Improvements in Means or Apparatus for Regulating and Controlling Connection Between Traction Cables and the Carriages Drawn thereby on Tram or other like Ways.
Year: 1893

page_text: Date of Application, 4th Oct., 1893
Complete Specification Left, 4th Aug., 1891-Accepted, 8th Sept., 1894
PROVISIONAL SPECIFICATION.
Improvements in Means or Apparatus for Regulating and Controlling
Connection Between Traction Cables and the Carriages Drawn
thereby on Tram or other like Ways.
I GEORGE LLEWELLYN DAVIES of 8 Fowkes Buildings, Great Tower Street
in the City of London, Electrical and Mechanical Engineer do hereby declare the
nature of this invention to be as follows:-
My improvements relate principally to those grippers which are used in con-
nection with tram-cars or street cars, where the car is drawn along the road by
means of a cable running in a channel below the level of the street.
In these cases the cable is driven at a certain uniform speed but the necessities
of the traffic may require the car to run at different speeds.
This is usually accomplished as follows:-
The car carries a gripper which projects down into the channel and this gripper
is furnished with jaws which take hold of or grip on to the cable, something after
the manner of the jaws of an ordinary vice. By means of mechanism, which is
under the control of the driver, these jaws can be made to grip more or less tightly
upon the cable. Thus when the driver wants to run at the maximum speed, he
tightens up the gripper jaws to their full extent so that the cable cannot slip
between the jaws and the car will now be carried along at the same speed as the
cable is being driven at. When the driver wants to run the car at a slower speed
than that of the cable he loosens out the jaws slightly, still keeping them sufficiently
tight to produce the necessary amount of friction to give the required motion to
the car.
The cable will now be, in part, slipping through the gripper jaws and, in part
dragging the car along by the friction taking place between the cable and the
gripper jaws, the speed of the car being the difference between the amount of slip
and the full speed of the cable.
Taking the speed of the cable at eight miles per hour and the average speed of
the car at six miles per hour, the "slip" will amount to two miles per hour, and of
course the "slip" will be more or less in the inverse proportion to the speed of the
This slip will be always taking place except when the car is running exactly
at the same speed as the cable.
car.
Heretofore so far as I am aware these grippers have been furnished with fixed
jaws and the consequence is, that, the cable, being dragged between these fixed jaws
with greater or less friction upon it, becomes rapidly worn away, the outside
strands of the cable being cut through or unequally worn in a comparatively short
time.
Now my invention consists in using an arrangement of rolling surfaces instead of
or in addition to fixed jaws in cable grippers or means for regulating and controlling
connection between traction cables and the carriages drawn thereby.
In carrying out my invention I may use two or more rollers mounted in such a
manner that the cable can be gripped or held more or less tightly between them,
the peripheries of the rollers being grooved to correspond to the shape of the
cable.
The action of the roller gripper or holder is as follows. Taking the cable to be
travelling at eight miles per hour and the car going at four miles per hour the
circumferential speed of the rollers will be four miles per hour consequently the
rollers themselves are moved forward at the rate of four miles per hour. Brakes
may be applied on the rollers and by tightening them up on letting them out the

page_text: circumferential speed of the rollers may be reduced or increased :—the roller
gripper and therefore the car can be made to travel bodily forward at any speed
required.
The brakes on the roller jaws may be dispensed with, the amount of slip allowed
being regulated by the tightness with which the roller jaws are caused to grip on to
the cable.
By the use of these roller grippers any amount of "slip" can be allowed without
involving any wear and tear on the cable as the "slip" and consequent friction is
transferred to the roller-studs or to the brakes on the rollers.
I may mention that I am aware that there has been described, a gripper with
anti-friction rollers mounted upon it but those anti-friction rollers were only for
the purpose of assisting in guiding the cable in between fixed jaws and did not
themselves perform the functions of jaws.
hh dow of October 1893
WM. BROOKES & SON,
55 & 56, Chancery Lane, London, W.C., Agents for the Applicant.
COMPLETE SPECIFICATION.
Improvements in Means or Apparatus for Regulating and Controlling
Connection Between Traction Cables and the Carriages Drawn
thereby on Tram or other like Ways.
I GEORGE LLEWELLYN DAVIES of 8 Fowkes Buildings, Great Tower Street
in the City of London, Electrical and 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 improvements relate to means or apparatus for regulating and controlling
connection between traction cables and the carriages drawn thereby on tram or
other like ways especially to those grippers which are used in connection with tram-
cars or street cars where the car is drawn by means of a cable running in a channel
below the level of the street.
In these cases the cable is driven at a certain uniform speed but the necessities
of the traffic may require the car to run at different speeds.
This is usually accomplished as follows. The car carries a gripper which projects
down into the channel aud this gripper is furnished with jaws which take hold of
or grip on to the cable, something after the manner of the jaws of an ordinary
vice.
By means of mechanism, which is under the control of the driver, these jaws can
be made to grip more or less tightly upon the cable.
Thus when the driver wants to run at the maximum speed, he tightens up the
gripper jaws until the cable no longer slips between the jaws and the car is carried
along at the same speed as the cable is being driven at.
Where the driver wants to run the car at a slower speed than that of the cable
he loosens the jaws slightly, still keeping them sufficiently tight to produce the
necessary amount of friction to give the required rate of motion to the car.
The cable will now be, in part, slipping through the gripper jaws, and, in part
dragging the car along by the friction between the cable and the gripper jaws, the
rate of speed of the car being the difference between rate of slip and the full speed
of the cable.
Taking the speed of the cable at eight miles per hour and the average rate of
travel of the car at six miles per hour, the "slip" will amount to two miles per
hour, and of course the "slip" will be more or less in the inverse proportion to the
speed of the car.
This slip will be always taking place except when the car is running exactly at
the same speed as the cable.

