resting on the ground as shown in fig2 the operator will maneuver the tractor 10 and operate the boom cylinders 20 so as to place the attachment holders 28 rearwardly of and adjacent to the mounting brackets 40 of the bucket 14 the hydraulic cylinders 34 are then extended to cause the attachment holders 28 to be rocked forwardly about the pivot pins 33 and the tractor 10 is driven forwardly to bring the u shaped recesses or saddles 38 into engagement with respective mounting bracket pins 46 the cylinders 34 are then retracted while the boom cylinders 20 are operated to lift the arms 22 such that the bucket 14 becomes suspended on the holders 28 the weight of the bucket 14 causes the latter to swing rearwardly about the pins 46 so as to engage the ramp surfaces 70 of the latch pins 54 with the ramp surfaces 72 of the block like coupler elements 30 as shown in fig3 this engagement causes the latch pins 54 to be shifted upwardly against the biasing force exerted by the springs 66 a distance sufficient for permitting the coupler elements 30 to move into the receptacles 48 as shown in fig4 as the coupler elements 30 move past the lower end of the latch pins 54 the springs 66 shift the latch pins 54 back to their latch positions the loader bucket 14 is then securely held for operation it is here noted that in the event that someone for some reason places the latch pins 54 in their raised unlatched positions shown in fig5 prior to attaching the bucket 14 to the holders 28 39 the operation will.