If the treadmill
operates normally without a person above, but slows or behaves
abnormally as soon as you step on it, the most likely causes are:
1) running belt
and/or the running deck are worn. (85% of cases).
2) running belt or
the drive belt is too tighten, think about this especially if you
have recently adjusted. (8% of cases).
3) motor lost torque
or is demagnetized. (5% of cases).
4) controller is
problems. (2% of cases)
Under these
conditions, do not attempt to operate the treadmill until you
understand exactly where the problem originates and solve it. You may
otherwise damage other components thus increasing the cost of
recovery.
Worn deck:
normally it is easy
to identify if the deck is worn out. The table is covered with a
perfectly smooth thin layer. If the layer is worn out or there are
hollows, bumps or actual cracks, deck must be replaced. You should
use a perfectly straight iron bar in order to check whether the table
surface is flat as some low lying areas may not be visible to the
naked eye. In some treadmills it’s possible to turn the deck upside
down. This is common for professional gym equipment. Sometimes
unsuitable lubricants and wax leave residues on the table, which must
be removed. If you can avoid degreasers and aggressive products.
Worn belt:
It is not at all
easy to identify if a belt is worn or not. Often the mere age of belt
(regardless of usage) will make it unsuitable! It goes without
saying, you should replace the belt if it shows cracks, tears or
holes in the texture below. But often you should replace it even
though the texture and the top surface looks in good condition. To
check the degree of worn of the belt is necessary to assess the
absorption (amperage) DC or AC depending on the treadmill. Solely
looking at the belt or evaluating its feeling is unreliable.
Unfortunately many service engineers neglect this aspect, because
they don’t have the appropriate instruments to measure the
absorption. It is difficult to measure the output current from the
PWM controller. That’s because of the particular type of treadmill
speed adjustment system (see other articles on our blog). If you are
not able to take the current measurement, consider as general rule
that if the treadmill works fine when no one and the problems start
when a person gets on the belt, the belt is almost certainly to be
replaced. Belts older than 5 years are to be replaced. This is
especially true for some brands of sports equipment, such as Proform,
Weslo, Nordic Track, Domyos, and in general for all treadmills
assembled with components marked Greenmaster, GMD or Icon. Those
manufacturers also produce as OEM for several brands. They use a
basic economic belt, which often presents over time this kind of
problem. Very thick belts (for example the so-called "orthopedic",
over 2 mm thickness) tend to give more problems than standard belts.
Another type of test
that can be done without special equipment is the tilt test. Set the
treadmill at maximum incline and walk at 4 km/h. If the treadmill
operates normally at high speed, and problems start if you lover,
that’s symptom that you need to replace the belt. In fact the
gravity effect counteracts the increased friction factor of the belt.
Note that sometimes bad belts still pass this test.
Motor belt or belt
too tight:
If you have adjusted
the running belt or the drive belt recently, double check. On the
treadmill, tight doesn't mean any better. You must be able to lift
the belt in the middle (with the treadmill off) being able to pass a
hand underneath without forcing. If too much tighten the belt gives
problems, but make also sure you haven't created a dangerous/slippery
situation. Check the instructions in this blog to tighten properly
running belt and drive belt. It should be possible to rotate 90
degrees the drive belt / motor belt (with the power off) effortlessly
by hands. Avoid it to be too tighten. Check the instructions in this
blog for proper tension. New belts grip easily on the roller and
don’t slip, thanks to their elasticity, so they need less tension.
With a new belt, you can save much more costly repairs. You also
reduce the electrical consumption of the treadmill, so it pays out.
Worn brushes / Motor
demagnetized:
After many years of
use, the engine may need a new pair of brushes. Removing the old
brushes you can see if they wear. In that case you can buy a new set.
Unfortunately sometimes the damage to the brushes is due to
irregularity of the collector. However given the limited cost you can
try to replace the brushes. If after some usage you notice an
irregular consumption even of the new pair purchased, you will need
to replace the motor.
The demagnetization
of the engine is not common but it is fairly easy to diagnose. This
happens more often on the engines marked ICON or MEGA MOTOR, and on
motors with lower than 180V rated voltage. To test if the engine is
demagnetized, dismount it. After removing the bolts and brushes
holder, lift the engine cover and check whether the internal magnets
attract metal objects with force. If they do, the magnets are intact,
otherwise the motor must be replaced.
Other engine damages
are due to breaks or short circuits in the armature filaments,
usually caused by overheating. It is difficult to determine such
situations without the use of special laboratory instrumentation.
There is some easy
way to check if a motor is damaged. We can assume an engine damage:
- when the motor
does not turn smoothly by hand,
- if you see leave
little pieces of plastic/resin coming out from the rear fan
- if you open the
motor and see "debris" of plastic on the armature.
All these symptoms
indicate that the engine was overheating up to melt the resin
insulation which insulates the individual filaments. In these cases,
the engine needs to be replaced, but it should also be paid attention
to proper maintenance to prevent the new engine from being damaged.
Controller:
It is one of the
rarest cases. In most cases, the engineer will replace the controller
but won't solve the problem which is more likely in the belt.
Normally, to see if a controller is good, you can perform a simple
test. The controllers have a current limiter that will automatically
lower the power to prevent a short circuit when it finds something
abnormal. For treadmills with DC motor (the most common for
household), if you can measure with a current probe or an ammeter the
output current from the controller. If the value reaches at least the
5A, the controller is OK and the fault is in other components.
Another test that you can do is to bring the treadmill up to max
speed without anyone on: if the controller is OK, it should reach
full speed. This test could also fail due treadmill engine damage or
problems in the speed sensor.
Finally one last
suggestion, the controller should be replaced in the case does not
bring any voltage to the motor output (symptom: the motor does not
move) or is shorted (symptom: the motor is at full speed and you
can’t adjust it). To do this test is advisable to connect a bulb to
the outputs M+ and M- of the controller instead of the original
engine. By starting the treadmill and pressing + and – speed, it
should be possible to adjust the intensity of the light bulb for a
few seconds. If the bulb does not light or lights fully and you can
not adjust the brightness, then the controller it must be replaced.