the longitudinal axis 38 and are suitably respectively engaged at about the midpoint of clevis quadrant segments 61 63 shown in fig2 d and fig7 which are separated by axial slots 37 the provision of two separate axially displaced pivot posts 45 47 for the respective manipulation members 90 92 in accordance with the present invention establishes a lever arm indicated at 70 in the end effector 34 open 34 position of fig5 c when push rod 60 is moved in the axial direction indicated at 72 lever arm 70 for manipulation member 90 is the distance from pivot 45 to the through hole 85 in member 90 which pivotally engages linkage means 87 linkage means is suitably a thin metal bar e g stainless steel to which flattened portion 62 of push rod 60 is pivotally engaged engagement is obtained by transverse pivot rod 89 which passes through hole 93 of metal linkage bar 87 a comparison between prior art devices such as seen in fig4 and the device of the invention shows that the prior art devices such as device 12 of fig4 have axial offsets 220 221 which are less than the offsets 120 121 of the device of fig5 of this invention comparison also shows that the lever arm 70 of the device of fig5 is and can always be greater in length than the lever arm 75 of the prior art axially in line arrangement of fig4 e g by at least the incremental distance shown at 74 in fig5 c this distance 74 extends from the longitudinal axis 38 to the hole 85 in the base portion of the manipulation member 90 the offset distance 220 of the prior art device of fig4 is limited to a distance of less than one.