Method and apparatus for dispensing a fluidic media onto a selected region of a workpiece

A rigid stabilizer bar is suspended from a quick-release cargo hook attachment point of the helicopter, and a yoke structure is releasably carried by the hook in fixed relation to the bar for suspending a load, opposite ends of the yoke having flexible lines connected to spaced apart locations on the load. Opposite ends of the stabilizer bar are connected by bungee cords to landing skid anchors for stabilizing the yoke. The load is oriented by yawing and rolling maneuvers of the helicopter. In an emergency, the yoke, together with the lines and the load, can be jettisoned from the vehicle by releasing the hook. The load can be a dispensing module for directing a fluidic medium such as crushed walnut shells in a high-pressure air blast from a nozzle that is located on a boom projecting from the module, onto an elevated workpiece such as an insulator of a tranmission line tower for cleaning the insulator. The cleaning module produces a stream of particulate. The helicopter can fly with the module suspended beside the insulator, the nozzle being aimed relative to the workpiece horizontally by yawing the helicopter and vertically by rolling the helicopter. The nozzle is also movable, and the boom can be raised and lowered by remote control for effective access in a variety of workpiece configurations. The module also generates foam for fighting fires.

BACKGROUND 
The present invention relates to maintenance of remote structures, and more 
particularly to the controlled application of a fluidic media in 
connection with such maintenance. 
The manipulation of loads in connection with tower structure construction 
and maintenance is a key to the viability of such structures. For example, 
some important structures have been erected at remote and foreboding sites 
only because it has been possible to fly the components to each site by 
helicopter, the parts being attached to each structure while the 
helicopter hovers with the load properly positioned and oriented. See, for 
example, U.S. Pat. No. 4,378,919 to H. Smith that discloses apparatus by 
which a load suspended from a helicopter is free to swing beneath the 
helicopter, yet the rotational position of the load about a vertical axis 
is controlled by yaw manipulation of PG,3 the helicopter. The Smith 
disclosure includes a yoke by which the load is suspended on a pair of 
cables, the yoke being restrained from rotation under the helicopter by a 
ring-shaped tubular structure that forms a pair of slots for receiving 
opposite ends of the yoke. A linkage allows the tubular structure to move 
back and forth in response to swinging of the cargo hook. 
The Smith device is subject to several disadvantages. For example, the 
linkage is somewhat complex, having several swinging joints. Also, the 
slot in the tubular structure must provide extra clearance for the yoke to 
allow for lateral tipping of the tubular structure, reducing the 
effectiveness of the structure in yaw control. Further, anchor points for 
the linkage must be provided on the aircraft structure. Moreover, there 
are times when further control of a suspended load beyond mere rotational 
control is needed. For example, in one aspect of tower structure 
maintenance, it is desired to clean critical portions of the structure, 
such as insulators of power high voltage power transmission towers. 
Presently, the insulators are cleaned at relatively long range using 
deionized water at high pressure. This can be done from the ground using 
what amounts to a fire truck, and a man carrying a hose can also climb the 
tower. Attempts to do this from the air have had limited success because 
water is too heavy for economical transport by helicopter, and a second 
crew member is required for operating a nozzle turret that is needed for 
directing the stream sufficiently accurately. This greatly increases the 
of weight to the load, and the hardware is expensive. The expense of the 
hardware is aggravated by the need for of FAA certification. See, for 
example, U.S. Pat. No. 4,477,239 to Kurtgis that discloses a tower 
insulator cleaning apparatus that is carried by helicopter. Also, when the 
helicopter is large enough for carrying a meaningful load, two pilots are 
required under FAA regulations. 
Water creates its own problems in that when it is contaminated by dirt from 
the insulator, it becomes conductive, creating a danger of arcing. 
Moreover, there are large reactive forces to contend with. "Dry cleaning" 
has also been done using a blast of air and particles of walnut shells, 
sand, corn husks or the like. But the air blast has a short range of only 
two or three feet, tending to preclude effective cleaning from a nozzle 
mounted on the helicopter, which must fly close to the wires. Also, when 
hoses are used, such as by a man climbing the tower, the losses are 
prohibitive. 
As mentioned above, a disadvantage of the Kurtgis apparatus is that at 
least two crew members are required, and only a relatively small quantity 
of the liquid spray can be carried. Also, the helicopter must fly at a low 
altitude approximately corresponding to the height of each insulator to be 
cleaned. This presents the danger that a gust of wind or other emergency 
might cause the helicopter to crash into the tower and/or the transmission 
lines, with disastrous consequences. Moreover, the center insulator on a 
conventional "single circuit" tower is nearly inaccessible from the side, 
and must be cleaned at long range. 
A further disadvantage of the Kurtgis apparatus is that the nozzle is 
located at the end of a long boom for clearing the ends of the rotor 
blades. This makes the nozzle particularly difficult to aim accurately. 
This difficulty is aggravated by the independent control of the position 
and orientation of the helicopter by its pilot, and the separate aiming of 
the nozzle in both yaw and elevation by the boom operator. Moreover, the 
nozzle and/or the boom can get caught in the tower, with the consequent 
likelihood of crashing the helicopter because neither the boom with its 
nozzle, nor the remainder of the heavy cleaning apparatus and its operator 
can be released in an emergency. 
Another use for the controlled dispensing of a media onto a remote 
workpiece is in fighting fires. See, for example, U.S. Pat. No. 2,779,421 
to Rust, disclosing an aerial fire extinguisher, and U.S. Pat. No. 
4,090,567 to Tomlinson, disclosing a fire fighting helicopter. 
A disadvantage of these firefighting systems is that the full weight of the 
applied medium must be carried by the helicopter. A further disadvantage 
of the Rust fire extinguisher is that there is little control of either 
the location or the amount of the applied media, because the media is 
applied by a plurality of outwardly directed nozzles that rotate about a 
central vertical axis, and because the full load is dispensed upon release 
of a valve by ground contact. 
A further disadvantage of the Tomlinson system is that at least two crew 
members are required as with the cleaning system of Kurtgis, discussed 
above. Directional control of the stream of media is difficult to 
maintain, as with the Kurtgis apparatus, because the orientation of a boom 
nozzle dispensing the media depends on the actions of both the pilot and 
the boom operator. Moreover, apparatus controlling the relative position 
of the nozzle is bulky, excessively heavy, slow to respond, and expensive 
to provide because the relatively long boom for the nozzle must be moved 
about in its entirety for aiming the nozzle. 
