Abstract: A drive transmitting device is disclosed which may be preset and will subsequently become locked if sudden or gradual rotation forces are applied, the device comprising a first member at least part of which is inside a second member, a rotation of one of the members in either direction about an axis of rotation causing a rotation of the other member about the axis. There are rollers around the axis which co-operate with wedging surfaces in the device to prevent a rotation of the said one of the members from its preset position about the axis as a result of a rotation of the said other of the members in either direction about the axis, the rollers being arranged in respective pairs around the axis, the number of such pairs being more than two. The forces required to restrain rotation are shared substantially equally between respective rollers of the pairs.