How to fix a wheel motor?


Hello friends!

Quite often, the motor-wheel motor cable at the exit from the axle does not have the necessary protection, and as a result of the bicycle falling, it will be damaged. In some cases, this damage is not significant and the engine continues to run as before.

But sometimes there is damage to the wires, which can lead to failure of not only the engine, but also the controller. If one of the phase wires closes with the signal wire, the Hall sensors in the engine and the five-volt circuit in the controller may fail.

Today we will consider the case when the power wire is damaged — half of its cores turned out to be torn. And although theoretically the system could continue to work in this form, over time, broken wires can be closed with adjacent wires.

On the two parallel red lines that I added in the photo, you can see how the left wall of the axis bent as a result of the impact at the point where the wire exits. After removing the old wire, we will simply push it back.

The engine is from an unknown manufacturer, rated for a nominal voltage of 48 volts and, as it turned out, has a 2-stage gearbox. First, remove it from the bike.

We unscrew the screws, remove the cover and take the motor out of the case. Then we unscrew the 6 long screws to gain access to the windings. Unfortunately, it was not possible to take a photo of this process. On occasion, I will definitely show it in one of the future articles.

Unscrew the 6 screws securing the axle shaft and 2 screws securing the board with sensors. All screws are seated on a thread lock, so when unscrewing them, you need to use a quality tool and be extremely careful not to rip off the screw slots.

We mark the position of the board (I usually also take pictures) in order to set it to its original position during assembly. This is necessary for the correct operation of the motor, since when the board is displaced, the Hall sensors are displaced relative to the motor windings.

We remove the axle shaft and the board with sensors.

Removing the cover, we gain access to the motor windings. As you can see, the joints, in addition to glass-reinforced pipes, are wrapped with additional insulating material.

We cut the binding thread and tighten the glass-reinforced tubes. We heat the connection with a soldering iron and at the same time untwist it with pliers. When disconnecting, the wire can spring back, so we first put on glasses to protect our eyes from possible splashes of solder. We repeat the operation for all three wires.

The power wires are unsoldered, and now we unsolder the board with Hall sensors. We memorize the position of the wires (take pictures), solder the wires, clean the holes and rinse the board.

We remove the old cable from the engine semiaxis and correct the bent angle of the semiaxis, which I wrote about at the beginning of the article. We check that the nut is screwed on normally.

We are preparing a new cable, the lengths of the wires are the same. If, to remove the old cable, you had to bite off the hard ends of the power wires, we take this into account when preparing a new one.

We put on the new cable everything that was removed from the old one in reverse order. In our case, this is only a half shaft, since the connector is thin enough to fit through the nut.

We put on glass-reinforced tubes. I preferred to take the new ones, but in principle, you can leave the old ones as well, if they are not saturated with resin and not too hard, otherwise they will be difficult to install.

We solder the signal wires of the sensor board, observing their sequence according to the photograph taken earlier.

After soldering, we wash off the remnants of the flux from the board and go to the power wires.

We put a glass-reinforced tube on the power wires, insert it through the cover of the inner case and solder it to the windings, observing the color arrangement of the wires.

We restore the strapping with nylon thread and impregnate it with epoxy for better fixation.

Although this was not the case in the original version, I decided to additionally apply glass-reinforced adhesive tape to the windings to protect the windings from contact with the case cover.

Bend the tape inward and put on the lid. In order to prevent the screws from loosening from vibration during engine operation, we apply a detachable thread lock to them.

It is strong enough to prevent spontaneous twisting, and at the same time not too strong so that the motor cannot be disassembled again if necessary.

This completes the work — it remains to return the engine to the motor-wheel housing and screw on the cover.

For some, the described work will turn out to be impossibly simple, but someone simply does not dare to take on it. In any case, you need to soberly assess your capabilities, including tools and equipment, but at the same time, I would advise you not to be afraid to try something new, especially if you are sure that your hands are growing from the right place.

If there are doubts and a desire to save personal time, you can always contact a specialized workshop. For example, in Samara it is

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THANKS for reading to the end!

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