Winsun… this is well-argued/never-located OimoJS problem with the maxForce second parameter of setMotor(speed, HERE). Last I knew… it needs to be a HUGE value.
HUGE discussion with little/no resolution…here…
https://forum.babylonjs.com/t/frozen-motor-bearings-on-the-oimo-car-and-oimo-paddlewheel
(sorry for this bad news). WAY down at bottom of thread, SOME work-arounds were found… by going WAY down to joint.shapeA and shapeB… and removing MASS settings on shapes at THAT level… which were seen to be FAR inflated beyond sanity.
After those “native tweaks”, THEN the hinge motors started working without “the jitters”… at a much more sane maxForce value (such as 3 instead of 1,000,000).
We never found the problem… but we DID manage to see at what version of BJS… this problem came into existence. Find it, fix it, and you become a super hero, and Oimo setMotor becomes usable again, and Oimo becomes valuable to us again.