a concavity 37 that engages a part of barrel 27 at the end portion of barrel 27 that is opposite oval shaped end portion 44 concavities 38 39 are provided on each locking arm 34 opposite concavity 37 end portion 36 of barrel 27 provides preferably three circumferentially spaced apart radially extending slots 42 when moving to an expanded position of fig3 4 and 7 each locking arm 34 extends through a slot 42 when moving to the extended position of fig7 each locking arm 35 engages a curved edge 48 of barrel 27 end portion 36 that is next to a slot 42 as shown in fig7 shaped end portion 44 joins to barrel 27 at shoulder 43 the shaped end portion 44 provides an oval shaped outer surface 45 coil spring 46 fits over shaped end portion 44 and engages annular shoulder 43 collar 47 is fitted upon shaped end portion 44 with shaft 29 and its enlarged end portion 50 which provides eyelet 49 in order to disengage pin assembly 14 from shackle bow 11 a user pulls spring loaded release pin 51 and then pushes collar 47 in the direction of arrow 55 which allows handle 52 to be rotated inversely by rotating handle 52 in opposite direction once locking arms 34 are fully extended the spring 46 pushes collar 47 onto eyelet 47 which locks central shaft 29 into a fixed position with locking arms 34 extended and no amount of vibration can disengage them handle 52.