Thus there is a need for a highly mobile apparatus for dispensing a fluidic 
medium, accurately in both yaw and elevation. Also, there is a need for 
such apparatus to be capable of delivering controlled amounts of a large 
effective quantity of the media. There is a further need that such 
apparatus be safe to operate in close proximity to high voltage power 
transmission lines and towers, and be adapted for effectively and rapidly 
cleaning large numbers of tower components, as well as being inexpensive 
to build and easy to operate. 
SUMMARY 
The present invention meets these needs by providing an apparatus and 
method for controllably positioning a load from a hoverable vehicle, and 
further to the application of the load in the form of a fluidic medium to 
an elevated workpiece for the purpose of cleaning same. In one aspect of 
the invention, the apparatus includes base means for defining a base; 
attachment means for releasably connecting the base means to a load 
attachment point on the vehicle, the attachment means being capable of 
holding the base means approximately fixed relative to the vehicle about a 
vertical axis and at least one horizontal axis of the vehicle; air 
compressor means attached to the base means; tank means for holding liquid 
and/or solid components of the fluidic medium; a feed conduit having a 
outlet and being connected for pressurization by the air compressor means; 
means for feeding the fluidic medium from the tank means into the feed 
conduit whereby a stream of the fluidic medium, mixed with air, is 
directed from the outlet; nozzle means connected to the feed conduit 
therefrom in response to air pressure in the feed conduit; and boom means 
for locating the outlet in a predetermined position and orientation with 
respect to the base means. 
The structural members can be located on opposite sides of a longitudinal 
axis of the vehicle, the horizontal axis of the biasing means preferably 
corresponding to the longitudinal axis for coupling roll motion of the 
vehicle to the load. Thus the present invention advantageously utilizes 
the roll attitude of the vehicle for controlling the attitude of the load 
about a horizontal axis, the vehicle typically having greater 
maneuverability in roll than in pitch. A further advantage of the present 
invention is that the combination of the roll coupling and the suspension 
of the load below the vehicle creates a pendulum effect that enhances the 
stability of the vehicle and the load. The structural members can be 
landing gear components of the vehicle, the apparatus including means for 
defining an anchor point on those components, the biasing means connecting 
the bar attachment points to the anchor points. Further, the biasing means 
can include a pair of extendable members connected between the bar 
attachment points and the respective anchor points. 
Preferably the biasing means produces a greater stiffness about the 
longitudinal axis than a lateral axis of the vehicle for permitting the 
vehicle to pitch relative to the load. Preferably the stiffness about the 
longitudinal axis is at least about ten times that about the lateral axis. 
More preferably, the stiffness about the longitudinal axis is between 
about ten and about fifty times that about the lateral axis. For this 
purpose, the anchor points can be spaced apart horizontally, the bar 
attachment points being located in a vertical anchor plane that intersects 
the anchor points. Also, the attachment points can define a bar axis that 
proximately intersects the attachment member. Further, the bar axis can be 
located vertically above the anchor points The extendable members can 
extend downwardly and laterally outwardly from the attachment points. 
Preferably each of the anchor points can include a pair of anchor members 
that can be spaced apart on opposite sides of the anchor plane for 
enhancing the stability about the vertical axis, an extendable member 
being connected to each anchor member. Also, the anchor members can be 
movable to proximate the anchor plane for facilitating connection of the 
extendable members. Moreover, the extendable members can include a bungee 
cord. 
Another aspect of the invention provides a method for controllably 
suspending a load from a hoverable vehicle, the vehicle having a load 
attachment point, a releasable hook being connected thereto, and a pair of 
structural members fixably located on opposite sides of the attachment 
point, the method comprising the steps of: 
(a) connecting a rigid stabilizer bar to the attachment point, the 
stabilizer bar extending on opposite sides of the attachment point to 
respective first and second bar attachment points; 
(b) biasingly connecting the first and second bar attachment points to 
respectively to the structural members; 
(c) connecting a yoke member to the releasable hook, the yoke fixably 
engaging the stabilizer bar; 
(d) connecting a pair of flexible tension members at one end thereof to 
opposite ends of the yoke member; and 
(e) connecting opposite ends of the load to respective opposite ends of the 
tension members. 
In a further aspect, the invention provides apparatus for cleaning an 
elevated workpiece from the hoverable vehicle, the apparatus including 
means for defining a base, means for attaching the base below the hook 
member, air compressor means attached to the base, tank means on the base 
for holding a particulate solid material, the tank means being connected 
to and pressurized by the air compressor means, nozzle means operatively 
connected to the tank means for producing a stream of the particulate 
material in response to air pressure in the tank means, and boom means for 
locating the nozzle in a predetermined position and orientation with 
respect to the base, whereby the stream of particulate material can be 
aimed relative to the workpiece horizontally by yawing the vehicle, and 
vertically by rotating the vehicle about a horizontal axis. The means for 
attaching the base below the hook member can include the stabilizer bar, 
the biasing means for yieldably holding the stabilizer bar, the yoke 
member, and means for suspending the base from the yoke member. The means 
for suspending can be tension members connected from opposite ends of the 
yoke to spaced apart locations on the base. The horizontal axis is 
preferably a longitudinal axis of the vehicle for vertically adjusting the 
stream by controlling the roll attitude of the vehicle. 
The attachment means can include register means rigidly connected to the 
base and being adapted for engaging a structural element of the vehicle, 
and a hook engagement member attached to the base for engagement by the 
hook. The combination of the hook engagement member and the registration 
means provides at least a yieldably fixed location of the base relative to 
the vehicle. The registration means can itself be capable of preventing 
rotation of the base about a vertical axis relative to the vehicle. For 
this purpose, the registration means can include an upwardly facing 
horizontally extending trough member for receiving an elongated 
cylindrical portion of the vehicle structural member that is off set to 
one side of the hook and extends parallel to a horizontal axis of the 
vehicle. Preferably the attachment means is capable of holding the base at 
least yieldably fixed in a first position proximate the vehicle, and a 
second position at least about six feet lower than the first position. The 
first position is particularly advantageous for cleaning dual circuit 
towers having three vertically spaced insulators on each side; the second 
position provides convenient access for cleaning the center insulator of a 
single circuit tower having the insulators spaced horizontally, in which 
case the vehicle flies above the tower with the module suspended proximate 
the center transmission line. For this purpose, the attachment means can 
further include the stabilizer bar, yoke member, biasing means, and means 
for suspending the base from the yoke member in the second position. 
The apparatus can further include means for controlling the air pressure in 
the tank for controlling the rate of particulate material in the nozzle 
means. 
