Means for Adjusting the Tension of Cycle Chains.
Year: 1897

page_text: PROVISIONAL SPECIFICATION.
Means for Adjusting the Tension of Cycle Chains.
ARTHUR GUNN, 26, Bridlington Street, Nottingham, and Victoria Factory,
Gamble Street, Nottingham, Cycle Maker, do hereby declare the nature of this
invention to be as follows:-
I
Fig. 1 Represents an eccentric (A) with a screw thread. This is fitted into (E)
the bottom bracket of a safety bicycle. (B) is a screw which goes clear through (D),
the lug on bracket (E), & gears into (A). By the movement of (B), (A) revolves,
causing the tension of the chain to be altered. (B) is locked by (C) which
screws into (D). (F) is merely a nut to prevent (B) from being drawn out of (D)
at leekad bive (0)
I, ARTHUR GUNN, of 26, Bridlington Street, Nottingham, and Victoria Factory,
Gamble Street, Nottingham, Cycle Maker, 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 relates to means and apparatus for adjusting the tension of cycle
chaius.
The apparatus consists of an eccentric with a screw thread fitted into the bottom
bracket of the frame of a safety bicycle, the said bracket is provided with a vertical
thumb screw which goes clear through a lug in the front of the bracket the threads
of which gear into the screw thread of the eccentric. By the movement of the
vertical thumb screw the eccentric revolves causing the tension of the chain to be
altered, this said vertical thumb screw is locked by another thumb screw in the
lug working in an horizontal direction.
And in order that my invention may be thoroughly understood, I now proceed to
describe the drawings filed with the Provisional Specification, reference being had
to letters and figures marked thereon.
Fig. 1, is a side view of the bracket showing the interior working of the
eccentric, vertical and horizontal thumb screws.

page_text: Fig. 2, is a longitudinal section showing the eccentric inside of the bracket.
Fig. 3, is an elevation of the eccentric.
Fig. 4, is a view of the lug on the bracket.
In carrying my invention into practice I construct an eccentric a with a screw
thread and fit the same into the bottom bracket E of a safety bicycle. At the
front of the bottom bracket E is a lug D this said lug is drilled and tapped to
receive a vertical thumb screw B this said screw B gears with the screw thread on
the eccentric a. By the movement of the vertical thumb screw B the eccentric
revolves causing the tension of the chain to be altered, the said screw is locked
by an horizontal thumb screw C passing through the lug D. At the base of the
vertical thumb screw B I screw on a nut F in order to prevent the vertical thumb
screw being drawn out of the lug 1 when not locked by the horizontal screw C.
The chain wheel and cranks are mounted on the spindle or shaft which revolves
on ball bearings inside the eccentric a as in Fig. 2.
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: :-
1. In an apparatus for adjusting the tension of cycle chains, the combination
of the eccentric a thumb screws B and C, nut F and bottom bracket E, substan-
tially as herein described and according to the drawing.
2. In an apparatus for adjusting the tension of cycle chains, the combination of
an eccentric with a screw thread fitted into the bracket, and the vertical thumb
screw which goes clear through the lug on the bracket and gears into the screw
thread on the eccentric by the movement the vertical thumb screw with the
horizontal thumb screw for locking the same, substantially as herein described and
according to the drawing.
Dated this 5th day of Tonnom 1800
J. P. BAYLY,
18, Fulham Place, London, W., Agent for the Applicant.