rod 23 for this purpose bushing 25 is shortened and the end remote from flange 26 is provided with larger bore 30 into which spring loaded plastic ring seal 31 is fitted the axial dimension of bore 30 is slightly in excess of the axial dimension of ring seal 31 say about 1 32 inch in excess to hold ring seal 31 in bore 30 of bushing 25 bushing segment 32 is kept abutted with bushing 25 by metal coil spring 33 disposed between bushing segment 32 and tapered end 34 of bore 24 in sleeve 21 clearly the inner lip of ring seal 31 is in pressing contact with slidable end rod 23 and thus provides a seal against the seepage of vapors along the interface between end rod 23 and bushing segment 32 fig5 shows the same end fitting 20 of fig4 comprising sleeve 21 with bores 22 and 24 end rod 23 and cap 28 with central opening 29 screwed on threaded end 27 of sleeve 21 however bushings 25 and 32 of fig4 have been replaced in fig5 with bushing 35 which has enlarged bore 36 dimensioned to hold spring loaded plastic ring seal 31 in pressing contact with end rod 23 the opposite end of bushing 35 has been turned down to a smaller outside diameter to provide central projection 37 dimensioned so that spring loaded plastic ring seal 38 fits between bore 24 of sleeve 21 and projection 37 on the end of bushing 35 washer 39 is held by metal coil.