Why does a treadmill motor break down? How to prevent treadmill engine failures

The engine failure are the most expensive repairs on a treadmill. You may be surprised to learn that the main causes of the engine failure are rarely the engine itself. The problem depends usually on an excessive or improper use of the equipment, or, very often, on lack of maintenance. Both of these factors can be affected directly by the user.

Excessive use of the treadmill

What can the user do?

1) Clean and lubricate regularly the running deck = reduces the friction factor

2) Always start with feet on the side rails (FIRST start the treadmill at 1.5 to 2 km / h, THEN step on it) = avoids current peaks and the effect "locked rotor starting"

3) try to maintain walking speed OVER 5km / h. = Reduces power consumption and overheating

4) after training check if the motor overheats. It should be possible to hold on one hand without burning. The outer surface of the motor must never exceed 50 ° C. If the engine gets very hot, try to:

a) better ventilate the treadmill, the engine itself and the room

b) increase the average speed, take breaks (eg. stretching) and reduce the continuous training time

c) check lubrication

d) check that running belt and drive belt are not be TOO TIGHTEN (too much tighten = premature wear).

Sometimes the running belts loose their ability to lubricate and cause high friction. In this case, the walking belt must be replaced to avoid problems for the motor and the board.

Let's see in more detail why these recommendations

When you use a treadmill, heat builds up inside the motor. Imagine two treadmills, both identical except for the fact that one has a small motor and the other has a large motor. If we use both at the same way, both will necessarily have to generate the same power, but to do this the smaller engine has to work more (and less efficiently) than the big engine. This means that more heat develops and consumption is higher. When the engine warms up, the winding insulation or windings can fail, causing problems inside the motor detectable only through special load bench test. The windings can fail and go shorted.

To prevent the engine to warm up, we must keep under control the "duty cycle" i.e. the time of utilization, especially continuous. The Duty Cycle is the recommended amount of "time on" and "off" to the engine. This is one of the factors that a manufacturer of treadmill will consider when selecting a motor for the treadmill. For example, a duty cycle of 30 minutes 50% means to perform a job for a 30 minutes, followed by 30 more minutes of cooling to allow to dissipate heat in the motor. The engines of treadmills most commonly used normally fall into a duty cycle of 50% between 20 minutes and an hour. The not domestic treadmills (for gyms) of the best brands, are rated for continuous use and sometimes include an additional internal cooling to ensure that the engine does not overheat. So the amount of continuous use for a treadmill is really important in determining its overall life. The outer surface of the motor can be cooled with external cooling fans. However, remove the heat from the center of the engine is not so easy to get. Similar problems can occur if the user's weight exceeds the weight design of the treadmill. Often manufacturers indicate over 100 kg maximum weight, but the actual is around 70/80 kg.

Lack of maintenance

The lack of maintenance can lead to the same type of fault. If you do not regularly lubricate the walking belt, it will increase the friction between the belt and the platform during training. The motor of the treadmill must work harder to overcome the increased friction and if it works more, will become warmer. Looking at the motor brushes, if there are burn marks, often this was the cause of the fault. These are signs that the engine has run too much. This problem can easily be avoided through regular maintenance of the belt and replace it when it becomes too worn. It’s not always easy to tell the belt is worn out by looking at its surface. Sometimes, the belt may look OK, but it is the problem. So, each time the engine warms up, belt replacement should be taken into consideration after a first stage of cleaning and maintenance. We suggest you to replace the belt with a new one with a low friction factor. You can buy them on the website www.partsfortreadmill.com

Consider that a tape with double friction factor (a tape of 4/5 years old often gives this) doubles engine work. It's like saying that a user of only 60 kg causes the motor effort of a 120 kg person!

Other failure modes

Of course, there are also other failure modes for engines that it is not possible to influence so easily. The control system (controller) adjusts the motor voltage through sudden PWM pulses (see more details on our blog). This adjustment is adopted on all DC current motors, virtually all of those used on domestic use treadmills. Albeit economical and reliable, this adjustment tends to greatly straining the engine, especially when the controller must adjust significantly speed (that is, when the user, and then the engine go SLOW). Other fault types relate to the phenomenon of demagnetization. Voltage spikes from the card and overheat can permanently destroy the magnetic field of the (permanent) magnet engine. In fact, the most efficient way to magnetize a metal object is to go through a strong electric field in order to align the micro structure of the metallic, and the same way you can de-magnetize objects by changing the electric field so as to destroy the micro structure. When the magnetism of the motor is reduced too far, the system of the treadmill must compensate for this by increasing the amount of electric current (A) flowing through the windings in order to obtain the same effective. In this way, however, it accumulates more heat in the motor, that can lead to the problems described above. While some engine manufacturers (Turdan, Te Wei, Lemmar) have magnets very resistant to this type of phenomenon, other (Megamotor, Icon), encounter this phenomenon of demagnetization more frequently.

