[0001] The present invention relates to an hydraulically-driven oscillating mechanism and
particularly, though not exclusively, is concerned with a mechanism for traversing
from side-to-side in an oscillatory angular manner the nozzle of a fire-fighting monitor
or the like liquid-projecting device. It is known to provide fire-fighting monitors
with mechanisms of this kind so that the monitor can be set up with its nozzle automatically
swinging through a predermined arc to play a jet of water or foam from side-to-side
over a desired target area. One such mechanism comprises a Pelton-wheel driven by
water taken from the main supply to the monitor, the wheel being connected through
a speed-reducing gearbox to a crank which is linked at its other end to the structure
bearing the monitor nozzle, so that the rotation of the Pelton wheel is transmitted
by the crank into oscillatory angular motion of the nozzle.
[0002] In one aspect the present invention seeks to provide an hydraulically-driven mechanism
for producing oscillatory angular motion of a monitor nozzle or other device and which
in a preferred embodiment may employ a primary transmission similar to that described
above, but furthermore where the sector of the horizon (or other plane in which the
angular motion is produced) in which the device operates can be readily adjusted without
altering the spatial disposition of the mechanism as a whole.
[0003] Accordingly in this aspect the invention resides in a mechanism comprising an hydraulically-driven
motor and a mechanical transmission for connecting the motor to a driving member whereby
operation of the motor produces oscillatory angular motion of said driving member
which is characterised by clutch means through which such oscillatory angular motion
of the driving member is transferred to a driven member,the clutch means being selectively
operable to disengage the driven member from the driving member to permit rotation
of the driven member independently of the driving member, and adapted to permit re-engagement
of the driven member with the driving member in different relative angular positions
thereof.
[0004] In use of a mechanism according to the invention the driven member can be connected
e.g to the nozzle of a fire-fighting monitor to oscillate that nozzle from side-to-side
through a predetermined arc and thereby play fire extinguishant over a corresponding
area. If it is then desired to change the direction of the nozzle to cover an area
not within its existing arc the clutch means can be operated to disengage the drive
from the motor to the nozzle and permit the nozzle-and said driven member to be rotated
into a new position, whereupon re-engaging the drive will recommence ocillation of
the nozzle through a new arc angularly displaced from the previous arc.
[0005] In a preferred arrangement the clutch means comprises a polygonal socket member and
a polygonal spigot member, one such member comprising or being in driving connection
with said driving member and the other comprising or being in driving connection with
said driven member, these members normally being biased into engagement to permit
angular drive transmission from one to the other but being selectively disengageable
to permit relative rotation between them. With this arrangement the two clutch members
can be engaged in a plurality of discrete relative angular positions determined by
the faces of the polygonal spigot and socket, so as to set the driven member to oscillate
the nozzle or other device in a corresponding number of angularly displaced sectors.
[0006] The invention will now be more particularly described, by way of example, with reference
to the accompanying drawings, in which:
Figure 1 is a side elevation, partly in section, of a mechanism according to the invention
set up to oscillate the nozzle of a fire-fighting monitor;
Figure 2 is a rear elevation, partly in section, of the mechanism of Figure 1;
Figure 3 is a front elevation, with some parts broken away, of the mechanism of Figure
1;
Figure 4 is a plan view, with certain parts removed, of the mechanism of Figure 1;
Figure 5 is a vertical section through the clutch employed in the mechanism of Figures
1 to 4; and
Figure 6 is a plan view, with the cover removed, of the clutch of Figure 5.
[0007] Referring to Figure 1, there is shown a fire-fighting monitor 1 which in the illustrated
embodiment is of the spherical head type and which in particular may be constructed
as described in our published United Kingdom patent application No 2071527A. Briefly,
this monitor comprises a head 2 which carries a nozzle via an outlet fitting 3 and
which is borne in a housing 4 for pivotal movement about a horizontal axis so as to
adjust the angular elevation or depression of the nozzle. In the illustrated embodiment
this adjustment is efected manually for which purpose a handle-bar 5 is provided.
The assembly of the head 2 and housing 4 is also rotatable as a whole about a vertical
axis so as to permit the nozzle to be traversed angularly from side-to-side, to this
end the assembly being fast on the upper end of a hollow vertical axle 6 which is
borne rotatably in a fixed body 7 and which also serves to lead water to the head
2 in use of the monitor. Associated with the monitor is a mechanism 8 (Figures 1 to
4) which is arranged automatically to oscillate the axle 6 through a predetermined
angle (and with it the head 2 and the nozzle carried thereby), so as to play repeatedly
from side-to-side the jet of water or foam which is discharged by the monitor. This
mechanism will now be described.
