Improvements in Hydraulic Lifting Apparatus applicable especially for Raising and Lowering the Seats of Dental Chairs.
Year: 1897

page_text: PROVISIONAL SPECIFICATION.
Improvements in Hydraulic Lifting Apparatus applicable especially
for Raising and Lowering the Seats of Dental Chairs.
We, LAWRENCE READ, Chairman of The Dental Manufacturing Company.
Limited, of 6, Lexington Street, in the County of Middlesex, and RICHARD
WILLIAM SONNEX, Engineer, of 13, Thornton Road, Barnet, Herts, do hereby
declare the nature of this invention to be as follows:-
under
The lifting apparatus is composed of a hollow ram rigidly attached to a pedestal
or base. The ram passes up through the bottom of a cylinder which surrounds it.
Another ram passes down through the top of the cylinder. When fluid
pressure is admitted through the fixed hollow ram the cylinder which surrounds
this ram and the ram which passes through the top of the cylinder are both
forced upwards and so a telescopic lift is obtained. The ram passing through
the upper end of the cylinder may be hollow and concentric with and capable
of passing around the exterior of the fixed ram the two rams need not however
be concentric they might be at the side of one another. In either case the cylinder
when lowered would surround the fixed ram and the upper or movable ram would
descend into the cylinder and all parts might then lie within an exterior casing
surrounding the whole apparatus.
When the two rams are concentric the upper ram may be guided in its up
and down movement by being fixed at the top to the upper end of a cylinder which
fits around and can slide over the exterior of the moving cylinder. The moving
cylinder may be guided by its lower end having an outer cylinder secured to it
at the bottom, this outer cylinder extending up through and fitting an opening
in the top of the casing.
The top of the outer cylinder may be made to fit around the exterior of the
cylinder which is fixed as above mentioned to the top of the upper ram.
When the outer cylinder passes through the opening in the top of the casing
and where the top of this outer cylinder embraces the cylinder which is fixed
to the top of the upper ram a close fit may be obtained by split ring bushings
slightly tapered on the exterior being interposed between the parts. The tapered
exterior of the rings being made to fit correspondingly tapered seats and means
being provided for pressing the rings downwards more or less into the seats to
more or less contract their diameter.
Dated this 26th day of October 1897
LAWRENCE READ,
RICHARD WILLIAM SONNEX.

page_text: Improvements in Hydraulic Lifting Apparatus applicable especially
for Raising and Lowering the Seats of Dental Chairs.
We, LAWRENCE READ, Chairman of The Dental Manufacturing Company,
Limited, of 6, Lexington Street, in the County of Middlesex, and RICHARD
WILLIAM SONNEX, Engineer, of 13, Thornton Road, Barnet, Herts, do hereby
declare the nature of this invention and in what manner the same is to be per-
formed to be particularly described and ascertained in and by the following
statement:
The lifting apparatus is composed of a hollow ram rigidly attached to a pedestal
or base. The ram passes up through the bottom of a cylinder which surrounds it.
Another ram passes down through the top of the cylinder. When fluid under
pressure is admitted through the fixed hollow ram the cylinder which surrounds
this ram and the ram which passes through the top of the cylinder are both
forced upwards and so a telescopic lift is obtained.
The upper ram may be guided in its up and down movement by being fixed
at the top to the upper end of a cylinder which extends around the exterior of
the moving cylinder and forms the innermost member of a telescopic guide or
support.
When the cylinder and upper movable ram are lowered all parts lie within an
exterior casing.
The drawings annexed shew the hydraulic lifting apparatus constructed in the
manner we prefer for carrying out our invention.
Figure 1 is a vertical section of the hydraulic mechanism-the parts being
shewn in their lowest position.
Figure 2 is a vertical section of the telescopic ram and telescopic guides when
extended.
Figure 3 is a cross section through the line a b Figure 2 and Figure 4 a cross
section through the line c d.
A is a hollow ram fixed to the base plate B. C is a cylinder fitting at its lower
end around the exterior of the fixed ram A and at its upper end around a movable
ram D. The top of this ram is secured to the upper end of a cylinder E which
fits telescopically within another cylinder F which in turn slides telescopically in
a cylinder G and outer casing or pedestal H which is secured to the base plate.
The cylinder F fits at FF2 around the exterior of the cylinder E and the
Guide sur-
cylinder G fits at G1 G2 around the exterior of the cylinder F.
faces H H on the cap H of the fixed outer pedestal H similarly fit around the
exterior of the cylinder G. I are U leather packings to avoid leakage.
The pedestal froms as usual a reservoir for containing liquid. J is a pump for
forcing liquid from the pedestal through a passage J to the bottom of the interior
of the fixed ram A. J2 is the suction valve and J³ the delivery valve. J is the
piston with a cup leather packing J on its lower end. Jo is a connecting rod
coupling the piston to an arm J7 on a spindle J8 which can be rocked by the action
of a treadle or otherwise in the ordinary manner.
When liquid is forced by the pump into the interior of the hollow ram A it
passes up through the interior of this ram and into the moving cylinder C caus-
ing this cylinder and the ram D to both rise. A flange C¹ which extends out-
wardly from the bottom of the cylinder C at the same time lifts the guide
cylinders E F and this continues until the outer part of the flange C¹ comes
against a shoulder G³ on the interior of the guide cylinder G and this guide
cylinder will then be lifted also until the cylinder C has completed its rise and is

page_text: arrested by a flange G on the exterior of the bottom of the guide cylinder G
coming against the bottom of the lower guide surface H2 carried by the cap H*
of the pedestal. Afterwards the ram D and guide cylinders E F continue to rise
until a flange F on the bottom of the guide cylinder F comes against the bottom
of the projection G³ whereby the guide cylinder F is arrested and the ram and
cylinder E continue their movement until a flange E¹ on the bottom of the guide
cylinder E comes against the bottom of F and is thereby arrested.
The guiding cylinders E F G are splined and feathers are fitted to same to
prevent them from turning in the pedestal. The cylinders and ram can be lowered
in the ordinary way by allowing liquid to pass back from the passage J¹ through
a valve into the interior of the pedestal.
Having now particularly described and ascertained the nature of our said inven-
tion and in what manner the same is to be performed, we declare that what we
claim is:-
1. The combination of a telescopic hydraulic ram with surrounding telescopic
cylindrical guides the parts of which fit concentrically one within the other and an
outer pedestal casing into which they can all descend.
2. A telescopic hydraulic lifting apparatus composed of a hollow ram a pedestal
or base to which it is fixed a moveable cylinder the lower end of which fits around
the fixed hollow ram and the upper end of which fits around a second ram in
such manner that when this cylinder and ram are lowered all the parts fit one
within the other substantially as described.
3. Telescopic hydraulic lifting apparatus constructed substantially as herein-
before described and illustrated in the drawings annexed.
1
T
1000
LAWRENCE READ,
RICHARD WILLIAM SONNEX.