Patent ID: 7914226

Claim:
A system for retaining engagement of first and second elements within a coupler, the system comprising: a coupler having a sidewall and an aperture formed therethrough; a safety pin insertable into an aperture formed through a sidewall of the coupler, the safety pin comprising a head, a shaft depending from the head along a longitudinal axis, a distal end of the shaft opposite the head, and an element that extends radially outwardly from a portion of the shaft, the shaft, the distal end of the shaft and the element disposed in the aperture of the coupler; and a removable plate fixed to the sidewall of the coupler occluding a portion of the aperture corresponding substantially in size and shape with the element of the safety pin to prevent passage of the distal end of the safety pin through the aperture, wherein when the removable plate is fixed to the sidewall of the coupler the portion of the aperture not occluded by the removable plate is sized to allow passage of the shaft through the aperture.