The present invention, moreover, includes a method for cleaning a 
workpiece, the workpiece being located at an elevation above ground level 
as a tower structure component, the method comprising: 
(a) suspending a cleaning module from an airborne hoverable 25 vehicle, the 
module comprising: 
(i) means for defining a base; 
(ii) air compressor means attached to the base means; 
(iii) tank means for holding a particulate solid material, the tank being 
connected to and pressurized by the air compressor means; 
(iv) nozzle means connected to the tank means whereby a stream of the 
particulate material is produced therefrom in response to air pressure in 
the tank means; 
(v) boom means for locating the nozzle in a predetermined position and 
orientation with respect to the base means; 
(b) maneuvering the vehicle for positioning the module proximate the tower 
structure with the nozzle having a positional elevation proximate the 
elevation of the workpiece; 
(c) yawing the vehicle for directing the stream laterally onto the work 
piece; and 
(d) rotating the vehicle about a horizontal axis for adjusting the stream 
vertically on the workpiece. 
The step of rotating the vehicle about the horizontal axis can include 
rolling the vehicle about a longitudinal axis. Also, the method can 
include the further step of controlling the air pressure in the tank means 
for controlling the rate of particulate flow through the nozzle means. For 
this purpose, the method can include the further step of controlling a 
source of power for the air compressor. The power can be controlled 
between a first high level for producing the stream and a second low level 
for preventing the stream. Moreover, the apparatus can further include a 
control valve between the tank means and the nozzle means, the method 
further comprising the step of operating the control valve for preventing 
the flow of the particulate material.

DESCRIPTION 
The present invention is directed to an apparatus and method for 
controllably positioning a load from a hoverable vehicle, and further to 
the application of the load in the form of a fluidic medium to an elevated 
or otherwise inaccessible workpiece. The medium can include an abrasive 
particulate for cleaning the workpiece, or foam for fighting fires. With 
reference to the drawings, particularly FIGS. 1-3 and 5, a helicopter or 
other hoverable vehicle 10 is equipped with a releasable cargo hook 12, 
the hook 12 being connected by an attachment bolt 14 to a cable 16, the 
cable 16 being attached to the vehicle 10 for suspending the hook 12 
underneath the vehicle 10. The vehicle 10 is also equipped with landing 
gear structure in the form of a pair of skids 18, the skids 18 being 
located on opposite sides of a longitudinal axis 20 of the vehicle 10, the 
longitudinal axis 20 intersecting the hook 12. As shown in FIG. 1, the 
skids 18 are spaced apart by a distance S, the attachment bolt 14 being 
located midway therebetween and elevated therefrom vertically by a 
distance H. 
According to the present invention, an apparatus 30 for manipulation of a 
load 32 includes a stabilizer unit 34 that is suspended from the hook 12 
and the attachment bolt 14 as described herein. The stabilizer unit 34 
includes a stabilizer bar 36 that extends horizontally on opposite sides 
of the hook 12 to respective bar attachment points 38, the bar attachment 
points 38 being spaced apart by a distance X and displaced below the 
attachment bolt 14 by a vertical distance C. Each of the bar attachment 
points 38 is biasingly connected to a respective skid 18 of the vehicle 10 
by a corresponding bungee means 40, the connection of each bungee means 40 
to the skid 18 defining an anchor point 42, the anchor point 42 being 
fixed relative to the respective skid 18. A yoke assembly 44 is suspended 
from the hook 12, the yoke assembly 44 including a yoke truss 46 that 
extends on opposite sides of the hook 12 to a pair of yoke attachment 
points 48, the yoke truss 46 being releasably connected to the hook 12 by 
an eye bolt 50, the yoke attachment points 48 being spaced apart by a 
horizontal distance Y and located a vertical distance D below the bar 
attachment points 38. 
The yoke assembly 44 is held in a fixed position relative to the stabilizer 
bar 36 by means of spaced apart pairs of leg members 52, each pair of the 
leg members 52 fixably depending from the stabilizer bar 36 from proximate 
a respective bar attachment point 38, the leg members 52 slidably engaging 
opposite sides of the yoke truss 46. A pair of cushion members 54 enclose 
the stabilizer bar 36, each of the cushion members 54 being located 
proximate a pair of the leg members 52 for bearing against the top of the 
yoke truss 46 when the eye bolt 50 engages the hook 12. A desired degree 
of pressure can be maintained between the cushion members 54 and the top 
of the yoke truss 46 by appropriately adjusting the eye bolt 50. The 
attachment bolt 14, the eye bolt 50, the bar attachment points 38, and the 
yoke attachment points 48 each lie in a common anchor plane, designated 
stabilizer plane 56 in FIG. 2. The stabilizer plane 56 is nominally a 
vertical plane that is normal to the longitudinal axis 20 of the vehicle 
10, the bungee means 40 and the anchor points 42 also being nominally 
located in the stabilizer plane 56. 
The load 32 is suspended from the yoke assembly 44 by a pair of flexible 
tension members 58, each tension member 58 being connected between one of 
the yoke attachment points 48 and a respective load attachment point 60 of 
the load 32, the load attachment points 60 being spaced apart horizontally 
by a load attachment distance W, the distance W being approximately equal 
to the yoke attachment distance Y between the yoke attachment points 48. 
The distance Y is less than the distance S, and the distance C plus the 
distance D is less than the distance H for locating the stabilizer unit 34 
above ground level when the vehicle 10 is at rest, and for permitting the 
tension member 58 to pass between the skids 18. Suitable tensioning of the 
bungee means 40 provides a high degree of yaw stiffness of the stabilizer 
unit 34 about a vertical axis 62 of the vehicle 10, the vertical axis 62 
intersecting the attachment bolt 14 and, nominally, the eye bolt 50. The 
distance X is preferably from about 50% to about 90% of the distance S 
between the skids 18 for enhancing the yaw stiffness. More preferably, the 
distance X is between approximately 65% and approximately 75% of the 
distance S. Also, the distance C by which the bar attachment points 38 are 
displaced below the bolt 14 assures that when the stabilizer unit 34 is 
unloaded, the stabilizer unit 34 is effectively prevented from flopping 
around, the stabilizer plane 56 remaining approximately vertical. On the 
other hand, the distance C is made relatively small compared with the 
vertical distance H by which the bolt 14 is located above the skid 18 for 
limiting bending stresses on the stabilizer unit 34 in a horizontal 
direction when the vehicle 10 rotates in pitch relative to the load 32. 