Finally, test the engine with a battery is not enough. It will not say anything about the amount of torque that the motor is able to generate for given amount of current (the magnetism and the current directly influence the torque). The only reliable way to test the torque is with special equipment in a laboratory, with special tester for DC motors.

My engine is failure. So what should I do?

If the engine is actually failure and you replace it, do not neglect other factors of maintenance and avoid overheat. No manufacturer does guarantee engine for overheating because it is obvious that the overheating of the motor depends on some conditions of improper use. Instead, you are careful you can restore the correct operation of the treadmill and guarantee yourself many years of pleasant workouts.

Treadmill with DC motor (DC) how to choose the best treadmill motor, beyond the measure of horsepower (HP)?

When buying a new treadmill it is good to take a look inside and watch some technical data in addition, in order of importance:

1) Has the engine a diameter of at least 8 cm (better 10 cm)?

2) Is the rated voltage at least 160V?

3) Is the speed less than 6000 RPM?

4) Is the brand reliable, such as Turdan, Te Wei or Lemmar? Or the motor is no brand and is present only the label of the treadmill manufacturer?

If you have said yes to all these questions certainly are doing a good deal, the engine is of good quality and probably other components (board, belt, deck) are too.

Let’s see in detail why:

HP (horsepower) motor of a treadmill is probably the most known figure when a consumer searches for the purchase of a new treadmill. Usually we believe that the larger the value is, the better is. However, the truth is that the numbers can be confusing and eventually turn out incredibly misleading.

Terms such as "Duty Treadmill", "PHP" (Peak HP) and "Duty Peak", different classes of thermal insulation and duty cycles were used in the past to deceive consumers and to increase the valuation of certain equipment at the expense of others. What does each of these mean?

• Duty Treadmill: measures the power for an average user of treadmill using at an average speed over an average time period. But since it is an average, is not a real representation of the real power.
• Duty Peak = PHP: theoretical maximum power that a motor can achieve when working at the maximum. This is a theoretical measure and sustainable only for a short period. It is measured a “peak” at the highest possible speed with minimum load. But an engine does not keep high rpm for all the time (you don’t keep running at max speed), so this is not an accurate measurement.

The most reliable standard of measurement is the so called "continuous duty". It measures the maximum power supplied once is reached the thermal regime of the engine. It’s used for commercial-grade equipment and applied to the treadmill used in gyms, health clubs and in the domestic high-end treadmills.

Unfortunately, often even this value is affected by uncertainly. This happens because different assessment on the maximum operating temperature (insulation class) or test mode at bench make this value subject to the discretion of the engine manufacturer or the imagination of the treadmill brand, which sometimes increase some values in order to attract more customers.

Another aspect to consider, are the revolutions per minute (RPM). They are really important in the design of a treadmill engine. The ratio of continuous power and RPM is the torque. This is the most important factor in determining the best motor suitable for your needs. The lower the nominal number of revolutions of an engine, the more torque is. Especially at low engine speeds required for a person using the treadmill for walking or for rehabilitation.

At the same user speed, an engine with very high rated speed will be subject to more intense adjustments and thus greater wear. It is therefore recommended when possible to select motors with a rated speed within the 6000 RPM. This allows the engine to last longer.

Since the mains voltage in Europe is 220 / 240V you should also avoid, whenever possible, the purchase of treadmills with motors with rated voltage of less than 160V. In fact, this involves an extra adjustment effort of the controller. It has to adjust heavily the voltage supplied to the motor, which is very far from the one supplied by the network.

A very practical selection methods available to everybody, is to consider motor size. The power of the motor mainly depends on the size of the armature, so the engines with a larger diameter will have a greater useful power. They will also tend to dissipate heat more effectively and so last longer.

You should avoid motors with a diameter of less than 8 cm. The best DC motors have a diameter of 10 cm or 12 cm.

One final aspect is the brand. Engines built with cheap materials, in fact, tend to deteriorate easily over time. The best brands are Turdan and Te Wei (the two leading brands in this market) and Lemmar.

Controlling treadmill motors by Pulse Width Modulation.

Permanent magnet DC motors used in fitness industry

Home use treadmills are equipped with DC (Direct Current) motors.  The Permanent Magnet DC Motor (PMDC) is the most commonly used type of direct current motor available producing a continuous rotational speed that can be easily controlled.

The rotational speed of a DC motor is proportional to the Voltage applied to the motor.

PWM Regulation as standard regulation for home use treadmills motors

PWM regulation on a treadmill DC motor

Pulse width modulation (PWM) speed control works by driving the motor with a series of “ON-OFF” pulses and varying the duty cycle, the fraction of time that the output voltage is “ON” compared to when it is “OFF”, of the pulses while keeping the frequency constant.

