components an internal channel not shown in the hollow coupling member 40 provides a passageway from the 3 way ball valve 50 to the hollow cylinder 56 as shown in the cross sectional view of the cylinder 56 in fig3 a piston 66 is located at the bottom of the cylinder 56 adjacent a support member 62 which supports the cylinder 56 on the internal wall 54 of first side plate member 16 the connection is made by the threaded bolt 58 the piston 66 comprises a head portion 68 and an extension portion 70 the head portion further comprises a circumferential groove 72 which houses an 34 o 34 ring sealing member 74 or alternatively a cup seal sealing member not shown which by way of example can be made of teflon the piston 66 is supported by piston rod 76 which at its upper end is inserted into the piston extension portion 70 the lower end of piston rod 76 is affixed to rod end coupling member 78 by way of example rod end coupling member 78 can be a generally h shaped piece of metal tubing with an upper face 80 a lower face 82 and a recessed mid portion 84 a pair of stationary support brackets.