Tucked in behind the pint-sized diesel shop at the Stuart Street Yard was a structure common to most locomotive servicing facilities; a tall, somewhat spindly appearing sand tower.
Traction sand has been a component of railroading ever since the creation of the steel wheel on steel rail combination. Given the inherent low level of contact friction and minute contact area, augmentation of steel on steel traction is essential. Grip for initial movement, smooth acceleration and controlled braking are all dependent to some degree upon proper sanding. Sanding also helps to maintain traction and motion on greasy rail conditions caused by moisture, oil or fallen leaves. Traction sand must be fine, uniform grain, free from contaminants, and most importantly, dry. First generation F units and switchers were typically equipped with four sand fill/hoppers located more or less above each truck side frame. Dick Dilworth’s legendary ‘Geeps’ had a single sand fill located in the prow of each high nose, with internal piping down to each side. Most modern locomotives are similarly configured, although so called ‘safety cab’ locomotives have two fill hatches either side of their wide nose. Delivery of sand to the rail head is accomplished via flexible rubber hoses and nozzles secured to the ends of each truck side frame.
|Blomberg Type ‘M’ rear truck on GP40-2L(W) No. 9468 (GMD 7/1974)|