[0008] Beneath the monitor is a main water supply pipe 9, fed from below and arranged to
deliver water into the rotatable axle 6. A branch flow is also taken from this pipe
and delivered via a shut-off valve 10, non-return valve 11, filter 12 and throttle
valve 13 to a Pelton-wheel motor (turbine) 14, of which the jet nozzle 15 and runner
16 are seen in Figure 3. The Pelton-wheel is driven to rotate at high speed by the
supplied water, and its rotation is transmitted by a speed-reducing gearbox 17 to
a drive wheel 18. As most clearly seen in Figure 4 a crank arm 19 is pinned eccentrically
to the wheel 18 and the arm 19 is pinned at its other end to a shorter drive arm 20
fast with a shaft 21. The shaft 21 constitutes the input member of a clutch 22 mounted
behind the monitor 1 and, as will be seen, its axis is parallel to that of the axle
6. It will also be appreciated that the effect of the linkage between the wheel 18
and the shaft 21 is to impart to the shaft an oscillatory angular motion as the wheel
18 rotates, the amplitude of which is determined by the throw of'the arm 19 and the
effective length of the arm 20. In normal operation the oscillatory motion of the
shaft 21 is transmitted through the clutch to a drive gear 23 coaxial with the shaft
(but not keyed or otherwise secured in driving relationship to the shaft except through
the clutch parts as described below), and this gear is in mesh with a ring gear 24
keyed to the axle 6 so that as the gear 23 oscillates so also does the axle 6.
[0009] Referring now particularly to Figure 5, the upper end 21A of the shaft 21 is of square
cross-section and engages in a complementary hole in a member 25 which also defines
a downwardly-facing polygonal (eg hexagonal) socket 26. Normally this socket member
is biased downwardly by a spring 27 so as to engage over a complementary spigot 28
integral with the drive gear 23, and in this condition the member 25 serves to transmit
the oscillatory motion of the shaft 21 to the gear 23. The biasing spring 27 for the
socket member 25 is, as shown, compressed between the member 25 and a ring member
29 held in the end of a fixed cylindrical casing 30. The socket member 25 can, however,
be slid upwardly on the square end of the shaft 21 so as to disengage from the spigot
28. To this end there is provided a stem 31 which is located relative to the socket
member 25 by means of a ring 32 screwed to the top of the socket member and engaging
over a flange 31A at the lower end of the stem, so as to permit relative rotary movement
between the member 25 and stem 31. At its upper end the stem 31 is secured to a cover
33 in the form of a control knob and which is axially and rotatably slidable on the
casing 30. By lifting the cover 33 by hand, therefore, the stem 31 lifts the socket
member 25 out of engagement with the spigot 28 and the oscillatory drive from the
shaft 21 to the axle 6 is thereby interrupted.
[0010] The stem 31 also carries a cross-pin 34 which, when the clutch is engaged, lies within
a complementary slot 35 in the member 29 (ie as shown in full line in Figure 6). By
means of the relative rotational connection between the socket member 25 and the stem
31 the stem is permitted to remain stationary in this position even though the socket
member, which is at all times in driven engagement with the shaft 21, continually
oscillates. In this way, the oscillation of the socket member is not transmitted to
the cover 33 which is therefore safe to manipulate to disengage the clutch without
having to shut down the Pelton-wheel 14.
[0011] When the cover 33 is lifted to disengage the clutch it can be retained in the disengaged
condition by turning the cover anticlockwise (as viewed in Figure 6) to rest the pin
34 on the upper surface of the member 29 between the heads of two screws 36 and 37
(ie as shown in broken line in Figure 6). The screw 36 has a round head to assist
in moving the pin 34 over it when the cover is turned manually, but will resist clockwise
displacement of the pin from its 'parked' condition when the cover is released. The
screw 37 has a cylindrical head to resist anticlockwise displacement of the pin 34
from its "parked" condition and to provide that the cover 33 can only be turned in
a single sense when engaging or disengaging the clutch.
[0012] While the socket member 25 remains disengaged from the spigot 28 by operation of
the clutch as described above, the gear 23 can be rotated relative to, and independently
of, the shaft 21 and the rest of the preceding transmission. When, therefore, the
apparatus has been set up to oscillate the monitor nozzle through a certain horizontal
sector and .it is subsequently desired to change the sector within which the nozzle
operates it is not necessary to shift the entire apparatus to point the nozzle in
the appropriate new direction; rather the clutch 22 is operated to disengage the drive
from the shaft 21 to the gear 23, and the monitor head 2 and casing 3 can then be
pivoted by manipulation of the handle-bar 5 to place the nozzle into the new sector
in which it is desired to operate, in so doing the gear 23 being rotated by the gear
24 fast with the axle 6 into a new direction; rather the clutch 22 is operated to
angular position relative to the shaft 21. Re-engaging the clutch thereafter reestablishes
the drive between the shaft 21 and gear 23, so that the nozzle is driven to oscillate
through the same angle as before, but in a sector angularly displaced from that previously.
