Ah, slider joint makes more sense :)
Try experimenting with the following functions using the same methods as mentioned above (constant low force and opposite forces)...
dJointSetSliderParam(joint,param,value#)
dJointAddSliderForce(joint,force#)
dJointGetSliderPosition#(joint)
dJointGetSliderPositionRate#(joint)
Try experimenting with the following functions using the same methods as mentioned above (constant low force and opposite forces)...
dJointSetSliderParam(joint,param,value#)
dJointAddSliderForce(joint,force#)
dJointGetSliderPosition#(joint)
dJointGetSliderPositionRate#(joint)