PURPOSE: To provide secure prevention of a draw bar pin from coming off by installing a stopper on a draw bar lever so that a pivotally connecting point may not go over a dead line in such a way as making a dead line which prevents the draw bar pin from coming off due to pushing-up to have an effective function.

CONSTITUTION: A draw bar pin 2 is disposed so that it may elevate in relation to a draw bar bracket 1 fixed securely on a vehicle body 90. The head of the draw bar pin 2 is connected to a draw bar lever 4 through a draw bar link 3. The draw bar lever 4 is pivotally connected with a lever bracket 5 fixed securely on the vehicle body 90 and is constructed so that it may rotate through an operating lever 96, whereas a stopper is installed on the draw bar lever 4. The stopper regulates a pivotally connecting point C between the draw bar lever 4 and a draw bar link 3 so that it may no elevate beyond a dead line D at the time of pushing-up of the draw bar pin 2 by a carriage.