[0013] With polygonal spigot and socket clutch parts as described above, the nozzle can
be made to operate in any one of a number of discrete sectors of the horizon, the
number of sectors being determined by the number of possible relative angular positions
of engagement between the spigot 28 and socket 25, or in other words between the gear
23 and shaft 21. It will also be appreciated that the clutch 22 can be' operated to
disengage the gear 23 from the shaft 21 whenever it is desired to override or shut
down the automatic oscillating mechanism and traverse the monitor nozzle manually
or by some alternative control system.
[0014] The amplitude of the automatic oscillation of the nozzle is open to variation as
well as its sectoral disposition. Thus the drive wheel 18 is provided with a plurality
of holes 38 (in the illustrated embodiment, five) as seen in Figure 4, to receive
the pinned connection of the crank arm 19. These holes are at different radii from
the axis of rotation of wheel 18 so that variation in the throw of the arm 19, and
thereby in the amplitude of oscillation, can be achieved by disconnecting the arm
from one hole 38 and reconnecting it to another. In one particular arrangement constructed
in accordance with the Figures a range of from 60° to 100° of arc in 10
0 increments is provided for the nozzle oscillation by this means.
[0015] The frequency of oscillation of the nozzle can also be varied by variation of the
speed of the Pelton-wheel, and this is achieved by controlling the water pressure
to the Pelton-wheel by means of the throttle valve 13. In one embodiment arranged
to work with a maximum flow through the pipe 9 of 2275 litres/minute at a maximum
pressure of 20.5 bar, the pressure of water tapped off to the Pelton-wheel is controlled
between 3.5 and 14 bar to give an oscillatory frequency range of from 3 to 15 cycles
per minute. The water supplied to the wheel drains from the motor through an outlet.39
(Figure 1). However, the maximum water consumption of the motor is only in the region
of 55 litres/minute which is a negligible proportion of the total flow to the monitor.
[0016] A further inlet to the Pelton-wheel water circuit is provided by a T-piece 40 located
between the non-return valve 11 and filter 12. This inlet is normally blanked off
but can be connected to a suitable water supply when it is desired to test the Pelton-wheel
and the rest of the oscillatory mechanism without having to discharge water from the
monitor itself, ie without having to supply the pipe 9.
1. A mechanism comprising an hydraulically-driven motor (14) and a mechanical transmission
(18,19,20) for connecting the motor (14) to a driving member (21) whereby operation
of the motor (14) produces oscillatory angular motion of said driving member (21);
characterised by clutch means (22) through which such oscillatory angular motion of
the driving member (21) is transferred to a driven member (23), the clutch means (22)
being selectively operable to disengage the driven member (23) from the driving member
(21) to permit rotation of the driven member (23) independently of the driving member
(21), and being adapted to permit re-engagement of the driven member (23) with the
driving member (21) in different relative angular positions thereof.
2. A mechanism according to claim 1 characterised in that the clutch means (22) comprises
a polygonal socket member (25) and a polygonal spigot member (28), one such member
(25) comprising or being in driving connection with said driving member (21) and the
other (28) comprising or being in driving connection with said driven member (23),
these members (25,28) normally being biased into engagement to permit angular drive
transmission from one (25) to the other (28) but being selectively disengageable to
permit relative rotation between them (25,28).
3. A mechanism according to claim 1 or claim 2 characterised in that the driven member
(23) is borne coaxially with, and circumjacent to, the driving member (21); and wherein
the clutch means (22) includes a socket member (25) in permanent driving connection
with, but slidable upon, a portion (21A) of the driving member (21), and means (31,33)
for shifting the socket member (25) upon the driving member (21) between positions
in which it (25) respectively engages with and disengages from the driven member (23).
4. A mechanism according to claim 3 characterised in that the shifting means comprise
a manually operable member(31,33) with which the socket member (25) engages with rotational
freedom relative thereto.
5. A mechanism according to claim 3 or claim 4 charactersed by means (34,36,37) for
retaining the shifting means (31,33) in a position in which the socket member (25)
is disengaged from the driven member (23).
6. A mechanism according to any preceding claim characteised in that the motor (14)
comprises a Pelton-wheel (16) and said transmission includes a crank (19,20) linked
to the driving member (21) whereby rotation of the Pelton-wheel (16) is transmitted
into oscillatory angular motion of the driving member (21).
7. A mechanism according to claim 6 characterised by means (38) for varying the effective
throw of the crank (19,20) thereby to vary the amplitude of the motion of the driving
member (21).
8. The combination of a fire-fighting or the like monitor (1) with a mechanism (8)
in accordance with any preceding claim, where the nozzle (3) of the monitor (1) is
borne by means (6) in driving connection (24) with said driven member (23) thereby
to transfer oscillatory angular motion from the driven member (23) to the nozzle (3).
9. A combination according to claim 9 characterised in that in use a portion of a
stream of water supplied (9) to the monitor for discharge therefrom is diverted (10)
to said motor (14) to drive the same.