Improvements in Electric Arc Lamps.
Year: 1896

page_text: Date of Application, 3rd Mar., 1896-Accepted, 4th Apr., 1896
COMPLETE SPECIFICATION.
Improvements in Electric Arc Lamps.
I, THOMAS EDGAR ADAMS of 938 Case Avenue in the City of Cleveland,
County of Cuyahoga and State of Ohio, United States of America Electrical
Engineer, do hereby declare the nature of my invention, and in what manner the
same is to be performed, to be particularly described and ascertained in and by
the following statement:-
My invention relates to the contact or gripping surfaces of friction clutches for
electric arc lamps. Its objects are to provide clutching surfaces of a character
that will not be affected by humidity, corrosion or the depositions of gases or oil;
that will remove such depositions if formed from the object to be clutched keeping
its surface bright and clean, and that will therefore always be in condition to
instantly clutch or release the object; responding quickly and accurately to all
requirements. It consists of lining or facing the clamping or gripping members of
a clutch with graphite, preferably in solid blocks which are suitably attached to
said members, and shaped to fit upon the diametrically opposite surfaces of the
object to be clamped.
My improvement is particularly designed for use in mechanisms where lubrication
of the frictional contact faces is difficult or undesirable, and where these surfaces
should be kept clean and free from sticky or rough depositions in order that the
action of the clutch should be positive and unvarying.
It is applicable to and particularly useful in electric arc lamps in which the rods
that carry the moving carbon sticks are held by clutches which release their hold
at frequent intervals to permit the minute step by step feed of the carbon as
required at the arc or point of combustion.
The continuity and steadiness of an are light is absolutely dependent upon the
promptness and accuracy of this feeding mechanism for failure to respond quickly
leaves the carbon points too far apart while too great a movement of the carbon will
bring the points together and close the arc; either of these conditions being
detrimental to the light.
Many of the metallic clutches now in general use in arc lamps will operate
reasonably well when all the parts are clean and bright, but become defective and
irregular in action when the parts become corroded through exposure to the
elements or coated by depositions from impurities in the atmosphere, or by the
gases and funies arising from the combustion at the arc immediately below them.
I have found that by the use of graphite in the frictional contact surfaces of
clutches the coating of the parts to an injurious extent is prevented; such deposits
having no detrimental effect on the graphite surface which will prevent
permanent deposits upon or remove them from a metallic surface to which it is
opposed. The prevention of permanent injurious deposits, or coatings upon metal
surfaces opposed to the graphite surfaces of clutches is due to the fact that the
minute pores and indentations in the surface of the metal soon become filled with a
fine graphite dust or powder, which is rubbed off from the opposing graphite block
and into the interstices of the metal which is thus kept smooth and bright by the
action of the graphite shoe.
Any deposit which might form upon the clear surface of the metal is largely
prevented from close adhesion thereto by this under filling of graphite powder,
which is constantly being renewed by the graphite block.

page_text: For these reasons my improvement is particularly valuable in mechanisms the
proper performance of whose functions are dependent upon the delicacy and
accuracy of the operations of clutches or brakes.
In the accompanying drawings; -
Figure 1 of the drawings shows a well known form of clutch mechanism
employed in electric are lamps for controlling the carbon rod, with the gripping
faces of the clutch lined or faced with graphite blocks in accordance with my
invention; the clutch members being in holding contact with the rod; some of the
parts being broken away for purposes of better illustration.
Figure 2 is a sectional view of the same on the line 2, 2 of Figure 3, and shows
the clutch members having released the rod.
Figure 3 is a plan or top view of the same showing the parts in the same position
as in Figure 2.
The rod A which carries the movable carbon in an arc lamp is held between the
members B B of a clutch, said members being connected by pivots c and e' to a
lever C the free end of which is rocked up and down by suitable mechanism in the
lamp to cause it to force the clutch members into contact with or release the rod A
as required.
The members B B are lined or faced with graphite blocks b, which come
into contact with and clamp upon the rod A. These blocks are attached to the
members in any suitable manner.
Having now particularly described and ascertained the nature of my said inven-
tion, and in what manner the same is to be performed, I declare that what I
claim is :-
In an electric arc lamp, the combination with the carbon rod and a clutch having
jaws disposed at diametrically opposite sides of said carbon rod, of graphite
facings on said jaws, said graphite facings being thus adapted to receive the
carbon rod between them and engage the same at diametrically opposite points,
substantially as set forth.
Dated this 3rd day of March 1896.
HERBERT HADDAN & Co.,
18, Buckingham Street, Strand, London, W.C., Agents for Applicant.