Accordingly, the distance C is made from about 20% to about 40% of the 
distance H, being more preferably about 30% of the distance H. Also, an 
angle A is formed in the stabilizer plane 56 between each bungee means 40 
and the anchor points 42, the angle A being approximately 45.degree.. 
As shown in FIG. 2, each of the anchor points 42 has two counterparts, 
designated anchor band 43, that are spaced apart on opposite sides of the 
stabilizer plane 56, each being formed as a band member that encloses the 
skid 18, and connecting a respective bungee means 40. Removable spacer 
means 66 are interposed between the bands 43 on each skid 18. This 
arrangement advantageously permits the bungee means 40 to be connected at 
reduced tension for ease of installation, and enhances the yaw stability 
of the stabilizer unit 34 for a given roll stiffness thereof. Further, the 
spacing between the bands 43 provides enhanced clearance between the 
bungee means 40 and the yoke assembly 44. 
The combination of the roll coupling between the load 32 and the vehicle 10 
with the location of the load beneath the vehicle advantageously enhances 
the stability of both the vehicle and the load. This is because the 
combined mass of the load and the vehicle is centered further below the 
center of thrust than is the case when the load is within the vehicle. 
An important aspect of the present invention is that the load 32 can be a 
cleaning or dispensing module 70, the dispensing module 70 being 
particularly useful in the maintenance of transmission line towers such as 
the tower 72 shown in FIG. 5. The tower 72 serves to support a plurality 
of transmission lines 74, each by a respective insulator or workpiece 76, 
the workpiece 76 requiring periodic cleaning maintenance for removing 
accumulations of foreign material that would otherwise eventually produce 
harmful arcing between the lines 74 and the tower 72. In FIG. 5, the tower 
72 supports three of the transmission lines 74 in a typical "single 
circuit" three-phase configuration, the respective workpieces 76 being 
horizontally disposed. Also, a pair of grounded sky lines 75 are supported 
from the top of the tower 72 for preventing circuit damage from lightning. 
The dispensing module 70 includes a frame or base 78 having an overhead 
load beam 80, the load beam 80 incorporating the load attachment points 
60. With further reference to FIG. 3, a tank 82 is mounted on the base 78 
for carrying the cleaning medium in the form of a particulate solid 
material 84, a control valve 86 being connected to a bottom outlet 88 of 
the tank 82 for dispensing the material 84 through a delivery line 90. The 
delivery line 90 is connected to the control valve 86 by a Tee fitting 92, 
and also to a nozzle 94, the nozzle 94 being mounted in a predetermined 
position and orientation with respect to the base 78 on a boom assembly 
96. An air compressor means 98 is connected to the tank 82 by a tank 
fitting 100, a manifold line 102 also connecting the tank fitting 100 to 
the Tee fitting 92. Thus the compressor means 98 simultaneously 
pressurizes the tank 82 while delivering a large quantity of air at the 
same pressure to the delivery line 90. The tank fitting 100 is also 
operatively connected through a solenoid valve 101 to the control valve 86 
for automatically opening the control valve 86 when the pressure at the 
tank fitting 100 reaches a predetermined level. Thus whenever the pressure 
at the tank fitting 100 is at or above the predetermined level, the 
material 84 is allowed to pass through the control valve 86 at a 
predetermined rate for mixing with the air in the delivery line 90 as long 
as the solenoid valve is also activated, the material 84 being ejected 
from the nozzle 94 with the air in a high-velocity stream 104. 
In an exemplary configuration of the air compressor means 98, a screw 
compressor unit 106 is operatively connected to a gasoline reciprocating 
engine 108 by drive belt means 110, the engine 108 being fed by a fuel 
supply 109. The compressor unit 106 includes a quasipositive displacement 
twin-screw pump 112 having an air inlet 114, an oil circulation system 
having a sump 115 and pump means 116, an air/oil separator 117, a fan 
cooler 118, and an outlet 120, the outlet 120 being connected to the tank 
fitting 100. A compressor unit suitable for use as the compressor unit 106 
in the present invention is available as Roto Model 2A, Roto being a 
trademark of Bauer Compressors Inc., of Norfolk, Va. The Roto 2A 
compressor is capable of delivering over 120 cfm of air at 100 psi 
compressor discharge pressure when driven with a power input of 30 
horsepower. The compressor operates with essentially positive displacement 
between 4000 rpm and a service maximum about 6000 rpm, there being no 
effective seal below 3000 rpm such that a negligible amount of power is 
required under idling conditions. The air flow rate ranges from about 75 
cfm at 4500 rpm up to about 130 cfm at the maximum of 6000 rpm. 
An engine suitable for use as the engine 108 in the present invention is 
available as Rotax Model 503 from California Power Systems of San Jose, 
Calif. In a single carburetor version, this engine is capable of 
delivering approximately 25 horsepower at 4000 rpm, 30 horsepower at 4500 
rpm, 35 horsepower at 5000 rpm, 40 horsepower at 5500 rpm, and 44 
horsepower at 6000 rpm. This engine, which weighs approximately 70 pounds, 
requires approximately 2.5 gallons per hour of fuel when producing 30 
horsepower. 
A torque converter unit 122 is connected between the compressor unit 106 
and the drive belt means 110 for enhancing the ability of the engine 108 
to deliver needed power to the pump 112 over a wide range of operating 
conditions. Alternatively, the drive belt means 110 produces a 1:1 drive 
ratio such that the speed of the engine 108 is the same as that of the 
pump 112. In fact, the engine 108 could be directly coupled to the pump 
112, except that one of the engine 108 and pump 112 would be required to 
be configured for running in an opposite direction to that of the readily 
available models of these components noted above. 
As further shown in FIG. 3, the dispensing module 70 is controlled by an 
air control switch 124 which is located within the vehicle 10, the switch 
124 being operatively connected to a solenoid actuator 126 for controlling 
a throttle member 128 of the engine 108. When the solenoid actuator 126 is 
activated by the air control switch 124, the throttle member 128 is moved 
to an adjustable substantially open position for producing a predetermined 
high power output from the engine 108. When the solenoid actuator 126 is 
deactivated, the throttle member 128 moves to an idle position for 
operating the engine 108 in an idling condition, the idling condition 
being at a speed substantially below 3000 rpm, such as 1000 rpm. A media 
switch 129 for controlling the solenoid valve 101 is also located within 
the vehicle 10. Accordingly, when the solenoid actuator 126 is 
de-energized, there is substantially no flow of either air or the material 
84 from the nozzle 94, the control valve 86 being closed in response to 
low air pressure at the tank fitting 100. When the solenoid actuator 126 
is activated, high air pressure is obtained at the tank fitting 100, but 
the control valve 86 remains closed until the solenoid valve 101 is 
activated by the media switch 129, at which time the control valve 86 is 
opened and operational quantities of the material 84 are driven through 
the nozzle 94 with the air for producing the stream 104. 
