application apparatus 10 the linkage structure 72 is comprised of an l shaped member 74 linking the containment hood 18 to the cam 70 and an l shaped member 76 linking the vacuum system 20 to the cam 70 between the cam 70 and the containment hood 18 the l shaped member 74 is translatably attached to elongate support members 78 and 80 by pins 82 and 84 respectively likewise between the cam 270 and the containment hood 18 the l shaped member 76 is translatably attached to elongate support members 78 and 80 by pins or bushings 86 and 88 respectively at their proximal ends 92 and 94 the l shaped members 74 and 76 are attached to rollers 96 and 98 respectively in addition the l shaped members 74 and 76 are biased by springs 90 the springs 90 bias the l shaped members 74 and 76 toward each other cam 70 may be driven between two positions as shown by a pneumatic hydraulic or electric linear motor cylinder 93 through a rod and pivot linkage 95 as shown the cam 70 may also be driven by a rotary electric motor or a pneumatic or hydraulic drive system that is capable of varying speeds and or incremental rotation in either such arrangement as the cam 70 rotates depending on the position of the cam 70 relative to the rollers 96 and 98 the containment hood 18 and the vacuum system plenum 21 are either in a closed or open position other methods and structures known in the art can be used to engage and disengage the containment hood 18 and the vacuum system 20 in a cyclic manner in addition those skilled in the art will appreciate that it may not be necessary.