Improvements relating to Slide Valves of Hydraulic Lifts, Hoists and the like.
Year: 1898

page_text: Date of Application, 5th Feb.,
1898
Complete Specification Left, 4th Mar., 1898-Accepted, 9th Apr., 1898
Improvements relating to Slide Valves of Hydraulic Lifts, Hoists
and the like. : .
JOSEPH STANNAH, 20, Southwark Bridge Road, London, S.E., Engineer, do
hereby declare the nature of this invention to be as follows:-
This invention has for its object an absolute deadlock should any accident happen
to the main during the night or when the lift, hoist, weighted crane chain or
other moving body is not in use.
At the back of an ordinary hydraulic slide valve, I fit a small plunger of an
area larger than the cylinder port, working in a cylinder, this cylinder being con-
nected by means of a pipe with the hydraulic lifting cylinder. This said plunger
is free to press on the top of the valve or not, there being about a sixteenth of an
inch clearance. In the ordinary course this plunger will be forced away from
the valve by the pressure from the main but should this main pipe get broken
the action will be reversed the pressure now being greater at the other end of this
plunger, the plunger will be forced against the valve and prevent it leaving the
face. It is evident but for some arrangement of this sort the lift, hoist, weighted
crane chain or other moving body must fall as soon as the main pipe is broken.
Dated this Fifth day of February 1898.
Improvements relating to Slide Valves of Hydraulic Lifts, Hoists
and the like.
JOSEPH STANNAH, 20, Southwark Bridge Road, London, S.E., 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 invention relates to the slide valves of hydraulic lifts, hoists and the like,
and it has for its object an absolute deadlock should any accident happen to the
main during the night or when the lift hoist, or lifting apparatus is not in use.
At the back of an ordinary hydraulic slide valve I fit a small plunger of an
area larger than the cylinder port, working in a small cylinder this small cylinder
being connected by means of a pipe or pipes with the hydraulic lifting cylinder,
this said plunger is free to press on the top of the valve or not, there being just
sufficient clearance for this purpose. In the ordinary course this plunger will be
forced away from the valve by the pressure from the main, but should the main

page_text: pipe get broken the action will be reversed the pressure now being greater at the
other end of this plunger, this plunger will be instantly forced against the valve
and prevent any movement whatever so that the valve will be held fixed in exactly
the same position as it was in before the main pipe got broken.
The accompanying drawing illustrates my invention applied to a lifting ram
and cylinder. C is the cylinder port, E is the exhaust port, M is the inlet, R is
a small plunger of greater area than the cylinder port C, working in a bored cylin-
der connected by means of a pipe P to the lifting ram R¹ and cylinder C', or by
a pipe P¹ to a teepiece T fitted on to the pipe 12 which connects the cylinder port
to the cylinder C¹.
Č
Having now particularly described and ascertained the nature of my said in-
vention and in what manner the same is to be performed I declare that what I
claim is:
The arrangement of a small plunger and cylinder on the top of the valve and
the pipe leading from this small cylinder to the lifting cylinder.
Dotod thin Fourth dor of Mah 1000