A nozzle suitable for use as the nozzle 94 is available as Super Blast 
model DCV-4 from Empire Abrasive Equipment Corp. of Langhorne, Penna. The 
DCV-4 nozzle includes a centered carbide venturi having a 0.25 inch ID, 
and is rated an air flow rate of 81 CFM and 494 pounds of sand flow per 
hour at a nozzle pressure of 100 psi, 18 horsepower being required. Other 
components appropriate for use as the tank 82, the control valve 86, the 
delivery line 90, the Tee fitting 92, and the tank fitting 100, and the 
manifold line 102, are similarly available from Empire Abrasive Equipment 
Corporation. 
The boom assembly 96 includes an A-frame member 130, opposite legs thereof 
being pivotably joined by a pair of frame joints 132 to the base 78, an 
arm or boom member 134 being pivotably connected to the apex of the 
A-frame member 130 by an arm joint 136. The nozzle 94 is pivotably mounted 
to the boom member 134 remotely from the arm joint 136 by a nozzle joint 
138. The boom member 134 is fabricated from an electrically non-conductive 
material for isolating the nozzle 94 from the A-frame member 130 and the 
base 78 of the dispensing module 70. Similarly, the delivery line 90 
comprises an electrically non-conductive material such as rubber. As shown 
in the drawings, the arm member 134 is fabricated from a tube of 
fiberglass, the delivery line 90 being supportively located therein. The 
boom assembly 96 can extend from the base 78 a distance L between frame 
joint 132 and the arm joint 136, plus a distance M between the arm joint 
136 and the nozzle joint 138, plus a distance N between the nozzle joint 
138 and the end of the nozzle 94. The distance L can be about 7 feet, the 
distance M can be from about 3 feet to about 7 feet, and the distance N 
can be about 8 inches. Thus the maximum distance between the frame joint 
132 and the end of the nozzle 94 is from about 11 feet to about 15 feet. 
The arm joint 136 and the nozzle joint 138 are fixably adjustable to 
predetermined relative orientations. For this purpose, the arm joint 136 
is provided with an adjustable arm joint clamp 140, and an adjustable 
nozzle joint clamp 142. A flexible arm tension member 144 is connected to 
the boom assembly 96 proximate the arm joint 136 and anchored to the base 
78 proximate the load beam 80, the tension member 144 being equipped with 
adjustment means 146 for adjustably defining an angle B of the A-frame 
member 130 relative to the base 78, except that the tension member 144 
permits the A-frame member 130 to be pivoted upwardly about the frame 
joint 132 to proximately a horizontal position when the dispensing module 
70 is at rest on the ground. Typically the tension member 144 is adjusted 
for maintaining the angle B between about 45.degree. and about 60.degree. 
for enhancing a vertical distance Z between the nozzle 94 and a rotor 22 
of the vehicle 10, and for permitting the boom assembly 96 to clear 
obstructions associated with the tower 72. 
In operation, the air switch 124 and the media switch 129 are both switched 
off until the vehicle 10, together with the dispensing module 70, 
approaches a tower 72 at which cleaning is to be done. Preferably, the air 
switch 124 is next turned on, activating the solenoid 126 for producing 
the high-pressure output of the compressor means 98 as described above. As 
the vehicle 10 is further maneuvered for bringing the nozzle 94 proximate 
the workpiece 76, the solenoid valve 101 is then activated by the media 
switch 129 for producing the stream 104 as also described above. Normally, 
the solenoid 126 is energized continuously while a full complement of the 
workpieces 76 of the tower 72 are cleaned. When it is desired to interrupt 
the stream 104 such as when moving between the workpieces 76, the media 
switch 129 is operated for de-energizing the solenoid valve 101. This is 
because the control valve 86 responds relatively rapidly to operation of 
the solenoid valve 101 as compared with operation of the solenoid 126, 
because of the time required for the engine 108 to change speeds, and for 
a corresponding change of air pressure in the tank 82. When the last 
workpiece 76 of the tower 72 has been cleaned, the solenoid 126 is 
deactivated by operation of the air switch 124, with a consequent savings 
of fuel expended from the fuel supply 109 during transit to the next tower 
72. 
An experimental prototype of the dispensing module 70 as described above, 
but without the arm joint 136, has been built and tested, the module 70 
having a weight of approximately 550 pounds, the tank 82 being capable 
carrying approximately 150 pounds of the material 84. The tests show that 
prototype is operable to produce the stream 104 continuously for about 45 
minutes. It is expected that by substituting slightly larger counterparts 
of the tank 82 and the fuel supply 109, along with a modest 
weight-reduction of the module 70, continuous operation for one hour or 
more will be possible. 
It has been determined that the dispensing module 70 is effective in 
cleaning the workpiece 76 with the nozzle 94 positioned at an operating 
distance O from the workpiece, the distance O being up to about 6 feet. 
Typically the workpiece 76 is an elongated cylindrical insulator 150 
having a spaced plurality of ring portions 152, as shown in FIG. 6. It has 
unexpectedly been discovered that by directing the stream 104 upwardly and 
laterally against the ring portions 152, the material 84 is deflected by 
the ring portions 152 such that substantially all of the insulator 150 can 
be cleaned while the nozzle 94 is positioned to one side only of the 
insulator 150, as shown in FIG. 6. 
With further reference to FIG. 4, an alternative configuration of the 
compressor means 98 includes a gas turbine compressor 160 and a cooler 
module 162, the compressor 160 being provided with a fuel control 164 that 
is responsive to the control switch 124. In this configuration, the 
dispensing module is capable of carrying a much larger payload because the 
weight efficiency of the compressor 160 is greatly improved over that of 
the compressor unit 106 and the separate engine 108. 
