TSDZ2 Torque Sensor Shattered

rippledabs

10 µW
Joined
Aug 24, 2019
Messages
5
Hi everyone, long time lurker of the site.

Looks like the torque sensor cracked and shattered into a million pieces. Looking for some advice to see if this is repairable. Is it just a matter of ordering another torque sensor and installing it? Should there be anything I should look at to be sure there's no permanent damage?

And out of curiosity, why did they made it out of such brittle ceramic? It just looks like a contact spring for the strain gage and a few magnets for the cadence sensor?

Photo of carnage and setup attached.

291604504_1176226019891577_5710104996033779904_n.jpg

download.png
 
I am not deeply familiar with these units, but isn't the torque sensor on TSDZ2's a little piece inside the pedal crank shaft? (AFAICR the hole/etc for the sensor, plus the circlip groove(s) for bearings/etc, are what sometimes causes the shaft to crack or even snap off.)

This thread is one example:
https://endless-sphere.com/forums/viewtopic.php?t=98665

I only ask because I am not sure which part is actually broken on yours to help you find a replacement, and wanted to make sure you are looking for the right part before you buy anything. :)
 
rippledabs said:
....why did they made it out of such brittle ceramic? ...
That (red circle) isn't the torquesensor, but a ferrite base for the coils that works like a transformer. So you have a wireless transmitter for the torquesignal, that comes from the hall sensor (behind the red arrow).
Also one of the coils have some magnets for the PAS sensor on the controller.

Torquefail.jpg
tsdz2-tongsheng-Torque-sensor-for-TSDZ2-electric-bicycle-central-mid-motor.jpg

I don't know what has happened that these coils are broken, but if both are gone you must replace the complete torque setup.
Otherwise it is possible to replace the seperated coil only.

FYI
Here has Wapous written about a problem with these coils. Maybe this could be the reason your ferrite has broken.
 
I see. That makes sense. These coils allow wireless transmission. I was assuming it was some kind of contact spring like on the steering wheel of your car. I was calling it torque sensor because it comes in a one big assembly if I got a replacement.

I think it shatter when I dropped and wedged my chain between the housing on the spider. That probably applied a bunch of lateral force into the axle and popped one of the circlips off resulting in some play. Eventually, a piece of the transformer broke off and took everything else with it. I was able to manually pedal the bike ~15 miles home. Had to take a long nap after that.
 
.... also make sure to not loose the 3(or 4?) tiny springs, which press the 2 coils together.
(i.e. as (barely) seen in this dismantling video at around 2:30 min: https://www.pswpower.com/tmp/madeimg/down_TSDZ2b/TSDZ2-TongSheng-2-dismantile-the-torque-sensor.mp4)
Because these are usually not included when you buy a replacement torque sensor (though availalbe on Aliexpress i.e. here:
https://de.aliexpress.com/item/1005...c16571810119642898ee156!12000017494975218!sea

These are also tricky to install (w/o breaking the sensir again...). Have a look here, where they use cleverly some magnets to hold these (and the static coil) in place:
https://www.pswpower.com/tmp/madeimg/down_TSDZ2b/TSDZ2-TongSheng-4-assembly-the-torque.mp4

Good luck & patience!
 
That (red circle) isn't the torquesensor, but a ferrite base for the coils that works like a transformer. So you have a wireless transmitter for the torquesignal, that comes from the hall sensor (behind the red arrow).
Also one of the coils have some magnets for the PAS sensor on the controller.

View attachment 319508
View attachment 319530

I don't know what has happened that these coils are broken, but if both are gone you must replace the complete torque setup.
Otherwise it is possible to replace the seperated coil only.

FYI
Here has Wapous written about a problem with these coils. Maybe this could be the reason your ferrite has broken.
The hall senor goes to the primary of the transformer, secondary of the transformer via the sling ring go to the torque output signal connector? Don't hall sensors have 3 wires and need a voltage supply?
 
The hall senor goes to the primary of the transformer, secondary of the transformer via the sling ring go to the torque output signal connector? Don't hall sensors have 3 wires and need a voltage supply?
There's additional circuitry on the controller that deals with the torque sensor - I started trying to work out how it works so I could potentially replace the motor controller with a vesc but keep the torque sensing function - i got most of the way there, but I had to pause the project due to building work and I've not got back to it yet...

 
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