AN IMPROVED MACHINE FOR COVERING OR COATING INSULATED ELECTRICAL CONDUCTORS OR CONDUCTING WIRES WITH LEAD
Year: 1881

page_text: PROVISIONAL SPECIFICATION left by William Robert Lake at the Office of
the Commissioners of Patents on the 8th December 1881. A communication
from abroad by Hiram Stevens Maxim, of Brooklyn, New York, United States
of America.
WILLIAM ROBERT LAKE of the Firm of Haseltine Lake and Co., Patent Agents,
Southampton Buildings London "AN IMPROVED MACHINE FOR COVERING OR
COATING INSULATED ELECTRICAL CONDUCTORS OR CONDUCTING WIRES WITH
LEAD." [A communication from abroad by Hiram Stevens Maxim, of Brooklyn,
New York, United States of America.]
When insulated wires are to be placed in damp or wet places or whero they are
liable to rough usage as for instance when placed in sewers or in the ground it
becomes necessary to cover the insulating inaterial with some waterproof and
durable substance to resist the corrosive action of foul gases and water and also to
resist a moderate amount of attrition which substance must at the same time ba
soft enough to allow the wire to be bent in any direction without cracking.
Lead is found to be the best material for this purpose and according to iny
Invention I provide a machine for covering insulated wires with lead.
In the accompanying Drawings Figure 1 shews a side clevation of my improved
nachine.
Figure 2 a transverse section and
Figure 3 a longitudinal section of portions of the same.
The ingots of lead are placed in the melting pot A where the heat of the gas
flame soon fuses them. The inelted led is then pumped by the three pumps T T T
through the chambers B B B into the annular chamber C whence it flows out
with the wire as shewn. The burners M. M M keep the lead hot in the annular.
chamber C while the three burners marked K are for regulating the heat of the
lead in the discharge and consequently the pressure in the annular chamber C.
Should the lead bo too soft and flow out too freely then it may be cooled by the
water jacket D.
To cover wire to the best advantago a very high pressure on the lead is required
hat is to say 5000 pounds to the square inch or more. The pressure on the lead
s regulated as follows.

page_text: If the lead, were, thoroughly melted throughout it would flow freely out of the
space about the wire and there would be no appreciable pressure in the annulus C.
Again if the lead were quite cold in the space about the wire in the discharge it
would require a very high and destructive pressure to press it through the narrow
outlet. It is therefore obvious that some intermediate temperature has to be
employed one that will allow the lead to flow out in a semi-plastic condition
having strength sufficient to require considerable pressure to draw it out and
solidity enough to hold its shape on the wire after it leaves the discharge. To
regulate this temperature I employ the piston rod H the lever E the spring a' the
nut F the water valve O and the gas valve J.
The piston H enters the chamber of melted lead and its rod is subjected to the
pressure in the chamber C. The spiral spring G holds this piston in the chamber
and is opposed to the pressure. When however the pressure is sufficiently great
to overcome the force of the spring the piston rod is forced out and closes the water
valvo O at the same time opening the gas valve J. The heat of the gas makes the
lead more plastic, allows it to flow out more freely, and reduces the pressure. This
allows the spring G to move the lever E in the direction necessary for opening the
water-valve and for closing the gas-valve.
It will therefore be seen that the machine is automatic; if the lead is too cold the
pressure rises and lets on more gas and less water whereas if it be too hot and too
soft it reduces the pressure, and this lack of pressure turns off the gas and lets on
the water. There being three pumps the flow of lead is constant.