What is
 

What is "cogging"? a fella has a problem at a club with what has been described as cogging? what is it? and what causes it please?

Sometimes happens to sensorless brushless motors at low speed or from a standstill. The car jutters along and wont pick up any speed. Not sure why it happens to some setups and not others though.

Is it something that can be sorted? Is it something that is the motor and not speedo? or is it both that can be the cause?

It's an issue with sensorless brushless motors/ESCs, causing stuttering movement when accelerating from a standing start.

It's caused (AFAIK) by the pulsing of the ESC and the rotation of the rotor getting out of sync (the best metaphor I can think of is the hula hoop - get your gyrations timed wrong, and the hoop falls to the floor). Sensored systems don't suffer this (the sensor cable provides the ESC with feedback about the rotor position), and some sensorless systems fair better than others.

So if this fella had a sensored speedo.. and it was cogging.. is it down to the speedo or motor? (sorry for all the questions).. just trying to help a buddy.

Presuming the ESC can do sensorless operation, it's a both/neither scenario - some combinations work better than others. He may be able to adjust the timing on the motor or ESC, that might help.

What does he have, ESC and motor?

it could be either or the sensor lead try replacing the one by one to eliminate them from fault eg try with a different sensor lead then try the speedo with a diff motor and the try a diff speedo if poss and you will be able to work out which one is at fault

Lrp sphere tc.. not sure on the motor...:confused:

Just looking into it, it seems a lot more complex than I thought, its not limited to sensorless motors. Its when you turn a motor and it jumps to the points where the magnets all line up, I think RC enthusiasts have kinda given it a new meaning by the stuttering acceleration thing. Some people suggested checking the sensor cable or timing of the motor.

Will pass on all the useful info you guys have provided.... any more info always a bonus.. thanks all..:)