Leadscrew mechanical drive with differential leadscrew follower structure and brake

Abstract

A leadscrew mechanical drive includes a leadscrew having a leadscrew axis and a leadscrew thread with a nonzero leadscrew thread pitch. A leadscrew follower structure is engaged to the leadscrew. The leadscrew follower structure includes a first leadscrew follower and, desirably, a second leadscrew follower. The first leadscrew follower and the second leadscrew follower are substantially identical, and each leadscrew follower includes a threaded insert having an insert thread with a nonzero insert thread pitch different from the leadscrew thread pitch. The insert thread is engaged to the leadscrew thread over a circumferential distance of less than one-half turn of the insert thread. Each leadscrew follower further includes a bearing in which the threaded insert is received and which permits the threaded insert to rotate about an insert axis that is inclined to the leadscrew axis by an angle θ for the first leadscrew follower and −θ for the second leadscrew follower, and a bearing support in which the bearing is receive. A preload structure biases each of the leadscrew followers against the leadscrew. A brake is selectively engagable to the threaded inserts to selectively permit the threaded inserts to rotate about the insert axis or prevent the threaded inserts from rotating about the insert axis.