fig4 and 7 a yoke 72 is mounted on female coupling members 34 and 36 by means of four retaining rings 73 which are located on both sides of the yoke 72 in grooves not shown provided in the locking collars 76 and 78 of the female coupling members 34 an 36 respectively the yoke 72 moves with that is follows the motion of the collars 76 and 78 of the female coupling members 34 and 36 respectively a yoke stop 80 is secured by two nuts 81 threaded on one end of a shaft 82 on both sides of the yoke stop 80 the other end 83 of shaft 82 is threaded through a support 85 connected to the table insert 33 the position of the yoke stop 80 may be threadably adjusted with respect to the table insert 33 by turning the rod 82 thereby moving it with respect to support 85 nut 84 on the other end 83 of the shaft 82 is used to lock the rod 82 with respect to the support 85 the nuts 66 adjust the position of the male and female coupling members longitudinally or in this application vertically so that when the pallet 10 is positioned on the table 30 the coupling members are relatively positioned to allow operation of the locking collars rotation of the rod 82 changes the position of the yoke stop 80 with respect to the yoke 72 and allows an adjustment of the point at which motion of the locking collar is inhibited thereby releasing the male coupling members 12 and 13 from the female coupling members 34 and 36 respectively a proximity switch 86 of fig7 is used to determine that the locking collars have reached their upward biased position thereby indicating.