Patent ID: 7543514

Claim:
A ball screw device comprising: a ball nut including a bore formed therein, and including an inner thread formed therein, a support, a screw shaft rotatably attached to said support and engaged into said bore of said ball nut and including an outer thread formed thereon for engaging with said inner thread of said ball nut and for allowing said ball nut to be rotated and moved relative to said screw shaft, and for forming a helical raceway between said ball nut and said screw shaft and for filling a lubricating oil into said helical raceway, a plurality of bearing members engaged in said helical raceway that is formed between said ball nut and said screw shaft for facilitating a movement between said ball nut and said screw shaft, a warning signal generating member provided for generating a warning signal when said lubricating oil is not suitably supplied into said raceway between said ball nut and said screw shaft, and an actuating device provided between said warning signal generating member and said screw shaft for selectively and electrically coupling said screw shaft to said warning signal generating member.