In another important aspect of the present invention, the dispensing module 
70 can be releasably carried proximate the vehicle 10 as an alternative to 
the vertically separated configuration that is shown in FIG. 5. As shown 
in FIGS. 1 and 2, and with further reference to FIG. 7, the load beam 80 
of the base 78 is equipped with a hook catch 160 for engagement by the 
releasable hook 12, the hook 12 also being capable of closing and latching 
about the catch 160. The vehicle 10 is also equipped with a winch means 
162 for vertically positioning the hook 12 as desired by the operator. An 
upwardly facing trough member 164 is rigidly attached to the load beam 80 
for engaging one of the skids 18 of the vehicle 10. Thus with the 
stabilizer unit 34 removed, the vehicle 10 can be made to hover above the 
dispensing module 70, the skid 18 being guided into engagement with the 
trough member 164; and the hook 12, initially in its released condition, 
is engaged with the hook catch 160. As shown in FIG. 7, a mirror 166 is 
provided on the vehicle 10 for establishing a line of sight 168 between 
the operator and the trough member 164, the trough member 164 being 
located on an opposite side of the vehicle 10 from the operator. This is 
because the hook catch 160 is located laterally slightly to one side of a 
center of gravity 170 of the dispensing module 70 for producing an upward 
force reaction at the trough member 164 that maintains the engagement with 
the skid 18. It is preferred that the trough member 164 be located 
opposite the boom assembly 96 because the lateral offset of the hook catch 
160 results in an increased extension of the boom assembly 96 beyond the 
rotor 22 of the vehicle 10, the boom assembly 96 being located on the same 
side of the vehicle 10 as the operator for facilitating effective aiming 
of the nozzle 94. 
In this alternative configuration, the dispensing module 70 is essentially 
rigidly coupled proximate the vehicle 10, the vertical distance Z between 
the nozzle 94 and the rotor 22 being substantially reduced by at least 
about six feet compared with the previously described configuration shown 
in FIG. 5. This alternative configuration is well suited for cleaning the 
insulators 150 of a "dual circuit" three phase transmission tower 172 as 
schematically depicted in FIG. 7. As further shown in FIG. 7, the nozzle 
94 protrudes a distance P laterally beyond the rotor 22 of the vehicle 10. 
Typically, the rotor 22 can have a radius R of approximately 13.2 feet. In 
an exemplary configuration of the present invention, the distance P is 
preferably between about 7 feet and 8 feet. 
With further reference to FIG. 8, another alternative configuration is 
provided by having two of the trough members 164 at opposite ends of the 
load beam 80, each of the trough members 164 engaging a respective skid 
18. In this configuration, the hook catch 160 is centrally located between 
the load attachment points 60, and between the trough members 164. The 
mirror 166 is not required in this configuration because the line of sight 
168 can be between the operator and the trough member 164 on the same side 
of the vehicle 10. Suitable precautions, however, must be taken to prevent 
the winch means 162 from raising the hook 12 above a level required for 
the engagement of the trough members 164 with the skid 18. Otherwise, the 
load beam 80 would be subject to bending by excessive upward movement of 
the hook 12. Suitable protection can be provided by a conventional limit 
stop means (not shown) that is operatively connected to the winch means 
162. With further reference to FIG. 9, a curve-shaped alternative 
configuration of the trough member 164 permits a rocking motion between 
the trough member 164 and the skid 18 for allowing the vehicle 10 to pitch 
relative to the dispensing module 70. 
With further reference to FIGS. 10 and 11, the boom assembly 96 extends to 
the left from below the vehicle 10 as described above, and as shown in 
FIG. 11a. In further accordance with the present invention, the base 78 of 
the dispensing module 70 is provided with a first pair of joint mounts, 
designated 174a and 174b in FIG. 10, for mounting the boom assembly 96 
with the nozzle 94 extending forwardly below the vehicle 10, laterally 
positioned left of a longitudinal axis 175 of the vehicle 10, as shown in 
FIG. 11b. The forwardly extending orientation of the boom assembly 96 is 
advantageous in that minor adjustment of the vertical position of the 
nozzle 94 is very conveniently accomplished by corresponding movements in 
the pitch attitude of the vehicle 10, the nozzle 94 being in the natural 
field of view ahead of the pilot when the vehicle 10 is piloted from a 
left seat (not shown). Similarly, an additional pair of joint mounts, 
designated 174c and 174d in FIG. 10, are provided on the base 78 opposite 
the mounts 174a and 174b for connecting the boom assembly 96 as shown in 
FIG. 11c. In the configuration of FIG. 11c, the dispensing module 70 is 
turned end for end relative to the vehicle 10, the boom assembly 96 
extending forwardly from beneath the vehicle 10, the nozzle 94 being in 
the natural field of view ahead of the pilot when the vehicle 10 is 
piloted from a right seat (not shown). As further shown in FIG. 10, the 
base 78 of the dispensing module 70 is provided with the trough members 
164 as described above in connection with FIG. 8, the winch means 162 
being mounted to the load beam 80 of the dispensing module 70 instead of 
to the vehicle 10, for avoiding problems related to certification of the 
vehicle 10 by relevant governing authorities. Preferably the winch means 
162 has an air motor drive powered by the compressor means 98. 
Conventional winch means having such air motor drives are available from a 
variety of sources. 
With further reference to FIG. 12, an alternative and preferred 
configuration of the boom assembly 94 includes means 176 for remotely 
positioning the nozzle 94 relative to the boom member 134, the positioning 
means 176 being operated by actuator means 178. The actuator means 178 is 
located at a distance from the nozzle 94 for reducing a polar movement of 
inertia of the dispensing module 70 about the vertical axis 62 controlled 
from within the vehicle 10 by a joystick control 180, shown 
diagrammatically in FIG. 12 as being incorporated in a pilot's kneepad 
182, the kneepad 182 also incorporating the air control switch 124 and the 
media switch 129. The signals between the kneepad 182 and the dispensing 
module 70 are preferably carried by an umbilical cord 184 as further shown 
in FIG. 12, the umbilical cord passing directly from within the vehicle 10 
to the dispensing module 70 without connecting the stabilizer unit 34 for 
facilitating manipulation of the module 70 relative to the vehicle 10. 
The positioning means 176 includes a spaced plurality of nozzle arm members 
186 rigidly extending radially from the nozzle 94 for selectively urging 
the nozzle 94 out of alignment with the boom member 134 as described 
herein, the arm members 186 including an orthogonal pair of upper arm 
members 186a and corresponding lower arm members 186b. As shown in FIG. 
