an end cap 74 that is threadedly secured to the fluid cylinder 70 in a manner well known in the art a piston 76 has a fluid seal 78 that retains fluid pneumatic or hydraulic within a fluid chamber 80 of the fluid cylinder 70 a port 82 supports the connection of a fluid supply line not shown to the cylinder 70 a rod 84 connected to a fluid end of the piston 76 has a piston position indicator 86 that reciprocates through a fluid seal 88 in the end cap 74 the position indicator 86 provides a visual indication of the position of a lock bolt 90 connected to an opposite side of the piston 76 in operation the lock bolt 90 is constantly urged through a circular port 92 in the inner end of the cylinder 70 by fluid pressure in the fluid chamber 80 fig9 is a schematic cross sectional diagram taken along lines 8 8 shown in fig1 of the module 20 with the ball retainer mechanism 58 in the ball released position shown in fig7 when the actuator moves the ball retainer mechanism 58 to the ball released position fluid pressure in the fluid chamber 80 of the cylinder 70 drives the lock bolt 90 through the lock bore 44 in the actuator stem 34 locking the.