Improvements in Friction Driving Gear.
Year: 1891

page_text: Date of Application, 23rd July, 1891
Complete Specification Left, 19th Apr., 1892-Accepted, 21st May, 1892
PROVISIONAL SPECIFICATION.
Improvements in Friction Driving Gear.
I, WILLIAM SPIERS FREEMAN of Invicta Works, Otford Kent Mechanical
Engineer do hereby declare the nature of this invention to be as follows:-
My invention refers to the driving of friction hoists and other machinery by
friction and instead of applying the frictional driving on the outside peripheral
surfaces of the wheels, pullies or discs (similar to the engaging of two externally
geared cog wheels) I apply the same to the interior in a similar manner to two
internally geared cog wheels by which a greater frictional surface is obtained. As
usually applied the friction is obtained between two convex surfaces in my improved
method a convex surface acts upon a concave surface the increase of frictional
surface is thus obvious.
Frictional gears are often grooved to give more grip but here a serious difficulty is
encountered with the externally driven friction gear as the external portion of the
grooving (i.e. the greatest diameter) runs at a greater surface velocity than the
bottom of the groove and in like manner its fellow also; thus causing a differential
rubbing or grinding action. With the internally driven arrangement all or nearly
all of this differential grinding is eliminated as the larger diameter of the apex of
the grooving engages with the larger diameter of the bottom grooving of its fellow.
Dated this 20th day of July 1891.
COMPLETE SPECIFICATION.
Improvements in Friction Driving Gear.
I WILLIAM SPIERS FREEMAN of Invicta Works, Otford, Kent Mechanical
Engineer do hereby declare the nature of this 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 refers to the driving of friction hoists and other machinery by
friction and instead of applying the frictional driving on the outside peripheral
surfaces of the wheels, pullies or discs (similar to the engaging of two externally
geared cog wheels) I apply the same to the interior in a similar manner to two
internally geared wheels by which means a greater frictional surface is obtained.
As usually applied the friction is obtained between two convex surfaces but in
my improved method a convex surface acts upon a concave surface the increase of
frictional surface is thus obvious.
Frictional gears are often grooved to give more grip but here a serious difficulty
is encountered with the externally driven friction gear as the external portion of
the grooving (i.e. the greatest diameter) runs at a greater surface velocity than the
bottom of the groove and in like manner its fellow also, thus causing a differential
rubbing or grinding action, but with the internally driven arrangement all or nearly
all of this differential grinding is eliminated as the larger diameter of the apex of the
grooving engages with the larger diameter of the bottom grooving of its fellow &
the driving power is also very materially increased at the same time.

page_text: 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-
The use of internal friction gear viz. a concave and a convex surface working
together by rolling friction instead of the usual convex and another convex surface
working together in the usual manner.
Dated this the Fourteenth day of April 1892.