achieve
the longest service life and
greatest returns possible from
their chains and the processes
■ Use a level to verify that shafts are
■ Confirm sprocket axial alignment
with a straightedge or laser tool. Axial
alignment is correct when there are
no gaps between sprockets and the
Chain elongation ("stretch") is the
increase in measured chain length
due to wear between the pin and
bushing. In general terms, 2% is
considered the wear-elongation
limit at which chain replacement is
suggested. Use a chain-wear scale to
easily measure this elongation.
Maintain a film of lubricant between pin and bushing to minimize chain-wear elongation and increase service life (see sidebar).
■ Manual lubrication: Oil is applied with an oil filler or brush on the slack side of the
chain. Apply at fixed intervals (usually about every 8 hr.) or as often as necessary to
prevent the bearing areas from becoming dry.
■ Drip lubrication: A simple case can be used. Oil from the oil cup is supplied by
drip-feeding. Apply 5 to 20 drops of oil/min. for every strand of chain. Actual
quantity depends on chain speed.
■ Oil-bath lubrication: The chain is installed in a leak-free casing. Chain should be
submerged in oil 1/4- to 1/2-in. deep. If too deep, the oil may overheat and lose
■ Adequate slack should be maintained for effective roller-chain operation. Excessively
tensioned chain may reduce chain life.
■ The chain slack that you can move by hand should be about 4% of the span. Reduce
the slack to 2% if one of the following conditions apply:
» centerline of sprockets is vertical or almost vertical
» center distance of sprockets is more than 3 ft.
» chain is subjected to heavy loads and frequent starts
» chain is subjected to suddenly reversing loads.
■ If the chain slack side is on top, eliminate the excess amount.
■ When the center distance is short, chain slack should be adjusted by increasing the
■ When the center distance is long, the chain slack should be adjusted by installing
■ If vibration occurs, due to high chain speed, install a guide.
■ If the centerline is vertical, install an idler, which functions to eliminate extra slack.
If the driving shaft is on the lower side, an idler must be installed. MT
To learn more about chains and other power transmission products, visit ustsubaki.com. To obtain a full-color poster on chain
maintenance with a detailed troubleshooting guide and a U.S. Tsubaki Chain Wear Scale for measuring elongation, email
MAINTENANCETECHNOLOGY.COM | 39
Table of Contents for the Digital Edition of Maintenance Technology November 2015
For on the Floor
Tiered Empowerment Drives PEX Reliability
Consider the Common-Cause Method
Think Like A Hacker
Take a "CSI" Approach to Asset Management
Maximize HVLS Fan ROI
Keep Your Planners Focused
Extend Chain Life
Scan Energy Wasters
Maintenance Technology November 2015