Page 19 - Equipment Echoes Issue #137

Sauerman Slackline Cableway Excavators

At 12 cubic yards, this is the largest capacity crescent bucket Sauerman offered in 1931.
Later, after the scope of this article, buckets as large as 20 yards were available.

electric, steam (with or without the boiler), gas, kerosene or diesel
Through belt drive, a traction engine could also serve a power unit for a slackline excavator. power or with belt drive. The power units were offered for specific
(Sauerman Bros. catalog, Shearar & Mayer Dragline Cable Excavators, n. d., HCEA Archives)
bucket sizes depending on each installation’s needs and working
a hand winch moved the tower. Self-supporting towers were better conditions.
suited for the largest projects requiring long spans and frequent The power unit needed to draw the bucket in slowly with a
relocation, but all else being equal the moveable guy tower was to strong pull for loading, then inhaul it at as high a speed as was
be preferred for its lighter weight and lower cost. safe to the dumping point. Loading speed was 100 to 250 feet
per minute, inhaul speed 300 to 1,350 fpm, and the track cable
Tail Tower and Anchorage was tensioned to lift the bucket out of the cut at 200 to 450 fpm.
An A-frame tail tower was needed on most installations to keep Electric power units simply used a two-speed motor, while on the
the bucket in the air at the extreme far end of the span from the others the front drum used two sets of independent gearing, each
head tower. The standard tail tower was built of wood and traveled with its own friction clutch. Each clutch was operated by a lever,
on rollers and planks; the track cable was threaded through a saddle and the two levers were interlocked so that as one clutch was
sheave and shackle assembly in the head of the tower. Behind the engaged, the other was released. Releasing both clutches allowed
tail tower, two anchor logs were buried in the ground about 120 the bucket to return by gravity to the cut. A three-speed motor was
feet apart. A sling cable was passed around each log and attached offered for longer spans, enabling a lower inhaul speed for short
to a bridle cable at the surface. The two bridle cables converged distances and higher for longer hauls.
and met the track cable at a bridle frame, and the position of the
end of the track cable relative to the mast was changed by means The Power Drag Scrapers
of hand winching one bridle line or the other. In the 1920s, Sauerman introduced an improved version of
the slackline dragline, the Power Drag Scraper. It operated by the
Power Units same basic principles, with two major differences. One was the
Although a slackline dragline’s hoist resembled a general service bucket. Patented by Harry A. Roe in1924, it was bottomless and
contractor’s hoist, its service requirements were much different. shaped like a wide crescent, so that it penetrated the ground like a
Sauerman called their hoists power units, and offered them with plowshare. The curved shape gave it the greatest strength at least

Arrangement of a standard Power Drag Scraper installation.

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