any failure to shafts 15 16 because the brake assemblies 31 32 are structurally connected directly to drum spools 17 18 instead of to shafts 15 16 i e shafts 15 16 are structurally isolated from the brake assembly while the sand drum spool 18 has one brake flange 20 mounted on it in accordance with this aspect of the invention it could have two brake flanges 20 attached to it as shown in fig3 the sand drum drumshaft 16 at one end is rotatably connected to sprocket 5 having two sets of sprocket teeth attached to it by way of a keyed hub 7 the opposite end of sand drum drumshaft 16 is rotatably connected to clutch 30 mounted via key 36 the torque necessary to rotate the sand drum spool 18 is input through sprocket 5 mounted on sand drum drumshaft 16 and is transmitted through key 36 which is loaded in shear to sand drum drumshaft 16 from there the torque is transmitted through key 7 loaded in shear to the hub of clutch 30 and upon application of air pressure the torque is transmitted through clutch drive ring 32 to spider 21 mounted on an extension to sand drum spool 18 spider 21 is also the component to which brake flange 20 for sand drum spool 18 is mounted the torque applied to sprocket 5 which.