Improvements relating to Direct Acting Hydraulic Hoists or Lifts.
Year: 1889

page_text: Date of Application, 5th Feb., 1889
Complete Specification Left, 4th Nov., 1889-Accepted, 7th Dec., 1889
PROVISIONAL SPECIFICATION.
Improvements relating to Direct Acting Hydraulic Hoists or
Lifts.
I, ROGER WRIGHT, of Elswick Works Newcastle upon Tyne, Engineer, do
hereby declare the nature of this invention to be as follows:-
This invention has for its object improvements relating to direct acting hydraulic
hoists or lifts and is applicable more especially to passenger lifts.
The lift cylinder is connected with another cylinder of the same capacity in which a
plunger works. This plunger is forced in by the combined action of three other
bydraulic cylinders.
The ram of one of these cylinders acts directly upon the plunger and this ram is of
the dimensions required for lifting the live load. The cradle and the lift ram are
balanced by means of two other cylinders and this is done in such a manner as to
compensate the varying immersion of the lift ram. The balancing cylinders are
constantly open to the pressure main; they are carried by trunnions and they are set
so that their rams act obliquely on the plunger. The obliquity increases as the plunger
passes from one end of its course to the other. When the lift ram is down the
obliquity is at its maximum and the efficiency of the thrust of the balancing rams upon
the plunger is at its minimum.
As the lift ram ascends the obliquity of the thrust of the balancing rams diminishes
and the efficiency of the thrust increases as is required.
The arrangement may be varied by connecting the lift cylinder with a pair of
cylinders set obliquely and mounted upon trunnions. The plungers in these cylinders
are connected with a cross head. Two stationary hydraulic cylinders operate on
the cross head. One is constantly connected with the pressure main and the other
receives water to lift the cage and is emptied in order to lower it. Or a dead
weight connected with the crosshead may be employed to balance the cradle and the
lift ram.
Dated this Fourth dan
1000
COMPLETE SPECIFICATION.
Improvements relating to Direct Acting Hydraulic Hoists or
Lifts.
I, ROGER WRIGHT, of Elswick Works, Newcastle upon Tyne, 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 :-
This invention has for its object improvements relating to direct acting hydraulic
hoists or lifts and is applicable more especially to passenger lifts in which the cage of
the lift is carried upon the upper end of a ram working in a lift cylinder which is
connected with another or second cylinder of the same capacity in which a plunger
works. In order to compensate the varying immersion of the ram and plunger I
employ cylinders so arranged that their rams operate obliquely and this obliquity
varies from one part of the stroke to another.
Figure 1 shows in elevation an arrangement in accordance with my invention. a is
a cylinder of the same capacity as the lift cylinder and with which the lift cylinder is
connected; its plunger is forced in by the combined action of three cylinders b c and d.
The ram of the cylinder acts directly upon the plunger and this ram is of the
dimensions required for lifting the live load when water at the available pressure is
admitted to the cylinder b.

page_text: The cradle and the lift ram are balanced by means of the cylinders c and d which
are constantly open to the pressura main. These cylinders are set obliquely and are
carried upon the frame e by their trunnions e¹ and d; their mums are jointed to the
head of the plunger. The parts are so proportioned that the water pressure on the
rums in the cylinders c and d nearly but not quite balances the lift ram and enge in all
positions but leaving sufficient preponderance to cause the cage to descend when there
is no pressure in the cylinder b. The action is as follows :—
When the cage is up a long length of the lift ram has emerged from the lift
cylinder; whilst at the same time the greater part of the plunger is in the cylinder a
and immersed from both causes the downward tendency of the lift ram is greater than
when it is in the lower part of its stroke; this is compensated and balanced by the
more direct action of the rams of the cylindore and d. On the other hand when the
cage is down the rams of the cylinders e and d act more obliquely and they counteract
each other to the required extent.
Figure 2 shows a modification. In this case the lift cylinder is connected through
the trunnions with the two cylinders which together are of the same capacity as
the lift cylimler. The plungers in the cylinders are connected with a cross head g
which can travel vertically in guides in the frame h.
The cross head is drawn downwards by means of two cylinders i and k. The
cylinder is the driving cylinder and is suitably proportioned with relation to the
available water pro-sure to lift the load when the water is admitted to press upon the
piston which the cylinder contains. The rod of this cylinder is fixed to the cross
head g. The other cylinder operates in a similar manner but it is always in fron
communication with the pressure main and it is so proportioned that the liquid
pressure upon its piston nearly balances the lift ram and cage but leaving sufficient
preponderance to canse the descent of the cage at a sufficient speed when there is no
pressure in the cylinder i.
The balance will remain approximately the same throughout the stroke because as
the lift descen is the cylinder acts with less efficiency to hold back the plungers
in the cylinders: The efficiency of the driving cylinder will also vary in the
course of the stroke. It is obvious that a dead weight may be substituted for the
cylinder k.
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 :-
1. Compensating the varying immersion of the lift ram and plunger or plungers by
the varying obliquity of cylinders forming a portion of the hydraulic gear substantially
as described.
2. The arrangement of direct acting hydraulic hoists or lifts substantially as describod
and represented in the annexed drawings.
Tandahin 54th day of Ontahan 1989.