page_text: a is the cable. b, b₁, 63, 3, are four grooved pulleys arranged in two pairs each
mounted on a pin or centre c, c', c or c³ a bush or ring d being interposed in each
case.
The pins or screwed stems c, c', c² and care passed through and serve to connect
the side plates e, e¹ and these plates e, e¹ are centred upon fulcrum pins ƒ, ƒ, ƒ¹, ƒ³,
secured in the lateral extension g', g' from the gripper shank 9.
To the opposite ends of the side plates e, e, el, are connected the links h, h¹ by
means of centre pins ³, 12 at one end thereof, whilst at their other ends the links
are forined (see Fig. 4) to engage one the other, by means of a hollow projection h³
on the one passing into a corresponding opening in the other. Into the hollow /*
of the projection passes the end of an arm i dependent from the car and the
movement of which causes the engagement, partial engagement, or release of the
pulleys from the cable.

page_text: These pulleys or rollers 6, 61, 62, 63 form pairs of roller surfaces and the whole a
roller gripper running with the peripheries of the rollers of each pair in contact
with and gripping between them the cable. The pulleys respectively rotate on a
centre pin of size proportionate to the size of the pulley that as pressure on the
pulleys is increased and brought to bear on the cable, rotation of the pulleys on
their centre pins owing to the increase of friction causes the pulleys to be turned
with greater and greater difficulty until the pressure being sufficiently increased
between pulley surfaces and the cable this pressure reacts on the contact parts of
the pins of the pulleys and increases their relative resistances to rotation constituting
an effective break which is not and cannot be independent of the force pressing the
opposing roller surfaces on to the cable but must increase and decrease directly as
that force, or the nip on the cable, increases or decreases therefore the cable cannot
be run at a high speed through gripper with a heavy pressure or nip on the cable
neither can the pulleys of the gripper be stopped without sufficient pressure or
nip being put on the cable between the opposing pair or pairs of pulleys to
prevent the cable slipping through the pulleys so as to wear the surface of the
cable.
Using this principle of proportionate diameters between the centre pins and the
roller surfaces transfers the wear on the surface of the cable caused by a vice
gripper to the rings or bushes inserted between the roller surfaces and the centre
pius or if no ring or bush be used to the centre pins or inner side of the roller
surfaces or to both.
The resistances to rotation under pressure of the centre pins and the inner
surfaces of the pulleys may be varied to suit different lubricants by varying the
proportionate diameters of the centre pins and the roller surfaces.
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 means or apparatus for regulating and controlling connection between traction
cables and the carriages drawn thereby on tram, or other like ways.
1. The construction and arrangement of rolling surfaces, in pairs with the cable
between them, said rollers being mounted on centre pins or parts of diameters
proportioned to the diameters of the rollers so that as the pressure of grip between
the pulleys and the cable is increased, the resistances to revolution between the
central supports or pins of and the inner surfaces of the pulleys is increased
accordingly substantially as and for the purposes set forth.
2. The arrangement and combination of rolling surfaces, proportioned pins or
central supports therefor and parts for carrying and operating the same in order to
obtain a variable and adjustable gripping action upon a cable substantially as and
for the purpose set forth.
Dated the 4th day of August 1894.
WM. BROOKES & SON,
55 & 56, Chancery Lane, London, Agents for the Applicant.