Improvements in Hydraulic Operating Chairs.
Year: 1895

page_text: Date of Application, 30th July, 1895-Accepted, 31st Aug., 1895
COMPLETE SPECIFICATION.
Improvements in Hydraulic Operating Chairs.
I, ERNST POTH of 12 Marienstrasse, Berlin in the Empire of Germany,
Machine Manufacturer, 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 :-
Operating chairs hitherto in use may be principally divided into two classes,
those that are adjusted mechanically, and those that have hydraulic means for their
adjustment.
The chairs which are raised mechanically have the advantage that the seat may
be revolved in all directions, whereas the chair raised by means of an hydraulic
pump only admits of a half revolution, this being due to the eccentric position of
the pump cylinder. The object of the present invention is to provide a chair
which may be raised hydraulically and at the same time admit of full revolution.
Fig. 1 of the annexed drawings represents an operating chair with the improve-
ments.
Figs. 2 and 3 are vertical and horizontal sections respectively of the lower frame
part illustrating the subject of the invention.
Figs. 4, 5 and 6 are details of the hydraulic lifting arrangement.
The seat frame A (Fig. 2) has a cylindrical extension B which is guided at two
places C and C in the socket D, and rests above on the end of the rod E. The
piston E slides in the cylinder F, the piston G' in the cylinder H. The reservou 1
is to receive the liquid by means of which the lifting of the seat is accomplished,
said reservoir being attached by screws a (Fig. 1) to the socket plate D. As the
above mentioned cylindrical extension B would constantly be surrounded by the
lifting liquid, said cylinder B is entirely enclosed by another cylindrical vessel K.
But as it still may occur that on raising the rod E liquid may pass out above at the
tube F, the latter is, in addition, surrounded by tube S. The liquid entering the
space between the two tubes S and F, is enabled to re-enter the reservoir I through
the ducts T.
The operation of the mechanism for lifting the chair is as follows:
On moving the pedal L (Fig. 1) the rod G¹ is raised, the valve M (Fig. 5) being
then opened whereupon the liquid passes into the cylinder H. When the rod Gi
is lowered again, the liquid is bound to pass through the duct N in which is
arranged a valve N' (Fig. 6) into the cylinder F thereby raising the piston E¹
and at the same time the seat A.
When it is desired to lower the seat, pressure should be exerted on the lever O,
whereupon the valve P (Fig. 4) iu the casing Q opens and the liquid leaves the
cylinder F through the port R into the reservoir 1. The rod E then will fall
and with it the seat frame A resting on the rod E.
Having now particularly described and ascertained the nature of this inven-
tion and in what manner the same is to be performed, I declare that what I
claim is :-
A hydraulic operating chair admitting of complete revolution of the seat, the
latter having a cylindrical extension guided in a socket, said extension enclosing a
hydraulic cylinder which, having no communication below with the inner space of
the outer tube or cylinder, but opening freely into the tube above, containing at

page_text: the same time a piston rod on the upper end of which rests loosely the middle of
the turning chair while the cylinder B thereof is secluded from the liquid by
another cylinder K.
Dated this 30th day of July 1895.
HERBERT HADDAN & Co.,
18 Buckingham Street, Strand, London, W.C., Agents to Applicant.