Abstract: An anti-backlash device for use in connecting a rotary drive to the drive shaft of a fuel injection pump, comprising a hub member within which at least one fixing pin is arranged to be moveable transversely of the hub axis, so that an abutment end of the fixing pin can be brought into contact with an end portion of such a drive shaft when the device is in use. Each fixing pin is in screwthreaded engagement with the hub member, and means are provided to rotate the or each fixing pin, thereby to bring about contact between the abutment end of the fixing pin and an end portion of such a drive shaft by virtue of the said screwthreaded engagement.