Abstract: A force feedback interface device includes improvements in a mechanical linkage and drive mechanism. The force feedback device is coupled to a host computer and includes a user manipulatable object graspable by a user, at least one actuator that outputs a force on the user object, and a sensor for sensing motion of the user object. A linkage mechanism provides the user object with degrees of freedom and includes five members rotatably coupled to each other. The linkage mechanism supports the bearings of the device with protrusions rotatably coupled to central members of the linkage. The drive mechanism is preferably a belt drive that includes an idler positioned adjacent to a drive pulley and which impedes radial displacement of a belt away from the drive pulley, and thus impedes losing positive engagement of the belt, without preloading the belt. The idler can be a passive idler that does not contact the belt during operation and/or an active idler that continuously contacts the belt.