Modular drilling machine and components thereof

A drilling machine includes a drilling substructure skid (20) which defines two spaced parallel skid runners (22) and a platform (26). The platform supports a draw works (138) mounted on a draw works skid (130), and a pipe boom is mounted on a pipe boom skid (80) sized to fit between the skid runners (22) of the drilling substructure skid (20). The drilling substructure skid supports four legs (50) which in turn support a drilling platform (52) on which is mounted a lower mast section. The legs are pivotably mounted both at the platform and at the drilling substructure skid and a pair of platform cylinders (68) are provided to raise and lower the drilling platform. A pair of rigid, fixed length struts (70) extend diagonally between the platform and the substructure skid away from the platform such that the struts do not extend under the platform and obstruct access to the region under the platform. Preferably, the pipe boom skid (80) mounts a pipe boom (90) as well as a boom linkage (97), a motor (100), and a hydraulic pump (102) adapted to power the pipe boom linkage. In a further embodiment described the substructure skid is formed in upper and lower skid portions, and levelling rams are provided to level the upper skid portion with respect to the lower skid portion. Mechanical position locks hold the upper skid in relative position over the lower skid.