Improvements in Controlling Mechanism for Fluid Pressure Motors.
Year: 1898

page_text: Date of Application, 1st Dec., 1898- Accepted, 14th Jan., 1859
COMPLETE SPECIFICATION.
Improvements in Controlling Mechanism for Fluid Pressure Motors.
I, JOSEPH HINSON HOADLEY, Engineer, of 222, West 23rd Street, New York,
County and State of New York, in the United States of America, 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:-
--
In the system formerly used by me for controlling fluid pressure motors and
particularly high pressure air motors a controller was employed which operated
simultaneously upon the throttle and the distributing valves of the motor. The
arrangement was such that when the throttle was closed, the reverse motion con-
trolling the distributing valves was in mid position. The result of this was
that when in coasting the fluid pressure being shut off by the throttle from the
motor, excessive pressures were generated in the cylinder of the motor owing
to the position of the distributing valves. The object of the present invention
is to avoid this difficulty by preventing the accumulation of such pressures in
the motor when the throttle is closed.
I accomplish this in various ways. I have illustrated in the accompanying
drawing one method of carrying out the invention. But it is to be understood
that various mechanical devices can be employed so long as they have the effect
hereinafter fully described.
The accompanying drawing is a diagrammatic representation of a form of
the invention in which A is a controlling handle or lever for a motor for
example, of a motor such as is employed for propelling tram cars and which
may be driven by compressed air. B is the throttle valve chamber containing
the throttle valve C and having pipes D and E leading respectively to the fluid
pressure reservoir and the motor. F is the link controlling the eccentrics G
of the usual distributing valves of the motor and controlled by rods and levers H.
The distributing valve rods and levers H are controlled in position by a lever I
whose pin J runs in a cam groove K on a cylinder or drum L controlled by the
controlling handle or lever A while the position of the throttle valve is controlled
by a lever M whose pin N travels in a cam groove upon the said cylinder or
drum L.
It will be seen that with this arrangement the cam slots are adapted to operate
the throttle and close it before the distributing valves arrive at mid position.
This position is at a point where it is found that the cylinders are without
accumulated pressure when the throttle is closed and the motor is in operation.
The slots are so arranged that the cams keep the throttle closed and operate
the roller connected to the reversing mechanism until such time as the distri-
buting valve has passed beyond mid position and to a like position on the reverse
side to operate motors in a reverse direction. Then the cam slot operating the
throttle is in such position as to immediately open the throttle and allow fluid
to pass to the motor in its reverse position. After closing throttle the link is
again opened a certain amount to still further reduce compression.

page_text: Starting at the extreme position of cut-off on back stroke the eccentric mechanism
is found operating the distributing valve to be in such position as to allow the
fluid to enter cylinder at maximum cut-off.
At this point the throttle is wide open. Moving controller so as to shorten
the cut-off and diminish the power on motor, the throttle remains in its position
until such time as the reversing mechanism operating eccentric to close the
distributing valve is nearly to its found position for operation without accumu-
lating pressure in cylinder during operation without fluid (coasting). At that
time the throttle is operated by the steep cam slot and in a very short portion
of the stroke of the reversing mechanism it is completely closed. Continuing
the movement of controller in the same direction the roller closing throttle
operates in a parallel slot which holds it closed while the roller operating the
reversing mechanism continues on its way first opening the distributing valves
to still further prevent accumulation of pressure and then by a further movement
carries the distributing valve to mid position.
Continuing in the same direction with controller the reverse mechanism by
action of the cam slot commences to open distributing valve on the forward
stroke. The cam operating throttle continuing in parallel slot the throttle being
closed until the cam slot operating reverse mechanism carries the distributing
valve to an open position and then nearly closes the same. At this point the
throttle immediately opens and remains open throughout the entire stroke of
the controller and until the reverse mechanism carries the distributing valve
to its full stroke on the forward stroke.
Having now particularly described and ascertained the nature of my said
invention and in what manner the same is to be performed. I declare that what
I claim is:-
In a controlling mechanism for motors, means for operating the throttle valve
and the distributing valves simultaneously so arranged that the distributing
valves are slightly opened after the throttle valve is closed to shut off fluid
pressure supply to the motor and closed and again opened when the throttle valve
is opened to supply such fluid pressure.
1000
HARRIS & MILLS,
23, Southampton Buildings, London, W.C.,
Agents.