The voltage applied to the motor can be controlled by varying the width of these applied pulses and thereby varying the average DC voltage applied to the motors terminals, ie, the longer the pulse is “ON”, the faster the motor will rotate and likewise, the shorter the pulse is “ON” the slower the motor will rotate.

Advantages and disadvantages of treadmill motor regulation by PWM

The use of pulse width modulation has the advantage in that the power loss in the switching transistor is small because the transistor is either fully “ON” or fully “OFF”. As a result:

• the switching transistor has a reduced power dissipation 
• linear type of control which results in better speed stability
• the motor can be rotated very slow without it stalling

The main disadvantage is that the motor is driven with high voltage pulses (about 300VDC for a network current of 230VAC, 150VDC for 110 VAC). When a reduced rotational speed is required by the application (such as walking at slow speed on the treadmill) associated with the heavy load (user weight, treadmill maintenance conditions, running belt friction factor) the motor is subjected to heavy stress and overheating. This could bring easily to electric leaks inside the motor and consequent damage to the motor itself and/or controller.

Adjusting treadmill motor position when replacing treadmill motor

When installing a replacement motor, a difference in the position of the fixing holes may be noted

In this case, you must not work on the threaded holes on the motor.

Drill the motor fixing bracket on the treadmill frame. If it's a curved bracket, it's better to do uninstall it before drilling

fix the motor in correct position, so that the belt is perfectly aligned, the motor is in good contact with the bracket and the fan doesn't touch anything in the back.

As an alternative to drilling the motor bracket, you could fix the motor with metal bands /jubilee clips (the one used in plumbing) as they are resistant enough for this.

Reinstalling the Rear Roller (Nautilus)

8.1   Slide the rear roller inside the belt and let it hang loose.
8.2   Install the alignment bolts through their holes in the  end cap and into the holes on the roller (see Figure 8.3).

8.3   Install the end cap onto the rear of the treadmill, making sure the alignment pins go into the holes on the ends of the side rails.
8.4  Hand tighten the adjustment bolts.
8.5   Align the walk belt so that the edges of the belt are equal distance from the side rails.
 8.6   Tighten the adjustment bolts to take the slack out of the walk belt.
8.7   Perform the belt tension and belt tracking procedures outlined before

9.    Reinstall the Treadmill Hood
9.1   Install all treadmill covers previously removed in step 1.2.
9.2  Plug the AC power cord into the treadmill, and turn on the treadmill circuit breaker switch.

Nautilus treadmill maintenance: Attaching the Deck & Reinstalling the Front Roller

6.  Attaching the running Deck

6.1  Align the deck mounting holes with the compression mounts.
6.2  Install all eight (8) deck screws and hand tighten.
6.3   Use Loctite 243 and a 10 mm socket to tighten all the screws to 15 in.lbs. (1.7Nm).

DO NOT OVER-TIGHTEN THE DECK SCREWS. OVER-TIGHTENING THE DECK SCREWS WILL DAMAGE THE COMPRESSION MOUNTS. 

7.  Reinstalling the Front Roller

7.1  Slide the front roller inside the walking belt.
7.2   Insert the end of the roller opposite the pulley into the cut-out on the side rail (see Figure 7.1).

7.3   With your free hand, slip the motor drive belt onto the Front roller pulley and the motor flywheel.
7.4   Align front roller pulley with motor flywheel, then install the retainer plates in the grooves on the roller. Tighten all the screws on the retainer plates. (see figure 7.2).

7.5  Place Tensioner assembly onto the tensioner bracket and screw in bolt finger tight.
7.6  With a 15/16 wrench. Place on the large nut of the assembly and push forward until the adjustment knotch is even with the top knotch on the left side of the wheel and hold. (See Figure 7.3 and 7.4.)

7.7  Place a 9/16 wrench on bolt and tighten (counter clockwise).

Inspection and Cleaning + Installing new running belt (Nautilus) checking Belt direction arrow

4.    Treadmill Inspection and Cleaning

4.1  Check the compression mounts for any wear and cracking. Make sure they are tight.
4.2  Check the deck for signs of wear.
  Important: Do not apply any cleaners or petroleum products to the deck surfaces.
4.3  Inspect the motor drive belt for wear and cracking. Cracking is prevalent between the grooves on
the belt.
4.4 Vacuum the deck and inside the motor housing.

5.  Installing the New Walk Belt

5.1   Slip the new belt over the deck. Make sure the arrow on the inside surface of the walk belt points in the proper direction of belt travel (see Figure 5.1) toward the rear of the machine.

5.2   Lift the deck with the installed new walk belt and place it on the compression mounts.
5.3   Lift and slide the belt until the arrow is visible on top of the deck. Verify that it points toward the back of the treadmill.