Chances are that you know someone on your maintenance staff that
relies totally on their experience, while disregarding the need to read
manuals. They just plow ahead and try to make things work; and the
fact is that as often as not, they are able to make things work. One of
the reasons companies have application support departments is that
while most of us can make things work, we don’t always get them to
In an environment of global competition it is increasingly
imperative that things work well, that they work efficiently and that
they last long. To achieve those goals, attention to detail, awareness
of proper installation and use are needed. Not only that, taking a few
extra steps at the start can be a time saver in the long run.
Take for instance the installation and tensioning of V-belt drives.
A new V-belt drive, regardless of size, will stretch some during an
initial 24 to 48 hours of run time. Some belts take advantage of
materials that stretch less while others trade off cost for a bit more
stretch. The best of belts will elongate perhaps 1% while other designs
will stretch up to 2-3%. What is true for all is that the majority of that
elongation will take place in the first few days of running. Left alone,
those elongated belts will slip more, wear more and overall run at a
lower efficiency and have lesser life than a unit that is re-tensioned
after the first 50 hours of run time. Taking the several minutes to
remove a belt guard, re-tension the belt does create a downtime event.
However, if those several minutes buy you a significant increase in
belt life so that the belt will need replacement less often, it is a good
investment of time since in the long run you will save the cost of
new belts plus save energy since the belts will transmit power more
efficiently. Plus, a planned downtime event to re-tension belts is much
better than an unplanned belt failure.
Perfectly Calibrated Hands and Wrists
Speaking of re-tensioning; along with our lack of manual reading
often comes an absolute sureness in our perfectly calibrated hands.
We know that our thumb can press on a belt and know that it is at the
proper tension for that installation. Belt drive installation manuals
as well as belt drive sizing programs provide belt tension for a given
drive system such as the example shown.
Using a simple V-belt tension tester will ensure that your belt is
getting to the proper tension even if your thumb is having an off day!
Along with our perfectly calibrated belt tensioning
thumbs many of us want to believe that we have wrists that
are perfectly calibrated for torque. We are just sure that
when we tighten those bolts that our calibrated wrists have
put just the right force on the wrench. Yet one of the most
common causes of belt failure is that belt alignment has
shifted when under-tightened setscrews or bushings have
shifted. Worse are those situations where over-tightening
of bushings cause them to crack or when over-tightening
of fasteners damages hubs. In either case, the result can
be shifting products that can become dangerous quickly.
Use of a torque wrench that is set to the manufacturer’s
recommended torque level will ensure that sheaves stay in
alignment and coupling fasteners stay in place.
Mallets and 2x4’s are not recommended adjustment tools
Warner Electric ER brakes consist of a set of
permanent magnets built into the electrically released
brakes so that when power is turned off the magnetism
from the permanent magnets causes the unit to engage and
stop the load. They are commonly used for applications
such as declining conveyors or vertical lifts where a
power failure could become a dangerous event if the load
were to accelerate under gravitational force. In these ER
brakes, when power is applied the electric coil creates an
offsetting magnetic field and the two sets of magnetism
balance each other out so that the result is zero magnetism.
To work correctly these brakes must be mounted against
a surface that is non-magnetic. If they are mounted to a
piece of simple steel or angle iron, the permanent magnets
in the brake will magnetize the mounting surface. For that
reason, in the catalog and in the manual is the following
Several years ago there was an instance where an
ER brake was mounted against a steel frame. When the
brake failed to operate properly, the maintenance staff
had to whack it three times with a two-by-four to get it to
disengage so it could be replaced.
Work in our industry long enough and you will see
it all. As the saying goes, "When your only tool is a
mallet, everything looks like
a nail". Mallets are used to
align gearboxes. Mallets
are used to ‘press on’
bearings. Tight fit? No
problem; just give it a few 'love taps' with the mallet.
But Seriously, it
is entertaining to share
stories of this sort, but in a world where factories compete
globally, installation and maintenance methods need to
follow best practices. Installing and operating products
to manufacturers' specifications will ensure that products
provide the most efficient possible performance and
longest possible life. Taking the time to read through a
manual to get it right saves time and money.