Abstract: A tool carrier assembly (100) comprising a main body (101), a quick hitch (102), and a rotatable locking device (103) between the quick hitch and the main body. The rotatable locking device employs releasable locking means (104,105) at opposite ends. A scroll plate (106), cylinder (107) and piston (108) which upon assembly is located inside the cylinder) are located between the releasable locking means (104,105). In normal operation the piston (108) is driven back and forth to tilt the hitch by reason of rotation of the cylinder as guide (109) travels in the helical guide way (110) of the scroll plate (106). The hitch is fixed to the cylinder and the main body is fixed to the scroll plate. The releaseable locking means (104) and (105) each comprise an internally tapered end cup (111), bearing (112), an unlock piston (113), a locking element (114) and a locking spring (115).