|
Direct Connected Drum Machines
The windlass was the earliest
device by which early man wound rope upon a drum; in the Gallery, "Birth
of Systematic Agriculture," a tree trunk was used as a drum. The drums
were gradually refined and many came to be driven by reciprocating pistons
of steam and gas engines. It was natural that elevator manufacturers
and engineers saw the drum as the answer to the need for a direct-connected
electricity-driven hoisting machine. It was also natural that several
other systems were developed that used electricity but not the drum.
As the roped hydraulic had been a popular choice for high-rise buildings
for a number years, a number of manufacturers and owners were prone to
remain with a system that had afforded the safety of multiple host cables.
The advent of the drum direct-connected machine was hotly contested
by the Pratt-Sprague system, but with the failure of the latter's core component -- the drive nut -- the drum emerged a winner. It was to
remain popular for low-rise heavy-duty lifting, but as elevators were
called upon to serve ever-higher buildings, the baton was passed on to
the direct traction machine.
|

|