brush 71 downwardly and forcefully against the surface s obviously during the latter defined movement of the rods 148 149 the fluid exhausts the cylinders 146 147 over the respective lines 153 154 as will be described more fully hereinafter just as obvious is the fact that fluid introduced through the lines 153 154 and vented through the lines 151 152 will result in the retraction of the rods 148 149 respectively and the counterclockwise rotation of the shafts 107 87 the arms 133 135 the arms 84 85 and the broom 71 carried by the latter means 164 165 fig7 are independently associated with each of the pivotal mounting means or mechanisms 94 95 and continuously apply spring biasing forces tending to urge or pivot the shafts 107 87 and the arms 84 85 thereof in a counterclockwise direction again as viewed in fig3 and 7 thus likewise continuously tending to urge the broom 71 away from the surface s the means 164 165 are in each case a tension spring having one end connected to the respective arms 132 134 and an opposite end connected to a respective threaded bolt 166 which in turn passes through an aperture unnumbered of a bracket 169 fig1 welded to the top wall 25 of the pick up head 10 a washer 167 and an associated nut 168 is threaded to each of the bolts 166 to draw the bolts 166 to the left as viewed in fig1 and 7 for increasing the tension of the springs 164 165 or vice versa accordingly the fluidic force of the piston cylinder mechanisms 144 145 when operated in a direction to urge the broom 71 toward the surface s is counteracted by the.