Abstract: A retaining pin assembly (16) for securing a replaceable earthworking tool (14) to a support member (12) includes a spring type pin (36) and a coacting sleeve (40). The pin assembly (16) is insertable through generally aligned openings (30,22) in the tool (14) and support member (12) and functions to lock the tool (14) to the support member (12) and to force an end portion (28) of the tool (14) into contacting relationship with shoulders (18,20) of the support member (12). Earthworking apparatus, such as impact rockbreakers and rippers, generally include a replaceable tool mounted on a shank or support member. Unless the tool is forceably held in contacting relationship with the support member, the retaining pin, tool, and support member are subject to damage. The retaining pin assembly (16) of the present invention secures the tool (14) and support member (12) in contacting relationship and maintains a continuous locking force between the tool (14) and the supporting member (12 ).