lever arm 21b through a clevis 22b and a pivot pin 23b as in the previous embodiments the body portion 24b includes an upward extension 58b and a lower extension 99 generally axially aligned therewith and an offset cylindrical passage 59b extends through both extensions and substantially tangentially intersects the stepped recess 38b in the body portion this assembly will utilize a one way spring clutch not shown such as shown in fig2 adapted to be in operative engagement with the cylindrical surface of the rotor 46b and the adjacent cylindrical surface of the worm shaft 40b however the torsion spring required in the previous embodiments is not utilized in the present assembly a radially extending actuating arm 51b integral with the rotor 46b extends into the cylindrical passage 59b and has an upper rounded surface 82b and a lower rounded surface 83b similar to that shown in the embodiment of fig5 the lower end of the cylindrical passage 59b terminates in suitable threads for threaded engagement with a screw cap 101 having an interior cylindrical recess 102 to receive the lower end of a return spring 103 a secondary hollow piston 104 is received in the lower portion of the cylindrical passage within the lower extension 99 and has a central passage 105 to receive the upper end of the return spring 103.