An Improved Friction Clutch.
Year: 1898

page_text: Date of Application, 18th Aug., 1898-Accepted, 29th Oct.,
1898
An Improved Friction Clutch.
We, THOMAS BARCROFT, of 9, Gorehill Terrace, Pendleton, Manchester, in the
County of Lancaster, Engineer, JOHN SMALLEY, of 44, Broomhall Road, Pendle-
bury, in the aforesaid county, Engineer, and SAMUEL REDFERN, of 2, Swan Lane,
New Brown Street, Manchester, aforesaid, 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 and accompanying
drawings.
Our said invention relates to an improved friction clutch for the transmission
of rotary motion as is well understood.
In constructing a friction clutch in accordance with our invention we employ
a number of blocks or wedges arranged to be partially revolved around a shaft.
The outer peripheries of such blocks are arranged in frictional contact with excen-
tric or cam surfaces formed on two half rings, and the outer peripheries of the
blocks are so proportioned that when moved about the axis of the shaft, their
entire surfaces bear with equal pressure against the cam surfaces of the half
rings. The half rings are thus thrust or jambed against the interior of the outer
clutch half or shell by which motion is received from or communicated to the
outer clutch half as the case may be. By means of the blocks the whole outer
bearing surface of the half rings is brought to bear with equal pressure against
the outer clutch half.
And in order that our invention may be fully understood we have attached
hereto a sheet of explanatory drawings to which we will now refer.
In the drawings,
Fig. 1 is a face view of the clutch, one half being an outside elevation, and
the other half partially in section.
Fig. 2 is a side view, the upper half being in section on the line X X, Fig. 1,
the lower half shown partially in section.
Fig. 3 is a view on a smaller scale to indicate the method of operating the
clutch.
Figs. 4 and 5 are detail parts.
In the drawings we have shown the internal clutch half A secured to the
driving shaft a and the external clutch half or shell B revolving loosely upon
a bush 6 upon the shaft. The external half B is thus driven at the required
times but it will be understood that the outer clutch half may be the driver if
desired.
Upon the shaft a 'we key a boss c provided with two oppositely arranged arms d.l.
The outer ends of the arms d d enter recesses or gaps e formed in two half rings
or segments ff whereby the rings f are driven. The half rings f are provided
with undercut recesses 9 for the reception of tee headed bolts h. The heads of
the bolts are introduced through the gaps i. Fig. 5 shows a plan of the interior
surface of half of one of the segments f indicating more clearly the gaps and
[Price 8d 1

page_text: recesses in the rings. The bolts h are screwed to four blocks j shown more clearly
in the sectional half of Fig. 1. Recesses ¹ are cut in the blocks within which
are disposed nuts provided with trunnions . A separate view of one of the
nuts k shown at right angles to Fig. 1 is given in Fig. 4. The trunnions k¹ rock
freely in bearings formed in the blocks j and cover plates 7 secured to the blocks
as shown in dotted lines in Fig. 2. The cover plates bear upon the boss cas
shown in Fig. 1 and are secured to the blocks by means of screws ¹.
The oscillating nuts k are tapped to receive right and left hand screws m formed
on the toothed bosses n. The right and left hand screws m are operated in the
usual manner by the sliding collar ¹ and links op as shown in Fig. 3 the
links p being formed at the ends with internally toothed surfaces to engage with
the teeth upon the bosses n.
It will be seen from an inspection of Fig. 1 that the half rings off are formed
with inner cam surfaces whilst their outer peripheries are concentric with the
inner periphery of the outer shell. The centres from which these cam surfaces
are struck are indicated in Fig. 1.
The outer surfaces of the blocks j are also formed to the same curve as the
cam surfaces upon the half rings f. Upon revolving the right and left hand
screws m by means of the sliding collar, the blocks are slightly rotated about
the shaft a in contact with the cam surfaces of the half rings f in the direction
indicated by the arrows, the squared portion of the bolts / sliding in the recesses g.
The oscillating nuts & freely permit the partial revolution of the blocks j, sufficient
clearance being allowed within the recesses ¹ formed in the blocks ; to permit of
the necessary rocking of the nuts.
As shown in Fig. 1 the two upper and two lower blocks converge towards
each other the cam surfaces being so arranged that equal expansion of the
blocks from toe to heel is obtained as shown in dotted lines in the upper left
hand corner of Fig. 1. This equal expansion of the blocks j exents an equal
pressure practically throughout the entire interior surface of the half rings or
segments which are thus thrust or jambed with great force into contact with
the interior periphery of the outer clutch half or shell B. The pressure obtained
from the blocks is thus equally distributed and imparted to the entire inner
circumference of the outer clutch half.
Our improved friction clutch besides being thus rendered extremely effective
does not exert unequal strain upon the shaft.
Having now particularly described and ascertained the nature of our said
invention and in what manner the same is to be performed we declare that what
we claim is:―
1) The improved friction clutch constructed arranged and acting in the manner
and substantially as described and showa.
2) A friction clutch composed of two half rings or segments rotated by arms
carried upon a boss, the half rings being formed with internal cam surfaces with
which engage the correspondingly curved surfaces of blocks which, when operated,
expand and act with equal pressure upon the half rings or segments throughout
the whole contact surface of the blocks so that the half rings are thrust or jambed
against the internal periphery of the outer clutch half or shell substantially as
described and illustrated.
Dated this 17th day of August 1890.
For the Applicants,
E. K. DUTTON & Co.,
Chartered Patent Agents, 5, John Dalton Street, Manchester.