Patent ID: 7837563
Filing Date: 2010-11-23
Classification: F16D

Abstract:
1. A power transmission device comprising: a rotating shaft including a rotating shaft body, a male thread section formed at a tip of said rotating shaft body and having a diameter smaller than rotating shaft body, and a stepped section formed between male thread section and said rotating shaft body; a wheel having a through hole formed in the center thereof and through which said male thread section is inserted, an abutment section facing toward said rotating shaft body and abutting against said stepped section, and an inner circumferential surface being formed on an inner circumference of this through hole; and a tubular member having a female thread section formed on an inner circumference thereof and screwed to said male thread section and an outer circumferential surface formed on an outer circumference thereof and press-fitted into said inner circumferential surface, wherein, when a normal load, which is less than a load required to cause an interruption of torque in the power transmission device, is applied between said rotating shaft and said wheel, due to the fact that said female thread section of said tubular member press-fitted into said inner circumferential surface of said wheel and said male thread section of said rotating shaft are screwed to each other, the abutment section of said wheel is pressed against the stepped section of said rotating shaft so as to transmit rotational torque and, when an excessive load, which is a load that is sufficiently high to cause an interruption of torque in the torque transmission device, is applied between said rotating shaft and said wheel, said wheel rotates with respect to said rotating shaft, and due to the fact that the female thread section of said tubular member and the male thread section of said rotating shaft are screwed to each other, said tubular member is pushed toward said rotating shaft body so that said tubular member is withdrawn from said inner circumferential surface of said wheel and the power transmission between said rotating shaft and said wheel is interrupted.