Originally Posted by
tucson
Has anyone ever tried to put a lite coat of vaseline in our electric brakes to prevent them from grabbing and locking.
i am runing out of ideas short of buying the xicoy controller with a gyro. One brake always grabs harder and i wind up with embarrassing stops that want to swerve.
It is taking the fun away from flying this airplane for me.stan
Originally Posted by
camss69
This was actually suggested to me today as well, not Vaseline but the grease they use for the o-ring pneumatic brakes.
Don't bother with any lubricant...it won't improve the problem. It is NOT the JP controller. I have spent hours investigating this issue and I am confident that I have found both the cause and a solution. The problem boils down to competing magnetic forces and requires a simple physical modification to resolve.
Problem:
What seemed to be a great design didn't work out so well in practical application. There are two competing magnetic forces...the electromagnetic brake core and three tiny-but-strong magnets in the hub. The brake disc floats on the hub screws that protrude just enough to engage the disc. I believe the idea was that the three magnets in the hub will keep the disc away from the core to reduce random friction between the core and the disc. When the electromagnetic core activates, it overcomes the force of the hub magnets and pulls the disc against the core to cause the brake friction.
The implementation problem is that by the time the electromagnetic core generates a magnetic field strong enough to pull the disc away from the hub magnets, the core magnet strength is already so powerful that the wheel locks as soon as the disc engages the core.
Solution:
Remove the tiny magnets in the hub. The little magnets in the hub are simply press-fit. You can easily pop them out with a few firm taps with a punch/hex driver and hammer. See the pictures below. Since the brake disc has a floating movement range of only a fraction of a millimeter, if it does touch the core while freely spinning, it won't be hard enough or long enough to cause any appreciable friction. I've drawn a simple diagram that shows the wheel and brake assembly so you can better see the arrangement of components and visualize the problem and solution. After this simple 5 minute modification I have fully proportional brake function through the entire range of the controlling channel. Please note this is a non-destructive mod and you can reinstall the magnets in the hub if this does not resolve your issue.
I hope this helps others with the same issue.
Wheel/Brake Layout:
Here you can see how the brake disc floats on the hub screws.
The location of the tiny-but-strong magnets in the hub:
The removed magnets:
