Abstract: A chuck (25) for chucking a journal (271) of a crankshaft (27) is attached to the distal end of a main spindle (22) rotated by a drive motor. A phasing rotary shaft (53) is connected to the chuck (25) to rotate about an axis offset from the axis of the main spindle (22). The chuck (25) is provided with a coupling (63) that releasably connects the phasing rotary shaft (53) and the chuck (25). Further, a locking mechanism for locking the phasing rotary shaft (53) is provided. The coupling (63) has a pair of coupling plates (64 and 65) that can be moved closer to and farther from each other. Opposing faces of these coupling plates (64 and 65) have teeth (641 and 651), which are meshed when the coupling plates (64 and 65) are brought close to each other.

Abstract: A crankshaft phase indexing apparatus of this invention is provided with a pair of spindles arranged in alignment with a first axis. The Spindles are rotated respectively by a pair of spindle driving motors, which are controlled to rotate at the same speed. Chucks are mounted to the respective spindles. The chucks hold ends of a crankshaft in alignment with a second axis, which is displaced from and parallel to the first axis. A phase conversion shaft is rotatably arranged in at least one of the chucks in alignment with the second axis. The phase conversion shaft is connected to the crankshaft for rotating the crankshaft to permit phase indexing of crankpins of the crankshaft into axial alignment with the first axis. A phase indexing shaft, which is coupled to the phase conversion shaft, is located concentrically with the spindles and is rotated by a phase indexing motor.