12, the delivery line 90 is slightly flexible, the nozzle 94 being coupled 
directly thereto by threaded engagement with a nozzle sleeve 188, the 
nozzle sleeve 188 also threadingly gripping an end portion 190 of the 
delivery line 90, the boom member 134 terminating short of the nozzle 
sleeve 188, a clamp 191 being applied to the boom member 134 for 
maintaining a desired spacing from the nozzle sleeve 188. As further shown 
in FIG. 12, the nozzle arm members 186 extend rigidly from the nozzle 
sleeve 188 such as by being formed integrally therewith. A control rod 192 
is pivotally connected to the outer end of each nozzle arm member 186 by 
means of a swivel rod end 194 and associated clevis pin 196, the control 
rods being designated upper control rods 192a and lower control rods 192b, 
respectively connecting the upper nozzle arm members 186a and the lower 
nozzle arm members 186b. Each control rod 192 extends along the boom 
assembly 96 and into responsive engagement with the actuator means 178, 
whereby opposite axial movements of diagonally opposing control rods 192a 
and 192b produce a corresponding flexure of the delivery line 90. The 
control rods 192 are located in spaced relation to the boom member 134 by 
one or more guide assemblies 198, each guide assembly 198 having a guide 
member 200 in axially sliding engagement with each of the control rods 
192, the control rods 192 also being slightly flexible for permitting the 
desired movement of the nozzle 94 relative to the boom member 134. The 
range of orientations of the nozzle 94 relative to the boom member 134 is 
asymmetrically disposed above alignment with the boom member 134 because 
of the need for the stream 104 to be inclined nominally upwardly as 
discussed above. Accordingly, the upper arm members 186a extend in a plane 
generally normal the nozzle 94, while the lower arm members 186b are 
inclined slightly rearwardly as shown most clearly in FIG. 12. 
In an exemplary configuration of the present invention, the actuator means 
178 includes a frame member 202 rigidly mounted to the boom assembly 96, a 
pair of levers 204 each pivotally connected to the frame member 202, 
opposite ends of each lever 204 being also pivotally connected to 
respective opposing ones of the control rods 192 by further counterparts 
of the rod ends 194 and clevis pins 196. 
Each of the levers 204 is coupled to a control actuator 206 for operation 
thereby, the actuators 206 being responsively connected to the joystick 
control 184 using methods known in the art of actuators. For example, the 
actuators 206 can incorporate motor-driven lead screws, appropriate 
electrical connections being made between the joystick control 184 and the 
actuators 206, and to a suitable source of electrical power. Preferably, 
the actuators 206 each include a pneumatic cylinder and appropriate 
control valves, the control valves being fluid-connected to the outlet 120 
of the compressor means 98. In this preferred configuration, the 
compressor means 98 provides a most convenient source of power for the 
actuator means 178. It will be understood that the actuator means 178 need 
not be powered when the engine 108 thereof is being operated at idle. 
With further reference to FIGS. 13 and 14, another preferred configuration 
of the apparatus 30 includes the trough member 164 at each end of the load 
beam 80 for rigidly coupling the dispensing module 70 to the skids 18 of 
the vehicle 10 as in FIG. 8, above, the boom assembly 96 also 
incorporating the positioning means 176 for the nozzle 94. The winch means 
162 is mounted to the load beam 80 of the base 78, in a similar location 
between the load attachment points 60 as in FIG. 10. In this 
configuration, however, a pair of winch lines 218 movably extend from the 
winch means 162, each winch line 218 passing through a snatch block 220 
that is connected to the base 78 proximate a respective one of the load 
attachment points 60, the line 218 being connected to one of the yoke 
attachment points 48 of the stabilizer unit 34. Thus the dispensing module 
70 can be suspended below the vehicle 10 from the stabilizer unit 34, the 
winch lines 218 functioning as the tension members 58 as described above 
in connection with FIGS. 1 and 5. Also, the module 70 can be moved 
according to the present invention between the position shown in FIG. 5 
and the rigidly coupled configuration of FIG. 8 by operation of the winch 
means 162, even while the vehicle 10 is airborne. Moreover, the vertical 
distance Z between the nozzle 94 and the rotor 22 is adjustable during 
flight for optimally selecting the distance Z according to the environment 
of each workpiece 76. 
In operational experiments with the prototype apparatus, it has been found 
desirable to increase the distance P (See FIG. 7) by which the nozzle 94 
extends beyond the rotor 22. It has also been found that the effectiveness 
of the stabilizer unit 34 is greatly enhanced by limiting a polar moment 
of inertia of the dispensing module 70 about the vertical axis 62 of the 
vehicle 10. Further, experience with the previously tested prototype of 
the delivery module 70 has shown that excessive flexibility of the boom 
assembly 96 is detrimental to precise control of the delivery stream 104 
from the nozzle 94. Accordingly, the apparatus 30 preferably includes a 
lightweight, elongate and particularly stiff form of the boom assembly 96 
as further shown in FIG. 13. This configuration of the boom assembly 96 
includes a plurality of guy wires 222 that are anchored proximate opposite 
ends of the boom member 134 for supporting a spider frame 224, the frame 
224 being mounted approximately midway along the boom member 134. This 
preferred configuration of the boom assembly 96 can extend a distance E of 
approximately 18 feet between the base 78 and the nozzle 94, an increase 
of from 3 to 7 feet over what was previously believed practical. Moreover, 
the nozzle 94 is preferably made primarily from a plastic material for 
reduced mass as compared with the DCV-4 nozzle that is discussed above. A 
lightweight nozzle suitable for use as the nozzle 94 is available as Model 
SSR-4 nozzle from Clemco Industries of San Francisco, Calif. 
As more clearly shown in FIG. 14, the control actuators 206 of the actuator 
means 178 are mounted to the spider frame 224. In the configuration of 
FIGS. 13 and 14, the actuators 206 are each connected for directly 
operating one of the control rods 192, the opposite control rod 192 being 
operated by a control lever 226, each control lever 226 being pivotally 
mounted relative to the boom member 134. The control levers 226, together 
with the associated guide members 200 and control actuators 206, are 
spaced apart a short distance along the boom member 134 for preventing 
interference between the control levers 226. A prototype of the boom 
assembly 96 as thus configured, including the delivery line 90, was found 
to have a weight of approximately 30 pounds. 
In a further enhancement of the dispensing module 70, an enlarged prototype 
of the tank 82 has been fabricated by winding a high-strength carbon 
filament material over an aluminum mandrel for providing improved payload 
capacity of the dispensing module 70 at a given gross weight thereof. The 
tank 82 was so constructed using a proprietary process of Hitco, of Los 
Angeles, Calif. This modified configuration of the tank 82 weighs only 40 
lbs., yet has a capacity of 4 cubic feet, and is capable of withstanding 
the full pressure output of the compressor means 98, up to 125 psi. The 
new tank 82, which has been successfully tested to withstand 500 psi, is 
90 lbs. lighter than the first prototype, with 33 percent larger volume. 
