Tools and Machinery of the Granite Industry, Part II

Chronicle of the Early American Industries Association, Inc., The, Sep 2006 by Wood, Paul

Introduction

This article, the second in a series of four on granite working, completes the description of the quarrying process. The final two articles, dealing with granite finishing and other granite working topics, will appear in the next two issues of The Chronicle.

Lifting and Moving

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A s long ago as the 1420s, Filippo Brunelleschi had invented an ox hoist with a five-foot diameter solid elm drum that lifted a total of seventy million pounds of marble, brick, stone, and mortar during the construction of the main dome on Florence's cathedral Santa Maria del Fiore (Figure 1). Brunelleschi also invented a balance crane that was similar to the modern tower crane with a long, horizontal, asymmetrical, counterweighted boom. Four centuries later, Solomon Willard (circa 1820s) invented or perfected a boom derrick (called a "hoisting apparatus" in Figure 2), which is in most respects the derrick used in today's granite quarries. He also invented or perfected other stone lifting and moving devices, including the geared lifting jack, the screw hoisting jack, and the pulling jack (Figure 2). A fifteen-ton capacity double-geared lifting jack, very similar to Willard's jack, was still being made and sold for $125 at the turn of the twentieth century (Figure 3). A modern counterpart of Willard's pulling jack is the "tugger," a small, one-drum, compressed-air hoist mounted on the front of a steel plate. The plate rests on the quarry floor and is secured in place by a wire rope fixed to two holes in the back corners of the plate and running around a two-inch steel anchor pin driven into the floor of the quarry. The operator stands on the back of the plate behind the hoist and controls the hoist by a lever that causes power to be applied to the drum and a second lever that brakes the drum. The tugger is most useful in areas that the boom derricks cannot reach.

During the latter part of the nineteenth century and most of the twentieth century, the boom derrick did the majority of the heavy lifting at the quarry and in the finishing shed yard. The "derrick sticks" (mast and boom) were made of Douglas fir, up to four feet in diameter and up to a hundred and fifteen feet long, and were fit into derrick irons made in local foundries. The derrick sticks were shipped on three forty-foot flatcars from Oregon and Washington. Although quarrymen liked the elasticity of wood, by the end of the twentieth century steel derricks had supplanted the wood derricks. Most derricks were guy boom derricks (Figure 4) with up to a dozen 1 ½-inch diameter guy ropes radiating out from the guy plate at the top of the mast and secured to granite ledges or deadmen (large buried blocks of granite).

The terms cable and rope were used interchangeably to refer to steel wire cables. (We will use the term rope.) Often adjacent derricks were guyed together, from mast top to mast top, with "sky guys." If there was not sufficient space for the guy ropes, a stiff-leg derrick (Figure 5) might be employed where the guys were replaced by two wooden poles secured to the top of the mast and anchored in the ground behind the mast. The boom, up to one hundred feet long, was attached at the bottom of the mast and swung as the mast rotated on an iron base called the "kettle." A six-foot diameter cast iron wheel, the "bull wheel," was fixed to the bottom of the mast and was used to rotate the mast and boom via the swing rope. The boom could be raised and lowered by the boom rope that came out of the derrick engine house roof and was reeved over the "rooster sheave" at the top of the mast. A derrick with a hundred-foot boom could reach any point within a circle of almost three-quarters of an acre in area. In the mid-19OOs, a typical boom derrick (including hoist equipment) cost twenty thousand dollars.

There were three moving derrick ropes, the swing rope for swinging the boom (¾-inch diameter), the boom rope for raising and lowering the boom (¾inch diameter), and the non-twisting fall rope (1 ¼-inch diameter) for raising and lowering the hook. Each derrick used about a mile of rope for guys, swing rope, boom rope, and fall rope. The fall and boom ropes, in constant motion, were replaced two or more times per year.

Early derricks were called dead-boom derricks (Figure 6) since they had no swing rope and the boom had to be manually swung by pulling sideways on the hook. The hoists for these early derricks had two drums, one for the boom rope and another for the fall rope, and were either manually-powered or horse-powered. The manually-powered hoist (Figure 7) was fastened to the base of the mast and had one or two crank handles for one- or two-man operation. A gear shift allowed power to be selectively applied to either the fall rope drum or the boom rope drum. Usually, the hoist had a pawl mechanism that prevented backward rotation of the drums. Many hoists had gearing for two speeds, fast for light loads and slow for heavy loads. Two men with the slow gear could lift five tons and with the fast gear twenty-five hundred pounds. Also, hoists usually had handles on the rims of the large gears that allowed rapid take-up of slack rope. A 'lazy shaft" was often provided so that the load (granite block or boom) could be let down without the crank handles turning. The horse-powered hoist (Figure 8) had a sweep that consisted of a long horizontal "sweep" pole that drove the drums through bevel gears. One or two horses were tethered to the end of the pole and walked in a circle. The sweep and hoist were normally located at some distance from the mast base so as to be out of the way of derrick operations. The rope from the hoist to derrick was recessed in a trench (note the trench in Figure 6). The horse-powered hoist provided much more lifting power-four to five tons in fast gear and twenty-five to thirty tons in slow gear.

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Tools and Machinery of the Granite Industry, Part II

Chronicle of the Early American Industries Association, Inc., The, Sep 2006 by Wood, Paul

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