With further reference to FIG. 15, the apparatus 30 of the present 
application is adapted for controlled delivery of expanded water or foam 
230 for extinguishing a remote or otherwise inaccessible fire 232. For 
this purpose, the tank 82 of the dispensing module 70 is filled with 
water, the water being mixed with a small quantity of a suitable foaming 
agent. It has been discovered that without modification, the apparatus 30 
as described above is capable of generating and delivering the foam 230 in 
controlled, effective quantities that are accurately positioned. The 
dispensing module 70, being suspended below the vehicle 10 from the 
stabilizer unit 34, is controllably oriented as described above, the boom 
assembly 96 being spaced well below the vehicle 10, and extending to one 
side for avoiding damage to the vehicle 10 that might otherwise result 
from the heat of the fire 232. Moreover, the foam 230 can be quickly aimed 
at selected portions of the fire 232 by operation of the positioning means 
176. Thus the apparatus 30 is particularly cost-effective, being suitable 
for cleaning and other maintenance of tower structure components as well 
as for fighting fires. 
It has been discovered further that improved operation for generating the 
foam 230 is achieved by removing the nozzle 94 from the nozzle sleeve 88, 
and by increasing to 1.25 inches the inside diameter of the delivery line 
90, an 0.75 inch inside diameter being sufficient for cleaning 
applications. This modification is practical with only a slight increase 
of the outside diameter of the delivery line 90, and with no increase in 
weight. Also, the larger inside diameter is compatible with the cleaning 
operations. Accordingly, the dispensing module 70 is preferably configured 
with the larger delivery line 90, the nozzle 94 being adapted with an 
appropriately larger entrance cone for efficient acceleration of the 
material 84. Thus conversion from the cleaning configuration to a 
preferred foam delivery configuration is possible by the simple removal of 
the nozzle 94. A hose suitable for use as the delivery line 90 as thus 
described is available as type SUPA lightweight blast hose from Clemco 
Industries, above. 
With further reference to FIGS. 16 and 17, a new prototype of the 
dispensing module 70 has been incorporated in the apparatus 30. In this 
new and preferred configuration, the module 70 includes the new prototype 
tank 82, described above, the boom assembly 96 having slightly modified 
versions of the nozzle positioning means 176 and the actuator means 178. 
As shown in FIG. 16, the positioning means 176 is configured for providing 
a maximum nozzle up-angle U of 80.degree. and a maximum nozzle down-angle 
V of 10.degree.. For this result, it was found advantageous to modify the 
actuator means 178 to provide a separate control actuator 206 for each of 
the control rods 192. Each of the control actuators 206 has a linear 
travel T of approximately 10 inches, and the lower nozzle arm members 186b 
are inclined rearwardly abut 45.degree.. In this configuration, the levers 
206 (FIG. 12), or the levers 226 (FIG. 13) are omitted. Suitable control 
of the control actuators 206 is provided as shown in FIG. 17, the control 
actuators 206 being designated therein as UL, UR, DL, and DR. The control 
actuators 206, being configured as a double-acting pneumatic cylinder 
having an inside diameter of approximately 0.75 inch, are operatively 
connected to corresponding 4-way valves 228. The 4-way valves 228 are 
manifolded to the compressor means 98 for providing a convenient source of 
air for moving the nozzle 94, the air being directed in response to 
separate valve solenoid signals 230 for selectively extending or 
retracting the associated control actuator 206. The valve solenoid signals 
230 are generated by a nozzle logic circuit 232 in response to the 
joystick control 180. In FIG. 17, the joystick control 180 is configured 
as a single pole double-throw, center off, switch 234 for controlling 
vertical movements of the nozzle 94, and a similar but separate switch 236 
for controlling horizontal movements of the nozzle 94. Also, the 4-way 
valves 228 are configured for blocking the path between the source of air 
pressure and the respective control actuators 206 when neither of its 
valve solenoid signals 230 are activated. 
As further shown in FIG. 16, the arm tension member 144 is implemented by 
boom actuator means 238 for raising and lowering the boom assembly 96 in 
response to remote control from the kneepad 182 (see FIG. 12). The boom 
actuator means 238 includes a pneumatic actuator 240 pivotally connected 
between the A-frame member 130 and the load beam 80, the actuator 240 
having an inside diameter of approximately 1.5 inches and a travel of 
approximately 24 inches. The actuator 240 is controlled by another of the 
4-way valves 228 (not shown), this valve 228 being directly responsive to 
a counterpart of the single pole double-throw, center off, switch 234 
(also not shown). The boom actuator means 238 is capable of moving the 
boom assembly 96 between an approximately horizontal position and 
downwardly inclined position, the angle B between the A-frame member 130 
and the base 78 being up to approximately 45.degree.. 
In this new prototype of the dispensing module 70, the torque converter 122 
has been replaced by a centrifugal clutch 142 for a further reduction in 
weight, the centrifugal clutch 142 momentarily isolating the pump 112 from 
the engine 108 when the air control switch 124 is activated as described 
above. The isolation facilitates acceleration of the engine 108 in that a 
momentary high torque requirement is presented by the pump 112 in a 
transition from idle to high rpm operation. Also, the fuel supply 109 has 
been relocated to below the compressor means 98 for a further reduction in 
the polar moment of inertia, and for limiting movement of the center of 
gravity 170 during operation of the apparatus 30. The control valve 86 is 
a Model PVR 04319 grit valve, available from Clemco Industries, above. The 
total dry weight of the module 70, including the boom assembly 96 is 
approximately 642 lbs. 
Although the present invention has been described in considerable detail 
with reference to certain preferred versions thereof, other versions are 
possible. For example, the upper ends of the bungee means 40 can be 
separately connected to front and rear counterparts of each of the bar 
attachment points 38, on opposite sides of the stabilizer bar 36, 
proximate the upper ends of the leg members 52, thereby providing further 
clearance between the bungee means 40 and the yoke attachment points 48. 
Thus the spacing Y between the yoke attachment points 48 can be increased 
beyond that which would otherwise be practical, thereby enhancing the 
effectiveness of the stabilizer unit 34. Also, the tank 82 can have a 
spherical shape for optimum volume and pressure resistance per unit of 
weight. Also, the air switch 124 and/or the media switch 129 can be 
operatively coupled to the dispensing module 70 by a radio link. 
Therefore, the spirit and scope of the appended claims should not 
necessarily be limited to the description of the preferred versions 
thereof.